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Head and Neck Anatomy Year 2 Revision Night MSc Clinical Anatomy Ryan McKennaOutline of the Session Head: Neck: Vessels: • Face • Pharynx and Larynx • Carotid Arteries • Trigeminal Nerve • Compartments of the Neck • Jugular Veins • Facial Nerve • Bones of the Neck • Lymphatics CONTENT • Orbits • Muscles of the Neck • Ear • Thyroid Gland • Nasal Cavities • Triangles of the Neck • Oral Cavity and Tongue CLINICAL Clinical applications of anatomy which appear frequently in examinations RELEVANCE MCQs Test your understandingFacial Skeleton / Viscerocranium 15 irregular bones: • 3 singular central bones • Ethmoid • Vomer • Mandible • 6 paired bilateral bones • Nasal • Zygomatic • Lacrimal • Inferior nasal conchae • Maxillae • PalatineSensory Innervation of the Face The three terminal branches of the trigeminal nerve (CNV) supply the skin, mucous membranes and sinuses of the face and scalp. • Ophthalmic Nerve (CNV1): Sensation to upper-third of face • Maxillary Nerve (CNV2): Sensation to middle-third of face • Mandibular nerve (CNV3): Sensation to lower-third of face Motor function (mastication)Trigeminal Branches Frontal Supraorbital Supratrochlear Nasociliary Infratrochlear Ophthalmic Nerve Anterior ethmoidal Posterior ethmoidal Lacrimal Zygomaticotemporal Maxillary Nerve Zygomaticofacial Infraorbital Superior alveolar Anterior Division Buccal Pterygoid branches Deep temporal Mandibular Nerve Masseteric Posterior Division Auriculotemporal Lingual Inferior alveolarOsteological Features of the Mandible Comprised of central body and two Head Mandibular rami projecting perpendicular to the Processonoid Neck Foramen body from the angle of the mandible Process Lingula External Features: • Each rami has a condyle (head and neck) Condyle / and a coronoid process Headdle / AAngle Mental • The body has an alveolar part and a base. Foramen The base has two mental foramina Internal Features: • The rami have a lingula and mandibular foramen. • The inferior alveolar nerve, artery and vein traverse the mandibular canalT emporomandibular Joint (TMJ) Superior articular cavity Inferior The TMJ is a modified hinge-type joint between Articular Disc articular cavity the head of mandible and temporal bone The joint capsule contains a fibrocartilaginous articular disc, separating the capsule into POST ANT superior and inferior articular cavities. Reinforced by three ligaments: • Lateral ligament • Sphenomandibular ligament • Stylomandibular ligament Joint capsule Lateral (tempomandibular) ligament Two types of movement occur at the TMJ: Sphenomandibular Ligament • Gliding in superior articular cavity Styloid process • Protrusion, Retrusion Stylomandibular ligament • Translation / Lateral Deviation (grinding) • Hinge in the inferior articular cavity • Depression and ElevationMuscles of Mastication Temporalis is a large-fan shaped muscle spanning from the temporal fossa to the condyle of the mandible • Anterior fibres run vertically and elevate the mandible • Posterior fibres run horizontally and retrude the mandible originating from the superior temporal line. Masseter is a thick quadrangular muscle between the zygomatic arch and the external surface of the mandible • It mirrors and has synergistic action with the medial pterygoid muscle. • Elevates mandibleMuscles of Mastication The pterygoids originate from the lateral pterygoid plate of the sphenoid bone. They are responsible for translation of the mandible. Lateral The medial pterygoid is a quadrangular Pterygoid muscle mirroring the masseter on the medial surface of the mandible. Deep and superficial heads elevate the mandible Medial The lateral pterygoid is a triangular muscle Pterygoid inserting on both the articular disc of the TMJ and on the neck of the mandible. Superior and inferior heads depress the mandibleSummary Muscle Origin Insertion Action Innervation (Branches of CNV3) Temporalis • Floor of the • Coronoid • Elevation