Head and neck prosection book Flashcards
Where is levator scapulae?
-Situated back and side of neck
-Lifts scapula
Where is levator scapulae?
-Situated back and side of neck
-Lifts scapula
Where is splenius capitis?
-posterior aspect of the neck arising from the midline and extending superolaterally to the cervical vertebrae
Where is masseter?
-most superficial muscle of mastication
Describe arrangement of deep fascia in neck
-External investing layer: surrounds entire neck deep to platysma,
-Middle layer anteriorly (pretracheal and carotid sheath)
-Deep layer posteriorly
Contents of each fascia:
External investing: SCM, trapezius
Pretracheal: thyroid, oesophagus, trachea
Carotid sheath: internal carotid, internal jugular, vagus, ansa cervicalis, lymph nodes
Prevertebral: Vertebral column and associated muscles
Function of SCM and how to test:
-Turn head towards opposite side of muscle
-To test R SCM: Turn head to left against resistance and palpate muscle
Function of trapezius and how to test:
-Elevation of scapula
-Ask pt to shrug shoulders against resistance while palpating muscle
What nerves are contained in posterior triangle?
-Spinal accessory nerve
-Cervical plexus
-Brachial plexus (superior, middle and inferior trunks)
Which vessels are contained in posterior triangle?
Arteries:
-Third part subclavian artery
-Transverse cervical artery (branch of thyrocervical trunk, branch of first part subclavian artery)
-Suprascapular artery (branch of thyrocervical trunk)
-Occipital artery
Veins:
-External jugular vein
What structures are contained in posterior triangle?
Nerves
-Spinal accessory nerve
-Cervical plexus
-Brachial plexus (superior, middle and inferior trunks)Arteries:
Arteries
-Third part subclavian artery
-Transverse cervical artery (branch of thyrocervical trunk, branch of first part subclavian artery)
-Suprascapular artery (branch of thyrocervical trunk)
-Occipital artery
Veins:
-External jugular vein
Lymph nodes
What are the surface markings of the spinal accessory nerve?
-Runs from transverse process of atlas to anterior border trapezius, 5cm above clavicle
What are the boundaries of the muscular triangle?
Superiorly – hyoid bone.
Medially – imaginary midline of the neck.
Supero-laterally – superior belly of the omohyoid muscle.
Infero-laterally – inferior portion of the sternocleidomastoid muscle
What passes through supraorbital foramen?
-Supraorbital artery
-Supraorbital nerve
-Supraorbital vein
What passes through infraorbital foramen?
Infraorbital artery
Infraorbital nerve
Infraorbital vein
What structures pass through superior orbital fissure?
Superior to inferior: Lazy french tarts sit nakedly in anticipation
Lacrimal nerve
Frontal nerve
Trochlear nerve
Superior division oculomotor nerve
Nasociliary nerve
Inferior division oculomotor nerve
Abducens nerve
Also:
-Ophthalmic veins (superior and inferior)
Describe arrangement of extraocular muscles
-Seven extraocular muscles
-one eyelid elevator, 4 recti and two obliques
Describe muscles involved in elevation of eyelid
-Levator palpebrae superioris originates from sphenoid, inserts into tarsal plate of upper eyelid
-Elevates upper eyelid, has supply from oculomotor nerve
-Mullers muscle is accessory muscle to raise upper eyelid
-Has autonomic innervation from sympathetic nervous system. Denervation causes partial ptosis
Describe actions of recti
-Pull in corresponding directions
-Superior and inferior recti slightly diagonally adduct: compensated for by superior and inferior oblique which diagonally abduct
Describe actions of obliques
-Superior oblique: depression and abduction (down and out)
-Inferior oblique: Elevation and abduction (up and out)
Describe bones of orbit
many friendly zebras enjoy lazy summer picnic
-Maxilla
-Frontal bone
-Zygomatic bone
-Ethmoid bone
-Lacrimal bone
-Sphenoid bone
-Palatine bone
Describe oculomotor palsy
-Down and out palsy due to unopposed lateral rectus and superior oblique
-Dilated pupil due to unopposed action sympathetic nerves on dilator pupillae
-Resulting strabismus causes diplopia
-Ptosis due to denervation levator palpebrae superioris: sympathetic supply to muller’s muscle insufficient to maintain eyelid open
How can facial artery be identified?
