High Yield Flashcards
Basal Ganglia: Description
The basal ganglia is a group of nuclei located in the deep white matter of the brain. That is interconnected with the cerebral cortex, thalami and brain stem.
Function: Memory formation and regulation of motor control
Basal Ganglia: Gross Anatomy
- Gross anatomy:
- It contains 3 paired nuclei that together comprise the corpus striatum:
- Caudate nucleus
- Putamen
- Globus pallidus
Caudate Nucleus
- Located lateral to the lateral ventricle
- Head indents the anterior horn
- Curves along the lateral ventricle
- Tail extends into the temporal lobe
- Bounded laterally by the internal capsule
- The head of the caudate is supplied by the recurrent artery of Heubner, the rest is supplied by the lenticulostriatal arterys
Putamen
- Paired rounded, most lateral structure of the basal ganglia
- Medial to the external capsule
- Connected to the substantia nigra and subthalamic nuclei to control movement
- Supplied by the lenticulostriatal arteries
Globus Palladus
- The paired, medialt to the putamen, lateral to the thalamus
- Subdivided into internal and exernal parts separated by a internal medullary lamina.
- Supplied by the lenticulostriatal arteries
Subthalamic Nuclei
- Small, located inferior to the thalamus
- Medial to internal capsule
Substantia Nigra
- Anterior midbrain, transition point of the tegmentum and cerebral peduncles
- Produces dopamine
Cerebellum: Description
There cerebellum is brain structure located in the posterior fossa below the tentorium and behind
the brain stem
Function: Integration and mediation of proprioceptor and movement data
Cerebellum: Gross Anatomy
- Globular structure located in the posterior aspect of the posterior fossa
- Three surfaces: anterior, superior and inferior
- Three fissures: Primary, horizontal and sub-occipital
- Two hemispheres: right and left
- Single median vermis
Cerebellar divisions
- Vermis: Divided into nine lobules
- Cerebellar hemispheres:
- Onion configuration of folia
- 18 lobules associated bilaterally associated with the vermis lobules
Cerebellum/Cerebrum connections
- Midbrain via the superior cerebellar peduncle
- Pons via the middle cerebellar peduncle
- Medulla via the inferior cerebellar peduncle
Cerebellum: Vasculature
- Arterial supply:
- Superior cerebellar arteries (from basil)
- Anterior and posterior inferior cerebellar arteries (basil and vertebral)
- Venous drainage:
- Occipital venous sinus
Cerebellar: Relations
- Anterior: 4 th ventricle
- Posterior: cisterna magna
- Superior: occipital lobes
- Inferior: basiocciput
- Lateral: cerebella-pontine angle cisterns
Cerebellar Variants
- Variable blood supply
- Megacisterna magna
- Tonsilar ectopia / Chiari malformation
- Agenesis
Corpus Callosum: Description
- The corpus callosum is the largest white matter tract in the brain
- Function: Interhemispheric communication
- Location: Between the cerebral hemispheres above the septum pellucidum
Corpus Callosum: Gross Anatomy
- C-shaped – concave up
- 10cm in length
Divisions:
- Rostrum anterior and inferior part (anterior hook of the c) continues as the copula then lamina terminalis
- Genu most anterior part (elbow like bend), location of forceps minor
- Body largely linear most superior part
- Splenium most posterior part location of forceps major
Corpus Callosum: Vasculature
- Arterial supply:
- Anterior and posterior pericallosal arteries (From ACA and PCA)
- Subcollosal artery
- Veins:
- Anterior and posterior pericallosal veins draining into the deep cerebral veins
Corpus Callosum: Relations
- Superior: Interhemispheric fissure, indusium griseum, falx cerebri, cingulate gyrus, callosal sulcus
- Inferior: septum pellucidum anteriorly and the body of the fornix posteriorly
- Lateral: corona radiata
- Anterior: Frontal lobes, fornix anterior
- Posterior: occipital lobes, fornix posterior
Corpus Callosum: Variants
- Agenesis/dygenesis of the corpus callosum
- Cavum septum pellucidum
- Cavum et vergae
- Cavum veli interpositi
Internal Capsule: Description
- The internal capsule is a deep subcortical structure that contains a concentration of white matter projections.
- Function: Transmision of the motor and sensory information to and form the cortex and the rest of the CNS
Internal Capsule: Gross anatomy
- Divided into 5 parts:
- Anterior limb: lies between the head of the caudate nucleus medially and the lentiform nucleus laterally. Contain thalamic radiations.
- Genu: Medial to the apex of the lentiform nucleus. Contains corticobulbar tracts.
- Posterior limb: between the thalamus and the lentiform nucleus. Contains corticospinal tracts.
- Retrolentiform: behind the lentiform nucleus. Contains optic radiation.
- Sublentiform: below the lentiform nucleus. Contains the auditory radiation.
Internal Capsule: Vasculature
- Arterial:
- Perforators from the MCA and ACA
- Lenticulostriatal and recurrent artery of Heubner.
- Internal carotid supplies the posterior limb
- Venous:
- Internal cerebral vein
- Inferior sagittal sinus
- Posterior vein of the corpus callosum
Temporal Lobe: Description
The temporal lobe is one of four lobes of the brain and largely occupies the middle cranial fossa
Function: Memory formation, communication
Temporal lobe: Gross Anatomy
- Gross anatomy:
- Second largest lobe (after the frontal lobe)
- Borders:
- Superiorly – Sylvian fissure
- Posteriorly – imaginary parietotemporal line
- The middle cranial fossa forms its anterior and inferor boundaries
- The temporal lobe can be divided into two main sections:
- Neocortex – lateral and inferolateral surfaces
- Mesial temporal lobe – hippocampus, amygdala, parahippocampal gyrus
- The temporal lobe is divide into five gyri, from superolateral to inferomedial:
- Superior temporal gyrus – containing Wernicke’s area
- Middle temporal gyrus
- Inferior temporal gyrus
- Fusiform gyrus
- Parahipocampal gyrus (anterior) lingual gyrus (posterior)
Temporal Lobe: Vasculature
- Arterial supply:
- Anterior choroidal
- Middle cerebral
- Basilar
- Venous drainage:
- Superficial middle cerebral vein
- Inferior anastomotic vein of Labbe
- Posterior choroidal vein
Temporal Lobe: Variants
Wernicke’s area can be on either side, most commonly the left
Frontal lobe: Description
The frontal lobe is by far the largest of the four lobes of the cerebrum (along with the parietal lobe, temporal lobe, and occipital lobe), and is responsible for many of the functions which produce voluntary and purposeful action.
Frontal Lobe: Gross Anatomy
The frontal lobe is the largest lobe accounting for 41% of the total neocortical volume. The frontal lobe resides largely in the anterior cranial fossa. Its most anterior part is known as the frontal pole, and extends posteriorly to the central (Rolandic) sulcus which separates it from the parietal lobe.
Posteroinferiorly it is separated from the temporal lobe by the lateral sulcus (sylvian fissure), although not seen from the surface is the insular cortex which is hidden deep to the lateral sulcus
The interhemispheric fissure separates its medial surface from the contralateral frontal lobe.
The frontal lobe is roughly pyramidal in shape, with three cortical surfaces:
- Lateral surface (largest)
- Medial (inter-hemispheric) surface
- Inferior surface
Frontal Lobe: Lateral surface
- Gyri:
- superior frontal gyrus
- middle frontal gyrus
- inferior frontal gyrus
- precentral gyrus (primary motor area)
- Sulci:
- superior frontal sulcus
- inferior frontal sulcus
- precentral sulcus
Frontal lobe: Medial Surface
The medial surface of the frontal lobe, abutting the falx in the midline, is primarily divided by the curving cingulate sulcus, which parallels the outer outline of the corpus callosum.
Above the cingulate sulcus is the medial continuation of the superior frontal gyrus
which is usually divided into two parts by a short ascending branch from the cingulate sulcus.
- medial frontal gyrus
- paracentral lobule
Frontal lobe: Inferior surface
Gyrus recti medially
Orbital gyri arranged in a H configuration (Medial, lateral, anterior and posterior orbital gyri)
Frontal Lobe: Relations
- anterior: frontal bone
- superiorly: frontal bone (anteriorly), coronal suture, and parietal bone (posteriorly)
- posterior: central sulcus and parietal lobe
- inferolaterally: lateral sulcus and temporal lobes
- inferior: floor of anterior cranial fossa
Frontal lobe: Arterial supply
- middle cerebral artery (MCA): lateral frontal lobe
- anterior cerebral artery (ACA): medial frontal lobe
Occipital lobe: Description
The occipital lobe is the smallest of the four lobes of the brain.
Location: Posterior to the temporal and parietal lobes, sitting on top of the tentorium
Function: Primary and secondary visual cortex
Occipital Lobe: Gross anatomy
- Triangular in shape
- Seperated from the parietal and temporal lobes by the parieto-occipital sulcus and the parietotemporal line
- Medially it is devided into hemisphere by the longitudinal fissure
- The calcarine sulcus runs horizontally across with the cuneus above and the lingual gyrus below
Occipital lobe: Functional areas
- Primary visual cortex – primary visual processing
- Secondary visual cortex – visual association
Occipital Lobe: Relations
- Anterior: parietal and temporal lobes
- Posterior: occipital bone
- Superior: Parietal lobe and parietal bone
- Inferior: tentorium cerebelli
- Medial: transverse sinuses, confluence of sinuses, straight sinus
Occipital lobe vasculature
- Arterial supply:
- Branches of the posterior cerebral artery
- Venous:
- Straight sinus
- Superior sagittal sinus
- Transverse sinuses
Parietal Lobe: Description
The parietal lobe is one of the four lobes of the brain located between the frontal and occipital lobes.
Function: Sensory processing, communication, proprioception
Parietal Lobe: Gross Anatomy
- Lobe extends from the central sulcus anteriorly to the parieto-occipital fissure posteriorly.
- The lateral sulcus corresponds to its inferolateral boundary, separating it from the temporal lobe. Divided by the medial longitudinal fissure
Gyri:
- postcentral gyrus (primary sensory area)
- superior parietal lobule
- inferior parietal lobule (Wernicke’s area)
Parietal Lobe: Relations
- Anterior: frontal lobe
- Posterior: occipital lobe
- Superior: parietal bone
- Inferior: temporal lobe
Parietal lobe: Vasculature
- Blood supply:
- middle cerebral artery (MCA)
- anterior cerebral artery (ACA): medial parietal lobe
- posterior cerebral artery (PCA): posterior medial parietal lobe
- Venous:
- Superior sagittal sinus
- Straight sinus
- Inferior superficial cerebral vein (Labbe)
Arterial supply of the cerebellum: Description
The cerebellum is a specialised part of the brain located in the posterior cranial fossa
Function: Computation of movement and proprioceptive data
Arterial supply of the cerebellum
- Superior cerebellar from the basilar –supplies the superior surface
- Anterior inferior cerebellar from the basilar – anterior inferior
- Posterior inferior cerebellar from the vertebral – posterior inferior
Basilar artery: Description
The basilar artery is a large artery of the posterior circulation of the brain.
Basilar artery: Gross anatomy
Origin: Formed from the confluence of the vertebral arteries at the base of the pons.