Deep temporal temporal fossa process • Retrusion branches • Temporal fascia • Anterior ramus Zygomatic arch • Angle • Elevation Masseteric nerve Masseter • External surface • Protrusion of ramus • Lateral • Angle • Elevation Medial pterygoid Medial Pterygoid pterygoid plate • Internal surface • Protrusion nerve • Tuberosity of of ramus • Translation maxilla Lateral Pterygoid • Greater wing • Joint capsule • Depression Lateral pterygoid of sphenoid • Pterygoid fovea • Protusion nerve • Lateral (of condyle) • Translation pterygoid plateFacial Nerve Mnemonic for the branches of CNVII: • Mixed nerve with sensory, motor and “To Zanzibar By Motor Car” parasympathetic functions • Exits skull via stylomastoid foramen. • Extracranial branches carry motor axons ONLY: 1. Posterior Auricular Nerve 2. Branches to Digastric and Stylohyoid mm Temporal 3. The main trunk of the nerve continues anteriorly and inferiorly into the parotid gland then Zygomatic terminates into the parotid plexus; 5 branches supplying the muscles of facial expression: • Temporal Buccal • Zygomatic • Buccal • Marginal Mandibular Marginal Mandibular • Cervical CervicalMuscles of Facial Expression Occipitofrontalis Elevates eyebrows Wrinkles forehead Orbicularis oculi Closes eyelids Orbicularis oris Closes mouth Zygomaticus major and Shifts lip superolaterally zygomaticus minor ‘Laughing muscles’ Levator anguli oris Elevates angle of lips to facilitate smiling Depressor anguli oris Depresses angle of lips to facilitate frowning Elevate + invert upper lip Levator labii superioris Nb. The muscles of facial expression are Depressor labii Depress + evert lower lip innervated by a branch of the inferioris facial nerve (CNVII)Parotid Gland The largest of the three paired salivary glands. It can be found wedged between the mandible and sternocleidomastoid muscle The parotid duct (of Stensen) emerges from the anterior border of the gland, pierces buccinator and enters the oral cavity at upper 2nd molar. Structures that travel through the gland: • Facial Nerve (CNVII) • External Carotid Artery • Retromandibular Vein However, it is innervated by the Glossopharyngeal Nerve (CNIX)Boundaries of the Orbit Roof: Frontal bone and lesser LAT MED wing of sphenoid bone Floor: Maxilla, palatine and zygomatic bones Medial wall: Ethmoid, maxilla, lacrimal and sphenoid bones Lateral wall: Zygomatic bone and greater wing of sphenoid Apex: Optic foramen Base: Orbital rim Sphenoid Contents of the Orbit Optic Canal Bone • Eyeball, eyelids (palpabrae) and orbital fat • Lacrimal gland Superior Orbital Fissure • Extra-ocular muscles • Superior and inferior oblique Inferior • Superior, inferior, lateral and medial recti Orbital Fissure • Levator palpabrae superioris Neurovasculature enter through 3 key openings: OpticCanal Superior Orbital Fissure Inferior OrbitalFissure Optic Nerve (CNII) Oculomotor Nerve (CNIII) Zygomatic Branch of Maxillary (CNV1) Ophthalmic Artery Trochlear Nerve (CNIV) Inferior Ophthalmic Vein Abducens Nerve (CNVI) Sympathetic Nerves Superior Ophthalmic Vein Frontal, Nasociliary, Lacrimal Nerves (CNV1) Fractures of Orbit Orbital Rim Fracture Blow-Out Fracture • Fracture of the bones forming the orbital • Fracture of the orbit resulting in partial rim – maxilla, zygomatic and frontal . herniation of the contents of the orbit • Most commonly occurs along the sutures through one of its walls. connecting the bones. • Medial and Inferior Walls are the weakest. • Results in herniation through the ethmoid and maxillary sinuses respectively. • Blunt force trauma to the eye. Both types of fractures result in exophthalmos (protrusion of the eye), swelling and bruising and often haemorrhage into a paranasal sinus.External Eye and Lacrimal GlandExtraocular Muscles Superior Oblique Trochlea Superior Rectus Lateral Rectus (cut) Common Tendinous Origin Inferior Inferior Oblique Rectus Right eye; lateral view Right eye; anterior viewExtraocular Muscles Muscle Action Innervation