-Tortuous course
-Can be palpated as it runs over mandible anterior to masseter
Where can marginal mandibular nerve be identified surgically?
Runs over facial artery as they cross the mandible
What are the clinical consequences of cutting marginal mandibular nerve?
-Paralysis of ipsilateral depressor angularis oris muscle
-Pt cannot depress lower lip and has assymmetrical smile/bites lip when eating
What are clinical consequences of cutting temporal branch of facial nerve?
-paralysis of forehead
-Pt cannot raise eyebrow
Describe course of facial nerve
-Mixed nerve comprising large motor and smaller sensory component
–>Motor component from pons,
–>sensory component from nervus intermedius
–>Emerges from junction between pons and medulla
–> petrous temporal bone via internal auditory meatus
–> Runs through facial canal
–> gives off ‘tear, hear, taste’ branches in facial canal
–> Exits skull via stylomastoid foramen
–> gives off posterior auricular nerve, nerve to posterior belly digastric, nerve to stylohyoid
–> enters parotid gland between superficial and deep lobes
–> gives off 5 branches within parotid
Describe greater petrosal nerve
-Parasympathetic fibres travel with V2 to supply lacrimal gland
Describe chorda tympani
-Parasympathetic and sensory fibres travel with lingual nerve
-Provides taste to anterior 2/3rd of tongue and parasympathetic to submandibular and sublingual
What does posteiror auricular nerve supply?
occipital belly occipitofrontalis
Desribe anatomy of parotid gland
Parotid region boundaries:
Superiorly – Zygomatic arch.
Inferiorly – Inferior border of the mandible.
Anteriorly – Masseter muscle.
Posteriorly – External ear and sternocleidomastoid.
-Parotid gland is divided into larger superficial and smaller deep lobe
-Enclosed within parotid sheath derived from investing layer deep cervical fascia
Describe surface anatomy of stensen’s duct
-Lies in middle 1/3rd of line from tragus to a point between ala of nose and lateral commisure of mouth
-Overlies masseter, pierces buccinator and opens into buccal vestibule at level of upper 2nd molar
What nerve runs with stensen’s duct? What is significance of this in facial trauma?
-Buccal branch of facial nerve runs alongside parotid duct
-With cut to cheek both structures can be damaged
-Laceration of parotid duct should be excluded by examining papilla for signs of bleeding/bruising
-Duct can be cannulated with lacrimal probe which will be visible in wound if injured
When should a facial nerve laceration be repaired?
-If it is cut lateral to line extending from lateral canthus of eye
-Cut medial to this line has similar outcomes with surgical/conservative measures
Innervation of external ear
Great auricular (branch of cervical plexus: inferior auricle
Lesser occipital (branch of cervical plexus): posterior auricle
Auriculotemporal (branch of V3): Antero-superior auricle and external auditory meatus
Arnold’s nerve: External auditory meatus and concha
Facial nerve: part of canal and tympanic membrane
Glossopharyngeal (jacobsen’s nerve): supplies small part external eaar
What are the clinical consequences of complex pattern of ear senosry supply?
-Receives innervation from 4 cranial nerves and 2 spinal levels (C2, C3)
-Can get referred pain from other places: e.g. trigeminal neuralgia, parotid gland, teeth.
-Chronic ear pain with normal ENT exam is occult head/neck ca until proven otherwise (commonly base of tongue/tonsil)
What are the sensory branches of cervical plexus?
Make a rhyme in this order:
Lesser occipital C2
Great auricular C2,3
Transverse cervical C2,3
Supraclavicular C3,4
What nerve roots contribute to cervical plexus?
-Ventral rami C1-4
-Only C2-4 contribute to sensory branches
Demonstrate dermatomes that correspond to cervical plexus
C1: no dermatome
C2: Superoposterior scalp
C3: upper neck and behind ear
C4: Lower neck down to clavicle
What is the name of the point where cervical plexus emerges through prevertebral fascia? What are the markings of this point?
-Erb’s point
-Cervical plexus emerges through prevertebral fascia at posterior border SCM around halfway down
-T6 vertebral level
Does Erb’s point have any clinical uses?
-Can be used to identify spinal accessory nerve during neck dissection
-Lies 1cm superior and 1 plane deeper (i.e. deep to investing layer of deep cervical fascia)
Which layers are cut during tracheostomy?
