Head and neuroanatomy Flashcards
What are the foramina present in the middle cranial fossa and what do they transmit
Optic canals: optic nerves and ophthalmic arteries
Superior orbital fissure: oculomotor nerve (CN III), trochlear nerve (CN IV), ophthalmic branch of the trigeminal nerve (CN V1), abducens nerve (CN VI), ophthalmic veins and sympathetic fibres
So it transmits 3,4,6,v1, ophthalmic veins and sympathetic nerves
Rotundum: cn5v2
Ovale: cn5v3 and accessory meningeal artery
Spinosum: Meningeal artery, vein and the meningeal branch of cn5v3
- Hiatus of the greater petrosal nerve – transmits the greater petrosal nerve (a branch of the facial nerve), and the petrosal branch of the middle meningeal artery.
- Hiatus of the lesser petrosal nerve – transmits the lesser petrosal nerve (a branch of the glossopharyngeal nerve).
- Carotid canal – located posteriorly and medially to the foramen ovale. This is traversed by the internal carotid artery
At the junction of the sphenoid, temporal and occipital bones is the foramen lacerum. In life, this foramen is filled with cartilage, which is pierced only by small blood vessels.
What are the foramina of the posterior cranial fossa and what do they transmit
Internal acoustic meatus: It transmits the facial nerve (CN VII), vestibulocochlear nerve (CN VIII) and labyrinthine artery
Foramen magnum: It transmits the medulla of the brain, meninges, vertebral arteries, spinal accessory nerve (ascending), dural veins and anterior and posterior spinal arteries. Anteriorly an incline, known as the clivus, connects the foramen magnum with the dorsum sellae.
Hypoglossal canal: Hypoglossal nerve
Jugular foramen: glossopharyngeal nerve, vagus nerve, spinal accessory nerve (descending), internal jugular vein, inferior petrosal sinus, sigmoid sinus and meningeal branches of the ascending pharyngeal and occipital arteries.
In a scalp laceration, the resting tone of which muscle inhibits closure of the bleeding vessel and surrounding skin?
Occipitofrontalis
What is the nervous innervation of the scalp
Trigeminal Nerve (SSZA)
* Supratrochlear nerve – branch of the ophthalmic nerve which supplies the anteromedial forehead.
* Supraorbital nerve – branch of the ophthalmic nerve which supplies a large portion of the scalp between the anterolateral forehead and the vertex.
* Zygomaticotemporal nerve – branch of the maxillary nerve, this supplies the temple.
* Auriculotemporal nerve – branch of the mandibular nerve which supplies skin anterosuperior to the auricle.
What are the boundaries of the infratemporal fossa
Superiorly: The infratemporal surface of the greater wing of sphenoid
Anteriorly: the infratemporal surface of the maxilla
Posteriorly styloid process
Laterally: Ramus of the mandible
medially: Lateral pterygoid plate
What are the boundaries of the pterygopalatine fossa
- Anterior: Posterior wall of the maxillary sinus.
- Posterior: Pterygoid process of the sphenoid bone.
- Inferior: Palatine bone and palatine canals.
- Superior: Inferior orbital fissure of the eye.
- Medial: Perpendicular plate of the palatine bone
- Lateral: Pterygomaxillary fissure
Anatomy of the sphenoid bone
Greater wing carries: There are three foramina present in the greater wing – the foramen rotundum, foramen ovale and foramen spinosum. They conduct the maxillary nerve, mandibular nerve and middle meningeal vessels respectively.
Lesser wing has: Optic canal through which the optic nerve and ophthalmic artery travel to reach the eye and the superior orbital fissure (which is in the junction of the greater and lesser wing)
Pterygoid process: The lateral and medial pterygoid muscles which form some of the muscles of mastication originate from the lateral pterygoid plate of the sphenoid bone
Anatomy of the ethmoid bone
Another projection of bone descends from the cribriform plate – the perpendicular plate. It forms the superior two-thirds of the nasal septum.
