Head and Neck Anatomy (Innervation + Blood supply + extra notes) PDF

Maxilla Forms roof of palate At the front: Incisive canals are on either side of the incisive fossa ○ Greater palatine vessels and nasopalatine nerves travel between the oral/nasal cavities At the back: Posterior nasal spine and posterior margin of horizontal palates...

Maxilla Forms roof of palate At the front: Incisive canals are on either side of the incisive fossa ○ Greater palatine vessels and nasopalatine nerves travel between the oral/nasal cavities At the back: Posterior nasal spine and posterior margin of horizontal palates ○ Attachment of soft palate Palatine canal (from pterygopalatine fossa) forms: ○ Greater palatine foramen - greater palatine n. and vessels to supply the hard palate ○ Lesser palatine foramen - lesser palatine n. and vessels to supply the soft palate  Mandible Important parts Made up of body and ramus Condylar process forms temporomandibular joint (TMJ) with temporal bone Coronoid process - attachment of temporalis m. Mandibular foramen forms mandibular canal which finishes as mental foramen ○ Inferior alveolar n. (from V3) supplies teeth as travels through this and turns into the mental n. as it exits to supply skin of chin ○ Inferior alveolar vessels also ttravels through Mylohyoid line forms mylohyoid groove ○ Lingual n. ○ N. to mylohyoid  Temporomandibular Joint (TMJ) Synovial joint Formed by: head of condylar process (mandible) and tubercle of tympanic part of (temporal bone) Ligaments: Lateral, sphenomandibular, stylomandibular Articular surfaces are covered with fibrocartilage and divided into 2 by articular disc Muscles of mastication: Masseter, temporalis, medial/lateral pterygoid Develop from 1st pharyngeal arch ALL INNERVATED BY mandibular nerve (V3) All muscles elevate ○ Except lateral pterygoid (oriented horizontally onto pterygoid process) which instead moves side to side + protracts ○ Temporalis m. (deep temporal n.) also retracts jaw by attaching to condylar process  Temporal, Infratemporal, Pterygopalatine Fossa Temporal Fossa: Temporalis m. Deep temporal n. and artery Middle temporal a. (from maxillary a.) Zygomaticotemporal branch of V2 Feeds into Infratemporal Fossa: between ramus of mandible and wall of pharynx Feeds into Pterygopalatine Fossa: under zygomatic arch Communicates with nose, eye, middle cranial fossa Maxillary n. (V2) and artery Pterygopalatine ganglion  Scalp Innervation: Trigeminal nerve [V] ○ V1 → Supratrochlear, supra-orbital ○ V2 → Zygomaticotemporal ○ Auriculotemporal Cervical plexus ○ Lesser occipital (C2-3) ○ Greater occipital (C2) Arterial Supply: Internal carotid (anteriorly only) ○ Supratrochlear ○ Supra-orbital External carotid (all the rest) ○ Superficial temporal ○ Posterior auricular ○ Occipital  Facial Muscles - Innervation Facial Nerve [VII] arises from posterior cranial fossa, runs through the internal acoustic meatus (temporal bone) and exits via the stylomastoid foramen to give off its motor branches to the muscles of facial expression: Lateral Cervical Muscles Rectus capitus Longus capitus Longus colli Scalenes All originate from transverse process then attach to: ○ First rib - anterior and middle scalenes ○ 2nd rib - posterior scalene Above the anterior scalene you can find: ○ Phrenic n. ○ Branches of thyrocervical trunk (suprascapular and transverse cervical a.) ○ Subclavian vein Between the anterior/middle scalenes you can find: ○ Brachial plexus ○ Subclavian artery  Cervical Cross Section and Fascias (HY) 1 Superficial cervical fascia Deep cervical fascia is split into Prevertebral fascia → endothoracic fascia and axillary sheath Pretracheal fascia → pericardium ○ Pharynx, larynx, oesophagus, trachea ○ Thyroid/parathyroid ○ Recurrent laryngeal n. ○ Strap muscles Carotid Sheath ○ Common carotid, IJV, CNX ○ Pierced by glossopharyngeal n. And ansa cervicalis ○ Connected by alar fascia Investing Layer ○ Traps and SCM Note: pre-... fascia because if you were to try to get to the vertebra, you would hit the fascia first  Cervical Plexus In the Posterior Triangle of the neck Cutaneous Branches Anterior rami (curls around