Head and Neck Revision Lecture PDF

Head and Neck Kartik Iyer Disclaimers - Huge credits to Daniel Ameen for his H&N Presentation, and to Monique Wisnewski and Fawzan Sugarwala - I cannot cover all of H&N in this presentation - I will give a brief overview of the most important/tough to grasp concepts - This...

Head and Neck Kartik Iyer Disclaimers - Huge credits to Daniel Ameen for his H&N Presentation, and to Monique Wisnewski and Fawzan Sugarwala - I cannot cover all of H&N in this presentation - I will give a brief overview of the most important/tough to grasp concepts - This is gonna be heavy on anatomy… - Know your cranial nerves! Know the origin, route, functions, hitchhikers - Focus your revision on the clinical aspects of anatomy - e.g. sure you know the cerebral circulation but how a stroke presents will vary depending on where the pathology is - Embryology does matter a lot here!!!  01 Cranial Anatomy Bone Voyage! (Sorry it’s not that humerus) Neurocranium and Viscerocranium Neurocranium Know the relations with the sphenoid bone - lots of structures pass through the foramina in the sphenoid Question Men Inges, 24M, is playing soccer and is hit on the side of his head by a flying A. Shearing of the bridging veins soccer ball. He loses consciousness, and between the dura and cerebrum eventually wakes up, but is drowsy, and B. Laceration of the middle gradually becomes comatose. He is rushed meningeal artery to emergency, where a CT Brain finds a C. Rupture of small vessel fracture at the site of impact, and a bleed. aneurysms Which of the following accurately describes D. Bleeding disorder the pathophysiology of this bleed? Question Men Inges, 24M, is playing soccer and is hit on the side of his head by a flying A. Shearing of the bridging veins soccer ball. He loses consciousness, and between the dura and cerebrum eventually wakes up, but is drowsy, and B. Laceration of the middle gradually becomes comatose. He is rushed meningeal artery to emergency, where a CT Brain finds a C. Rupture of small vessel fracture at the site of impact, and a bleed. aneurysms Which of the following accurately describes D. Bleeding disorder the pathophysiology of this bleed? Sutures and Fontanelles Fontanelles Fontanelles → allow for some laxity in the skull so the brain can grow Fontanelles can tell us what is going on inside the skull Sunken → Dehydration? Bulging fontanelle → brain problem , raised ICP? Raised ICP → Macrocephaly in children rather than brain compression in adults Epidural Hematoma Classic epidural haematoma presentation: ○ LOC → lucid → deterioration ○ Brain shock → bleeding → cerebral herniation CT Brain - lenticular (biconvex) shaped density, limited by suture lines Most common cause - trauma to pterion (e.g. sports injuries, MVA) Management - Craniotomy and hematoma evacuation Question Mrs Willis (75F) has a fall in her A. Concave, crescent-shaped kitchen, and is admitted to hospital for density on the outer border of the observation. On examination, you hemisphere notice a bruise on her forehead. Over B. Biconvex, lenticular density that the next week, she develops a does not cross suture lines worsening headache and becomes C. Diffuse patchy densities within confused, and starts to vomit. What the parenchyma findings do you expect on CT Brain? D. Discrete rounded mass in the frontal cortex Question Mrs Willis (75F) has a fall in her A. Concave, crescent-shaped kitchen, and is admitted to hospital for density on the outer border of observation. On examination, you the hemisphere notice a bruise on her forehead. Over B. Biconvex, lenticular density that the next week, she develops a does not cross suture lines worsening headache and becomes C. Diffuse patchy densities within confused, and starts to vomit. What the parenchyma findings do you expect on CT Brain? D. Discrete rounded mass in the frontal cortex Subdural Hematoma Bleeding into subdural space due to shearing of bridging veins Risk factors - elderly, anticoagulation, alcoholics, blunt trauma (e.g. falls) More gradual onset of symptoms than EDH, more likely to have fluctuations in consciousness rather than complete unconsciousness CT Brain - concave, crescent-shape density (hyperdense if acute, hypodense if chronic) Can cross suture lines, but not midline Management - conservative or burr hole/craniotomy Meninges Dural folds Scalp Arterial supply: External carotid artery ○ Superficial temporal - frontal and temporal regions ○ Posterior auricular - superior and posterior to the auricle ○ Occipital - back of scalp Ophthalmic artery ○ Supraorbital - accompanies nerve ○ Supratrochlear - accompanies nerve Veins - superficial follows arteries, deep drains into pterygoid venous plexus -> maxillary v Innervation - CN V (anterior to vertex and ear auricle), C2/C3 (posterior to vertex and auricle)  Clinical features 💡 Loose connective tissue = danger zone Contains emissary veins - valveless veins connecting the extracranial scalp veins to the intracranial dural venous sinuses Pathway for infection spread into the brain Why do deep scalp lacerations bleed HEAPS?! The pull of the occipitofrontalis muscle prevents the closure of the bleeding vessel The scalp’s vessels are adhered to deep connective tissue, preventing the usual vasoconstriction The blood supply of the scalp is made up of many anastomoses, contributing to profuse bleeding  02 Cranial Nerves “Where did you come from, where did you go” Question Which of the following nerves emerges A. Optic n from the posterior cranial fossa? B. Oculomotor n C. Hypoglossal n D. Abducens n Question Which of the following nerves emerges A. Optic n from the posterior cranial fossa? B. Oculomotor n C. Hypoglossal n D. Abducens n Cranial Base and Foramina Not that scary… CN I (Olfactory n) exits most anteriorly, CN XII (Hypoglossal) exits most posteriorly Most important foramina - optic canal, superior/inferior orbital fissures, foramen rotundum, foramen Ovale, internal acoustic meatus, jugular foramen, hypoglossal canal Foramen magnum - spinal cord Cranial Foramina  Foramen Structures Conducted Cranial Fossa Cranial Bone Cribriform Olfactory n. (CN I) Anterior Ethmoid Anterior ethmoidal nerves Optic canal Optic nerve (CN II) Ophthalmic artery Superior orbital fissure Lacrimal n. Frontal n. (branch of CN V) Occulomotor n.