Lastly, the ethmoid bone contains two ethmoidal labyrinths. These are large masses located at either side of the perpendicular plate, which contain the ethmoidal air cells (sinuses). Two sheets of bone form each labyrinth:
- Orbital plate – the lateral sheet of bone, which also forms the medial wall of the orbit
- Medial sheet – forms the upper lateral wall of the nasal cavity, from which the superior and middle conchae extend into the nasal cavity.
How do the cranial nerves emerge
First 2 arise from the cerebrum and the rest arise from the brain stem
* Midbrain – the trochlear nerve (4) comes from the posterior side of the midbrain. It has the longest intracranial length of all the cranial nerves.
* Midbrain-pontine junction – oculomotor (3).
* Pons – trigeminal (5).
* Pontine-medulla junction – abducens, facial, vestibulocochlear (6-8).
* Medulla oblongata (9-12)
o Posterior to the olive: glossopharyngeal, vagus, accessory (IX-XI).
o Anterior to the olive: hypoglossal (XII).
What are the intracranial branches of the facial nerve
o Greater petrosal nerve – parasympathetic fibres to mucous glands and lacrimal gland.
o Nerve to stapedius – motor fibres to stapedius muscle of the middle ear.
o Chorda tympani – special sensory fibres to the anterior 2/3 tongue and parasympathetic fibres to the submandibular and sublingual glands.
What are the nerve branches of the glossopharyngeal nerve
The nerve enters the pharynx by passing between the superior and middle pharyngeal constrictors. Within the pharynx, it terminates by dividing into several branches – lingual, tonsil and pharyngeal.
* Tympanic nerve: sensory innervation to the middle ear, internal surface of the tympanic membrane and Eustachian tube.
* carotid sinus nerve: provide information about blood pressure and oxygen saturation respectively.
* Pharyngeal branch – combines with fibres of the vagus nerve to form the pharyngeal plexus. It innervates the mucosa of the oropharynx.
* Lingual branch – provides the posterior 1/3 of the tongue with general and taste sensation
* Tonsillar branch – forms a network of nerves, known as the tonsillar plexus, which innervates the palatine tonsils.
What helps in opening of the EU tubes and what are the innervations of these muscles
Tensor veli palatini: Tenses the soft palate during swallowing. Larges contribution to tube opening and is innervated by CNV3
Levator Veli Palatini: Vagus
Salpingopharyngeus: Vagus
Tensor tympani
Muscle of the middle ear. It is attached to the cartilaginous portion of the Eustachian tube.
Main action is as part of the acoustic reflex, but a secondary action is to open the Eustachian tube.
Innervated by the mandibular nerve (branch of the trigeminal nerve).
What is the embryological origin of the cerebrum
Proenchephalon
What are the functional divisions of the cerebellum?
- Cerebrocerebellum – the largest division, formed by the lateral hemispheres. It is involved in planning movements and motor learning. It receives inputs from the cerebral cortex and pontine nuclei, and sends outputs to the thalamus and red nucleus. This area also regulates coordination of muscle activation and is important in visually guided movements.
- Spinocerebellum – comprised of the vermis and intermediate zone of the cerebellar hemispheres. It is involved in regulating body movements by allowing for error correction. It also receives proprioceptive information.
- Vestibulocerebellum – the functional equivalent to the flocculonodular lobe. It is involved in controlling balance and ocular reflexes, mainly fixation on a target. It receives inputs from the vestibular system, and sends outputs back to the vestibular nuclei.
Described the blood supply to the cerebellum
The SCA and AICA are branches of the basilar artery, which wraps around the anterior aspect of the pons before reaching the cerebellum. The PICA is a branch of the vertebral artery.
Describe the location and function of the pineal gland
- Pinealocytes – hormone secreting cells.
- Glial cells – supporting cells.
In middle age, the gland commonly becomes calcified, and can be subsequently identified on radiographs and CT scans of the head.
posterior wall of the third ventricle
posterior choroidal arteries are the main supply; they are a set of 10 branches that arise from the posterior cerebral artery.
Venous drainage is via the internal cerebral veins
Where does the pituitary gland receive blood from
Superior and inferior hypophyseal arteries.