SCM) Posterior rami Lesser occipital (C2) Greater occipital (C2) Great auricular (C2-3) Dorsal rami of C3, 4, 5 Transverse cervical (C2-3) Supraclavicular (C3-4) Muscular Branches C1 (travels w/ hypoglossal n) Suprahyoids Ansa Cervicalis (C1-3) Straps (sternohyoid, sternothyroid), omohyoid Phrenic (C3-5) Diaphragm and pericardium Segmental branches (C1-4) Anterior/middle scalenes Other branches Other cervical muscles Triangles of the Neck Anterior Δ: mandible, SCM, midline Associated with structures between head and thorax Structures: Midline structures: hyoid bone, larynx, thyroid/parathyroid, oesophagus Carotid sheath: carotid a. Bifurcation, internal/external jugular v., CNX Glossopharyngeal and hypoglossal n. Spinal accessory n. ← pic is lateral to medial Triangles of the Neck Posterior Δ: clavicle, SCM, trapezius Associated with axillary inlet (upper limb structures) Structures: Accessory n. [XI] - innervates SCM and trapezius muscles. Very superficial so commonly damaged, presenting as: ○ Issues with rotating neck (SCM) or shrugging shoulders (trap) against tension ○ Vague pain in left shoulder Omohyoid m. splits triangle into supraclavicular and occipital regions Subclavian a. Comes up just at the base (between anterior and middle scalenes) ← pic is lateral to medial Vasculature of Head and Neck Carotid Arteries Carotid arteries come from right brachiocephalic trunk and aortic arch (left) Bifurcates at C4 by upper border of thyroid cartilage into: ○ External carotid arteries → head and neck ○ Internal carotid arteries → brain and CNS with vertebral arteries (from thyrocervical trunk) With exception of 1 branch: ophthalmic artery External Carotid Artery Don’t learn all the branches of the branches, but the important ones are: Facial artery: curves around inferior border of mandible Angular a. - medial corner of eye Superior/inferior labial a. - anastamose around lip Superficial temporal a. Transverse facial a. Maxillary a.: in infratemporal fossa → pterygopalatine fossa Before mandible: middle meningeal artery (through foramen spinosum, one associated with blow to pterion), inferior alveolar Under lateral pterygoid: supplies TMJ Some Attendings Like Freaking Out Potential Medical Students Pterygopalatine fossa: infra-orbital, greater palatine, pharyngeal, sphenopalatine, posterior superior alveolar Internal Carotid Artery Generally supplies CNS but one branch contributes to the face: Ophthalmic artery Enters orbit with optic n. Via optic canal Branches into: ○ Lacrimal branch → Zygomatic bone Zygomaticofacial a. Zygomaticotemporal a. ○ Dorsal nasal a. ○ Supraorbital and supratrochlear a. → scalp ○ Anterior/posterior ethmoidal a. → nasal cavity  Venous Drainage Eventually all drains into subclavian vein External Jugular Vein (posteriorly) ○ Retromandibular vein (from maxillary and superficial temporal v.) ○ Posterior auricular vein Internal Jugular vein (anteriorly) ○ Facial vein Intracranial venous connections Facial vein communicates with superior ophthalmic vein (which leads to cavernous sinus) *** CAVERNOUS SINUS THROMBOSIS** Emissary veins from pterygoid plexus Facial and cranial veins are valveless - therefore infection risk Lymphatics ½ of the lymph nodes in the body lie in the head and neck The closer the structure is to the midline, the more likely it is to have bilateral lymphatic drainage Cancer = enlarged and hard, infection = enlarged and tender Lymphatic Drainage Submental - chin Submandibular - middle of face Pre-auricular/parotid - eyes, nose, lateral cheek → All end up draining into the deep cervical group Virchow’s Node (Supraclavicular node) = drainage of intra-abdominal/thoracic organs Jugulodigastric lymph node (upper cervical) = tonsil (sore throat, often permanently enlarged in children) Innervation of Head and Neck An Overview The head and neck is supplied largely by the cranial nerves Glands have autonomic innervation which have: ○ PNS roots from cranial nerves ○ SNS roots from the thoracic region → they feed into the sympathetic chain → exit via T1 superior cervical ganglion → travel on plexuses on blood vessels to reach their destination The cervical