(CN III) Nasociliary n. (branch of CN V1) Middle Sphenoid Abducens n. (CN VI) Branch of inferior ophthalmic v. Foramen rotundum Maxillary branch of trigeminal n. (CN V) Foramen ovale Mandibular branch of trigeminal n. (CN V) Foramen spinosum Middle meningeal a. Middle meningeal v. Sphenoid Meningeal branch of CN V3 Middle Internal acoustic meatus Facial n. (CN VII) Petrous part of Vestibulocochlear n. (CN VIII) temporal bone Vestibular ganglion Lanyrinthe a. Jugular foramen Glossopharyngeal n. (CN IX) Anterior aspect: Vagus n. (CN X) petrous part of Accessory n. (CN XI) temporal bone Jugular bulb Inferior petrosal and sigmoid Posterior Posterior aspect: sinuses Occipital bone Hypoglossal canal Hypoglossal n. (CN XII) Foramen magnum Vertebral aa. Medulla and meninges CN XI (spinal division) Occipital bone Dural veins Anterior and posterior spinal aa. Learning Cranial Nerves is like this… Cavernous sinus Danger Triangle of Face Region between the corners of the mouth and the top of the nose Veins here can either drain superficially into facial v then IJV, or deep into the cavernous sinus Any infections (e.g. from abscesses, infected wounds) in this region can spread into the cranium and then lead to cavernous sinus thrombosis, meningitis, sepsis Which of the following is true of the trigeminal nerve? A. It is a parasympathetic nerve, providing innervation to the lacrimal gland via the ophthalmic division of the trigeminal nerve B. It is a purely sensory nerve C. It innervates tensor tympani D. It exits through the foramen ovale Which of the following is true of the trigeminal nerve? A. It is a parasympathetic nerve, providing innervation to the lacrimal gland via the ophthalmic division of the trigeminal nerve- it is NOT a parasympathetic nerve!!! It allows for hitchhiking from CN. more on this soon… B. It is a purely sensory nerve → motor function for muscles of mastication + a few other muscles C. It innervates tensor tympani → true. It innervates muscles of mastication + tensor veli palatini, tensor tympani, mylohoid D. It exits through the foramen ovale → V3 does but trigeminal nerve itself doesn’t Main divisions Sensory innervation to the face AND innervation to muscles of mastication V1 - ophthalmic (purely sensory) - exits via Superior orbital fissure V2 - Maxillary (purely sensory) - exits via foramen rotundum into the pterygopalatine fossa V3 - Mandibular (Sensory AND motor) - exits via foramen ovale into infratemporal fossa NOT A PARASYMPATHETIC NERVE - but parasympathetic fibres from other nerves hitchhike (convenient) Trigeminal ganglion Divided into 3 branches in cavum trigeminale V1 AND V2 go into the cavernous sinus then leave the skull Motor and sensory root V1 - Ophthalmic nerve Many branches and many many more subbranches: Frontal nerve → divides further to give sensation of forehead Lacrimal nerve - parasympathetic + sensory fibres Sensory innervation of lacrimal gland HITCHHIKING Parasympathetic fibres from the facial nerve (VII) synapse at the pterygopalatine ganglion and travel with zygomatic branch of V2 THEN with lacrimal branch of V1 Nasociliary nerve - sensory + sympathetic → does sensation of the cornea + sinuses Sympathetics getting to the dilator pupillae (from superior cervical ganglion) → NO ACTUAL PARASYMPATHETICS, JUST HITCHHIKERS  V2 - Maxillary nerve Goes through foramen rotundum -> pterygopalatine fossa -> then branches course through inferior orbital fissure Function: ○ Sensory innervation to: Lower eyelid and its conjunctiva Inferior posterior portion of the nasal cavity Lateral nose Cheeks and maxillary sinus Upper lip, teeth, gingiva and palate Parasympathetic innervation to: ○ Lacrimal gland (VII → V2 zygomatic branch → V1) ○ Mucous glands of the nasal mucosa (VII → V2 nasopalatine and greater palatine) Again, these fibres do not originate from the trigeminal nerve  V3 - Mandibular nerve branches From the trigeminal ganglion, V3 exits the cranial cavity through the foramen ovale, passing through the infratemporal fossa to give rise to 4 sensory branches: Auriculotemporal nerve (actually the convergence of two separate roots) ○ Superior root → Sensory fibres →Anterior auricle, external acoustic meatus and tympanic membrane ○ Lateral temple ○ Inferior root → Parasympathetic fibres from CN IX → Otic ganglion → Parotid Buccal → Sensory fibres only ○ Buccal membranes of the mouth (cheek) ○ 2nd and 3rd molar teeth Mylohyoid branch → Motor nerve to mylohyoid and anterior digastric Inferior Alveolar → Sensory and motor ○ Remaining sensory fibres run through the mandibular canal to supply the mandibular teeth V3 - Mandibular nerve - branches After emerging from the mental foramen it becomes the mental nerve → sensation to lower lip and chin Special note about the Lingual Nerve → Sensory only ○ General sensory fibres → Anterior ⅔ of tongue ○ Special sensory fibres (taste) to the anterior ⅔ of tongue is from CN VII but travels with lingual - HITCHHIKER! ○ Autonomic fibres from CN VII also follow lingual → submandibular ganglion → submandibular and sublingual glands - HITCHHIKER! V3 - mandibular nerve (motor) Muscles of mastication (masseter medial and lateral pterygoid, temporalis) Tensor tympani Tensor veli palatini Suprahyoid muscles - both innervated by n to mylohyoid ○ Anterior belly of digastric (posterior is innervated by facial nerve) ○ Mylohyoid muscle Mnemonic - Rule of 2s - 2 big muscles (masseter + temporalis) - 2 pterygoids - 2 tensors - 2 muscles on the floor of the mouth (anterior digastric, mylohyoid) TMJ Arch 1 derivatives → V3 4 muscles → mandibular nerve Muscles: Masseter, temporalis, medial/lateral pterygoids - All muscles elevate except lateral pterygoid - Lateral pterygoids protract - Do not memorise attachments - be aware of function and innervation!! Question A Surgeon is removing a deep infratemporal fossa tumor. Whilst operating, he accidentally cuts the lingual nerve immediately at its origin. Which of the following will occur? A. Somatic sensation to the anterior ⅔ of the tongue will be lost B. Taste sensation to the anterior ⅔ of the tongue will be lost C. Reduced salivation from the submandibular gland D. Reduced salivation from the sublingual gland Question A Surgeon is removing a deep infratemporal fossa. Whilst operating, he accidentally cuts the lingual nerve immediately at its origin. Which of the following will occur? A. Somatic sensation to the anterior ⅔ of the tongue will be lost - V3 portion of the lingual nerve is gone. B. Taste sensation to the anterior ⅔ of the tongue will be lost - chorda tympani is fine C. Reduced salivation from the submandibular gland - chorda tympani is fine D. Reduced salivation from the sublingual gland - chorda tympani is fine Infratemporal fossa and pterygopalatine fossa Infratemporal fossa: between ramus of mandible and wall of the pharynx Diagram shows site of pterygopalatine fossa → important content is the pterygopalatine ganglion Key arteries course through here Key cranial nerve branches course (remember the pic of the interchange I showed earlier? This is what I meant) Infratemporal fossa relevance - super high yield! Chorda tympani = taste sensation to anterior ⅔ + preganglionic parasympathetics Lingual nerve (V3 portion) - Somatic sensory components A lesion will produce sensory deficits depending on it occurs before or after they join together Key Structures of Infratemporal Fossa- Maxillary artery Remember the middle meningeal artery? It originates from the Maxillary a in the infratemporal fossa, then courses into the cranium Enters cranium at Foramen Spinosum Continues on as the sphenopalatine artery into the pterygopalatine fossa Question A surgeon is resecting a parotid gland tumor. Which of the following is not at risk during this procedure? A. Facial nerve B. Auriculotemporal nerve C. Retromandibular vein D. Internal jugular vein E. External carotid artery Question A surgeon is resecting a parotid gland tumor. Which of the following is least at risk during this procedure? A. Facial nerve B. Auriculotemporal nerve C. Retromandibular vein D. Internal jugular vein E. External carotid artery Parotid gland Contents of the parotid gland (Superficial → deep) Facial nerve (5 terminal branch) Retromandibular vein External carotid artery - gives off terminal branches in the parotid gland Lymph nodes Innervation of parotid gland - Very Important Parasympathetic innervation (salivation) for the parotid gland is: Preganglionic : Lesser petrosal nerve branch of glossopharyngeal nerve Ganglion : Otic ganglion Post-ganglionic: auriculotemporal nerve  Submandibular and sublingual glands The submandibular and sublingual glands are separated by the mylohyoid muscle Surgical problems/considerations - Below submandibular duct is the lingual nerve → prone to injury surgically - Facial a. Courses through submandibular gland (see diagram)  Functions: CN VII - Facial nerve MOTOR: Muscles of facial expression, posterior belly of digastric, stylohyoid and Derived from the second pharyngeal arch stapedius muscles SENSORY: Small area around the concha Course - intracranial: of the external ear Arises in the pons (brainstem) as motor SPECIAL SENSORY: Taste to anterior ⅔ and sensory root of the tongue via chorda tympani Travel out of the acoustic meatus into PARASYMPATHETIC: Glands; the facial canal, after which the roots submandibular, sublingual, nasal, palatine, fuse pharyngeal mucous, lacrimal Forms the geniculate ganglion Course - extracranial: Gives off: greater petrosal nerve Gives off: posterior auricular nerve (motor) (parasympathetic), nerve to stapedius Travels through the parotid gland (but doesn’t (motor) and chorda tympani (special innervate it) as the motor root sensory) Splits into branches: temporal, zygomatic, buccal, Exits the facial canal (and cranium) via marginal mandibular and cervical → innervate the the stylomastoid foramen muscles of facial expression  Bell’s Palsy Facial n. CN VII palsy ○ Reactivation of HSV → affects schwann cells and ganglion cells of facial n. ○ A similar syndrome occurs if an external/middle ear infection affects the facial nerve Sx and anatomy: Disruption of facial nerve before parotid gland → paralyses muscles of facial expression (includes forehead, UNLIKE STROKES) The other sx depend on location of lesion and affected branches Chorda tympani → ipsilateral loss of taste in the anterior ⅔ of tongue and reduced salivation Nerve to stapedius → affects ability of the stapedius muscle to stabilize stapes when conducting sound → ipsilateral sound sensitivity (hyperacusis) Greater petrosal nerve → ipsilateral reduced lacrimal fluid Tx and prognosis: May be permanent but if temporary it’s due to inflammation ○ Treated with anti-inflammatory meds Physical therapy and muscular