Origin Insertion (SO4LR6) Superior Oblique Depress and Trochlear Nerve Body of sphenoid Sclera via trochlea medially rotate eye (CNIV) bone posterior to SR Lateral Rectus Abduct eye Abducens Nerve Common Tendinous (CNVI) Ring Inferior Oblique Elevate and laterally Orbital floor rotate eye Sclera Elevate, adduct and Common Tendinous Superior Rectus medially rotate eye Ring Oculomotor Nerve Inferior Rectus Depress, adduct and (CNIII) Common Tendinous laterally rotate eye Ring Medial Rectus Adduct eye Common Tendinous Ring Levator Palpabrae Elevate and retract Lesser wing of Superior tarsal plate Superioris eyelid sphenoid bone Third, Fourth and Sixth Nerve Palsies Oculomotor (CNIII) Trochlear (CNIV) Abducens (CNVI) Paralysis of: Paralysis of: Paralysis of: • Levator palpabrae superioris • Superior Oblique • Lateral Rectus • Inferior oblique • Superior, inferior, medial recti Symptoms: Symptoms: • Sympathetic nerves • Eye displaced upwards • Adducted eye • Vertical diplopia • Horizontal diplopia Symptoms: • ‘Head-tilt’ away from lesion. • ‘Lateral gaze palsy’ • ‘Down and out eye’ • Ptosis (drooping) • Dilated non-reactive pupilExternal Ear Functionally and structurally divided into 2 parts: • Auricle • External Acoustic Meatus ending at the Tympanic Membrane (ear-drum) Auricle / Pinna External Acoustic Meatus Tympanic Membrane Handle of Malleus Umbo Otoscopy Otoscopy allows for visualisation of middle-ear structures through the translucent tympanic membrane. It is a crucial part of the ear exam and can provide several spot diagnoses: Normal: Otitis Externa: • Pearly-grey • External ear infx Perforated • Inflammation • Concave Tympanic • Narrowing of • Features of Membrane external auditory middle ear meatus clearly visible • Discharge Cholesteatoma: Otitis Media: • Abnormal • Middle ear infx collection of Tympanosclerosis: • Erythematous squamous • Scarring of • Bulging tympanic epithelial cells membrane • Cannot visualise • Mass of white • White deposits / middle ear e.g. debris / crust plaques cone of light • Foul smellMiddle Ear Found within the temporal bone. Separated into the tympanic cavity and epitympanic recess. Features: • Ossicles: Malleus, Incus, Stapes • Connected in a chain-like manner. • Vibration of the tympanic membrane creates oscillation of the malleus à incus à stapes à oval window of inner ear transmitting sound. • Mastoid Air Cells • Found posterior to the epitympanic recess. The eustachian tube is part cartilage / part bone • ‘Buffer system of air’ releasing air to increase middle ear pressure when it drops too low. It opens into the • Muscles nasopharynx • Tensor tympani (CNV3) Acts to equalise pressure • Stapedius (CNVII) of middle ear to that of • Auditory / Eustachian Tube external auditory meatus Spread of Infection from Middle Ear Infection in the middle ear (otitis media) Mastoid air cells (mastoiditis) Middle cranial fossa If mastoiditis is suspected , child should be referred to ED for urgent ENT review. • IV antibiotics • Myringotomy Brain (meningitis) • Tympanostomy tube placementInner Ear Two functions: • Hearing: Converts mechanical signal from middle ear to electrical signal conducted to Bony Labyrinth Feature Membranous Labyrinth the brain. Associated with cochlea. Feature Within Cochlea Cochlear Duct • Balance: By detecting position and motion. Associated with vestibule and semicircular canals. Semicircular Canals Semicircular Ducts Two parts: • Bony labyrinth: Series of bony cavities Vestibule Saccule: Receives cochlear duct • Membranous labyrinth: Lies within the bony UtricleReceives semicircular duct labyrinth and filled with endolymph. Innervated by the Vestibulocochlear Nerve (CNVIII) which contains two functionally distinct nerves: • Vestibular nerve: Vestibule and S-C canals • Cochlear nerve: CochleaOral CavityT ongue Neurovasculature of Tongue IJV Lingual Vein Root of tongue Lingual ECA Artery Arterial Supply: Lingual artery Branch of External Carotid Artery Venous