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HEAD VIVAS Sample viva, 2010-2 (skull), 2010-1, 2009-1, 2008-2 (skull), 2006-2, 2005-2, 2004-2 (skull) (X-Ray – AP face) What bony landmarks can you demonstrate on this film? Bones Nasal Maxilla Zygomatic Sphenoid Mandible Lacrimal Vomer Ethmoid Frontal Mandible Sinuses Frontal Maxillary Ethmoid Mastoid What bones form the orbital margins? Margins = rim: Frontal -> maxilla -> zygomatic - Superior wall: Orbital part of frontal bone, w/ trochlea spine - Medial wall: Orbital plate of ethmoid (paper thin), lacrimal w/ fossa and maxilla - Inferior wall: Maxilla continues around to meet zygomatic, thin and shared w/ maxillary sinus - Lateral wall: demarcated by the inferior orbital fissure, formed by frontal process of zygomatic - Apex: the lesser wing of the sphenoid with the optic cnal and superior orbital fissure laterally What structures pass through the superior orbital fissure? 2008-2 - Opthalmic nerve (V1) - Occulomotor nerve (III) - Trochlear nerve (IV) - Abducens nerve (VI) - Opthalmic veins - Sympathetic fibres Where would you expect to find the infraorbital nerve? What structures does it innervate? - From V2 – maxillary nerve - Via inferior orbital fissure -> infraorbital groove/canal -> infraorbital foramen - Supplies: Maxillary sinus, medial maxillary teeth, inferior eyelid, cheek, lateral nose, anterior tip of nasal septum, skin and oral muscosa of upper lip 2010-2, 2009-1 (post circ), 2007-2 (MCA), X-ray: CT Head Identify the non–bony features on this CT scan. - Orbits - Temporal lobes in middle cranial fossa - Pons - 4th ventricle - Cerebellum and vermis Which bony sinuses are shown? Ethmoid, sphenoid, mastoid What is the blood supply of the cerebellum? Vertebral –> Basilar –> SAP (superior, anterior inferior, and posterior inferior) cerebellar arteries Identify the anatomical features on this CT scan through base of the skull 2009-2 - Bones: Occipital (w/ internal occipital protuberance), temporal (w/ petrous part/ridge), sphenoid (w/ dorsum sellae/posterior clinoid and anterior clinoid processes), nasal - Air spaces: Mastoid air cells, sphenoid sinus, ethmoid sinus, nasal cavity - Intracranial: 4th ventricle, cerebellum, vermis, temporal lobes, pons 2007-2 X-ray: CT Brain Basal ganglia: Caudate nucleus Putamen Globus pallidus Claustrum 2007-2 Name the visible intracranial structures on this noncontrast CT scan - Lobes: (frontal,parietal/temporal,occipital) - Lateral ventricles: (B)anterior and (F) posterior horns - Choroid plexus (F) - Pineal gland (E) - Thalamus (D) - Straight sinus (G) - Internal capsule (C) - 3rd ventricle - Basal ganglia - Sylvian/lateral fissure (not shown) Describe the circulation of CSF - 400-500ml/day formed in choroidal epithelial cells (plexus) in lateral, 3rd and 4th ventricles - Lateral ventricles -> 3rd ventricle via intraventricular foramina - 3rd ventricle—> 4th ventricle via aqueduct - Some CSF passes into subarachnoid space via median and lateral apertures - Most CSF passes into interpeduncular and quadrigeminal cisterns - CSF from the various subarachnoid cisterns flows superiorly through sulci and fissures on medial and superolateral surfaces of the cerebral hemispheres - Absorbed in arachnoid granulations esp. those that protrude into superior sagittal sinus What are the functions of CSF - Protects brain by providing cushion effect - Buoyancy effect to prevent compression of nerves and vessels 2010-1, 2009-1 (CT – post circulation), 2008-2, 2006-2 Draw or describe the circle of Willis - - A ferocious spider lives in the brain. His name is Willis! Note that he has a nose [pituitary gland], two suckers [mamillary bodies], eyes that look outward [internal carotid arteries], a crew cut [anterior communicating artery - blood flows in either direction], antennae [anterior cerebral arteries], a fuzzy beard [posterior communicating arteries again, blood flows in either direction], 8 legs, a belly that, according to your point of view, is either thin (basilar artery) or fat (the pons), two feelers on his rear legs [posterior inferior cerebellar arteries], and male genitalia [anterior spinal artery] Willis has hairy armpits – the third cranial nerve exists between the posterior cerebral artery and the superior cerebellar artery [the first two sets of legs]. The cerebellar arteries