plexus (C1-5) supplies some cutaneous and muscular innervation to the neck More details on cranial nerves in Elina’s slides on cranial nerves, and more details on cervical plexus in Neck section  Cranial Nerve Summary 12 cranial nerves usually represented by roman Formen CN Other numerals S = sensory, M = motor, B = both: some say money Cribriform Plate 1 matters but my brother says big brains matter more Optic canal 2 Ophthalmic a. Anterior view: Superior orbital fissure 3, 4, 5(1), 6 Sup ophthalmic v. Foramen rotundum 5(2) Foramen ovale 5(3) Foramen spinosum Middle meningeal a./v. Carotid canal Internal carotid a. Internal acoustic meatus 7, 8 Jugular foramen 9, 10, 11 Inferior petrosal and sigmoid sinus → IJV Hypoglossal canal 12 Foramen magnum Medulla oblongata, meninges, vertebral a. Cranial Nerve Summary  Autonomics Autonomics supply the glands (salivary, mucous, lacrimal etc) of the head and neck. Parasympathetics arise from cranial nerves: 3, 7, 9 (and 10 to rest of body) and distribute along branches of trigeminal [V] Sympathetics mostly arise from T1-6 sympathetic chain → T1 superior cervical ganglion and travel along the internal carotid artery External Ear External acoustic meatus is made of cartilage for lateral ⅓ of the wall, the other ⅔ is formed by the temporal bone. It is not straight - for examination pull upward, posteriorly, and outward. From external to internal it travels upward anteriorly, upward posteriorly, downward anteriorly Cerumen = wax Associated muscles are innervated by facial nerve [VII] Innervation: ○ Auricle: Auriculotemporal branch of mandibular nerve [V3], and lesser occipital nerve (C2), greater auricular nerve (C2-C3) of cervical plexus ○ External acoustic meatus: Auricular branch of vagus nerve [X] which causes fainting during ear washing, and facial nerve [VII] which sends a branch to the auricular branch of [X] Arterial supply / Venous drainage: ○ External carotid —> posterior auricular a. ○ Superficial temporal a. —> anterior auricular branches ○ Occipital artery Lymphatic drainage: anterior/posterior auricular nodes draining into upper deep cervical nodes  Tympanic Membrane Pars flaccida is thin and slack, pars tensa is thick and taut Because handle of malleus is in the tympanic membrane, tubes needs to go through lower part Grommets tube through membrane allows stuff to come out - used for glue ear/otitis media Innervation: Outer surface: ○ Auriculotemporal nerve - branch of mandibular n. [V3] ○ Auricular branch of vagus n. [X] ○ Branch of facial n [VII] to auricular branch of vagus n. [X] ○ Glossopharyngeal n. [IX] Inner surface: ○ Glossopharyngeal n. [IX] via tympanix plexus Middle Ear - Neurovasculature Arterial Supply: External carotid artery: Tympanic branch of maxillary a. and Mastoid branch of occipital/posterior auricular arteries (as well as other small branches) Venous drainage: pterygoid plexus Innervation of mucous membranes: Tympanic plexus formed by tympanic n. (branch of glossopharyngeal n [IX]) and branches of internal carotid plexus). Note this plexus gives off lesser petrosal nerve which supplies SNS to the otic ganglion  Middle Ear - The Room (Learn) Tegmental wall (roof) Separated from middle cranial fossa by tegmen tympani on petrous part of temporal bone Jugular wall (floor) Composed of thin layer of bone and mastoid air cells Internal jugular vein right underneath Entrance of tympanic branch of glossopharyngeal n. [IX] to later form tympanic plexus Membranous wall (lateral) Tympanic membrane Mastoid wall (posterior) Lower part composed of bone (mastoid air cells), superiorly forms mastoid antrum Stapedius muscle attachment (to stapes) Entry of chorda tympani - branch of facial n. [VII] to later supply taste to anterior ⅔ of tongue Anterior wall Separates from internal carotid artery Exit of chorda tympani pharyngotympanic tube Tensor tympani muscle attachment (to malleus) Labyrinthine wall (medial) Also the lateral wall of the inner ear Round and oval window (attachment of stapes) Promontories for: cochlea - on which lies tympanic plexus, facial canal (containing facial nerve [VII]), lateral semicircular canal