Drainage: View: Dorsum of the Tongue Lingual vein Tributary of Internal Jugular VeinIntrinsic Muscles of the T ongue Four paired muscles named by their arrangement within the substance of the tongue in various directions: • Superior longitudinal Thin muscles • Inferior longitudinal tracing outline of tongue • Transverse • Vertical tongue to facilitate speech, eating and swallowing Supplied by the hypoglossal nerve (CNXII)Extrinsic Muscles of the T ongue Palatoglossus Four paired muscles arising from outside the tongue substance and attach onto the tongue Styloglossus • Genioglossus Genioglossus Hypoglossal • Hyoglossus nerve (CNXII) Hyoglossus • Styloglossus • Palatoglossus – Vagus nerve (CNX) Nb. Genioglossus is large and thick, shape of the tongue Produce movement of the tongue The other three muscles overly itSubmandibular and Sublingual Glands The two smaller paired salivary glands that assist the parotid gland in production of saliva • Submandibular: Submandibular (ant) triangle in the neck • Sublingual: Floor of oral cavity Both receive autonomic innervation from the chorda tympani branch of the Facial nerve (CNVII) which travels with lingual nerve (CNV3).Nasal Cavity Olfactory Region The nasal cavity is functionally divided: • Respiratory region Opening of • Olfactory region Eustachian Tube The vestibule is the area surrounding the external opening of the nasal cavity Vestibule Nasopharynx Respiratory Region Branches of the olfactory nerve (CNI) provide special sensory innervation (olfaction / smell) Nasal skeleton is comprised of the nasal bones, maxillae and various cartilagesOpenings into the Nasal Cavity • Four Paranasal Sinuses • Frontal • Ethmoid • Maxillary • Sphenoid • Cribriform Plate • Roof of nasal cavity • Small perforations (CNI) Frontal Sinus • Nasolacrimal Duct • Eustachian Tube Ethmoid Sinus Maxillary Sinus Epistaxis The nose is highly vascularised to modify the temperature of inspired air. It receives blood from branches of the internal and external carotid arteries. These branches anastomose with each other, forming Kiesselbach’s plexus in the anterior third of the nose. Therefore, nosebleeds (epistaxis) are most likely to occur in the anterior third of the nose termed ‘Little’s Area’. Triangle of Danger Venous drainage of the nose is by the facial vein. The facial vein is connected to the cavernous sinus (located within the cranial cavity) by the ophthalmic vein. Infection of nose can therefore lead to: • Cavernous Sinus Thrombosis • Meningitis • Brain abscessPharynx Pharynx is a musculofascial tube, common to both the respiratory and alimentary system (Naso)pharynx begins at (connects to larynx and oesophagus). nasal cavityl, posterior to Divided into three regions according to their anterior relation: Oropharynx begins at level of soft palate • Nasopharynx • Pharyngeal tonsils Laryngopharynx begins at tip of epiglottis • Eustachian tube • Oropharynx inferior border of at • Palatine and lingual tonsils cricoid cartilage • Posterior third of tongue • Superior constrictor muscle • Laryngopharynx • Piriform recesses / fossae • Middle and inferior constrictor musclesPharyngeal Muscles Functions are accomplished by six muscles: Pharyngeal Constrictors Longitudinal Muscles Superior Palatopharyngeus Middle Salpingopharyneus Inferior Stylopharyngeus The constrictor muscles form an incomplete circle around the pharynx. They contract sequentially to constrict the pharyngeal lumen and propel the food inferiorly into the oesophagus The longitudinal muscles assist by elevating the pharynx Innervation from the pharyngeal plexus (CNX and CNIX)Larynx The laryngeal skeleton is composed of a framework of nine cartilages. Unpaired Cartilages Paired Cartilages • Thyroid cartilage • Arytenoid cartilage • Cricoid cartilage • Corniculate cartilage Superior horn • Epiglottis • Cuneiform cartilage Laryngeal Prominence The laryngeal cavity extends from the laryngeal inlet of the epiglottis (connection Inferior to