The hypophyseal portal system allows communications between the hypothalamus and the pituitary glands and controls the release of hormones
What is the largest part of the brainstem
Pons
What is the blood supply of the scalp
What is the sifnificance of the carotid artery passing through the cavernous sinus
The cavernous sinus is the only site in the body where an artery (internal carotid) passes completely through a venous structure. This is thought to allow for heat exchange between the warm arterial blood and cooler venous circulation.
Describe in detail, the veins of the cerebrum
- Superior cerebral veins: Drain the superior surface, carrying blood to the superior sagittal sinus.
- Superficial middle cerebral vein: Drains the lateral surface of each hemisphere, carrying blood to the cavernous or sphenopalatine sinuses.
- Inferior cerebral veins: Drain the inferior aspect of each cerebral hemisphere, depositing blood into cavernous and transverse sinuses.
- Superior anastamotic vein (Trolard): Connects the superficial middle cerebral vein to the superior sagittal sinus.
- Inferior anastamotic vein (Labbé): Connects the superficial middle cerebral vein to the transverse sinus.
What are the ligaments that keep the odontoid in place
Transverse ligament
Alar ligaments
Superior and inferior ligaments
Where does the medial pterygoid muscle attach
Posteriorly, medial aspect of the angle of the mandible and anteriorly, it runs down from the medial pterygoid plate
What structures pass through the inferior orbital fissure
Infraorbital and zygomatic branches of the maxillary nerve
Inferior opthalmic vein
Branches of the pterygopalatine ganglion
What is the nerve supply of the lacrimal gland
Parasympathetics from the pterygopalatine ganglion, greater pertrosal nerve and this is a branch of the facial nerve
Symp from sup cervical gang
Sensory from the lacrimal branch of the opthalmic nerve
What are the clinical features of an orbital blowout fracture
Enopthalmos
Diplopia
Infraorbital numbness
Orbital emphysema
What is the blood supply of the parotid
Transverse facial artery which is a branch of the ECA
Multiple branches of veins that drain into the internal and external carotid
What structures pass through the parotid gland
Facial nerve
retromandibular vein
ECA branches MA and STA
What atructures pass through the jugular foramen
IJV and CN 9,10,11
What nerves are at risk during carotid surgery
During surgery on the carotid artery (e.g. carotid endarterectomy) the
following nerves are at risk of damage:
vagus nerve (including laryngeal nerve branches)
ansa cervicalis
hypoglossal nerve
sensory branches of the cervical plexus, especially the great auricular nerve
glossopharyngeal nerve
marginal mandibular branch of the facial nerve.
How common is subclavian steam syndrome
2% of the population has it and out of these 5% will have symptoms
Where does the blood supply of the scalp run
In the superficial connective tissue layer. This is why when a flap is raised, it is subgaleal as it provides an easy plane of dissection and is less bloody
What nerves can be damaged during submandibular gland surgery
The following nerves are at risk during submandibular gland surgery:
lingual nerve
nerve to mylohyoid
hypoglossal nerve
marginal mandibular nerve
Which muscle separates the submandibular gland into deep and superficial lobes
The mylohyoid muscle forms the floor of the mouth. The submandibular gland
is wrapped around the free posterior border of this muscle, thus separating the
gland into superficial and deep lobes.
What is the secretory nerve supply of the submandibular gland
Secretion of saliva is stimulated by parasympathetic fibres that run in the
chorda tympani branch of the facial nerve. The chorda tympani hitch-hikes
with the lingual nerve (sensory branch of the mandibular division of trigeminal
nerve). These fibres synapse in the submandibular ganglion, and then the
postganglionic fibres pass directly into the gland
Compare the acini types of the salivary glands
The parotid gland is composed of predominantly serous acini, the
submandibular gland has a mixture of serous and mucous acini, and the
sublingual gland has almost all mucous acini.
When does the frontal sinus develop
At 8 years old
What is the innervation of the muscles of the palate
All of the muscles of the palate are supplied by the pharyngeal plexus (vagus
and accessory nerves), apart from the tensor veli palatini, which is supplied by
the mandibular division of the trigeminal nerve (branch to medial pterygoid
muscle).
What are the muscles of the palate
There are five paired muscles that act on the soft palate:
tensor veli palatini
levator veli palatini
palatoglossus
palatopharyngeus
muscularis uvulae.