training Facial muscles Muscles of facial expression Testing facial muscles/CN VII function: Raise eyebrows and wrinkle forehead ○ Frontalis muscle and temporal branch Shut eyes tightly ○ Orbicularis oculi muscle and zygomatic branch Smile ○ Levator anguli oris muscle and zygomatic branch Puff out cheeks ○ Buccinator muscle and buccal branch  03 Eyes and Orbit Question A child suffers a blunt trauma to the face. Following this, the ED doctor orders a CT head to rule out intracranial hemorrhage. The following is seen. There is also failure of elevation of the right eye on the eye exam. Which of the following is the best explanation for this? A. Oculomotor deficit causing superior rectus paralysis B. Facial nerve paralysis C. Entrapment of the inferior rectus on the right eye in the maxillary sinus D. Base of skull fracture Question A child suffers a blunt trauma to the face. Following this, the ED doctor orders a CT head to rule out intracranial hemorrhage. The following is seen. There is also failure of elevation of the right eye on the eye exam. Which of the following is the best explanation for this? A. Oculomotor deficit causing superior rectus paralysis B. Facial nerve paralysis C. Entrapment of the inferior rectus on the right eye in the maxillary sinus D. Base of skull fracture Bony orbit Walls of the orbit Roof Floor Medial wall (thinnest wall) Lateral wall Fractures of Bony orbit Two types: 1. Orbital rim fracture Fracture of the bones forming the outer rim of the bony orbit Occurs at the sutures joining the maxilla, zygomatic and frontal bones 2. Blowout fracture Rim is intact but the walls of the orbit are fractured Partial herniation of orbital contents occurs usually due to a blunt force trauma Most commonly occurs inferiorly into the maxillary sinus, medial into ethmoid common as well  Trap door What is it: Happens in children due to the elasticity of their bones - rather than just snapping, the bone initially breaks outwards but returns to its original position Why is it bad: Upon return, the fracture may entrap some soft tissue of the orbit, such as orbital fat or sometimes musculature (eg. inferior rectus) What do you see: Often not a lot - it can look very normal from the outside because not a lot of displacement occurred, usually has little to no swelling or redness. If soft tissue is trapped, they may have restricted mobility of the eye, especially when looking up/down Openings into the orbit (from the cranium) Optic canal: optic nerve and ophthalmic artery Superior orbital fissure: Located between greater and lesser wing of sphenoid bone → CN III, IV, branches of V1 and superior ophthalmic vein, CN 6 Inferior orbital fissure: zygomatic branch of maxillary nerve, inferior ophthalmic vein and SNS nerves Fissure contents Superior orbital fissure: - CN V1 branches - CN III, IV, VI - Ophthalmic artery, veins Inferior orbital fissure - Branches of maxillary n - infraorbital and zygomatic n - Infraorbital a, v Question Jack is a 50 year old male. He presents with a one month history of diplopia. This is what he looks like at rest A. CN2 palsy B. CN 3 palsy C. CN 4 palsy D. CN 6 palsy Question Jack is a 50 year old male. He presents with a one month history of diplopia. This is what he looks like at rest A. CN2 palsy B. CN 3 palsy C. CN 4 palsy D. CN 6 palsy What is the next most important thing to check on examination?  Extraocular eye muscles- MUST KNOW!!!!! 3 groups of muscles: Recti (4 muscles) → all originate from the common tendinous ring (ring that surrounds the optic canal) Superior rectus - elevation, intorsion, adduction Medial rectus - Adduction Inferior rectus - Depression, extorsion, adduction Lateral rectus - abduction Obliques Mnemonic for innervation: LR6 Superior oblique - depression and abduction SO4 O3 Inferior Oblique - elevation and abduction Lateral rectus → CN VI Superior Oblique → CN IV Misc (Levator palpebrae superioris (elevates the Everything else → CN III eyelid, includes some sympathetic fibres termed superior tarsal muscle)  CN III anatomy This nerve innervates the following muscles: ○ Inferior rectus ○ Medial rectus ○ Superior rectus ○ Inferior oblique ○ Levator palpebrae superioris It supplies PNS to the sphincter pupillae (constricts pupil) and ciliary muscle (lens becomes more spherical, better for short range vision) via the short ciliary nerve. HITCHHIKER: It supplies SNS to the superior tarsal muscle CN III palsy You lose everything except: Lateral rectus and superior oblique Presents with “Down and out” ptosis Mydriasis Causes: - Raised ICP - Posterior communicating artery aneurysm (can be a false localising sign) - Cavernous sinus infection/trauma Question You are testing the extraocular eye muscles and their innervation in a patient experiencing periodic double vision. When you ask them to turn their right eye inward toward their nose, and look downward, they are able to look inward but not down. Which nerve is involved A. Abducens n. B. Nasociliary nerve C. Oculomotor, inferior division D. Oculomotor, superior division E. Trochlear Question You are testing the extraocular eye muscles and their innervation in a patient experiencing periodic double vision. When you ask them to turn their right eye inward toward their nose, and look downward, they are able to look inward but not down. Which nerve is involved A. Abducens n. B. Nasociliary nerve C. Oculomotor, inferior division D. Oculomotor, superior division E. Trochlear CN IV palsy CN IV has the LONGEST INTRACRANIAL COURSE - take note of the decussation (where is the lesion?) The nerve only innervates Superior oblique (which normally intorts) So you try and compensate and just rotate your head instead