Course: Ascends parallel to the ventral pons in the central groove of the pons in the pre-pontine cistern
Branches: Numerus small braches to the pons and cerebellum including the:
- The anterior inferior cerebellar artery (AICA)
- Labyrinthine arteries (normally from AICA)
- Superior cerebellar arteries
Termination: bifurcates to form the two posterior cerebral arteries at the upper pontine boarder
Basilar artery: Relations
- Anterior: clivus
- Posterior: Basilar pons
- Superior: Posterior cerebral arteries
- Inferior: vertebral arteries
- Lateral: Origin; origin of the abducens nerve, termination: origin of the oculomotor nerve
Basilar artery: Variants
- Fenestration
- Persistent carotid-basilar artery anastomosis
Internal carotid artery: Description
Internal carotid arteries are the primary supply to the anterior circulation of the brain
Function: supply oxygenated blood to the brain and meninges
Internal Carotid Artery: Gross anatomy
Divides into the following segments (Bouthillier classification):
- Cervical
- Petrosal
- Lacerum
- Clinoid
- Caverous
- Ophthalmic
- Communicating
Origin:
Bifurcation of the common carotid at the level ~L4
Course: ascending through the carotid space, enters the cranial cavity via the carotid canal
Termination: Branches to for the anterior and middle cerebral arteries
Internal carotid artery: Branches
2nd segment:
- Caroticotympanic
- Vidian
4th segment:
- Meningohypophyseal
- Inferolateral trunk
6th segment
- Ophthalmic artery
- Superior hypophyseal
7th segment:
- Posterior communicating artery
- Anterior choroidal artery
- Anterior communicating artery
- Middle cerebral artery
Internal carotid artery: Relations
- Anterior: External carotid artery
- Lateral: internal jugular vein
- Medial: larynx, oropharynx, nasopharynx
- Superior: suprasellar cistern
- Inferior: Carotid bulb
Internal Carotid artery: Variants
- Aberrant ICA course
- Kissing carotids
- Persistent carotid-vertebrobasilar anastomoses
- Retropharyngeal ICA
Middle cerebral artery: Gross anatomy
Origin: Terminal bifurcation of the Internal carotid artery (the other branch is the anterior cerebral artery
Course:
Divided into segments: (HIOC)
- M1 – the horizontal segment – from origin to bi/trifurcation
- M2 – insular segment from bi/trifurcation to the circular sulcus of the insular lobe
- M3 – Opercular branches – within the sylvian fissure
- M4 – Cortical segment – branches emerging from the sylvian fissure
MCA Branches
Branches:
M1: (PAUL)
- Medial and lateral lenticulostriate
- Anterior temporal
- Polar temporal
M2:
- Superior and inferior trunks
M1 Supply
M1:
- Basal ganglia
- External and internal capsule
- Anterior third of the superior, middle and inferior temporal gyri
- Polar Regions of the temporal lobe
Cerebral Venous sinuses: Description
The cerebral venous sinus are venous system formed from folds of the meninges
Function: return of deoxygentated blood from the brain to the system circulation
Cerebral venous sinuses: Gross anatomy
Folded dura form sinus which drain from veins to other sinuses or veins
Valveless
There are paired and unpaired cerebral venous sinuses
Paired Cerebral venous sinuses
Transverse sinuses – from the confluence of sinuses to the sagittal sinuses, receives the superficial cerebral vein of labbe
Sigmoid sinuses – from the transverse sinus s-shaped course draining into the jugular bulbs , also receives the sphenoparietal sinus and the superior petrosal sinsu
Superior and inferior petrosal sinuses – From the right and left cavernous sinuses to the sagittal and jugular bulb respectively
Sphenoperietal sinus courses along the ridge of the greater wing of the sphenoid to the cavernous sinsus, also receives the middle superficial cerebral vein
Caverous sinuses located either side of the sella, receives the ophthalmic veins (superior and inferior) connected by the anterior and posterior intercavernous sinsus, drains into the superior and inferior petrosal sinuses and basiclival plexus
Unpaired cerebral venous sinuses
Internal cavernous sinuses as noted earlier
Superior sagittal sinus midline between the falx drains into the confluence of sinuses
Inferior sagittal sinus runs in the over the corpus callosum drains into the straight sinus
Straight sinus – from the vein of Galen to the confluence of sinuses
Occipital sinus – from the occipital bone midline between the cerebellar hemispheres drains into the confluence of sinuses
Cerebral venous sinuses: Variants
No confluence – straight and superior sagittal sinuses drain into the right and left transverse sinuses separately
No confluence – straight and superior sagittal sinuses fork prior to drain into the straight sinuses
Cerebral venous drainage: Description
The cerebral veins drain the brain parenchyma and are located in the subarachnoid space. They pierce the meninges and drain further into the cranial venous sinuses.
Cerebral venous drainage: Gross anatomy
The cerebral veins lack muscular tissue and valves.
The cerebral venous system can be divided into:
- superficial (cortical) cerebral veins
- deep (subependymal) cerebral veins
Venous drainage of the orbit
The venous drainage of the orbit is the venous system to drain deoxygenated blood from the orbit to the systemic circulation.
Intracranial Cisterns: Description
The subarachnoid cisterns are discrete named spaces within the subarachnoid space where the pia mater and arachnoid membrane are not in close approximation. The subarachnoid tissue is not as abundant here as in the normal subarachnoid space and cerebrospinal fluid (CSF) gathers to form pools or cisterns (Latin: “box”).
As they are interconnected, the patency is essential for CSF circulation. Being within the subarachnoid space, the cisterns may have vessels and/or cranial nerves passing through them.
Named intracranial cisterns (9)
- cisterna magna: the largest of the subarachnoid cisterns
- prepontine cistern: anterior to the pons
- suprasellar cistern: surrounding the infundibulum
- interpeduncular cistern: between the cerebral crura
- quadrigeminal cistern: superior cistern or cistern of the great cerebral vein
- ambient cistern: surrounds the back of the midbrain
- cerebellopontine cistern: at the cerebellopontine angle
- premedullary cistern: anterior to the medulla
- sylvian cistern: superficial to the insular cortex
Bony Orbit: Gross Anatomy
- Gross anatomy
- Superiorly
- Frontal bone
- Sphenoid (lesser wing)
- Medially
- Maxilla
- Lacrimal bone
- Ethmoid (lamina papyracea)
- Sphenoid (lesser wing)+/- palatine
- Inferiorly
- Maxilla
- Zygomatic (laterally)
- Palatine(inferomedial)
- Laterally
- Zygomatic
- Sphenoid (greater wing)
- Foramina
- Optic foramina
- Superior orbital fissure
- Inferior orbital fissure
- Superiorly
- Contents
- Orbit
- Lacrimal gland
- Optic foramina
- Optic nerve (CN2)
- Ophthalmic artery (C6 ICA)
- Superior orbital fissure
- CN 3 occulomotor
- CN 4 trochlea
- CN 5 (V1 ophthalmic division of trigeminal)
- CN 6 abducens
- +/- middle meningeal contribution to ophthalmic artery (variantion)
- Inferior orbital fissure
- Infraorbital nerve
- Infraorbital artery
- Inferior ophthalmic vein
Bones of the orbit
The bony orbit is made up of:
- Maxillary bone
- Lacrimal bone
- Ethmoid bone
- Zygomatic bone
- Frontal bone
- Orbital process of the palatine bone
- Greater and lesser wings of the sphenoid
Spaces of the Orbit
- Optic nerve sheath complex – optic nerve, central retinal artery and vein, meninges
- Intraconal space – orbital fat, ophthalmic artery, cranial nerves
- Conal space – extra ocular muscles
- Extraconal space – fat, lacrimal gland, lacrimal and frontal braches of V1
Communication with the orbit
- Optic canal to intracranial cavity
- Superior orbital fissure also to the intracranial cavity
- Inferior orbital fissure to infratemporal fossa
- Anterior ethmoidal foramen
- Posterior ethmoidal foramen
- Supra and infra orbital foramen
- Nasolacrimal foramen
Mandible: Description
The mandible is a large single midline bone of the lower face
Function: respiration, verbalisation, mastication
Location: Jaw
Mandible: Gross Anatomy
Irregular bone. It consists of a curved horizontal portion the body and two perpendicular portions, the rami. The rami and the body unite at almost right angles (the angle of the jaw).
Mandible: Features
Body:
- Mandibular symphysis – midline point of fusion
- Mental foramen - inferior to the second pre-molar (mental vessels and nerve, the terminal branches of the inferior alveolar vessels and nerves)
- Fossae for the sublinguinal and submandibular glands
- Alveolar process of the teeth
- Groove for the facial artery of the inferior border
Ramus:
- Mandibular foramen – opening of the mandibular canal, which transmits the inferior alveolar vessels and nerves
- Coronoid process – anteriorly
- Condylar process – posterior
- Mandibular notch – space between the above two
- Mandibular canal – between the mandibular foramen and the mental foramen
Mandible: Articulation
- Gomphosis joints with the lower row of teeth
- Temporomandibular joint – between the condylar process of the mandible and the mandibular fossa and the articular eminence of the temporal bone. Atypical synovial joint with a fibrocartilage articular disc
Temperomandibular joint: Description
Bilateral joint of the jaw. Modified hinge joint.
Function: Mastication, verbalisation, respiration
TMJ: Anatomy
The temporomandibular joint (TMJ) is an atypical synovial joint located between the condylar process of the mandible and the mandibular fossa and articular eminence of the temporal bone.
It is divided into a superior discotemporal space and inferior discomandibular space by the TMJ disc (or meniscus).
TMJ: Movement
- upper compartment: protraction, retraction and gliding side-to-side
- lower compartment: opening and closing
TMJ: Ligaments
- temporomandibular
- stylomandibular
- sphenomandibular
TMJ: Muscles
- Medial and lateral pterygoids
- Masseter
- Temporalis
TMJ: Neurovasculature
Arterial:
Superficial temporal
Vein:
Retromandibular
Innervation:
- auriculotemporal nerve
- masseteric nerve
Extra-ocular muscles: Description
The extra-ocular muscles are the six muscles that insert onto the eye and hence control eye
Extraocular muscles: Gross Anatomy
- superior rectus: elevation, annulus of Zinn to the superior globe
- superior oblique: intorsion, sphenoid bone via catelaginous trochlear to superior lateral globe
- medial rectus: adduction, annulus of Zinn to the medial globe
- lateral rectus: abduction, annulus of Zinn to the lateral globe
- inferior oblique: extorsion, Maxillary bone to inferior lateral globe
- inferior rectus: depression, annulus of Zinn to the inferior globe
Extra-ocular muscles: innervation
oculomotor nerve:
- superior, medial, and inferior rectus
- inferior oblique
trochlear nerve:
- superior oblique
abducens nerve:
- lateral rectus
Extra-ocular muscles: neurovasculature
Arterial:
Ophthalmic artery
Vein:
Superior and inferior ophthalmic veins
Nasolacrimal apparatus: Description
The nasolacrimal apparatus is the system responsible for drainage of tears. Production of tears by the lacrimal gland is included in some text under this heading.