The tensor veli palatini arises from the medial pterygoid plate, auditory
tube and spine of sphenoid. It descends to the pterygoid hamulus and hooks
around this bony point. From here the tendon opens into a broad aponeurosis,
which blends with the aponeurosis of the opposite side. The hamulus changes
the direction of pull of the muscle. Instead of elevating the soft palate it pulls it
laterally, thus flattening and tensing the palate. The levator veli palatini arises
from the petrous temple bone in front of the carotid canal. The paired muscles
slope down in a V to attach to the soft palate. As the name implies, they elevate
the palate, thus closing it against the posterior pharyngeal wall (Passavant’s
ridge). This prevents the passage of food into the nasopharynx during
swallowing. Both the tensor and levator muscles also open the cartilaginous
auditory tube to allow equalisation of middle ear pressure. The palatoglossus
arises from the palate and inserts into the lateral portion of the tongue. These
muscles form the anterior pillars of the fauces and form the junction between
mouth and pharynx. Their action is to raise the tongue and depress the palate.
The palatopharyngeus arises from both the hard and the soft palate. These
What are the muscles supplied by the marginal mandibular nerve
The marginal mandibular branch of the facial nerve supplies the mentalis,
depressor anguli oris and depressor labii inferioris.
What is the most superior part of the cranium called
The vertex
Are there any areas of the skull that are not covered by periosteum
THe lateral skull temporal fossa where the temporalis muscle lie. The periosteum is continuous with the temporalis fascia
How many bones does the sphenoid bone articulate with
temporal
parietal
frontal
Vomer
occipital
zygomatic
palatine
ethmoidal.
What are the muscles supplied by CN5
Muscles of mastication
Mylohyoid
Ant belly of diagastric
Tensor tympani
What is the cat of nine tails arrangement of the CNV3
Anterior group:
− two branches to lateral pterygoid
− two branches to temporalis
− nerve to masseter
− buccal nerve (only sensory branch).
Posterior group:
− auriculotemporal nerve
− lingual nerve
− inferior alveolar nerve (gives off nerve to – myelohyoid – only motor
branch)
What structures pass through the foramen OVALE
OVALE
O - Otic ganglion
V - V3
A - Accessory meningeal artery
L - lesser petrosal nerve
E - emissary veins
What are the emissary veins
They are intra and extracranial veins
What is the anatomy of the cavernous sinus
The cavernous sinuses are paired venous sinuses about 2 cm long on either side of
the sella turcica and lateral to the sphenoid air sinuses, immediately posterior to the
optic chiasm. Draining into these sinuses are the superior and inferior ophthalmic
veins, the superficial middle cerebral vein and the sphenoparietal sinuses. The
cavernous sinuses communicate with each other via the intercavernous sinuses and
drain into the inferior and superior petrosal sinuses.
What are the 3 main branches of the internal carotid artery
ophthalmic artery
anterior choroidal artery
Posterior communicating artery
What are the 2 terminal branches of the ICA
MCA and ACA and the MCA is bigger
What are the branches of the basilar artery
The basilar artery gives off four major branches:
L pontine branch
L anterior inferior cerebellar artery
L labyrinthine artery
L superior cerebellar artery.
It then terminates by dividing into the left and right posterior cerebral
arteries
What are gyri and sulci
Gyri are elevated folds on the cerebral hemisphere, and sulci are the grooves
between them. This structural pattern serves to increase the surface area of the
cerebrum
Location of broca and wernike areas
There are two distinct areas within the brain that are responsible for speech.
Broca’s area is one of these; it is located in the left inferior frontal gyrus
(Brodman areas 44 and 45). It is named after the French pathologist Pierre
Broca.
9. Wernicke’s area is the other region that contributes to speech function. It is
located in the left posterior part of the superior temporal gyrus (Brodman area
22). It is named after the German neurologist Carl Wernicke.
Where does the optic tract terminate
The optic tract terminates in the lateral geniculate body of the thalamus and the
visual cortex in the occipital lobe.