AWAY from the affected side Hence it presents with: - Head tilt away from affected side (simulate extortion) - Vertical diplopia when looking down (walking down stairs) Causes: - Microvascular disease (diabetes) - Raised ICP - Cavernous sinus thrombosis CN VI palsy Innervates lateral rectus Presents with: Medially deviated eye Diplopia Causes: Cavernous sinus compression Space occupying lesion at the pons Diabetes Compartments of the eyeball Aqueous humour is produced in the posterior chamber Fluid from here then goes into the anterior chamber and the vitreous cavity Usually, fluid is drained outside of the anterior chamber by the canal of schlemm Problems in the drainage → increased intraocular pressure → glaucoma Can be open (muck that reduces drainage) or closed angle (closure of the iridocorneal angle blocking fluid outflow) Eye anatomy 3 layers: Fibrous layer - cornea and sclera (continuous with the dura mater) Vascular layer - choroid, ciliary body and iris Inner or neural layer - retina Other unlabelled important things: Posterior chamber: behind the iris in front of the suspensory ligaments Glaucoma Progressive optic neuropathy that occurs due to raised intraocular pressure Open angle (left side) Gradual clogging of the trabecular meshwork that drains the aqueous humour Gradual loss of peripheral vision Chronic presentation Closed-angle (right side) Acute presentation - peripheral part of the iris is forced against trabecular meshwork preventing drainage Classically - precipitated by something that dilates the eye (being in the cinema, then getting incredible pain) Question D)  Accomodation Distant vision When ciliary muscle relaxes → suspensory ligaments taut → lens is pulled thin → distant vision Close vision When ciliary muscle contracts → suspensory ligaments relax → lens becomes thick → close vision Vasculature of the eye Arterial supply Ophthalmic artery ○ Branch of ICA ○ Arises immediately distal to cavernous sinus ○ Temporal arteritis → occlusion can produce blindness ○ Occlusion of CRA = amaurosis fugax (TIA, Temporal Arteritis) Venous drainage: Super and inferior ophthalmic veins drain into cavernous sinus Ophthalmoscopy Macula - Responsible for the central, high-resolution, color vision that is possible in good light. Contains the central fovea Central fovea - tiny pit located in the macula of the retina that provides the clearest vision of all as light falls directly on the cones.. Optic disc - where the optic nerve exits. This area has no rods or cones, so creates a blind spot. Papilledema Swelling/blurring of the optic disc due to raised ICP Subarachnoid space extends into the optic nerve sheath So raised ICP → increased pressure transmitted into optic nerve sheath → papilledema ○ Signs: hyperemia, elevation and cupping of optic disc margins -> obliteration of optic disc cup Cannot do a Lumbar Puncture if you suspect, or identify signs of raised ICP - else brain will herniate! Lacrimal gland Located superolaterally in the orbit, within the lacrimal fossil of the frontal bone Arterial supply → ophthalmic artery → lacrimal artery Venous: → superior ophthalmic vein → cavernous sinus Innervation: Parasympathetic → stimulates secretion (Greater petrosal nerve but hitchhikes onto V2) Preganglionic: Facial nerve → greater petrosal nerve → nerve to pterygoid canal → Pterygopalatine ganglion Postganglionic: Pterygopalatine ganglion → maxillary nerve (hitchhike) → zygomatic nerve (branch of maxillary n.) Corneal reflex Sensory: to the eye (nasociliary branch of ophthalmic nerve V1) Motor: Orbicularis oculi (muscle of facial expression) - Facial nerve branches CN V in, VII out Question A patient presents with gradual onset of vision loss. To determine if the defect is due to a brain or nerve problem, what is the MOST important thing to determine on examination? A. Visual acuity B. Cranial nerve 3,4 and 6 function C. Visual fields D. Blind spot testing Question A patient presents with gradual onset of vision loss. To determine if the defect is due to a brain or nerve problem, what is the MOST important thing to determine on examination? A. Visual acuity B. Cranial nerve 3,4 and 6 function C. Visual fields D. Blind spot testing Anterior to the chiasm = unilateral visual field loss Posterior to the chiasm = ALWAYS have visual field loss on both eyes (e.g. homonymous hemianopia) So any problem with the brain that affects vision will cause a visual field defect on both eyes Visual pathway Really helps to know the anatomy in detail here so you can map clinical findings and localize the site of pathology 04 ENT Question A third year medical student is learning to intubate in theatre. The anaesthetist asks the medical student, where he will be aiming the tube once in the pharynx. The student correctly states that he will aim the tube: A. In an anterior direction to ensure tracheal intubation B. In a posterior direction to ensure tracheal intubation C. Superiorly to ensure tracheal intubation D. Laterally to ensure tracheal intubation Question A third year medical student is learning to intubate in theatre. The anaesthetist asks the medical student, where he will be aiming the tube once in the pharynx. The student correctly states that he will aim the tube: A. In an anterior direction to ensure tracheal intubation B. In a posterior direction to ensure tracheal intubation C. Superiorly to ensure tracheal intubation D. Laterally to ensure tracheal intubation ENT connections Nasal sinuses drain into the nasal cavity Middle ear connected via the eustachian tube Oral cavity and nasal cavity separated by hard and soft palate Pharynx → oesophagus Larynx → trachea Ears Ear overview: 1. External (⅓ cartilage ⅔ bone) 2. Middle (connected to nasopharynx) 3. Internal (sensorineural) Middle ear anatomy  H C I Middle ear Air filled area internal to tympanic membrane and external to the oval window 3 auditory ossicles (malleus, incus and stape) Chorda tympani nerve passes just medial to tympanic membrane→easily injured Facial nerve can be damaged if infections erode through the wall Middle ear - boundaries → please know this Medial - labyrinthine wall) ○ Separates tympanic cavity from internal ear ○ Contains oval window, round window, prominence lateral semicircular canal, facial nerve canal Lateral - membranous wall - tympanic membrane Roof - tegmen tympani separating cranium from middle ear Floor - jugular wall Posterior - mastoid wall ○ Pyramidal eminence (stapedius m.), aditus leading to mastoid antrum Anterior - carotid wall ○ Pharyngotympanic tube to nasopharynx for pressure equalization. Also has tensor tympani muscle Middle ear- ossicles 3 small bones - Malleus - Incus - Stapes Connect the tympanic membrane to the oval window Receives vibrations from tympanic membrane and amplifies them, to the fluid of the inner ear Otitis media Inflammation of middle ear → usually infectious Common in children → horizontal pharyngotympanic/eustachian tube. So URTI can spread easier Can cause effusions due to the inability to drain (hence ossicles can't vibrate) Presents with: fever, earache, discharge, bulging red tympanic membrane on otoscope Complications: Think about any anatomical place the infection can erode to → mastoiditis, tympanic membrane perforation, meningitis CN VIII - Vestibulocochlear n Vestibulocochlear (special sensory) Vestibular component - afferent, balance and stabilisation of the eyes Cochlear component - hearing Both fibres combine in the pons → vestibulocochlear nerve → emerges at the cerebellopontine angle → exits the cranium via the internal acoustic meatus (temporal bone) Within the distal internal acoustic meatus, the nerve splits → vestibular nerve and the cochlear nerve Nose - Quick Summary Know the outlets through which the sinuses drain into the nose, and know the anatomy of the nasal septum and nasopharynx Nose question Apixa Ban suffers from frequent nosebleeds. An ENT surgeon examines Apixa and sees evidence of dilated vasculature. Which of the following is LEAST likely to be involved in Apixa’s nosebleeds? A. Anterior ethmoidal artery B. Posterior ethmoidal artery C. Sphenopalatine artery D. Lesser palatine artery E. Super labial branch of facial artery Nose question Apixa Ban suffers from frequent nosebleeds. An ENT surgeon examines Apixa and sees evidence of dilated vasculature. Which of the following is LEAST likely to be involved in Apixa’s nosebleeds? A. Anterior ethmoidal artery B. Posterior ethmoidal artery C. Sphenopalatine artery D. Lesser palatine artery E. Super labial branch of facial artery Kiesselbach's plexus Oral cavity (TONGUE) Tongue All paired muscles All supplied by hypoglossal nerve (XII) EXCEPT palatoglossus by vagus nerve (CNX) Intrinsic muscles: alter shape of tongue by lengthening/shortening, curling, flattening Extrinsic muscles: genioglossus, hyoglossus, palatoglossus Important relation: (from medial to lateral) Genioglossus → lingual a → Hyoglossus → lingual n. -> hypoglossal n. Tongue innervation IMPORTANT Issue with vagus [X] = Uvula deviate toward normal side Motor (thats where the pull is) Issue with hypoglossal n. [XII] Muscles controlling tongue → hypoglossal nerve = Tongue deviates toward abnormal side (lick your EXCEPT palatoglossus wounds) Sensory Anterior ⅔ - Lingual nerve (general sensory) (CNV), Chorda Tympani branch CN VII (special sensory) Posterior ⅓ - Glossopharyngeal (IX) (general and special sensory) Epiglottis + soft palate - Vagus n (general and special sensory) Throat/Pharynx Pharynx → ENT highway - Tube that connects the oral cavity + nasal cavity + larynx + oesophagus - Begins at base of skull - Ends at inferior border of cricoid cartilage (becomes oesophagus) Larynx → (voice box) - Functions include phonation, cough reflex, protecting Lower respiratory tract Pharynx relationships Pharynx ○ Nasopharynx - connected to the nasal cavity (which connects to the orbit via nasolacrimal duct) and middle ear (via the Eustachian tube) ○ Oropharynx - connected to the oral cavity ○ Laryngopharynx - connected to the larynx and esophagus (becomes that at level C6/7) Larynx ○ Connected to the laryngopharynx and trachea Question Which of the following is true regarding innervation of the pharynx? A. All pharyngeal muscles are innervated by the glossopharyngeal nerve B. All pharyngeal muscles are innervated by the vagus nerve C. The stylopharyngeus is innervated by the glossopharyngeal nerve D. The circular muscles are innervated by vagus, and longitudinal are innervated by the glossopharyngeal nerve Question Which of the following is true regarding innervation of the pharynx? A. All pharyngeal muscles are innervated by the glossopharyngeal nerve B. All pharyngeal muscles are innervated by the vagus nerve C. The stylopharyngeus is innervated by the glossopharyngeal nerve D. The circular muscles are innervated by vagus, and longitudinal are innervated by the glossopharyngeal nerve Pharyngeal muscles Same as ANY part of the GIT→ it's just swapped (outer circular instead of inner circular in GIT) Outer Circular muscle layers (superior, middle and inferior constrictors) Inner Longitudinal muscles (stylopharyngeus, palatopharyngeus, salpingopharyngeus) Innervation: All innervated by Pharyngeal branch of vagus n.