Lacrimal gland Gross Anatomy
- Location in the superior lateral orbit in the extraconal space
- Almond shaped
Lacrimal Apparatus: Gross anatomy
Location: From the medial canthus to the inferior concha
Consists of:
- Lacrimal canaliculi which drain the lacrimal lake via the lacrimal puncta
- Lacrimal sac – the superior and inferior lacrimal canaliculi drain into the lacrimal sac which lies in the lacrimal fossa, it drains into the nasolacrimal duct via the valve of Krause, the sac is enclosed in the lacrimal fascia and the orbicularis oculi
- Nasolacrimal duct – Is the inferior continuation of the lacrimal sac, it is approximately 17mm in length, it has 2 parts: intraosseous part which lies within the nasolacrimal canal of the maxilla, the membranous part which runs in the nasal mucosa. It terminates below the inferior nasal meatus as a slit like opening where it is covered by a mucosal fold called the valve of Hasner
Nasolacrimal Apparatus: Neurovasculature
Artery: lacrimal artery from the ophthalmic artery
Vein: Superior ophthalmic vein
Nerves: greater petrosal nerve (from facial nerve) and lacrimal nerve (ophthalmic division of the trigeminal nerve)
Nasolacrimal apparatus: Relations
- Medial: the maxilla
- Lateral: Lacrimal lake
- Superior: Superior orbital rim
- Inferior: Floor of the nasal cavity
- Posterior: ethmoid labyrinth and nasal cavity
- Aterio-medial: Nasal vestibule
Nasolacrimal Gland Variants
- Incompetent valve of Hasner
- Absence
- Accessory glands
- Draining to the middle meatus
Extra-ocular spaces of the orbit: spaces
The orbit is a space of the anterior face
Function:
- Contain the globe and associated support structures and organs
- Passage of nerve arteries and veins
Orbit: Relations
- Superior: frontal bone, and anterior fossa
- Inferior: Maxillary sinus
- Lateral: infratemporal space
- Medial: ethmoidal air cells
- Posterior: the cavernous sinuses
- Anterior: Superior and inferior palabra
Constrictors of the pharynx
The constrictor muscles of the pharynx are a set of 3 pharyngeal constrictors that constrict the pharynx to deliver a bolus of food to the oesophagus.
Type: skeletal muscles under semi-voluntary control
Superior pharyngeal constrictor
- Origin: pterygoid hamulus, pterygomandibular raphe and mandible
- Insertion: Pharyngeal raphe
- Artery: ascending pharyngeal artery, branch of the external carotid artery
- Nerve: pharyngeal plexus from vagus
Middle Pharyngeal constrictor
- Origin: Greater and lesser conu of the hyoid bone
- Insertion: Pharyngeal raphe
- Artery: Ascending pharyngeal artery (external carotid artery)
- Nerve: pharyngeal plexus from vagus
Inferior pharyngeal constrictor
- Origin: Cricoid and thyroid cartilage
- Insertion: Pharyngeal raphe
- Artery: Ascending pharyngeal artery
- Nerve: pharyngeal plexus from vagus
- Incorporates cricopharyngeus inferiorly
Pharyngeal constrictors: Relations
- Anterior – pharynx
- Posterior – Cervical spine vertebrae and retrophpharyngeal space
- Lateral – carotid sheath and it’s contents
- Superior – base of the skull
- Inferior – Cricopharyngeus muscle
Pharyngeal Constrictors:Variants
- Cricopharyngeal bar
- Zenker’s diverticulum
Sternocleidomastoid Muscle
The sternocleidomastoid (SCM) is a muscle of the neck. It has two heads that meld to form one insertion. SCM, along with the trapezius muscle, is invested by the superficial layer of the deep cervical fascia, which splits around it. SCM divides the neck into anatomical anterior and posterior triangles.
SCM: Gross Anatomy
origin: manubrium (sternal head – tendinous), medial clavicle (clavicular head – muscular)
insertion: mastoid process of the temporal bone, superior nuchal line of the occipital bone
Artery: Superior thyroid and occipital arteries
innervation: accessory nerve (CN XI)
action: lateral flexion, flexion and rotation of the head on the neck, raise sternum (secondary muscle of respiration).
SCM: Relations
upper half:
anteriorly: platysma muscle, external jugular vein
Medial: anterior scalene muscle, common carotid artery, internal jugular vein, carotid sheath
lower half:
anteriorly: platysma
posteriorly: anterior scalene muscle, common carotid artery, internal jugular vein, carotid sheath
SCM: Variants
- absent mastoid insertion (occipital insertion only)
- absent clavicular or sternal head
- fusion with trapezius muscle
- additional clavicular head
- separate muscle bellies for sternomastoid and cleidomastoid
- separate muscle bellies for cleidooccipital and sternocleidomastoid
External Carotid artery: Description
The primary blood supply to the face and neck
ECA: Gross anatomy
Origin: at the common carotid bifurcation level C4
Course:
- Through the carotid sheath
- Divided from the internal carotid artery by styloglossus and stylopharangeus
- Exiting to pass through the parotid gland
Termination: bifurcation in the maxillary and superficial temporal artery
Distinguishable from ICA due to the many branches of the ECA
Branches of the ECA
- Superior thyroid artery
- Asecnding laryngeal
- Lingual
- Facial
- Occipital
- Posterior auricular
- Maxillary
- Superficial temporal
Relations of ECA
- Anterior – sternocleidomastoid
- Posterior – internal carotid artery
- Medial – larynx
- Lateral – sternocleidomastoid
Variants of the ECA
- Branch height
Trunks:
- Lingofacial trucnk
- Thryolingual
- Thyrolingualfacial
- Occipital and posterior auricular have common trunk
Jugular veins: Description
There are 4 paired jugular veins which provide drainage of deoxygenated blood from the face, head and brain:
- Internal jugular veins
- External jugular veins
- Posterior external jugular veins
- Anterior jugular veins
Internal jugular vein: Gross Anatomy
Origin: Formed by the union of the inferior petrosal and sigmoid dural venous sinuses at the jugular foramen.
Course: Descending in the carotid sheath, anterior to the internal carotid and vagus nerve, enters the thorax posterior to the two heads of the sternocleidomastoid
Drains to: unites with the subclavian vein to form the brachiocephalic vein
Internal jugular vein: Tributaries
Tributaries:
(medical school lets fun people in)
- Middle thyroid v
- Superior thyroid v
- Lingual v
- Facial v
- Pharyngeal v
- Inferior petrosal sinus
External Jugular veins: Gross anatomy
Origin: Retromendibular and posterior auricular veins unite to form the external jugular vein at the angle of the mandible
Course: Descends deep to the platysma but superficial to SCM, pierces the cervical fascia posterior to the head of the clavicle
Drains to: subclavian veins
External jugular veins: Tributaries
- Anterior jugular vein
- Posterior external jugular vein
- Suprascapular vein
- Transverse cervical vein
Anterior jugular veins
Origin: Arise in the region of the hyoid bone confluence of multiple submandibular vessels
Course: Descending medial to the anterior boarder of the sternocleidomastoid
Drains to: passes deep to SCM to drain into the external jugular vein
Tributaries: Small submandibular, laryngeal and thyroid veins
Variant: may drain directly to the subclavian veins
Posterior jugular veins
Origin: Confluence of superficial veins of the posterosuperior neck and scalp
Course: Supeficial course over the posterior triangle
Drains to: External jugular vein
Level 1 lymphatics in the neck
Submental and submandibular nodes
- Below mylohyoid muscle and above the lower margin of the hyoid bone (or the carotid bifurcation)
- anterior to the posterior border of the submandibular glands
- level Ia: submental nodes, i.e. between the anterior bellies of the digastric muscles
- level Ib: submandibular nodes between the anterior and posterior bellies of digastric muscles
Level II lymphatics in the neck
Superior Internal jugular (deep cervical) chain
- base of the skull to the inferior border of hyoid bone (or the carotid bifurcation)
- anterior to the posterior border of sternocleidomastoid (SCM) muscle
- posterior to the posterior border of the level I glands
Level III lymphatics in the neck
Middle Internal jugular (deep cervical) chain
- lower margin of hyoid to lower margin of cricoid cartilage (or the intermediate tendon of Omohyoid)
- anterior to the posterior border of SCM
- Posterior to the anterior boarder of SCM
Level IV lymphatics in the neck
Inferior Internal jugular (deep cervical) chain
- lower margin of cricoid cartilage to level of the clavicle
- anterior and medial to an oblique line drawn through the posterior edge of SCM and the posterolateral edge of the anterior scalene muscle
- Posterior to the anterior border of SCM
Level V lymphatics in the neck
Posterior triangle (spinal accessory) nodes, posterior to posterior edges of SCM and scalenus anterior
- level Va: superior half, posterior to levels II and III
- level Vb: inferior half, posterior to level IV
Level VI lymphatics in the neck
prelaryngeal / pretracheal / Delphian node
- from the inferior margin of hyoid bone to the manubrium
- anterior to levels III and IV
Level VII lymphatics in the neck
- superior mediastinal nodes
- between CCAs, below superior aspect of manubrium to level of the brachiocephalic vein
Thyroid gland: Description
The thyroid gland is an endocrine gland located in the pre-tracheal fascia of the neck
Function: endocrine control of metabolism
Location: Pre-tracheal fascia anterior to the thyroid, cricoid and first 3 tracheal cartilages
Thyroid: Description
- Butterfly shaped with a lobe bilaterally joined by a central isthmus
- Each lobe may be divided into an upper and lower pole
- Parathyroid glands lie with each pole and are sometime intracapsular
Thyroid: Neurovasculature
Arterial supply:
- Superior thyroid artery (from the ECA)
- Inferior thyroid artery (from the thyrocervical trunk)
Venous drainage:
- Superior, middle and inferior thyroid veins (internal jugular, internal jugular and brachiocephalic vein)
Innervation:
- Superior, middle and inferior cervical ganglia
Lymphatics:
- Level 6 cervical nodes
Thyroid relations
- Anterior – strap muscle
- Posterior – thyroid and cricoid cartilage, trachea
- Posterior medial – trachea-oesophageal groove with the parathyroid glands and the recurrent laryngeal nerves
- Posterior lateral – carotid space
Thyroid: Variants
- Pyramidal lobe
- Lobar hemigenesis
- Thyroglassal duct cyst
- Ectopic thyroid tissue – lingual thyroid
- Zuckerkandl’s tubercle
- Thyroidea Ima artery
Humerus: Description
Single long bone of the arm Location: between the shoulder and the elbow
Humerus: Gross Anatomy
- Proximal: Rounded head covered with articular cartilage, greater and lesser tubercles, intertubercular groove
- Mid: Surgical neck inferior to the tubercles, deltoid tuberosity, spiral groove from radial nerve
- Distal: condyle of the humerus which consists of: capitulum, trochlear, medial and lateral epicondyles, radial fossa, olecranon fossa, coronoid fossa
Humerus: Articulations
- Proximal: the head of the humerus articulates with the glenoid of the scapula
- Distal: capitulum with the radial head, trochlear with the trochlear notch of the ulnar
Humerus: Ligaments
- Superior, middle, inferior and spiral glenohumeral ligaments
- Radial and ulnar collateral ligaments
Humerus: Relations
- Anterior: brachialis, bicep brachii, coracobrachialis
- Posterior: Profunda brachii, radial nerve, triceps brachii
- Lateral: deltoid
- Medial: brachial plexus, brachial artery, supratrochlear nodes
Humerus: Neurovasculature
Blood supply:
- Anterior and posterior humeral circumflex arteries and veins
- Perforators from profunda brachii
Lymphatics:
- Supratrochlear and axillary nodes
Innervation:
- Radial nerve
Humerus: Variants
- Supracondylar process
- Olecranon foramen
Elbow Joint: Description
The elbow joint is a complex synovial joint between the arm and the forearm
Has a joint capsule
Synovial
Elbow Joints: Movements
Combination hinge pivot joint:
Internal and external rotation of the arm
Flexion and extension of the arm
Elbow Joint: Articulation
- Proximal head of the radius the capitulum of the humerus
- Trochlea notch of the ulnar with the trochlear of the humerus
- Proximal radial head the proximal radial notch of the ulnar
Elbow Joint: Muscles
- Brachioradialis
- Biceps brachii
- Triceps brachii
Elbow Joint: Ligaments
- Annular ligament
- Proximal radial and ulnar collateral ligament complexes
- Oblique cord- thickening of the supinator
Elbow Joint: Fat Pads
- Coronoid and radial fossa fat pads anteriorly
- Olecranon fat pad posteriorly
Elbow Joint: Neurovasculature
Blood supply:
- Anastomotic arcade formed from branches of the radial, ulnar and brachial arteries
Nerves:
- Median, radial, ulnar and musculocutaneous nerves
Elbow Joints: Relations
- Anterior: biceps brachii tendon, brachialis muscle, median nerve, brachial artery
- Posteriorly: Olecranon bursae, triceps brachii tendon
- Laterally: Common extensor tendon, supinator muscle
- Medially: ulnar nerve
Elbow Joint: Variants
- Variation in carry angle between males and females, females have larger angles usually
- Synovial folds
- Capitellar and olecranon pseudofacets
- Accessory ossicles: os supratrochlear dorsale, patella cubiti
Glenohumeral Joint: Description
The shoulder joint also known as the gleno-humeral joint is a ball and socket synovial joint between the humerus and the glenoid.