laryngopharynx) to the inferior part of the horn cricoid cartilage at C6Functional Anatomy of the Larynx 1. Phonation: • Vocal cords each have a vocal ligament and vocalis muscle • located between the vocal cordsure • Several muscles assist vocalis in cords to facilitate phonation.al 2. Protection of Airway: • Ligaments keep rima glottidis and epiglottis patent during respiration • These are closed shut during swallowing to prevent aspiration. Recurrent Laryngeal Nerve Paralysis The laryngeal muscles are innervated by the recurrent laryngeal nerve*, a branch of the vagus nerve (CNX) Damage to the nerve results in vocal cord paralysis. Symptoms: Hoarseness, changes in vocal pitch, dyspnoea. Causes: Surgery, Tumour, Infection (almost always unilateral). Cricothyroid Stretch and tense vocal ligament *EXCEPTION (external laryngeal nerve). Vocalis Relax posterior part of vocal ligament. Maintain tension anteriorly Relax vocal ligament Thyro-arytenoid Posterior crico-arytenoid Abduct vocal cords Lateral crico-arytenoid Adduct vocal cords Transverse and oblique Close posterior rima glottidis arytenoid Compartments of the Anterior Neck Four Key Compartments • Visceral Compartment • 2x Vascular compartments • Vertebral compartment • Musculofascial Collar Carotid sheath is formed by condensation of the three deep fascias Coronal section at C6 Level 3 Viscera 3 Vessels (Carotid Sheath) 3 Muscles 3 Deep Cervical Fascia Trachea Internal Jugular Vein Sternocleidomastoid Superficial (investing) Oesophagus Carotid Artery (CC or IC) Infrahyoid group Pretracheal Thyroid Vagus Nerve Postural muscles PrevertebralCervical Vertebrae Dens / Odontoid Process Atypical vertebrae: • C1: Atlas Joints: • Atlanto-occipital: Condyloid • Medial atlanto-axial: Pivot • Lateral atlanto-axial: Plane • C2: Axis • Characterised by dens • C7: Vertebra prominens • Long, non-bifid spinous process Typical vertebrae C3-C6: • Common features of spine • Unique features: • Bifid spinous process • Tvertebral arteries (from C6)s • Triangular vertebral foramen • Anterior / Posterior Tubercles on Natural lordosis of transverse processes (C6- Carotid) cervical spineHyoid Bone and Suprahyoid Muscles U-shaped bone of anterior neck, inferior to mandible. Comprised of a body and paired greater horns and lesser horns The suprahyoid muscle group act to elevate the hyoid bone during swallowing, they all insert onto the bone Muscle Origin Innervation Digastric Anterior belly: Mandible Anterior Belly: Inferior alveolar Posterior belly: Mastoid Posterior Belly: process of temporal bone Facial Stylohyoid Styloid process Facial Geniohyoid Hypoglossal Mandible Inferior alveolar Mylohyoid See notes for detailed descriptionSternocleidomastoid and Infrahyoid Group Sternocleidomastoid is formed from two heads Infrahyoid Group act to depress the hyoid (sternal and clavicular) which insert together on bone. Also known as the strap muscles. the mastoid process of the temporal bone. • Action: • Superficial: • Unilateral à Lateral flexion + rotation of the neck. Omohyoid and Sternohyoid • Bilateral à Extension at atlanto-occipital joints • Superficial: • Innervation: Accessory nerve [CNXI] Sternothyoid and Thyrohyoid Mastoid ProcessThyroid and Parathyroid Glands • Bilobed endocrine gland The thyroid is highly vascularised: • 2/3 Arteries: Superior, Inferior +/- Ima • Right and left lobes separated by an isthmus nd rd th • 3 Veins: Superior, Middle, Inferior • Isthmus overlies 2 , 3 , 4 tracheal rings 4 parathyroid glands on posterior of thyroid – 2 superior, 2 inferiorAnterior Triangle of Neck Boundaries: Contents : Suprahyoid group • Superior: Inferior border of mandible Muscles • Lateral: Anterior border of SCM Infrahyoid group • Medial: Mid-line (imaginary) Vasculature Common Carotid Bifurcation à ICA + ECA Internal Jugular Vein Nerves Facial (XII) Glossopharyngeal (IX) Vagus (X) Accessory (XI) Hypoglossal (XII)Posterior Triangle of Neck Boundaries : Contents : • Anterior: Posterior