were named by a real SAP (S – superior, A – anterior inferior, and P – posterior inferior) [SA - the last two sets of legs] and supply the cerebellum and brainstem. Which part of the brain is supplied by each of the major arteries ACA - medial/sup surface of cerebrum except occipital lobe MCA - Lateral surfaces of both cerebral hemispheres excluding anterior part of frontal lobe and occipital lobe, including basal ganglia but not thalamus PCA - occipital lobe, inferior cerebrum What areas of the brain do the main arteries of the posterior circulation supply 2009-1 - Vertebral: cranial meninges & cerebellum (via AP) - Basilar: brainstem, cerebellum (via S) & cerebrum - Posterior cerebral: inferior aspect of cerebral hemispheres & occipital lobe - Posterior communicating: optic tract, cerebral peduncle, internal capsule and thalamus What motor and sensory areas lie in distribution of middle cerebral artery 2006-2 - Precentral gyrus (motor area) -> opposite half of body except legs and perineum - Post central gyrus (sensory area) -> opposite half of body except legs and perineum - Auditory and speech areas 2011-2 (discuss), 2009-2, 2007-2, 2005-1 Model: Orbit. Extraocular muscles and eye movements Identify the muscles responsible for eye movement and describe their function and nerves SR Elevates Medial rotation III MR Adducts IR Depresses Lateral rotation IO Elevates Lateral rotation LR Abducts VI SO Depresses Medial rotation IV Medial rotation = intorsion, lateral rotation = extorsion SO and IR act together to depress What are the effects of an oculomotor (CN III) nerve palsy? 2011-2, 2007-2 1. Ptosis (levator palpebrae superioris paralysis, unopposed orbicularis oculis by VII) 2. Dilated pupil fixed pupil (sphincter pupillae paralysis, unopposed dilator pupillae) 3. Adducted and depressed -> “pupil down and out” (unopposed LR and SO) What is the effect of a trochlear (CN IV) nerve lesion? 2005-1 1. Loss of superior oblique, over activity of inferior oblique 2. Diplopia when looking in (walk down stairs, reading) 3. Extorsion - compensate by tilting to opposite shoulder Additional: Abducent (CN VI) nerve palsy 1. Lateral rectus paralysis 2. Loss of abduction 3. Unopposed action of MR -> adduction 2006-2, 2006-1 Model: Eye Using the model, describe the structures of the eye. - Vitreous body Lens Ant & post chambers (aqueous humour) Iris Pupil Describe the structure of the walls of the eyeball 1. Fibrous: cornea, conjunctiva, sclera 2. Vascular (uveal tract): choroid, ciliary body, iris 3. Nervous: retina, optic disc, macula Describe the pupillary light reflex arc 2006-2 Afferent: Light –> retina -> CN II (optic nerve) -> Pretectal nucleus –> both Edinger-Westphal nuclei Efferent: preganglionic parasympathetic CN III to ciliary ganglion -> short ciliary -> sphincter pupillae Dilator pupillae: is from cervical sympathetics, via internal carotid a, CNV1 (nasociliary) -> long ciliary Describe the formation and drainage of aqueous humour 2006-1 1. Production by ciliary processes (capillary diffusion) 2. Enters posterior chamber 3. Passes thru pupil to anterior chamber 4. Filters thru iridocorneal angle to Canal of Schlemm 5. Drains into anterior scleral veins 2008-1 Model: Tongue and muscles On this model, identify structures that make up the floor of the mouth - Mandible - Tongue (intrinsic m: sup long, trans, vert, inf long) - Lips - Teeth - Geniohyoid muscle - Hyoid bone - Stylohyoid muscle - Genioglossus muscle Describe the innervation of the tongue Motor - All except palatoglossus innervated by CN XII (Hypoglossal) - Palatoglossus is actually a palatine m, therefore supplied by pharyngeal plexus (CN X, vagus) Sensation, Anterior 2/3 - Touch and temperature by lingual nerve (branch of CN V3, mandibular) - Taste for ant 2/3 (not vallate papillae) is via chorda tympani (branch of CN VII), the chorda tympani joins the lingual and runs anteriorly in it’s sheath Sensation, Posterior 1/3 of tongue and vallate papillae, both general sensory and taste are supplied by the lingual branch of glossopharyngeal (CN IX) Twigs of internal laryngeal (branch of vagus CN X) supply mostly general but some special sensation to a small area of tongue just anterior to epiglottis. These mostly sensory fibres also carry parasympathetic secretomotor fibres to serous glands of tongue Parasympathetic