(CNX) Except stylopharyngeus (CNIX) Pharynx sensory innervation Nasopharynx = maxillary nerve (CN V2) Oropharynx = glossopharyngeal nerve (CNIX) Laryngopharynx = CN X Gag reflex = 9 sensory - 10 motor (pharyngeal/palate muscle response) Innervation of the pharynx Innervation: ALL muscles via the VAGUS nerve EXCEPT for the stylopharyngeus muscle which is innervated by the glossopharyngeal nerve Larynx innervation question During a thyroidectomy, a surgeon accidentally damages the recurrent laryngeal nerve on the left side. Which of the following is true in this circumstance? A. The patient will begin to stridor B. The patient will have a hoarse voice C. The patient requires urgent intubation to prevent death D. Nothing will happen Larynx innervation question During a thyroidectomy, a surgeon accidentally damages the recurrent laryngeal nerve on the left side. Which of the following is true in this circumstance? A. The patient will begin to stridor → if bilateral maybe B. The patient will have a hoarse voice → correct, C. The patient requires urgent intubation to prevent death → maybe if bilateral D. Nothing will happen → most of your laryngeal muscles on the ipsilateral side are gone Larynx anatomy Muscle actions  Larynx muscle innervation All innervated by branches of the VAGUS nerve Only the Cricothyroid muscle is innervated by the superior laryngeal nerve All other muscles of the larynx are innervated by recurrent laryngeal nerve SCAR: Superior laryngeal nerve (external branch) Cricothyroid muscle All other muscles Recurrent laryngeal nerve Laryngeal Muscle Function Posterior cricoarytenoid only muscle that abducts!!! → important to know this All other ones adduct, tense vocal cord When you tense the vocal cord -> higher pitched -> cricothyroid When you relax the vocal cord -> lower pitched -> thyroarytenoids Vocal Cords - Alignment Question During a carotid endarterectomy, a surgeon accidentally injures the superior laryngeal nerve. Which of the following is MOST accurate with the defects seen post-operatively A. The patient will have a hoarse voice B. The patient will be unable to hit high notes C. The patient will have a stridor D. Nothing will happen as the other side can compensate Question During a carotid endarterectomy, a surgeon accidentally injures the superior laryngeal nerve. Which of the following is MOST accurate with the defects seen post-operatively A. The patient will have a hoarse voice B. The patient will be unable to hit high notes C. The patient will have a stridor D. Nothing will happen as the other side can compensate Parasympathetic innervation of the head and neck - hitchhiking business 05 Neck Almost there… Question You are an ED doctor working at 2am. A patient with severe tonsilitis presents with suspect, and you suspect a peritonsillar abscess with formation of a deep neck space infection. You decide to do a CT of the neck to characterize this which shows retropharyngeal abscess. You remember your anatomy well and perform the the most important next step in the ED: A. CT of the chest B. CT of the brain C. Look to see if it has spread to the ear using an otoscope D. Look to see if there is nasal spread Question You are an ED doctor working at 2am. A patient with severe tonsilitis presents with suspect, and you suspect a peritonsillar abscess with formation of a deep neck space infection. You decide to do a CT of the neck to characterize this which shows retropharyngeal abscess. You remember your anatomy well and perform the the most important next step in the ED: A. CT of the chest → connected to the posterior mediastinum so really bad infections may spread down and cause mediastinitis B. CT of the brain C. Look to see if it has spread to the ear using an otoscope D. Use to see if there is nasal spread Fascial layers and contents Superficial cervical fascia → platysma, skin, subcutaneous tissue and superficial nodes Deep cervical fascia split into: Prevertebral fascia → endothoracic fascia and axillary Pretracheal fascia → pericardium ○ Pharynx/larynx, oesophagus, trachea ○ Thyroid ○ Recurrent laryngeal n. ○ Strap muscles Carotid sheath ○ Common carotid, IJV, CN X ○ Pierced by glossopharyngeal n. And ansa cervicalis ○ Connected by alar fascia Investing layer ○ Traps, SCM Spaces in the Pharynx  Clinically important fascial spaces Retropharyngeal space - potential space Bound by buccopharyngeal fascia anteriorly and alar fascia posteriorly Contains retropharyngeal lymph nodes Continuous with posterior mediastinum → neck space infections here can spread down causing mediastinitis (not good) → see next slide Danger space → another pathway for similar spread to occur - can also spread to prevertebral space from here Between alar fascia anteriorly and prevertebral fascia posteriorly Don’t learn this diagram in detail! Basically, the only thing you need to take out from this is: Any infection in the head and neck can spread through multiple pathways because of all the communications between the different structures This is why a dental abscess can lead to endocarditis, osteomyelitis, empyema, PEs and strokes Cervical vertebrae C1 (Atlas) Anterior + posterior arch (no vertebral body) Fracture = Jefferson Fracture C2 (Axis) Dens (odontoid process) Typical Transverse processes with transverse vertebrae foramen C3-C7 Vertebral arteries and veins (except C7) Vertebral body (rectangle) and foramen (triangular) Bifid spinous processes (nuchal ligament in between)  Cervical muscles Understand the main division of muscles, and the innervations Anterior muscles ○ Superficial muscles (Platysma, SCM, subclavius) ○ Suprahyoid muscles (digastric,mylohyoid, geniohyoid, stylohyoid) ○ Infrahyoid muscles Lateral muscles 3 scalene muscles (anterior, middle and posterior) Posterior muscles (super low yield but they exist) Key neck muscle relationships Interscalene block → anaesthesia for upper limb surgery - preferentially targets superior trunk (gravity!)  