border of SCM Muscles Omohyoid (strap) • Posterior: Anterior border of Trapezius Vertebral: Scalenes, splenius capitus, levator scapulae • Inferior: Middle 1/3 of Clavicle Vasculature External Jugular Vein Subclavian vessels Suprascapular vessels Transverse cervical vessels Nerves Accessory Nerve (CNXI) Phrenic nerve Trunks of brachial plexusArteries of the Head and Neck The carotid arteries are a major The common carotid arteries bifurcate at superior margin of thyroid cartilage (C4): component of the anterior neck. ↓Internal Carotid: Intracranial ONLY Origin: Arch of Aorta ↓External Carotid: Supply head + neck ↓Brachiocephalic trunk ↓Right Common Carotid ↓Right Subclavian ↓Left Common Carotid The branches of the ECA can be ↓Left Subclavian remembered with a mnemonic: (Inferior to superior): “Some (superior thyroid) Anatomists (ascending pharyngeal) Like(lingual) Freaking (facial) Out (occipital) Poor (posterior auricular) Medical (maxillary) Students”(superficial temporal)Veins of the Head and Neck Tributaries of the three jugular veins drain blood from the head and neck: Internal Jugular Vein • Internal Jugular Vein Jugular Vein Scalp and Face Anterior Sternocleidomastoid • External Jugular Vein Jugular Vein • Anterior Jugular Vein Neck Important tributaries: • External Jugular Vein: Posterior auricular, retromandibular • Internal Jugular Vein: Facial, maxillary, superior temporalLymphatics of the Head and Neck 1. Submental 2. Submandibular 3. Parotid 4. Pre-auricular 4 1 5. Post-auricular 5 2 6. Occipital 6 3 7 7. Anterior chain 9 8. Supraclavicular 9. Posterior chain 8 Drain into right and left jugular trunksMCQ SectionMCQ #1 Which of the following is not a branch of the external carotid artery? A. Lingual artery B. Maxillary artery C. Occipital artery D. Retromandibular artery E. Superior thyroid arteryMCQ #2 Which muscle is indicated by the arrow? A. Orbicularis oris B. Zygomaticus major C. Orbicularis oculi D. Mentalis E. OccipitofrontalisMCQ #3 A 31-year-old woman presents with a throbbing pain and a feeling of pressure in her forehead above her eyebrows. Examination reveals an infection of the sinus in this region. Which paranasal sinus is most likely infected, causing pain in the region the patient describes? A. Ethmoid B. Frontal C. Sphenoid D. Maxillary E. TemporalMCQ #4 A 43-year-old woman who presented to the emergency department with a sudden onset2 headache is being assessed by the emergency doctor. Her body mass index is 33 kgm . On examination of her cranial nerves, she is found to have papilloedema on fundoscopy, and she also reports a loss of taste in the posterior third of her tongue. Which one of the following nerves may be responsible for the loss? A. Facial B. Trigeminal C. Hypoglossal D. Vagus E. GlossopharyngealMCQ #5 A 57-year-old woman presents to the clinic complaining of recent onset double vision that worsens when she looks to her right. Additionally, she mentions experiencing persistent headaches over the same period. She has a known history of breast cancer, which was treated 5 years ago. On examination, a lateral gaze palsy in her right eye is present. A lesion of which nerve is most likely the cause? A. Abducens B. Optic C. Oculomotor D. Trochlear E. OphthalmicMCQ #6 A young child undergoes a difficult craniotomy for mastoiditis and associated abscess. During the procedure the trigeminal nerve is severely damaged within Meckels cave. Paralysis of which muscle is likely to be present? A. Buccinator B. Sternocleidomastoid C. Masseter D. Genioglossus E. OccipitofrontalisMCQ #7 A 60-year-old man has occasional blackouts and light-headedness. Studies reveal atherosclerotic plaques within the common carotid arteries and the bifurcation of the vessels. A carotid endartectomy is undertaken. Which vessel running vertically within the carotid sheath must the surgeon be careful not to injure? A. Accessory Nerve B. Phrenic Nerve C. Vertebral Artery D. Vagus Nerve E. External Jugular vein