Lesser petrosal n. from tympanic plexus enters otic ganglion via foramen ovale  Internal Ear - Vessels and Nerves Associated Nerves Blood Supply Vestibulocochlear nerve [VIII] Bony labyrinth - same as surrounding temporal bone, Special afferent fibres for hearing and balance external carotid a. From lateral surface of brainstem between pons and maxillary artery - anterior tympanic branch medulla, entering via internal acoustic meatus Posterior auricular a. - stylomastoid branch Branches into cochlear nerve (forming spiral ganglion in modiolus) and vestibular nerve (forming vestibular Middle meningeal a. - petrosal branch ganglion which divides into superior and inferior parts) Membranous labyrinth - flows with brain circulation Labyrinthine artery (from anteroinferior cerebellar a. or basilar a.) dividing in the internal acoustic meatus into: ○ Cochlear branch Facial Nerve [VII] ○ Vestibular branch (es) Associated with middle ear as it travels through the facial Venous drainage via labyrinthine vein into inferior canal petrosal sinus/sigmoid sinus Forms the geniculate ganglion to give off the greater petrosal n. - inflammation of the geniculate ganglion causes hemifacial paralysis Gives off the nerve to stapedius and chorda tympani (which runs across tympanic membrane to exit the skull) Entry and Exit - Nerves Sphenopalatine foramen Sphenopalatine a. (maxillary a.) - Communicates with Maxillary (V2) branches: nasopalatine n. pterygopalatine fossa (medial wall), posterior lateral nasal nerves (Posterior nose stuff) (lateral wall) Incisive canal Greater palatine a. enters Nasopalatine n. Exits → oral cavity (Anterior nose stuff) Foramen Cecum Nasal vein → superior sagittal sinus Cribriform plate Olfactory n. (CNI) Anterior ethmoidal n. (Ophthalmic V1 branch) Anterior/posterior ethmoidal a. Around naris Internal nasal branches of infraorbital n. (from V2) Alar branches of nasal a. From facial a. Small foramina Inferior nasal branches from greater palatine branch of V2 Entry and Exit - Arteries Sphenopalatine foramen Sphenopalatine a. (maxillary a.) - Communicates with Maxillary (V2) branches: nasopalatine n. pterygopalatine fossa (medial wall), posterior lateral nasal nerves (Posterior nose stuff) (lateral wall) Incisive canal Greater palatine a. enters Nasopalatine n. Exits → oral cavity (Anterior nose stuff) Foramen Cecum Nasal vein → superior sagittal sinus Cribriform plate Olfactory n. (CNI) Anterior ethmoidal n. (Ophthalmic V1 branch) Anterior/posterior ethmoidal a. (From internal carotid) Around naris Internal nasal branches of infraorbital n. (from V2) Alar branches of nasal a. From facial a. Small foramina Inferior nasal branches from greater palatine branch of V2  Kiesselbach’s Area/ Little’s Area Huge vascular supply + anastomosis between internal and external carotid a. are on both medial and lateral walls of the nasal cavity Kiesselbach’s is on the nasal septum - site of epistaxis due to anastomosis between: Internal carotid → ophthalmic a. → anterior/posterior ethmoidal a. External carotid → maxillary a. → greater palatine a., sphenopalatine a.  Nose - Venous and Lymphatic Drainage Veins: *Note chance of infection of CNS Anteriorly → facial v. Posteriorly → pterygoid plexus Superiorly → ethmoidal v. → superior ophthalmic v. → cavernous sinus Nasal vein (1% people) passes through foramen cecum into superior sagittal sinus Lymphatics: Anteriorly → forward onto face → submandibular nodes Posteriorly → upper deep cervical nodes  Nasal Sinuses Air-filled spaces in your skull formed in childhood (to make your skull more lightweight). They all open into the nasal cavity. Sinus Drainage Innervation Arterial Supply Frontal Middle meatus: Supra-orbital n. (from Anterior Semilunar hiatus [V1]) ethmoidal Ethmoidal Middle meatus: Anterior/ posterior Anterior/ - anterior - ethmoidal ethmoidal branches posterior infundibulum/ semilunar of nasociliary n. (from ethmoidal hiatus [V1]) - Middle - ethmoid bulla Superior meatus: Orbital branches - posterior cells from pterygopalatine ganglion (from [V2]) Sphenoidal Sphenoethmoidal Pharyngeal recess Maxillary Middle meatus: Infraorbital and