Glenohumeral Joint: Movement
- Most mobile joint in the body
- Flex/extension, int. ext. rotation, ab and adduction
Glenohumeral joint: Articulation
Head of the humerus with the glenoid fossa of the scapula. The glenoid labrum adds depth to the glenoid fossa.
Glenohumeral Joint: Capsule
- Attached to the margin of the glenoid fossa to the anatomical neck of the humerus, the long head of the biceps travels through it.
- It is re-enforced by the rotator cuff except inferiorly where it is at its weakest
Glenohumeral Joint : Bursa
- Subacrominal – subdeltoid bursa
- Subscapular bursa (communicates with the joint by the foramen of Weitbrecht)
Glenohumeral Joint: Ligaments
- Superior, middle and inferior glenohumeral ligaments
- Coracohumeral ligaments
- Transverse humeral ligament
Glenohumeral Joint: Muscles
- abduction
- produced by the deltoid assisted by the supraspinatus
- adduction
- produced by the short scapular muscles (except supraspinatus) when the deltoid relaxes. Assisted by the pectoralis major and latissimus dorsi
- flexion
- clavicular head of the pectoralis major and the anterior fibers of the deltoid, assisted by the coracobrachialis and biceps
- extension
- latissimus dorsi, posterior fibers of the deltoid and the long head of the triceps
- rotation
- lateral rotation: infraspinatus and teres minor
- medial rotation: subscapularis and teres major
Glenohumeral Joint: Neurovasculature
Arterial supply:
- Anterior and posterior humeral circumflex and subscapular arteries
Innervation:
- Axillary (C5-C6), suprascapular, subscapular, musculocutaneous nerves
Lymphatics:
- Axillary
Glenohumeral joint: Variants
- Buford complex – cord like middle glenohumeral ligament
- Os acrominale
- Capsule attached to labrum
- Long head of biceps insertion – glenoid, glenoid and labrum, labrum only
Biceps Brachii: Description
The biceps brachii muscle (also known simply as biceps) is a two-headed muscle in the anterior compartment of the arm that flexes at the elbow and supinates the forearm.
Biceps Brachii: Attachments
- Origin:
- Short head: coracoid process of the scapula
- Long head: supraglenoid tubercle of the scapula
- Insertion:
- Radial tuberosity of the proximal radius
Biceps Brachii: Innervation
musculocutaneous nerve
Biceps Brachii: Action
- arm abduction, arm adduction and ventral flexion
- supination
- flexion of the supinated forearm
Biceps Brachii: Variants
- Duplicated long head of biceps tendon: can mimic longitudinal tear
- Bifid/bifurcated insertion: anatomic variant that arises from persistent division between the short head and long head of the distal biceps brachii tendon
Brachial Plexus: Description
A plexus of nerves innervating the arm and part of the upper thorax
Location: in the neck extending into the axilla, posterior to the clavicle
Supply: motor and sensory to upper limb and upper thorax
Brachial Plexus: Components
Roots – C5 to T1
Trunks – upper C5-6, middle C7, lower C8-T1
Divisions – anterior and posterior
Cords – named to their relation to the axillary artery – medial, lateral, posterior
Branches:
- Axillary (C5-6)
- Musculocutaneous (C5-7)
- Radial (all)
- Medial (all)
- Ulnar (C7, 8 T1)
Brachial Plexus: Course
Emerges between the middle and anterior scalenes
Course intimately related to the axiallary artery
Brachial Plexus: Variant Anatomy
- ~50% Pre-fixed – C4 contribution or Post-fixed – T2 contribution
- Variation in branching patterns
Venous drainage of the left upper limb: Description
Venous drainage of the upper limb is a vascular system for the return of deoxygenated blood from the capillary beds of the upper limb to the heart via the superior vena cava.
Venous drainage of the left upper limb: Deep System
The deep veins are located under the deep fascia. They are typically paired and lie on either side of an artery from which they take their name (venae comitantes).
Venous drainage of the left upper limb: Hand
- Deep venous palmar arch - receives the palmar metacarpal veins, drains to the radial veins
- Radial veins - Receives the deep venous palmar arch, run with the the radial artery, drains into the brachial veins
- Ulnar veins – Receives the surficial venous palmar arch, runs with the ulnar artery, drains into the brachial veins
- Brachial veins – Origin at the union of the radial and ulnar veins, course following the brachial artery, ending at the inferior border of teres major, at this point the brachial veins join the basilic vein to form the axiliary vein
- Axillary veins – the axillary vein continues with the axillary artery and is joined by the cephalic vein, subscapular vein, circumflex humeral vein, lateral thoracic vein and thoraco-acromial vein. It terminates at the lateral margin of the first rib where it becomes the subclavian vein.
Venous drainage of the left upper limb: Superfical System
- Superficial venous palmer arch: accompanies the superficial palmer arch, drains the commo palmer digital veins, drains into the ulnar vein
- Dorsal venous network: formed from the dorsal metacarpal veins drains into the basilic and cephalic veins
- Cephalic – origin the dorsal venous plexus, runs up the superficial space of the lateral aspect of the arm, drains to the median cubital and axially vein
- Basilic – origin the dorsal venous network, up the superficial tissue of the medial aspect of the arm, also receives the median cubital vein, drains to the brachial veins mid arm
1st rib: Description
The ribs are the main structural element of the thorax.
Function: Protection, respiration
1st Rib: Gross Anatomy
There are 12 ribs which are separated by intercostal spaces.
The first 7 ribs increase in length the lower five decrease in length.
The 1st, 11th and 12th ribs are considered atypical ribs.
Ribs: Description
True ribs – First 7 attached to the sternum directly by their own costal cartilage
False ribs – 8th to 10th, converge anteriorly via the costal cartilage to the 7th costal cartilage thus have indirect connection to the sternum.
Floating ribs – the 11th and 12th have no anterior direct or indirect sternal attachment
The first rib is the most superior of the twelve ribs. It is an atypical rib because of number differentiating features and is an important landmark for the borders of the superior thoracic aperture.
1st Rib: Features
- Compared to a typical rib the first rib is short and thick.
- It has a singular articular facet of the costovertebral joint.
- The first rib has a head, neck and shaft but lacks a discrete angle.
- Groove for the subclavian artery – laterally
- Groove for the subclavian vein – anterior to the scalene turbicle
- Transverse tubercle – Posterior and lateral to the neck it bears a facet for the transverse process of T1
- Scalene tubercle – anterior between the grooves for the subclavian artery and vein.
1st Rib: Articulation
- Costovertebral joint
- Costotransverse joint
- Costochondral joint
1st Rib: Attachments
- Anterior and middle scalene
- Intercostal muscles
- Subclavius muscle
- Serratus anterior
- Costoclavicular ligaments
1st Rib: Neurovasculature
Blood supply:
Arterial: internal thoracic and superior intercostal arteries, venous: intercostal veins
Innervation: first intercostal nerve
1st Rib: Relations
- Anterior: Sympathetic trunk over the neck, superior intercostal artery, ventral T1 nerve root
- Superior: lower trunk of the brachial plexus, subclavian artery and vein, clavicle
- Inferior: Intercostal vessels and nerves, parietal pleura
- Medial: contents of the superior thoracic aperture
- Lateral: Axillary artery and vein, divisions and cords of the brachial plexus
1st Rib: Variants
- First cervical rib
- Bifid (forked) rib
- Hypoplastic rib
Aortic Arch: Gross anatomy
Layers: adventitia, media and intima
Origin: T4 plane continuation of the ascending aorta
Course: posterior and to the left in the superior mediastinum
Termination: continuation as the descending aorta pass the level T4
Branches: brachiocephalic trunk, Left common carotid artery, left subclavian artery
Aortic arch: Relations
Superior: Large vessels of the superior mediastinum
Inferior: recurrent laryngeal (which one), ligament arteriosum, the bifurcation of the pulmonary trunk
Anterior: thymus or thymic reminant, fat
Posterior: trachea, oesophagus, thoric duct crosses from right to left
Lateral: right superior vena cava, terminination of the azygos, right upper lobe left: left upper lobe lung
Variants of the Aortic arch
- Double arch
- Bovine arch common origin of the left common carotid and brachiocephalic trunk
- Left common carotid from the brachiocephalic trunk
Branches directly from the aorta:
- Thyroid Ima
- Vertebral artery (most commonly the left)
- Right subclavian and right common carotid
Right sided arch:
- Type 1 - mirror
- Type 2 – absent left subclavian
- Type 3 – isolated left subclavian
Thoracic duct
The thoracic duct is the main lymphatic channel for the return of chyle to the venous system.
Thoracic duct: Gross anatomy
- Origin: continuation from the cistern chyli
- Course in the retroperitneum posterior to the great vessels ascending, entering the thoracic cavity via the aortic hiatus at T12, continues to ascend in the posterior mediastinum on the right hand side initially, swapping sides at the level T4, continuing superiorly through the thoracic inlet, anterior to the subclavian artery, anterior to the anterior scalene, draining in the convergence of the left subclavian and internal jugular.