-Skin
-Subcutaneous fat
-Platysma
-Investing layer deep cervical fascia
-Strap muscles (sternohyoid and sternothyroid)-usually pulled aside rather than cut
-Pretracheal fascia
-Trachea
What are the strap muscles?
-Also known as infrahyoid muscles
-Group of paired muscles that run in anterior neck
-Lie between investing layer deep cervical fascia + pretracheal fascia
-As name describes they are long, flat, strap-like muscles
What are the names of the strap muscles?
-Sternohyoid
-Thyrohyoid
-Sternothyroid
-Omohyoid
What are the attachments of Strap muscles?
Sternohyoid
–> manubrium inferiorly
–>body of hyoid superiorly
Thyrohyoid
–> lower border of body of hyoid superiorly
–> oblique line of thyroid cartilage inferiorly
Sternothyroid
–> Inferiorly to manubrium
–> superiorly oblique line thyroid cartilage
Omohyoid
–> inferiorly to scapula
–> superiorly to hyoid
Orientation of strap muscles to each other
-Most superficial: sternohyoid
-Deep to sternohyoid superior neck: Thyrohyoid
-Deep to sternohyoid lower neck: Sternothyroid
-Lateral to sternohyoid: omohyoid
Nerve supply of strap muscles:
Sternohyoid + sternothyroid + omohyoid –> ansa cervicalis
Thyrohyoid –> C1 fibres that hitchike with hypoglossal
Actions of strap muscles
-Sternohyoid: depress hyoid
-Thyrohyoid: Depresses hyoid and elevates larynx
-Sternothyroid: Depresses larynx
-Omohyoid: depress hyoid
How can you remember orientation of thyrohyoid and sternothyroid to sternohyoid?
-They have same path as sternohyoid, but have intermediate attachment
-Since they have deep attachment, they must lie deeper
What is notable about omohyoid?
-Has intermediate tendon that runs through sling attached to clavicle
-Therefore has superior and inferior belly
What is the blood supply of the strap muscles?
Segmental blood supply via branches from superior and inferior thyroid arteries
Why is omohyoid a useful landmark when performing a selective neck dissection?
-Marks boundaries between levels 3 and 4 in anterior triangle
-e.g. if performing neck dissection for tongue SCC with no evidence mets, standard practice would be to dissect only 1,2,3 of neck as the most likely levels for tongue mets
-1-3 are also called supraomohyoid neck dissection
What are the surface markings of the seven cervical vertebrae levels?
C1: hard palate
C2: angle of mandible
C3: hyoid bone
C4: superior thyroid notch
C5: thyroid cartilage
C6: cricoid cartilage
C7: upper tracheal rings
List the branches of the internal carotid artery in the neck
-The internal carotid artery has no branches in the neck
-After the cavernous sinus it divides into anterior and middle cerebral and gives of posterior communicating artery
What vertebral level corresponds to birfurcation of common carotid?
C4
Where does the vertebral artery originate?
Vertebral artery is branch of first part of subclavian artery
Describe course of vertebral artery in neck
-Originates from first part subclavian artery
-Pass between longus colli and scalenus anterior
-Ascend in neck by passing through transverse foramen of upper 6 cervical vertebrae
-Run accross posterior arch of atlas
-Enter skull through foramen magnum
How does vertebral artery terminate and where?
Two vertebral arteries join to become midline basilar artery as they reach anterior surface medulla oblongata
What is the eponymous name for this anastamosis of arteries in the brain ? What does the anastamosis consist of?
Basilar artery anastomoses with internal carotid arteries to form circle of willis
Describe subclavian steal syndrome
-Describes neurological impairment in presence of proximal subclavian artery stenosis
-Occurs with occulsion proximal to origin of vertebral artery, causing reduced blood flow to ipsilateral arm
-To compensate, blood passes around stenosis by going up carotids, through circle of willis and then retrograde down ipsilateral vertebral artery to supply arm
-Blood is shunted away from brain to supply arm
Clinical features subclavian steal. Which side more commonly affected?