fibres from chorda tympani travel with lingual to submandibular and sublingual salivary glands -> synapse in the submandibular ganglion which hangs from the lingual nerve 2008-1, 2005-1 Bone: Mandible Demonstrate the features of the mandible - Condylar process (head & neck) Notch Coronoid process Ramus Angle Body Mental foramen Mandibular foramen with lingula Mental tubercle and symphysis Alveolar process Describe the features of the TM Joint Bones: Condyle of mandible, articular tubercle, mandibular fossa Disc: separates superior synovial cavity (gliding in/out) and inferior synovial cavity (hinge up/down) Stability from: - Postglenoid tubercle and temperomandibular (lateral) ligament prevents posterior dislocation - Stylomandibular (styloid to angle) and Sphenomandibular (sphenoid to lingual) ligaments are medial and weak - Shape, joint capsule, teeth occlusion, muscles Describe the mandibular attachments of the muscles of mastication Temporalis: temporal fossa -> medial coronoid & anterior ramus Masseter: maxillary process & zygomatic arch -> angle & lateral ramus Lateral Pterygoid: greater wing sphenoid and ateral surface Lateral Pterygoid Plate -> joint capsule, disc & pterygoid fossa on neck of mandible Medial Pterygoid: medial surface Lateral Pterygoid Plate & tuberosity of maxilla -> medial ramus below foramen 2006-1 Face - Sensory distribution to the ear Identify the sensory supply to the pinna - Greater auricular nerve (C2,3): Cranial surface and lower half - Auriculotemporal (V3): Upper half and most of the meatus What other nerves supply the ear and the canal. - Lesser occipital - Vagus - Glossopharyngeal - Facial nerve allowing for the tympanic membrane 2011-2 Discuss: Trigeminal Nerve (CN V) What are the main branches of the trigeminal nerve Nerve Foramina Supplies V1: Opthalmic Superior orbital fissure Suprorbital, supratochlear, lacrimal, infratrochlear, Sensory external nasal, anterior and posterior ethmoidal V2: Maxillary Foramen rotundum Zygomatico-temporal, zygomatico-facial, infraorbital, Sensory pterygopalatine ganglion V3: Mandibular Foramen ovale Auriculotemporal, buccal, inferior alveolar, mental Sensory V3: Mandibular Anterior trunk -> muscles of mastication: temporalis, Motor masseter, lateral and medial pterygoid (also tensor tympani and myohyoid) All three divisions supply meningeal branches also to supply dura of anterior (V1 and V2) and middle (V2 and V3) cranial fossa and tentrorium (V1). The posterior fossa is via C2 and C3 fibres. Bonus Q: Which nerve branch would you anaesthetize before repairing a lower lip laceration Mental nerve: as it emerges from mental foramen (terminal branch of inferior alveolar nerve, which in turn is a branch of mandibular division). 2010-2 (discuss), 2006-2 (discuss), 2005-2, 2005-1, 2003-2 Photo: Face (pg 49) Please identify the branches of the facial nerve on this photograph. 1. 2. 3. 4. 5. Temporal Zygomatic Buccal Mandibular Cervical Mnemonic: “Please Tell Ziggy Bob Marley Called” Please identify and name some facial muscles innervated by the facial nerve. 1. Temporal: frontal belly of occipitofrontalis, auricularis, superior obicularis occuli 2. Zygomatic: inferior orbicularis oculi, zygomaticus major, zygomaticus minor 3. Buccal: buccinator, nasalis, levator labii superioris 4. Mandibular: orbicularis oris, depressor anguli oris, depressor labii inferioris, mentalis 5. Cervical: platysma Please describe the course of the facial nerve once it exits the skull base. - Through stylomastoid foramen, near the origin of digastric - Gives of the posterior auricular branch - Divides into superior and inferior divisions - Before entering the posteromedial surface of the parotid gland - Within which it forms the parotid plexus (pes anserinus) divides into 5 branches What other branches are there of this nerve? 2010-2, 2006-2 Intermediate nerve: Carries the sensory and parasympathetic fibers of the facial nerve - Via greater petrosal nerve -> pterygopalatine ganglion: parasympathetic fibres to lacrimal gland, sinuses and nasal cavity - Via chorda tympani (w/ lingual nerve) -> special sensory taste fibers for anterior 2/3 of tongue, and parasympathetic secretomotor via submandibular ganglion to submandibular and sublingual glands The facial nerve also supplies the stapedius muscle prior to exiting the skull.