Thoracic Duct: Relations
- Anterior: oesophagus, left atrium, carina
- Posterior: vertebral column, symphathetic chain of ganglion
- Left lateral: descending aorta, left lung and pleura
- Right lateral: azygos vein, right lung and pleura
Thoracic Duct: Variants
- Variant anatomy in 40% of the population
- Duplication
- Aberrant termination
- Multiple terminal channels
Continues on the right to terminate in the right internal jugular vein
Trachea: Description
The trachea is the primary trunk of the conductive airways
Function: transmission of gas between the larynx and the main bronchi
Location: Visceral space of the neck and posterior mediastinum
Trachea: Gross anatomy
Made up of posteriorly incomplete cartilage rings with interspaced annular ligaments
Enveloped by the trachealis muscle which is particularly prominent posteriorly
Lined with ciliated epithelium
Divided into: cervical and thoracic trachea
Origin: continuation of the airway distal to the cricoid cartilage (C6)
Termination: birfucates at the carina level L4
Trachea: Neurovasculature
Arterial supply:
- Inferior thyroid arteries
- Bronchial arteries
Venous drainage:
- Inferior thyroid veins
- Azygos system
Lymphatics:
- Drainage into deep cervical, peri and para-tracheal nodes of the mediastinum
Innervation:
- Vagus and sympathetic trunk
Trachea: Relations
- Posterior: oesophagus and recurrent laryngeal nerve
- Anterior: Thyroid strap muscle, jugular notch, manubrium, great vessels of the superior mediastinum
- Lateral: Sternocleidomastoid, brachiocephalic veins and arteries
- Superior: larynx
- Inferior: Sub-carinal lymph nodes, main bronchi
Trachea: Variants
- Trachea oesophageal fistula
- Tracheal atresia
- Pig bronchus
- Lunate trachea
- Tracheal diverticulum
Bronchial tree: Description
Branching tree of airways beginning at the carina.
The lumen diameter decreases with each branching.
Airways down to the level of the bronchioles contain c-shaped rings of hyaline cartilage to maintain the patency of the lumen.
Function: transmission of gas between the trachea and the respiratory airways of the lungs
Branches of the Bronchial tree
Right side:
- Right main bronchus
- Bronchus intermedius
- Right Upper lobe bronchus
- Right middle lobe bronchus
- Right lower lobe bronchus
Left side:
- Left main bronchus
- Left upper lobe bronchus
- Left lower lobe bronchus
Further branches:
- Segmental bronchi
- 20 to 25 generations of bronchioles
- Terminal bronchioles
Bronchial tree: Vasculature
Arterial supply:
- Bronchial arteries
- Branches of the descending aorta
Venous drainage:
- Bronchial veins draining into the azygos system
Lymphatic drainage:
- Hilar nodes
Bronchial Tree: Variants
- Bronchial cyst
- Pig bronchus
- Oesophageal branch
- Azygos bronchus
- Cardiac bronchus
Superior thoracic apeture: Description
The superior thoracic aperture is the superior opening into the thorax
Function: Allow the passage of a large number of structure into and out of the thorax
Location: Encircled by the first rib, the T1 vertebrae and the manubrium
Thoracic inlet: Organs
- Lung apices
- Trachea
- Oesophagus
- Thymus
- Sometimes the thyroid
Thoracic inlet: Vasculature
- Brachiocephalic veins
- Internal thoracic arteries
- Brachiocephalic truck
- The left common carotid artery
- The left subclavian artery
Lymphatics:
- Cervical lymph nodes
- Thoracic duct
Thoracic inlet: Nerves
- Vagus nerves
- Phrenic nerves
- Ascending laryngeal nerves
- The sympathethetic chain of ganglion
Thoracic inlet: Muscles
- Part of sternocleidomastoid
- Sternohyoid
- Sternothyroid
Thoracic inlet: Variants
- Right common carotid and subclavian can pass through
- Thyroid IMA artery can pass through
- Thyroid can extend through
- Cervical ribs
Biliary Tree: Description:
The biliary tree is the system of biliary vessels of the liver and abdomen
Location:
Intrahepatic and within the free edge of the lesser omentum
Biliary tree: Gross Anatomy
Dividable into intrahepatic and extrahepatic ducts
Each liver segment has its own biliary drainage duct, where biliary canaliculi unite to form segmental ducts. There ducts join to form:
- Right posterior duct
- Right anterior duct
- Right hepatic duct
- Left hepatic duct
Biliary Tree: Course
The right and left hepatic duct unite to form the common hepatic duct, segment I drains directly here also. The common hepatic duct then leaves the liver parenchyma.
The common hepatic duct is joint by the cystic duct of the gallbladder arfter ~2-3cm, they unite to form the common bile duct.
The common bile duct runs in the free edge of the lesser omentum, behind the head of the pancreas to join with the main pancreatic duct forming the ampulla of Vater draining into the D2 via the sphincter of oddi.
Biliary Tree: Neurovasculature
Blood supply:
- Right and left hepatic artery
- Cystic artery
- Branches of the common hepatic artery
- Posterior pancreaticoduodenal artery branches
- Gastroduodenal artery
Venous:
- Into the portal system
Lymphatics:
- Porta hepatis nodes
- Coeliac nodes
Innervation:
- Coeliac plexus
Biliary Tree: Relations
At the porta hepatis:
The common hepatic duct lies in front and is to the right of the hepatic artery, the portal vein is between the two
Biliary Tree: Variants
Cystic duct:
- Duplication
- Low insertion
- High insertion
- Cystic artery posterior to the right hepatic duct
Common hepatic duct:
- Triple confluence
- Aberrant hepatic duct
- Non-union of the left and right hepatic ducts
CBD:
- May pass behind through or around the pancreatic head
- Variable location of the ampulla
- CBD may drain separately from the main pancreatic duct
- Pancreatic divisum
Extrahepatic Biliary Tree: Description
The extra hepatic biliary tree is the system responsible for the drainage and storage of bile from the liver to the D2 segment of the duodenum.
Extrahepatic biliary tree: Gross Anatomy
The left and right intrahepatic ducts join to form the common hepatic duct which leaves the liver parenchyma at the porta hepatis anterior to the hepatic artery and to the right of the portal vein.
The common hepatic duct joins the cystic duct to form the common bile duct.
The common bile duct initially travels in the free edge of the lesser omentum, then courses posterior to the duodenum and the pancreas joining the main pancreatic duct to form the ampulla of Vater.
The ampulla of Vater drains into D2 via the major duodenal papillae
Extrahepatic Biliary Tree: Neurovasculature
Arteries:
- Cystic
- Right hepatic
- Posterior superior pancreaticoduodenal artery
Venous:
- Drains to portal vein
Lymphatics:
- Porta hepatis
- Coeliac
Extrahepatic Biliary Tree: Variants
Cystic duct:
- Low insertion
- Medial insertion
- Parallel course
- Cystic artery anterior to the cystic duct
Common hepatic duct:
- Triple confluence
- Aberrant hepatic duct
- Non-union of the right and left hepatic ducts
Common bile duct:
- Partially covered posteriorly
- Completely covered
- Completely uncovered
- Lateral to pancreatic head
Duodenum: Description
- The duodenum is the first part of the small intestine
- Location: between the pylorus of the stomach and the jejunum, in the anterior pararenal space
- Function: Alkalinisation of chym, mixing of bile with chyme, sensing of chyme to produce gastrointestinal reflexes
Duodenum: Gross Anatomy
C-shape of small bowel lies at the level L1-3
Encompasses the head of the pancreas in the duodenal sweep
Length 20-30 cm in length
Duodenal Segments
- D1 from the pylorus of the stomach courses to the right, features duodenum bulb
- D2 from the D1 segment descending approximately 3-4cm, features major and minor duodenal papilla
- D3 from D2 turn to the left around the pancreatic head course
- D4 from D3 continues to course to the left however also ascends to the ligament of Treitz, after the small bowel continues as the jejunum
Duodenal Relations
- SMA and SMV are anterior to the D3 segment
- Inferior vena cava and the abdominal aorta are posterior to the D3 and D2
- D1, D2, D3 form a c shaped around the pancreatic head
Duodenum: Neurovasculature
Arterial:
- Duodenal cap – right gastric and right gastroepiploic arteries
- Superior and inferior, posterior and anterior pancreaticoduodenal arteries
Venous drainage:
- Duodenal cap – prepyloric vein into the portal vein
- Superior and inferior, anterior and posterior pancreaticoduodenal veins draining into the superior mesenteric vein
Lymphatics:
- Coeliac and superior mesenteric nodes
Innervation:
- Vagus and superior mesenteric plexus
Duodenal variants
- Duodenal papilla inserts into different segments
- Duodenal duplication
- Duodenal diverticulum
Left kidney: Description
The kidneys are paired retropenritoneal organs. Function: production of urine, water and electrolyte homeostatsis, hormone production Location: Perirenal space, long axis parallel to psoas, lies on quadratus lumborum
Left Kidney: Gross Anatomy
- 9-14cm long, left usually larger than the right
- Bean shaped
- Fibrous capsule
- Divided in the superior, mid and inferior poles
- The parenchyma consists of cortex and medulla.
- The renal sinus consists of the renal pelvis, calyces, vessels, nerves, lymphatics and fat
- The renal cortex lie peripheral
- The medulla consists of 10-14 hilum facing pyramids, separated by renal columns
- Each pyramid drains into minor calyces via a papilla, which inturn 3-4 join to form the major calyces, of which 2-3 join to drain into the renal pelvis
Left kidney: Neurovasculature
- Arterial: right and left renal arteries from the abdominal aorta level L1
- Venous: Right and left renal veins into the inferior vena cava
- Innervation: Renal plexus
- Lymphatics: Peri-renal and para-aortic
Right Kidney: Relations
- Anterior: Hepatic flexure, liver
- Posterior: Diaphragm, quadratus lumborium
- Superior: right adrenal gland, liver
- Inferior: Right ureter
- Medial: duodenum, inferior vena cava
Left Kidney: Relations
- Anterior: Splenic flexure, stomach, lesser sac
- Posterior: quadratus lumborum
- Superior: Spleen
- Inferior: Left ureter
- Medially: Jejunum and pancreas
Kidney: Variants
Horseshoe, agenesis, cross fused renal ectopia, pancake, pelvic kidney, colomn of bertin, dromedary
hump, accessory renal arteries, duplex collecting system, retrocaval ureter
Pancreatic Duct: Gross Anatomy
Main pancreatic duct (Wirsung) – runs the length of the pancreas terminates at the ampulla of Vater, formed by the fusion of the dorsal and ventral ducts.
Accessory pancreatic duct (Santorini) – Variant, usually connects to the main duct, runs in the head of the pancreas drains to the minor duodenal papilla. Ruminant of the dorsal duct.
Smaller ducts – clusters of exocrine pancreastic cells for acini which are connected to:
intercalated ducts
Intralobular ducts join to the main pancreatic duct in a herringbone pattern
Pancreatic Duct Variants
- Pancreatic divisum – most common variant, failure of fusion of the dorsal and ventral ducts. As a result the majority of pancreastic secretions are drained via the minor papilla, believed to increase the risk of pancreatitis. Types;
- 1 no connection
- 2 Absent ventral duct
- 3 Inadequate connection
- Santorrinicele – cystic dilation of the of the dorsal duct in the setting of pancreatic divisum
- Meandering main pancreatic duct – maybe z-type or loop type
- Ansa pancreatica – loop like connection between the main and accessory ducts
- Anomalous pancreaticobiliary junction – union of the pancreatic duct and the common bile duct outside of the duodenal wall
Segmental Anatomy of the liver: Descriptions
The liver can be divided into 8 functionally independent segments using the Couinaud classification
system.