-Neurological symptoms (vertigo, syncope, tinnitus, visual loss) when ipsilateral limb is exercised
-Left side more commonly affected
Causes
-Atherosclerosis
-Cervical rib
(important) branches maxillary artery
-Middle meningeal
-Accessory meningeal
Layers of scalp
Skin
Connective tissue
Aponeurosis (of occipitalis/frontalis muscles-also called galea)
Loose areolar tissue
Periosteum
Describe arterial supply to scalp and where arteries originate from
Scalp receives supply from 5 paired arteries: 2x from internal carotid, 3x from external carotid
Internal carotid:
Supraorbital and supratrochlear: from ophthalmic
–> above orbit and trochlea (of superior oblique)
External carotid:
Superficial temporal: laterally in front of ear
Posterior auricular (behind ear)
Occipital : posteriorly
Why do scalp lacerations bleed profusely?
-Rich blood supply
-Blood vessels attached to and embedded in dense fibrous tissue
-Reduces normal vasospasm, retraction and contraction
-vessels are held open by tight adherence
In which layer are flaps raised in scalp?
Subgaleal (aponeurotic) plane: loose areolar layer provides easy plane for dissection with few vessels or fibrous attachments
What is the venous drainage of scalp?
-Same as arteries
-Also valveless emissary veins which connect superficial valves of scalp with diploic veins of skull
-Drain into dural venous sinuses
Why does pattern of venous drainage in scalp have potential to spread infection?
-Can spread infection to diploic veins of skull–> osteomyelitis
-Can spread to cavernous sinuses –> cavernous sinus thrombosis
What is sensory supply of scalp?
Z-GLASS
Zygomaticofrontal (branch of V2)
Greater occipital
Lesser occipital (C2: cervical plexus)
Auriculotemporal (V3)
Supraorbital (V1)
Supratrochlear (V1)
What incision is made for approach to submandibular gland? Why is it made here?
-3cm below lower border of mandible
-Avoids marginal mandibular nerve, which runs below mandible
What nerves can be damaged during submandibular gland excision?
-Lingual
-Nerve to mylohyoid
-Hypoglossal
-Marginal mandibular
Which muscle separates superficial and deep lobes submandibular gland?
mylohyoid
Which vessels are encounted during approach to submandibular gland?
-Facial artery
-Facial vein
Compare acini type of parotid, lingual and submandibular gland
-Parotid: Serous
-Submandibular: mucous and serous
-Sublingual: mucous
Why are stones most common in submandibular gland?
-Long upsloping duct
-Mucous acini
-more alkaline saliva: predisposes to calcium salt deposition
What is nerve supply to mylohyoid? What else does this nerve suppy?
-nerve to mylohyoid from V3
-Also supplies anterior belly digastric
At what age does frontal sinus form?
Frontal sinus not present at birth but appears as air-filled space by age 8. Not fully developed until puberty
The pharynx can be divided into 3 parts. What are these parts called?
-Nasopharynx
-Oropharynx
-Laryngopharynx
Describe the arrangement of the pharyngeal muscles
Three circular muscles:
-Superior constrictor
-Middle constrictor
-Inferior constrictor (upper fibres thyropharyngeus, lower fibres cricopharyngeus
Three longitudinal muscles
-Stylopharyngeus
-Salpingopharyngeus
-Palatopharyngeus
-Constrictor muscles overlap posteriorly, with lower muscle sitting outside muscle above
-This arrangement is analogous to three pint glasses stacked inside each other
What is the motor supply of the pharyngeal muscles?
-All supplied by pharyngeal plexus (vagus and accessory nerves), apart from stylopharyngeus, supplied by glossopharyngeal
Describe the muscles of the palate
5 paired muscles that act on soft palate:
-Tensor veli palatini
-Levator veli palatini
-Palatoglossus
-Palatopharyngeus
-Muscularis uvulae
Describe attachments of the tensor veli palatini and function
Attachments: Originates from the medial pterygoid plate of the sphenoid and inserts into the palatine aponeurosis.
Function: Tenses the soft palate
Describe attachments and function of levator palatini
-Attachments: Arises from the petrous temporal bone and the eustachian tube, before inserting into the palatine aponeurosis.
-Function: Elevation of the soft palate.
Describe attachments and function of Palatoglossus
Attachments: Originates from the palatine aponeurosis, and travels anteriorly, laterally and inferiorly to insert into the side of the tongue.