Infra-orbital and Semilunar hiatus alveolar branches of superior alveolar [V2]  Nasal Sinuses - Drainage (High Yield) Air-filled spaces in your skull formed in childhood (to make your skull more lightweight). They all open into the nasal cavity. Sinus Drainage Frontal Middle meatus: Semilunar hiatus Ethmoidal Middle meatus: - anterior - ethmoidal infundibulum/ semilunar hiatus - Middle - ethmoid bulla Superior meatus: - posterior cells Spheno-ethmoidal recess Sphenoid sinus Sphenoidal Sphenoethmoidal recess Superior meatus Posterior ethmoidal cells Middle meatus Semilunar hiatus: Frontal sinus, anterior ethmoidal cells Maxillary Semilunar hiatus Maxillary sinus Openings on ethmoid bulla: Middle ethmoidal cells Inferior meatus Nasolacrimal duct, pharyngotympanic tube Oral Cavity - Boundaries and Structures Roof Hard and soft palate Floor Muscles: both paired, working to open mouth Mylohyoid (forming diaphragm) ○ From hyoid bone to molar (mylo) ○ n. to mylohyoid from inferior alveolar branch of mandibular n. [V3] Geniohyoid (above mylohyoid) ○ From hyoid bone to chin (genio) ○ C1 hitchhiking from neck along hypoglossal n. Tongue Sublingual and submandibular glands and ducts Important relation: lingual nerve underneath submandibular duct Lateral Cheeks - mainly buccinator Anterior Oral fissure - Lips - Philtrum, formed by fusion of medial nasal processes - Median labial frenulum - connecting lip to gum Posterior Oropharyngeal isthmus - formed by palatoglossal arches, opened/closed by soft palate and tongue Soft Palate Muscles All innervated by vagus nerve [X] via pharyngeal branch to pharyngeal plexus EXCEPT tensor veli palatini - mandibular nerve [V3] via branch to medial pterygoid Palatoglossus is anterior to palatopharyngeus ○ Glossus = tongue, anterior to pharyngeus = throat ○ Forms the palatoglossal/palatopharyngeal arches with the palatine tonsil resting in between ○ Acts to depress soft palate/ or pull the pharynx up, forward, medially during swallowing ○ Palatoglossus is attached to palatine aponeurosis and draws tongue and palate together (palat-glossus) Tensor veli palatini (TVP) is anterior to levator veli palatini ○ Both elevate soft palate but only LVP above neutral - think levator to elevate ○ TVP comes from above wraps around pterygoid hamulus before attaching at the palatine aponeurosis ○ TVP opens the pharyngotympanic tube during yawning/swallowing Musculus uvulae pulls uvula superiorly Palate - Neurovasculature Arteries: Greater and lesser palatine arteries Maxillary artery gives off greater palatine branch, which gives off lesser palatine branch in palatine canal Travel through greater and lesser palatine foramen (in palatine bone) respectively Greater branch → hard palate → incisive canal Lesser branch → soft palate → uvula Veins follow arteries and drain into pterygoid or pharyngeal plexus Lymphatics: deep cervical nodes Innervation: branches of pterygopalatine ganglion Greater/lesser palatine nerve (hard and soft palate respectively) Nasopalatine nerve (through incisive canal) Note the ganglion recieves branches from: ○ Maxillary n. [V2] - general sensory ○ Facial n. [VII] - PNS to glands and taste to soft palate ○ T1 sympathetic trunk - SNS  Tongue (glossus) Structure: Terminal sulcus: ○ Separates oral and pharyngeal surfaces (⅔ from the apex) ○ Margin of oropharyngeal isthmus ○ Apex of V is foramen cecum (site of invagination to form thyroid gland, when the thyroglossal duct persists, thyroid gland is here) Divided left/right by median sagittal septum Papillae on the oral surface increases SA ○ All except filiform have taste buds on surface Lingual tonsil sits on pharyngeal surface Inferior surface from medial to lateral has: frenulum → lingual v. → fibriated fold  Tongue - Muscles All paired All supplied by hypoglossal nerve [XII] EXCEPT palatoglossus by vagus nerve [X] (considered part of palate muscles) Intrinsic muscles: alter shape of tongue by lengthening/ shortening, curling, flattening Superior and inferior longitudinal Transverse and vertical Extrinsic M Attachment Action Genioglossus Superior mental spines Depress central part (genio= chin) Poke tongue out Hyoglossus Hyoid bone (greater horn Depress ish) Styloglossus Styloid process Elevate and retract Important relation: (from inner to outer) Palatoglossus Inferior surface of Elevate Genioglossus → lingual a → Hyoglossus → palatine aponeurosis + depress soft palate hypoglossal/lingual n.  