Segmental anatomy of the liver: Gross anatomy
Each segment has its own dual blood inflow, lymphatic and biliary drainage
Each segment is a wedge pointed at the porta hepatis
The segement are divided in to a superior and inferior group by a horizontal plane drawn at the level of the bifurcation of the portal vein.
The segments are divided right to left by vertical planes following the hepatic veins.
Segments of the liver
Segment 1 – caudate lobe special in this system as is can receive supply from the left and right portal system, location – around the vena cava, divided into medial caudate process and lateral papillary process. Drains directly into the IVC
Segment 2 and 3 – to the left of the left hepatic vein, superior and inferior to the portal vein bifurcation
Segement 4 – between the left and middle hepatic veins, divided into A for part above the bifurcation of the portal vein and B for below
5 and 6 – Both inferior to the portal bifurcation, 5 between the middle and the right hepatic veins, 6 to the right of the right hepatic vein
7 and 8 - both above the portal vein bifurcation, 7 to the right of the right hepatic vein, 8 between
the right and middle hepatic veins
Segmental anatomy of the liver: Variants
- Right or left supply to the caudate
- Hepatic vein duplication
- Reidels lobe
- Beavertail liver
Spleen: Description
The spleen is an unpaired haematological organ of the abdomen
Function: Immune, red cell production and maturation
Location: left hypochondrium
Spleen: Gross Anatomy
- Wedge shaped
- ~12.5cm in length
- Enclosed by a thin capsule
- Tissues consists of inner red pulp and outer white pulp
- Has a upper and lower pole
- Has a visceral and diaphragmatic surface
- Covered by peritoneum except the hilum which has the:
- Gastrosplenic ligament
- Splenorenal ligament
Spleen: Neurovasculature
Arterial: Splenic artery (coeliac trunk)
Venous: splenic vein into portal
Lymphatics:
Splenic hilar, retropancreatic, coeliac
Innervation:
Coeliac plexus (vagal trunks)
Spleen: Relations
Diaphragmatic surface – dome of the left hemidiaphragm
Visceral surface – tail of the pancreas, left kidney, adrenal gland, stomach
Spleen: Variants
- 10% accessory spleen
- Wondering spleen
- Polysplenia
- Aspenia
- Splenogonal fusion
- Retrorenal spleen
Stomach: Description
Muscular organ between the oesophagus and duodenum.
Location: upper abdomen
Function: storage and digestion of food
Stomach: Gross Anatomy
- Divided into:
- Cardia – receives the oesophagus
- Fundus – superolateral dome
- Body – main region
- Pyloris – lower section exit point
Stomach: Muscles
- Lower oesophageal sphincter
- Pylorus
Stomach: Neurovasculature
Arterial supply:
- Right gastric common hepatic
- Left gastric from the coeliac trunk
- Right gastroepiploic from the superior gastroduodenal
- Left gastroepiploic from the splenic
- Short gastric from splenic and terminal left gastroepiploic
Venous drainage:
- Right and left gastric veins to the portal vein
- Right gastroepiploic to the superior mesenteric vein
- Left gastroepiploic veins and short veins to the splenic
Lymphatics:
- Coeliac and para-aortic nodes
Innervation:
- Gastric plexus (coeliac and vagus)
Stomach: Relations
- Anterior: left lobe of the liver, anterior abdominal wall
- Posterior: lesser sac and stomach bed
- Medial: abdominal aorta, coeliac trunk and nodes
Stomach: Variants
- Situs inversus
- Hypertonic or hypotonic stomach
- Pyloric stenosis
- Congenital hiatus hernia
Rectus Abdominis and Sheath: Gross Anatomy
Has three to four horizontal tendinous intersections that divide the muscle into segments.
Origin: Pubic symphysis, tubercle and crest
Insertion: Xiphisternum and the 5-7 th costal cartilages
Rectus Abdominis and Sheath: Features
- The linear alba divides the recti into right and left
- Laterally the rectus sheath fuses to form the linea semilunaris
- Above the arcute line the IO splits to form the rectus sheath
- Below the arcute line the transversalis fascia passes anterior to the rectus abdominus
Rectus Abdominis and Sheath: Neurovasculature
Arterial supply:
- Superior and inferior epigastric arties
Venous drainage:
- Superior and inferior epigastric veins
Innervation:
- Anterior rami of T6 to L1 spinal nerve
Lymphatics:
- Above the umbilicus to the axillary nodes
- Below the umbilicus to the inguinal nodes
Rectus Abdominis and Sheath: Relations
- Anterior: Rectus sheath, Camper’s fascia, Scarper’s fascia
- Posterior: pre-peritneal fat, peritoneum
- Lateral: hiatus semilunaris
- Medial: Linea alba
- Superior: xiphoid process and the 5 th to 8 th costal cartilages
- Inferior: Pubic symphysis
Rectus Abdominis and Sheath: Variants
Variation in the number of segments
Pyramidalis
Arterial supply and venous drainage of the kidneys: Description
The kidneys are retroperitoneal organs involved in the filtration of blood, production of urine, water
and electrolyte balance and the production of hormones
Arterial supply of the kidneys: Origin
Typically a single renal artery from the aorta at the level L1 inferior to the origin of the
superior mesenteric artery, however there is commonly additional accessory arteries.
Arterial Supply of the kidneys: Course
the right renal artery passes posterior to the IVC and the right renal vein, the left renal
artery courses posterior to the left renal vein
Arterial Supply of the Kidneys: Branches
- Dorsal and ventral rami
- The dorsal and ventral rami divide into segmental branches within the renal hilum these branches are:
- Apical
- Anterior superior
- Posterior superior
- Inferior
- Posterior
- The dorsal and ventral rami divide into segmental branches within the renal hilum these branches are:
- These segmental branches divide to form the:
- Arcute
- Interlobar
- Interlobular
- Inferior adrenal artery
- Ureteric artery
- Capsular artery
Inferior Mesenteric Artery: Description
The inferior mesenteric artery is the primary arterial supply for the hindgut
Inferior Mesenteric Artery: Gross Anatomy
- Origin: 3 rd unpaired/anterior branch of the abdominal aorta at the level L3
- Course: Obliquely descends in the retroperitoneum, initially anterior to the aorta then to the left.
- Termination: continues as the superior rectal artery
Inferior Mesenteric Artery: Branches
- Left colic
- Two to four sigmoid arteris
- Superior rectal artery
Inferior Mesenteric Artery: Supplies
Bowel from the splenic flexure to the upper 2/3 of the rectum
Inferior Mesenteric Artery: Relations
- Anterior: D3
- Posterior: abdominal aorta, left psoas, left common iliac artery
- Lateral (left): Inferior mesenteric vein
Inferior Mesenteric Arteries: Variants
- Doubled IMA
- Absent IMA
- Common trunks
- Absent left colic branch
- Arc of Riolan (SMA/IMA connection)
Coeliac Trunk
Also known as the coeliac axis is the primary abdominal arterial supply to the foregut.
Location: first unpaired branch of the abdominal aorta (T12)
Coeliac Trunk: Gross Anatomy
- Origin: anterior branch of the abdominal aorta at the level of T12, just under to the medial arcuate ligament
- Course: Very short course before under the median arcuate ligament
- Termination: trifurcation into its three branches:
- Common hepatic – (right gastric, properhepatic, gastroduedenal)
- Splenic
- Left gastric arteries
Coeliac Trunk: Supplies
- Gut from the distal oesophagus to the D2
- Liver
- Gallbladder
- Spleen
- Pancreas
Coeliac Trunk: Variants
- Classical branching is seen in 70%
- Branches may arise independently from the aorta
- Coeliacomesenteric trunk
- Other branches may arise from the trunk including:
- Dorsal pancreatic artery
- Right hepatic artery
- Inferior phrenic artery
IVC: Description
- The inferior vena cava is the primary blood return pathway from the abdomen and lower limbs back to the heart
- Function: return of de-oxygenated blood from the abdomen and lower limb to the heart
- Location: Retroperitoneum and short course in the posterior mediastinum
IVC: Gross Anatomy
- Has valves
- Origin: Formed as the confluence of the common iliac veins at the level L5
- Course: Ascending in the great vessel space, passes through the posterior aspect of the liver, through the caval hiatus of the diaphragm at the level T8 short course in the posterior mediastinum
- Termination: right atrium
IVC: Tributaries
- Common iliac veins (L5)
- Lumbar veins (L1-L5)
- Right gonadal veins L2
- Bilateral renal veins L1
- Right adrenal veins L1
- Right and left inferior phrenic veins T8
- Right, middle and left hepatic veins T8
IVC: Relations
- Anterior: Right common iliac artery, right gonadal vessels, D3, common bile duct, portal vein, head of the pancreas, D1, epiploic foramen, liver
- Posterior: Lower lumbar vertebrae and discs, anterior longitudinal ligament, Right psoas belly, sympathetic trunk
- Lateral left: abdominal aorta, caudate lobe of the liver, right crus
- Lateral right: right kidney, right ureter, D2
IVC: Variants
- Duplication
- Agenesis
- Circumcaval ureter
- Circumaortic vena cava
- High union
- Double inferior vena cava
- Left sided vena cava
- IVC webs
- Portocaval shunt
Portal Vein: Gross Anatomy
- Origin: L1 confluence of the splenic and superior mesenteric veins
- Course: runs in the free edge of the lesser omentum enter the porta hepatic as a posterior structure
- Termination: bifurcated to form right and left braches, the level of bifurcation in used to define the boundaries of the liver segments
Portal Vein: Variants
- Portal trifurcation
- Absent right portal vein
- Portal vein duplication
- Left renal veins drains into the portal system
- Absent SMV, all branches converge to for the portal vein
- Abernathy malformation portosystemic shunt
Retroperitoneal Spaces: Description
The retroperitoneum is a space in the abdominal cavity
Location: between the posterior parietal peritoneum and the muscle of the back
Retroperitoneal Spaces: Gross Anatomy
Dividable into 4 spaces by the pararenal fascia
- Anterior pararenal space –anterior to the kidneys, extends from the diaphragm to the pelvis
- Perirenal space – around the kidney, from the bare area of the liver and subphrenic space, continuous with the mediastinum through the diaphragmatic hiatuses, inferiorly it is closed below the kidneys
- Posterior pararenal space – posterior to the kidneys, extends from the inferior phrenic fascia opens into the pelvis
- Great vessel space - the space around the abdominal aorta and inferior vena cava, only named in some sources
Anterior Pararenal Space: Contents
Duodenum, pancreas, ascending and descending colon, roots of the small bowel mesentery and transverse mesocolon.
Perirenal Space: Contents
kidneys, adrenal glands, the proximal collecting system, perirenal fat, renal vessels
Posterior pararenal space: contents
small space containing olny fat, lymphatics, blood vessels, no major organs
Great Vessel Space: Contents
Abdominal aorta and inferior vena cava
Anterior Perirenal Fascia
thinner of the two courses from the lateral origin at the lateral
parietal peritoneum to cross anterior to the great vessels of the abdomen. Also known as Gerota’s fascia.
Posterior Perirenal Fascia
thicker of the two origin is the psoas fascia coursing laterally to
become the laterconal fascia continuing on as the lateral parietal peritoneum. Also known as Zuckerkandl’s fascia.