Function: Elevate tongue, depress palate
Describe attachments and function palatopharyngeus
Attachments: Arises from the palatine aponeurosis and the hard palate, and inserts into the upper border of the thyroid cartilage.
Function: Tenses soft palate and draws the pharynx anteriorly on swallowing.
Describe attachments and function of muscularis uvulae
Attachments: Arises from the posterior nasal spine and the palatine aponeurosis, and inserts into the mucous membrane of the uvula.
Function: Shortens the uvula.
What is the motor innervation of the palatal muscles?
-Pharyngeal plexus (vagus and accessory) except for tensor veli palatini, supplied by mandibular division trigeminal nerve (branch to medial pterygoid
Which vertebral levels correspond to position of the larynx?
-C3-C6
What are the cartilages of the larynx?
9 cartilages: 3 unpaired, 3 paired
Unpaired (in the midline)
-Thyroid
-Cricoid
-Epiglottic
3 Paired (bilateral)
-Arytenoid x2
-Corniculate x2
-Cuneiform x2
What is the blood supply to the larynx?
-Laryngeal branches of superior and inferior thyroid arteries
Name extrinsic and intrinsic membranes of the larynx
Extrinsic membranes connect the laryngeal cartilage to the surrounding structures for support. They include the:
-Thyrohyoid
-Hyoepiglottic ligament
-Cricotracheal
Intrinsic membranes include the:
-Quadrangula
-Cricothyroid
-Thyroepiglottic ligament
Name the extrinsic muscle of the larynx and their function
Extrinsic muscles move the larynx as a whole
Suprahyoid (elevates larynx)
-Stylohyoid
-Mylohyoid (originates from mandible near ‘molars’)
-Geniohyoid (‘chin’)
-Digastric
Infrahyoid (depresses larynx)
-Sternothyroid
-Sternohyoid
-Thyrohyoid
-Omohyoid
Name intrinsic muscles of larynx
Easy to remember:
Adductors: lateral cricoarytenoid
Abductors: posterior cricoarytenoid (most important: only abductor of the vocal cords)
Sphincters: transverse/oblique arytenoids
Tensors: cricothyroid muscle (only intrinsic muscle not innervated by the recurrent laryngeal)
Relaxers: Vocalis, thyroarytenoid
- Abductors/adductors (muscles to open and close vocal cords)
–> adductor: lateral cricoarytenoid muscle (main), transverse arytenoids muscles
–> Abductor: posterior cricoarytenoid muscles–> most important as only abductor
- Sphincters (muscles to close the laryngeal inlet during swallowing)
–> lateral cricoarytenoid
–> transverfse arytenoids
–> oblique arytenoids - Tensors (muscles to raise pitch of voice)
–> cricothyroid - Relaxers (muscles altering pitch of voice)
–> thyroarytenoid
–> vocalis
What is the function of the intrinsic muscles of the larynx?
Intrinsic muscles move and alter length and tension of vocal cords and size and shape of rima glottidis
The rima glottidis is the opening between the two true vocal cords anteriorly, and the two arytenoid cartilages posteriorly. It is part of the larynx
Name the subdivisions of the laryngeal cavity
Can be divided into 3 major regions:
- Vestibule
- Middle (ventricle/laryngeal sinus)
- Infraglottic space
Name some causes of a vocal cord palsy
- Malignancy (30%) especially of the bronchus, oesophagus, thyroid gland, nasopharynx
- Iatrogenic (25%) in thyroid, parathyroid, oesophageal, pharyngeal pouch and left lung surgery
- External trauma (15%)
- Idiopathic (15%)
- Others (15%) in neurological disorders, myopathies
What are the different types of vocal cord palsies/
The different types of vocal cord palsy include:
–> unilateral or bilateral
–> Temporary or permanent
What is the clinical significance of a bilateral recurrent laryngeal nerve palsy
Bilateral recurrent laryngeal nerve palsy presents with stridor
–> note: unilateral recurrent laryngeal nerve palsy presents with hoarseness
Where does the carotid artery bifurcate
C4
What vertebral level is the isthmus of thyroid?
C7
What structures can be damaged during ligation of vessels in thyroidectomy?
Superior thyroid artery–> superior laryngeal
Inferior thyroid artery –> recurrent laryngeal
Where are the parathyroid glands found?