What are the branches of the oculomotor nerve
The oculomotor (third cranial) nerve has superior and inferior divisions. The
superior division supplies superior rectus and levator palpebrae superioris
muscles. The inferior division supplies inferior and medial rectus, inferior
oblique, and the ciliary and sphincter pupillae muscles.
What goes through all of the foramina
What is the cranial nerve track on the clivus?
Abducens
What is the juvenile structure that forms from the clivus
Spheno-occipital synchondrosis
Benign tumors of the posterior cranial fossa?
- Hemangioblastoma * Acoustic neuroma * Ependymoma * Ependymoblastoma
What is the blood supply to the temporalis muscle
Deep temporal arteries from the maxillary artery
What are the cranial nerves that transmit parasympathetic fibres
The only cranial nerves that transmit parasympathetic fibers are the Oculomotor (III), Facial (VII), Glossopharyngeal (IX), and Vagus (X) nerves
What is the surface anatomy and the opening of the parotid duct
Surface anatomy? The middle ⅓ of a line drawn between intertragic notch to the middle of the philtrum
Opening? Crosses the masseter, pierces the buccinator and drains adjacent to the 2nd upper molar tooth (Stensen’s duct).
What are the structures passing through the parotid gland
Facial nerve (most superficial structure) (“The Zebra Buggered My Cat” Temporal Zygomatic, Buccal, Mandibular, Cervical)
* External carotid artery * Retromandibular vein * Auriculotemporal nerve (from posterior trunk of V3) * Deep parotid lymph nodes
What is the surface anatomy of the parotid gland
Upper end: curved line from the tragus to the center of mastoid bone * Anterior border: a line from the tragus of the ear to the center of the posterior border of the masseter then to the point 2 cm below and behind the angle of the mandible
* Posterior border: straight line from the mastoid process to a point 2cm below and behind the angle of the mandible
What is the roof of the middle ear
Tegmen tympani
What are the relations of the middle ear
- Roof (Tegmental wall): Tegmen tympani; separates tympanic cavity from MCF
- Floor (Jugular wall): Thin bone separates tympanic cavity from superior bulb of IJN
- Anterior wall: Thin bone; separates tympanic cavity from ICA and at its upper part are openings into two canals (auditory tube and canal for tensor tympani)
- Posterior wall (mastoid wall): Aditus to the mastoid antrum superiorly and pyramid inferiorly (for stapedius)
- Lateral wall (membranous wall): Tympanic membrane (doesn’t extend superiorly) and lateral wall of epitympanic recess (superiorly)
- Medial wall: Lateral wall of the inner ear
Where does the foramen lacerum lie
Lateral to the clivus
What lies posterior to the clivus and what is the cranial nerve that tracks on it
Basilar artery
CNVI tracks on it
What derivatives ant and post diagastric
Ant is 1st and post is 2nd pharyngeal arch derivative
Where can the lingual artery be found
Deep to the hyoglossus muscle
what is the name of the juvenile structure that form the clivus?
Sphenooccipital synchondrosis
What is the difference in location between the carotid body and the carotid sinus
carotid body: on the post.aspect of the bifurcation of CCA contains
chemoreceptors sensitive to changes in PH.
carotid sinus: the carotid sinus is a dilated area at the base of the internal carotid artery
just superior to the bifurcation of the internal carotid and external carotid at the level of the
superior border of thyroid cartilage. It contains baroreceptors for maintaining blood
pressure
Parasagittal haematoma
It arises from the arachnoid cap cells of the arachnoid villi in the meninges
What is meant by a ring-enhancing lesion
What is meant by ring enhancement : is an abnormal radiologic sign on MRI or CT scans obtained using radiocontrast. On the image, there is an area of decreased density, surrounded by a bright rim from concentration of the enhancing contrast dye. This enhancement may represent breakdown of the blood-brain barrier and the development of an inflammatory capsule
This could be because of
M: metastasis A: abscess G: glioblastoma I: infarct (subacute phase) C: contusion D: demyelinating disease R: radiation necrosis or resolving hematoma
Where does the isthmus of the thyroid gland lie
C7
How many spinal nerves are in total
There are 31 pairs of spinal nerves: 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal.