Sacrum: Gross anatomy
Inverted triangle in shape
Formed by the fusion of 5 sacral vertebrae
Concave anterior
Sacrum: Features
- Sacral prominence
- Superior articular processes with associated facets
- Sacral body
- Alar wings laterally
- Median sacral crest
- Sacral canal (triangular in shape)
- Termination of the sacral canal is at the sacral hiatus
- First four nerve roots exit via the paired anterior and posterior foramen
- The fifth sacral nerves exit via the sacral hiatus
Sacrum: Articulation
- Superiorly with the L5 vertebrae via the sacral prominence and the body of L5 and via the superior articular facets with the inferior articular facets of the L5 vertebrae
- Laterally the sacrum articulates with the ilium via the sacroiliac joints (mixed fibrous/synovial joints)
- Sacrococcygeal – inferiorly the sacrum articulates with the first coccygeal segment
Sacrum: Ligaments
- Lumbosacral
- Iliolumbar
- Sacroiliac ligaments
- Sacrospinous
- Sacrotuberous
- Sacrococcygeal ligaments
Sacrum: Neurovasculature
Blood supply:
- Iliolumbar arteries (Posterior division of the internal iliac arteries)
- Lateral sacral arteries (post. Div. int. iliac)
- Median sacral artery from the aorta
Venous drainage:
- Via the internal and external vertebral plexuses to the median and lateral sacral veins
Lymphatics:
- Perirectal and internal iliac nodes
Sacrum: Variants
- Lumboralisation of the S1
- Sacralisation of the L5
- Sacral agenesis
Levator ani: Description
The lavatory ani also known as the muscular pelvic diaphragm is the musculotendinous sheet that forms the majority of the pelvis floor.
Function: supports the pelvic viscera and aided in urinary and faecal continence
Levator ani: Gross anatomy
Pubococcygeus:
- From the inner surface of the pubis merging medially to form the perineal body
Iliococcygeus:
- From the inner tip of the coccyx to the ischial spine.
Puborectalis:
- From the body of the pubis forming a sling around the rectum
- Coccygeus is not formally part of lavatory ani however it is an important element of the pelvic floor. It is between the sacrospinous ligament/ischial spine and the lateral border of the coccyx and sacrum.
Levator ani: Neurovasculature
Arterial supply:
- Inferior gluteal artery
Venous drainage:
- Inferior gluteal veins
Innervation:
- Pudendal nerve (internal surface)
- Branches of S3,4 (external surface)
Anterior division of internal iliac: Description
The internal iliac artery is the primary blood supply to the pelvis, pelvic viscera, external genitals, perineum, buttocks and medial thigh
Anterior division of internal iliac artery: Gross anatomy
Origin: The bifurcation of the common iliac artery at the level of the pelvic brim
Course: Posteromedial toward the greater sciatic foramen.
Termination: Divides into the anterior and posterior division just prior to the greater sciatic foramen
Branches of the anterior division of internal iliac artery
Rule of 3’s: 3 bladder, 3 muscular, 3 female
ISO POG MUV
- Superior vesicular
- Inferior vesicular
- Obliterated umbilical
- Inferior gluteal
- Obturator
- Internal pudendal
- Middle rectal
- Uterine
- Vaginal
Anterior division of internal iliac artery: Variants
- Persistent sciatic artery
- Obturator artery origin from the external iliac
Posterior division of internal iliac artery: Gross anatomy
Origin: The internal iliac artery divides into anterior and posterior divisions at the superior border of the greater sciatic foramen
Course: Posterior towards the great sciatic foramen
Posterior division of internal iliac artery: Branches
Iliolumbar artery – with lumbar and ilial branches – ilium, iliacus, L5/S1 foramen
Lateral sacral artery – with superior and inferior branches – supplies the sacrum and piriformis
Superior gluteal artery – superficial and deep braches – supplies the gluteal muscles
Posterior division of internal iliac artery: Variants
- Persistent sciatic artery
- Superior and inferior branches of the lateral sacral origin directly from the posterior division of the internal iliac artery
- Superior gluteal may arise directly from the internal iliac
Uterus: vasculature
the ovarian and uterine arteries unite and form an anastomotic network, venous drainage uterine veins into the internal iliac veins
Uterus: lymphatic drainag
- Uterus fundus – pre and para-aortic lymph nodes due to the anastomotic network
- Uterus body and cervical – predominantly to the internal and external iliac chains however there is some drainage to the superficial inguinal nodes via the round ligament
Anal canal: Description
The anal canal is the section of the gastrointestinal tract between the rectum and the anal verge.
Function:
- Control of defecation
Anal canal: Gross anatomy
- Approximately 4cm in length
Origin: anorectal angle (the right angle turn at lavator ani)
Termination: The anal verge
- Dentate line – separates the anal canal into an upper and lower part. These parts differ in structure and neurovascular supply. The dentate line is formed by the anal columns (of Morgani), which are a series of anal sinuses that drain the anal glands. It is located at approximately the middle of the anal canal.
- Above the dentate line the epithelium is a mucous membrane and below the dentate line the epithelium is a stratified squamous cells.
- Anal sphincters – divided into internal and external. Internal is a continuation of the inner rectal muscle, thickened muscular ring, composed of visceral muscle. External skeletal muscle with deep, superficial and subcutaneous parts
- The anal margin is the 5cm of skin around the anal verse
Anal canal: Relations
- Laterally – inchioanal fossa
- Anterior – bulbospongiosus, perineal body, vagina
- Posterior – tip of the coccyx
Anal canal: Neurovasculature
Blood supply:
- Above the dentate line: superior and middle rectal arteries. (Superior from the inferior mesenteric, middle rectal from the internal iliac artery) and median sacral artery.
- Below the dentate line: inferior rectal artery a branch of the internal pudendal artery
Venous drainage:
- Above the dentate line: superior rectal vein to the inferior mesenteric vein (portal system)
- Below the dentate line: inferior and middle rectal veins to the internal iliac veins
Lymphatic drainage:
- Above the dentate line: internal iliac nodes
- Below the dentate line: superficial inguinal nodes
Innervation:
- Above the dentate line: inferior hypogastric plexus
- Below the dentate line: Inferior rectal branches of the pudendal nerve (S2-4)
Anal canal: Variant anatomy
Imperforate anus
Uterus: Description
The uterus is a primary reproductive organ of females
Function:
Gestation of an embryo to birth
Location: Extraperitoneal pelvis, peritoneum drapes over the fundal uterus
Uterus: Gross anatomy
Inverted pear shaped, most of the bulk is myotrium -> smooth muscle
Typically 7.5cm in length, can grow to 40 in length during pregnancy
Consists of:
- Body
- Isthmus between the body and the cervix
- Cervix at the base
- Rounded fundus superiorly above the plane of the insertion of the fallopian tubes
- Cornu laterally
- Endometrial cavity internally which is lined with endometrial tissue
Uterine ligaments
- Pubocervical
- Uterosacral
- Transverse cervical
- Broad ligament
- Round ligament
- Suspensory ligament of the ovaries
- Ovarian ligament
Uterus: Neurovasculature
Blood supply:
Uterine arteries, branches of the anterior division of the internal iliac arteries
Venous drainage:
Uterine veins into the internal iliac veins
Lymphatics:
- Fundus: para-aortic nodes
- Body/cervix: internal and external iliac nodes, superficial inguinal nodes via the round ligament
Innervation:
Inferior Hypogastric plexus, uterovaginal and ovarian plexus
Uterus: Relations
- Posterior: Rectum and pouch of Douglas
- Anterior: Urinary bladder, uterovesical pouch
- Lateral: the adexal spaces, multiple vessels, the ovaries, broad ligament
- Superior: the intraabdoinal cavity
- Inferior: vagina
Uterus: Variants
- Bicornate
- Arcuate
- Septated
- Unicornated
- Agenisis
- Anteverted
- Retroverted
- Uterus didephys
Typical thoracic vertebra: Description
T2 to T8 are considered typical thoracic vertebrae.
Typical thoracic vertebra: Description
T2 to T8 are considered typical thoracic vertebrae.
Typical thoracic vertebra: Description
T2 to T8 are considered typical thoracic vertebrae.
Typical Thoracic vertebra: Gross anatomy
Relative to cervical and lumbar vertebrae, thoracic vertebrae have:
- medium-sized, heart shaped vertebral bodies
- medium-sized vertebral canal
- prominent transverse processes with costal facets
- long spinous processes angulating downwards
Typical thoracic vertebra: Features
Anterior components of thoracic vertebrae:
- body
- pedicle
- superior and inferior costal demifacets
Posterior components of typical thoracic vertebrae:
- downward angled spinous processes
- transverse processes with transverse costal facets
- Superior and inferior articular facets
- lamina
- intervertebral foramen
Typical thoracic vertebra: Articulations
Ribs
Each vertebra contains three points of articulation with ribs.
- The superior demifacet of a thoracic vertebra articulates with the corresponding rib (costovertebral joint).
- This rib articulates again with the costal facet on the transverse process (costotransverse joint).
- The inferior demifacet articulates with the rib below.
Intervertebral:
Facet (zygapophyseal) Joints
- The superior articular process arises from the upper border of pedicle. An oval facet faces posterolaterally.
- The inferior articular process arises from the lower border of the pedicle. The facets face anteromedially.
Intervertebral discs
- Similar to other vertebrae, discs are interposed between hyaline cartilage on the centrum of the vertebral bodies. The disc height is slightly less than cervical vertebrae.
Atlanto-occipital joint
The atlanto-occipital articulation is comprised of a pair of condyloid synovial joints that connect the occiput to the first cervical vertebra (atlas/C1).
Atlanto-occipital joint: Gross anatomy
- Concave surface on the lateral mass articulates with the convex surface of the occipital condyle.
- The joint is reinforced by fibrous capsules which support each joint.
Atlanto-occipital joint: Attachments
- anterior atlanto-occipital membrane – continuation of the anterior longitudinal ligament, between the anterior arch and the anterior foramen magnum.
- posterior atlanto-occipital membrane – continuation of the posterior atlantoaxial membrane, connects the posterior aspect of the posterior edge of the foramen magnum.
Atlanto-occipital joint: Neurovasculature
Arterial supply:
Vertebral arteries
Venous drainage:
Internal and external, posterior and anterior vertebral plexi
Innervation:
The joint capsule is innervated by the C1 nerve.
Atlanto-occipital joint: Variant anatomy
- Variable degree of communication between the atlanto-occipital joint and the cavity between the dens (odontoid peg) and transverse ligament
- Third occipital condyle (condylus tertius) which may articulate with the anterior arch of the atlas, or the dens
- Paracondylar process
- Occipital condyle hypoplasia
- Division of the superior articular facet of the atlas
Calcaneus: Description
The calcaneus is the largest of the tarsal bones and is colloquially refered to as the heel bone.
Function: Inversion and eversion, transfer of force between the leg and the heel pad.
Location: below the talus
Calcaneus: Gross Anatomy
- Irregular box shaped bone
Features:
- Calcaneal tuberosity (heel) – posterior projection with:
- Lateral process
- Medial process
- Posteriorly – superior, middle (attachment for the Achilles) and inferior facet
- Sustentaculum tali – antero-medial process inferior to which is a groove from the flexor halluces longus
- Dorsal surface – location of the anterior, middle and posterior talocalcaneal facets, the tarsal sinus runs between the middle and posterior facets.