Triangles of the neck Key muscles that form the triangles: Omohyoid SCM Anterior triangle Muscular triangle Carotid triangle Submental and submandibular Posterior triangle Subclavian Occipital Anterior triangle Borders: Mandible, SCM, midline Associated with structures between head and thorax Structures: Midline structures: - hyoid, thyroid, parathyroid , larynx Lateral structures: Carotid sheath: (Internal and external JV, CCA, CN X) Ansa cervicalis Posterior triangle of the neck Borders: SCM (anteriorly), Trapezius (posterior) clavicle (inferiorly) Structures: CN XI (accessory nerve) → very superficial and easily injured, presents: Inability rotating neck (SCM) Inability shrugging shoulder (CN XI) Vasculature of the head and neck Carotid arteries arise from: Right brachiocephalic trunk (right), aortic arch (left) Bifurcates at C4 at upper border of thyroid cartilage ○ external carotid → head and neck supply ○ Internal carotid → brain and CNS (along with vertebral a. From thyrocervical trunk) External carotid artery Some Anatomists Like Freaking out poor Medical Students (they really do…) Note the rough courses and areas of supply CN IX - Glossopharyngeal Nerve Leaves cranium via jugular foramen - gives rise to tympanic nerve (with sensory and parasympathetic fibres) Immediately outside the jugular foramen lie two ganglia (collections of nerve cell bodies). They are known as the superior and inferior (or petrous) ganglia – they contain the cell bodies of the sensory fibres in the glossopharyngeal nerve. Now extracranial, the glossopharyngeal nerve descends down the neck, anterolateral to the internal carotid artery. At the inferior margin of the stylopharyngeus, several branches arise to provide motor innervation to the muscle. It also gives rise to the carotid sinus nerve, which provides sensation to the carotid sinus and body. 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. CN X - Vagus Nerve Exits the cranium via the jugular foramen and travels through the neck in close proximity to the vasculature. Breaks into left and right branches before giving rise to: Pharyngeal branches - motor to pharynx and soft palate Superior laryngeal nerve - motor/sensory to larynx Right recurrent laryngeal nerve - intrinsic larynx muscles In the thorax, forms posterior and anterior trunks, forms the esophageal plexus AND gives rise to: Left recurrent laryngeal nerve - intrinsic larynx muscles Cardiac branches - regulate HR and provide visceral sensation Terminates in the abdomen to supply the oesophagus, stomach and small and large bowel up to the splenic flexure. CN XI - Spinal Accessory Nerve Has spinal (C1-5/C6, travels up foramen magnum to join cranial part) and cranial components; These exit via the jugular foramen and descend along the internal carotid artery to supply the sternocleidomastoid before moving across the posterior triangle to supply the trapezius.  CN XII - Hypoglossal Nerve Hypoglossal nucleus in medulla ->passes laterally across the posterior cranial fossa, within the subarachnoid space Exits via hypoglossal canal Receives a branch of the cervical plexus that conducts fibres from C1/C2 spinal nerve roots - hitchhikers Passes inferiorly to the angle of the mandible, crossing the internal and external carotid arteries, and moving in an anterior direction to enter the tongue.  Thyroid anatomy Endocrine gland Has two lobes joined at the isthmus Covered by fascia of the pretracheal fascia RANDOM THINGS TO KNOW THAT MAY OR MAY NOT HAVE COME UP: Thyroid IMA → random variant - can be injured in emergency tracheostomy Thyroglossal cyst -> moves on swallowing AND on sticking tongue out (think back to embryology!) Thyroid clinical Thyroidectomy complications: External laryngeal n. Damage - lower pitch. Which muscle do we lose? Recurrent laryngeal n. Damage – hoarse voice if unilateral, airway obstruction if bilateral Parathyroid gland removal → hypocalcaemia Post-thyroidectomy haemorrhage ○ Bleeding beneath cervical fascia and strap muscle layer ○ Pressure obstructs lymphatic drainage → laryngeal oedema → airway emergency ○ If you are ever the surg intern and a post-thyroidectomy patient, this is such an emergency that should open up the sutures all the way down until you see trachea → at the bedside Question A patient is day 1 post-op total thyroidectomy. They complain of muscle spasms and have some perioral numbness. Which of the following is true? A. This may be the first sign of impending airway obstruction B. This presentation is likely due to parathyroid gland removal C. The patient should immediately have the sutures removed on the ward D. This is a normal side effect of anaesthetic Question A patient is day 1 post-op total thyroidectomy. They complain of muscle spasms and have some perioral numbness. Which of the following is true? A. This may be the first sign of impending airway obstruction B. This presentation is likely due to parathyroid gland removal C. The patient should immediately have the sutures removed on the ward D. This is a normal side effect of anaesthetic Parathyroid glands 4 parathyroid glands → produce PTH regulating blood calcium Embryology → Superior parathyroid glands → 4th pouch Inferior parathyroid glands → 3rd pouch Highly variable locations because of the embryology- sparing them is so difficult because of this Hypoparathyroidism - most commonly iatrogenic (i.e. removal of parathyroid during thyroid surgery) - Features of hypocalcemia - perioral tingling/numbness, muscle tetany Hyperparathyroidism - signs of hypercalcemia (bones, stones, groans, moans, psych overtones)