2 superior, 2 inferior
2 superior: posterior to thyroid at level of first tracheal ring
2 inferior:
–> variable position
–> can be behind inferior pole of thyroid
–> can be within thyroid gland, or within mediastinum (parathyroids and thymus both derived from 3rd pharyngeal pouch)
What is the blood supply/venous drainage of the parathyroids?
All supplied by inferior thyroid artery
Superior: also receives blood from superior thyroid artery
Venous drainage: superior, middle and inferior thyroid veins
What is the relationship of the thyroid to the fascias of the neck?
-Lies within thyroid fascia, which is derived from visceral layer of pretracheal fascia
-Visceral layer also invests trachea and oesophagus
-Also muscular (covers infrahyoids) and buccopharyngeal (covers pharnx)
-Surrounded by external investing layer deep cervical fascia
-Deeper lies prevertebral fascia
Which dural venous sinuses are found in falx cerebri of dura mater?
-Superior and inferior saggital
-Straight sinus
Which dural venous sinuses are drained by the confluence?
-Straight sinus
-Superior and inferior saggital
Where do the dural venous sinuses ultimately drain?
Internal jugular vein
What does straight saggital sinus drain?
It is a continuation of the inferior saggital sinus and great cerebral vein
Describe the transverse sinus
-From the confluence the transverse sinus curves bilaterally to join sigmoid sinus
-Then meets opening of internal jugular vein
Describe cavernous sinus
-The cavernous sinus drains the ophthalmic veins and can be found on either side of the sella turcica
-From here, the blood returns to the internal jugular vein via the superior or inferior petrosal sinuses
What forms internal jugular vein?
-Inferior petrosal sinus
-Sigmoid sinus
Describe the emissary veins
-Don’t have any valves
-Connect intracranial and extracranial veins
Describe clinical relevance of the cavernous sinus
-Infections and tumours can spread from valveless ophthalmic and facial veins causing thrombosis
Manifests as:
-Swollen painful eye with venous congestion
-Palsy of 3, 4, 5 and 6
-Can spread to contralateral sinus due to intercavernous sinuses
Describe flow of CSF from lateral ventricle
Lateral ventricle –> foramen of munro –> 3rd ventricle –> aqueduct of sylvius –> 4th ventricle –> foramen of magendie (medial and luschka (lateral) –> cisterns in subarachnoid space
Describe the course of the internal carotid artery
-Arises from common carotid artery in neck
-Ascends neck in carotid sheath and enters skull via carotid canal in petrous part of temporal bone
-Passes through cavernous sinus and enters subarachnoid space
What are the branches of the internal carotid artery?
- Ophthalmic artery
- Anterior choroidal
- Anterior cerebral
- Middle cerebral
- Posterior communicating
What are the terminal branches of the internal carotid artery?
-Middle cerebral artery
-Anterior cerebral artery
What structures are supplied by basilar artery?
-Cerebellum
-Pons
What are the branches of the basilar artery?
-Anterior inferior cerebellar artery
-Pontine branches
-Superior cerebellar artery
Two terminal branches:
-Left and right posterior cerebral arteries
Describe pathology of a berry aneurysm
-Congenital malformations
-Result from inherent weakness and thinning of vessel wall
-No tunica media or elastic lamina
-Vulnerable to raised hydrostatic pressure and bulge out
What are gyri and sulci?
-Gyri are elevated folds in cerebral hemisphere
-Sulci are the grooves between them
-Allows increase in surface area of cerebrum
What separates the temporal lobe from frontal and parietal lobes?
Lateral sulcus (sylvian fissure)
Which structure links the two cerebral hemispheres?
Corpus callosum is the white matter structure that links the two cerebral hemispheres
Within the cerebral cortex, which areas are responsible for sensory and motor signals?
best foot forward–> motor
-Post central gyrus (posterior to central sulcus): sensory information
-Pre central gyrus (anterior to central sulcus (motor information)
What is the location of the visual cortex?
occipital lobe
What is the histological composition of the cerebrum?
Grey matter
–> superficial
–> composed of neuronal bodies
White matter
–> deep
–> axonal tracts of neurons
What is broca’s area?
-Left inferior frontal gyrus
-Motor speech area
What is wernicke’s location?
-posterior part of superior temporal gyrus in dominant hemisphere (usually left)
-Involved in comprehension of language
Which cranial nerves carry parasympathetic fibres?