- Anterior process - anterior projection the anterior surface of which has the facet for the cuboid
Calcaneus: Articulation
- Talus via the anterior, middle and posterior articular facets
- Cuboid via the facet for the cuboid on the anterior surface
- Shares a joint space with the talonavicular joint forming the talocalcaneonavicular joint
Calcaneus: Relations
- Superior: talocalcaneal joint, talus, sinus tarsi
- Inferior: fad pad, long and short plantar ligaments
- Anterior: calcaneocuboidal joint, cuboid bone
- Posterior: Achilles tendon
- Medial: Tendon of flexor hallucis longus, deltoid ligament of the ankle, tibial nerve, posterior tibial artery
- Lateral: Tendons of peroneus longus and brevis
Calcaneus: Neurovasculature
- Medial and lateral calcaneal arteries from the posterior tibial and fibular arteries
- Artery of the tarsal sinus
Innervation:
- Tibial, sural and deep fibular nerves
Calcaneus: Variants
- Talocalcaneal coalition
- Calcaneonavicular coalition
- Os calcaneus secundaris
Femur: Description
Long bone of the thigh
Function: transfer force between the hip and leg
Femur: Gross Anatomy
Proximal portion:
- Head globular hemisphere covered in synovial cartilage except for the central fovea (attachment of ligamentum terres)
- Neck thinner process through which a large majority of the blood supply to the head flows
- Greater trochanter – large irregular lateral attachment site
- Lesser trochanter – conical posteromedial attachment site
- Intertrocanteric line anteriorly
- Intertrocanteric crest posteriorly
Shaft:
- Long
- Linea aspera – posterior ridge that serves as the attachment for multiple muscle and the intermuscular septa, 3 ridges superiorly becomes two ridges inferiorly that diverge to for the triangular popliteal surface
Distal:
- Flared head with two rounded synovial line condyles
- Synovial surface anteriorly for articulation with the patella
- Bilateral epicondyles superior to each condyle
Femur: Joints
Femoroacetabular – femoral head with the acetabulum, synovial ball and socket with fibrous capsule
Patellofemoral – between the patella groove and the articular surface of the patella
Tibiofemoral – between the medial and lateral condyles and the medial and lateral tibial plateau
Femur: Neurovasculature
Arterial:
- Artery of ligamentum terres
- Anterior and posterior humeral circumflex
- Perforating braches from profunda femoris
- Popliteal and genicular arteries distally
Venous:
- Anterior and posterior femoral circumflex veins to the greater saphenous veins
- Popliteal and deep femoral veins to the common iliac veins
Innervation:
- Femoral and tibial nerves
Femur: Variants
- Coxa valgus/varus
- Hip dysplasia
- Os acetabula
Patella: Description
The patella is the largest sesamoid bone in the human body. It lies within the quadriceps tendon / patellar ligament and forms part of the knee joint.
Patella: Articulation
Articular surface is covered in hyaline cartilage. It articulates with the trochlear groove of the femur (anterior distal surface between the medial and lateral condyles).
Patella: Gross Anatomy
- The patella is triangular in shape with a superior base and inferior apex.
- The posterior surface is smooth, composed of articular cartilage, and is divided into medial and lateral facets, which are sub divided into superior, middle and inferior portions.
- The lateral facet is the largest (this counters the tendency for the quadriceps to pull the patella laterally).
- The anterior surface is rough, for attachment of tendons and ligaments.
Patella: Attachments
Ligaments:
- Patellar ligament – from the apex of the patella to the tibial tuberosity
- Medial and lateral patellar retinaculum
- Medial and lateral patellofemoral ligament (MPFL and LPFL).
Muscles:
- Quadriceps tendon superiorly (really the same thing as the patellar ligament).
Patella: Relations
- superior: common tendon of quadratus femoris, suprapatellar bursa
- inferior: patellar tendon, infrapatellar bursa, infrapatellar fat pad
- lateral: lateral patellar retinaculum
- medial: medial patellar retinaculum
- posterior: knee joint, femur
- anterior: prepatellar bursa
Patella: Neurovsculature
Blood supply:
- Anastomotic rings formed from the branches of the superior and inferior geniculate arteries
Innervation:
- branches of nerves to vastus medialis and vastus lateralis
Patella: Variants
- bipartite patella
- multipartite patella
- absent patella
- variation in shape (see: Wiberg classification)
- dorsal defect of the patella (may occasionally be symptomatic)
Knee Joint: Description
The knee joint is a modified hinge joint between the thigh and the leg
Movements: Flexion and extension
Knee Joint: Gross Anatomy
Type: Synovial joint with a capsule (largest synovial joint in the body)
Articulations:
- Femoral condyles with tibial plateaus
- Patella with the patella groove of the femur
Knee Joint: Ligaments
- Medial collateral ligament
- Lateral collateral ligament
- Anterior cruciate ligament
- Posterior cruciate ligament
- Meniscofemoral ligaments
- Anteriolateral and posterolateral ligaments
Knee Joint: Menisci
- Medial – larger, c-shaped, attached to the MCL laterally
- Lateral – smaller, almost a complete circle
Knee Joint: Bursa
- Pre-patella bursa
- Supra-patella bursa
- Deep and superficial Infrapatella bursa
- Semimembranous bursa
Knee Joint: Fat pads
- Hoffa’s deep to the patella tendon
- Suprapatella fat pad
Knee Joint: Neurovasculature
Arterial supply:
- Superior and inferior, medial and lateral, Genicular branches of the popliteal artery
- Descending genicular from the femoral
- Descending branch of the lateral circumflex
- Circumflex fibular
Venous: into the popliteal and femoral veins
Innervation: Femoral and genicular branches from the tibial and fibular nerves
Knee Joint: Variants
- Patella – dorsal patella defect, bipartite, absent
- Baker’s cyst
- Discoid meniscus
- Flabella
Hamstrings: Description
The hamstrings are the muscles of the posterior compartment of the thigh and include the:
- lateral: biceps femoris
- medial: semimembranosus and semitendinosus
Function: flex knee and extend hip
Hamstrings: Gross anatomy
Apart from the short head of biceps femoris, the muscles share two common features:
- span both the hip and knee joints
- originate from the ischial tuberosity
The short head of the biceps femoris originates from the linear aspera
Hamstrings: Biceps femoris
2 heads (long and short)
Origin is the Ischial tuberosity (long) and linea aspera (short)
Insertion is the fibular head
Innervation: tibial nerve
Artery: Inferior gluteal and popliteal artery
Hamstrings: Semitendinosus
Origin Ischial Tubersotirty
Accompanies semimembranoiss however forms tendon 2/3 down thigh
Inserts on the medial superior tibial condyle, pes anserisus posterior to the gracillis
Innervation: tibial nerve
Artery: Inferior gluteal and popliteal artery
Hamstrings: Semimembranosus
Origin Ischial tuberositiy
Inserts on the medial tibial condyle and posterior joint capsule
Innervation: tibial nerve
Artery: Inferior gluteal and popliteal artery
Hamstrings: Pes Anserius
- Sartorius
- Gracilis
- Semitendinoisis
Gastrocnemius: Attachments
- origin: above the lateral and medial femoral condyle
- insertion: calcaneal (Achilles) tendon into mid-posterior calcaneus
Gastrocnemius: Neurovasculature
- arterial supply: sural arteries
- innervation: tibial nerve (sciatic nerve nerve roots S1 and S2)
Gastrocnemius: Description
antagonist: tibialis anterior
action: plantar flexes foot and flexes knee
Gastrocnemius: Relations
- superficial to soleus
- forms the inferior borders of the popliteal fossa
Gastrocnemius: Variants
Fabella
Arterial Supply of the foot: Description
Arterial supply of the foot is the vascular system that supplies oxygenated blood to the foot
Gross anatomy:
The arterial supply of the foot can be divided into plantar and dorsal components:
Medial Plantar artery
Origin: posterior tibial branch
Supplies: the medial side of the foot and the first toe
Termination: the 1 st medial plantar digital artery
Lateral Plantar artery
Origin: Posterior tibial artery
Course: Cross the foot toward the base of the 5 th metatarsal
Supplies: lateral intrinsic muscle of the foot
Termination: As the Plantar arch
Plantar arch
Connects the dorsalis pedis with the lateral plantar artery
Lies deep to the plantar aponeurosis
Branches: Plantar metatarsal arteries
Termination: connects with dorsalis pedis in the first metatarsal interspace
Dorsal Arterial Supply of the foot
Dorsalis pedis
Origin: Continuation of the anterior tibial artery
Course: Runs lateral to the extensor halluces longus tendon
Termination: continues as the first metatarsal artery
Branches:
- First dorsal metatarsal artery
- Medial tarsal arteries
- Lateral tarsal arteries
- Arcuate artery
- Dorsal metatarsal arteries
Popliteal Artery: Description
Large artery of the popliteal fossa
Supplies: Primary supply for the leg below the knee
Popliteal Artery: Gross Anatomy
Origin: A continuation of the superficial femoral artery as it passes out of the adductor hiatus
Course:
- Through the popliteal fossa where it is the deepest structure
- Through the fibrous arch of soleus
Termination:
Bifurcation into the anterior tibial and the tibioperoneal trunk
Popliteal Artery: Branches
Medial and lateral, superior and inferior genicular arteries
Middle genicular artery
Popliteal Artery: Relation
Popliteal artery is the most deep structure in the popliteal fossa
Deep to the popliteal vein
Popliteal Artery: Variation
- Trifurcation
- Peroneal from the anterior tibial
- High origin of the anterior tibial
- High origin of the posterior tibial
- Very long tibioperoneal trunk
- Hypoplastic infrapopliteal vessels
- Popliteal artery entrapment
Great Saphenous Vein: Description
The long and short saphenous veins are superficial veins of the lower limb
Function: return oxygenated blood from the lower limb to the iliac veins
Gross anatomy:
Both have valves
Origin: continuation of the medial marginal vein of the foot
Termination: Pierces the deep facia of the femoral triangle draining into the spahenofemoral
junction. 99% have a valve within 2mm of the SFJ
Great Saphenous Vein: Course
It passes anterior to the medial malleolus, ascending in the saphenous space between the
saphenous fascia superficially and the deep fascia, it is closely related to the saphenous nerve(s)
below the knee.
Great Saphenous Vein: Tributaries
- Small saphenous vein
- Unnamed superficial veins of the leg
- Medial marginal vein of the foot
- Superficial epigastric
- Superficial circumflex iliac
- Superficial external iliac
- Superficial external pudendal
- Multiple deep perforators to the deep system
Lesser Saphenous Vein: Description
Origin: Confluence of the lateral aspect of the venous network of the dorsum of the foot
Termination: Pierces the deep fascia of the popliteal fossa to drain into the popliteal vein
Lesser Saphenous Vein: Course
Posterior to the lateral malleolus, ascending in the subcutaneous tissues of the lateral leg
Lesser Saphenous Vein: Tributaries
- Multiple unnamed superficial branches
- Great saphenous vein
- Multiple perforators to the deep venous system
Lesser Saphenous Vein: Relations
Course closely associated with the sural nerve
Lesser Saphenous Vein: Variants
- Vein of Giacomini
- Duplication
- Absence
- Fenestration