-3, 7, 9, 10
Which structures accompany optic nerve through its passage in optic canal?
-Ophthalmic artery
-Central retinal vein
In which structure does the optic tract terminate?
-Lateral geniculate body of thalamus
-Optic radiations then travel to visual cortex of the occipital lobe
What structures do the divisions of the oculomotor nerve innervate?
-Superior division: superior rectus and levator palpebrae superioris
-Inferior division: medial and inferior rectus, inferior oblique, ciliary muscle and sphincter pupillae
Describe pathophysiological process involved in brain swelling causing oculomotor nerve dysfunction
-Raised ICP
-Leads to uncal herniation and compression of 3rd nerve
-Leads to fixed and dilated pupil on ipsilateral side to herniation, due to loss of parasympathetic innervation to sphincter pupillae
What deficit results from 4th nerve palsy?
-Inability to depress eye, particularly in adduction
Where is the cerebellum located? What is its main role?
-Located in posterior fossa
-Complex role in coordination of movement and posture
Describe arterial supply to cerebellum
Superior cerebellar artery –> branch of basilar artery
Anterior inferior cerebellar artery –> branch of basilar
Posterior inferior cerebellar artery –> branch of vertebral
What are the basal ganglia, and what are the 5 nuclei that comprise them?
Basal ganglia are grey matter nuclei located in base of cerebral hemispheres. Involved in coordination of voluntary motor funciton
-Caudate nucleus
-Putamen
-Globus pallidus
-Substantia nigra
-subthalamic nucleus
What is the role of the pons?
-Regulates hearing and balance and contains various autonomic centers
What is the role of the medulla?
-Contains tracts to and from spinal cord
-Contains autonomic centeres that regulate cardiorespiratory and GI physiological mechanisms
What are the 3 meningeal layers?
-Dura mater
-Arachnoid mater
-Pia mater
What separates the dura mater from the arachnoid mater?
Subdural space (a potential space)
In anatomical terms, what causes an extradural and a subdural haemorrhage?
-Extradural: rupture of an artery (e.g. middle meningeal artery) within potential space between dura and skull
-Subdural: rupture of cerebral veins as they travel from cerebrum to dural venous sinuses
How do you differentiate subdural vs extradural on CT?
-Extradural: lens
-Subdural: crescent
What is spina bifida?
-Group of congenital malformations that result from failure of fusion of two halves of neural arches
-Most commonly found in lumbosacral region
-Spina bifida occulta: no symptoms or consequence
Spina bifida cystic: protrusion of meningeal cyst. Can have;
–> no content (meningocele)
–> spinal cord or cauda equina (myelomeningocele). Often results in lower-limb paralysis/bladder/bowel dysfunction
How might you clinically examine vagus nerve?
-Ask pt to phonate with open mouth (‘say ah’) and observe midline elevation of soft palate and uvula
What is the most superior part of the skull?
Vertex
What are the contents of the foramen magnum?
Soft tissue
-End of medulla, beginnign of spinal cord
Nerves
-Spinal root of accessory nerve
Vessels
-Anterior and posterior spinal arteries
-Vertebral arteries
How many other bones does sphenoid articulate with? What are they?
8
Temporal
Parietal
frontal
vomer
occipital
zygomatic
palatine
ethmoidal
What is the sensory distribution of trigeminal neve?
Ophthalmic: forehead, upper eyelids, eye, anterior nose, nasal mucosa
Maxillary: cheek, lower eyelid, lateral nose, upper teeth, upper lip, maxillary sinuses
Mandibular: skin over mandible, lower teeth { lip, temporal skin, lower oral cavity
What are the muscles supplied by CN 5?
-Muscles of mastication (medial and lateral pterygoids, masseter, temporalis)
-Tensor tympani
_mylohyoid
-Anterior belly digastric
What are branches from mandibular branch of trigeminal before it divides?
-Tensor veli palatini
-Tensor tympani
-Medial pterygoid
How do you differentiate between upper and lower motor neurone lesions in face?
-Superior facial muscles have bilateral innervation from both right and left sides motor cortex
-UMN lesions have sparing of ipsilateral superior facial muscle function
-LMN lesion will have complete ipsilateral facial paralysis (superior and inferio)