Tongue - Vessels Branches of lingual artery (enters through oropharyngeal triangle and travels above genioglossus, under hyoglossus) Dorsal lingual a./v. - back Deep lingual a./v. - inferior surface of tongue (travels with hypoglossal n.) Sublingual a./v. - underneath tongue Lymphatic drainage → deep cervical and submental l.n. Tongue - Innervation (HIGH YIELD) IMPORTANT Issue with vagus [X] = Uvula deviate toward normal side Issue with hypoglossal n. [XII] = Tongue deviates toward abnormal side Motor Muscles of tongue Hypoglossal n. [XII] Palatoglossus Vagus n. [X] Sensory Anterior ⅔ Trigeminal [V] - general sensation Facial [VII] via chorda tympani - special sensation (taste) Posterior ⅓ Glossopharyngeal [IX] - general and special sensory Epiglottis and soft palate Vagus n. [X] - general and special Tongue - Innervation (HIGH YIELD) Reasoning: Hypoglossal [XII] = muscles of tongue as hypo = under, and nerve runs underneath tongue to access all the muscles Vagus [X] is all of palate (except TVP) therefore: motor to palatoglossus and sensory to epiglottis and soft palate General sensory is same as surroundings ○ Closest to face (ant ⅔) = trigeminal [V] ○ Closest to pharynx (post ⅓) = glossopharyngeal [IX] Taste is provided by same sensory nerve except anterior ⅔ of tongue via facial nerve [VII] chorda tympani  Salivary Glands Mostly small glands in submucosa or mucosa of oral epithelium. Larger glands are paired: Parotid Gland Submandibular Gland Sublingual Gland Relations Deep and superficial lobes separated by facial nerve Curls around mylohyoid (diaphragm) Pierced by (from superficial → deep): Facial artery loops over superficial lobe Facial nerve [VII] → 5 terminal branches (between lobe and mandible) Retromandibular vein External carotid artery Lingual nerve loops under duct Lymph nodes Duct opens to 2nd upper molar Sublingual caruncle (beside frenulum) Numerous along sublingual fold Arteries External carotid artery Facial and lingual artery/vein Veins External jugular vein Lymphatics Parotid nodes → deep/superficial cervical Submandibular nodes → deep cervical Innervation Sensory: Auriculotemporal n. [V3] and greater auricular n. PNS: Chorda tympani of facial [VII] PNS: glossopharyngeal [IX] via otic ganglion → auriculotemporal n. SNS: T1 via external carotid  Pharyngeal Muscles Consist of constrictor (circular) and longitudinal (vertical) muscles Muscles from each side are joined by pharyngeal raphe All innervated by pharyngeal branch of vagus n. except stylopharyngeus (glossopharyngeal n.) Constrictor Muscles Constrictor muscles - superior middle and inferior Arranged like telescope (inferior most outside) Forms 2 sphincters ○ Palatopharyngeal sphincter (pharyngeal isthmus) ○ Inferior constrictor acts as a sphincter Oropharyngeal triangle (superior/middle) - oral cavity ○ Glossopharyngeal, stylopharyngeus, lingual nerves Between middle/inferior constrictors - into larynx ○ Internal laryngeal n ○ Laryngeal a.v. Under inferior constrictor ○ Recurrent laryngeal n./v. Pharyngeal Spaces Parapharyngeal Internal maxillary a. Base of skull to greater horn of hyoid Ascending bone pharyngeal a. Pterygoid venous plexus Mandibular division of trigeminal n. Retropharyngeal Retropharyngeal l.n. Posterior to pharynx/oesophagus Fat and vessels between pretracheal and prevertebral fascia (alar fascia runs through) Joins C6-T5 → posterior mediastinum Danger Space Potential path of infection Posterior to retropharyngeal space from pharynx to superior between alar fascia and prevertebral and posterior mediastinum fascia Joins skull → thorax, superior mediastinum → base of diaphragm Vasculature Arteries: external carotid branches Ascending pharyngeal Branches of facial, lingual, maxillary Major blood supply to palatine tonsil is from tonsillar branch of facial artery Veins form pharyngeal venous plexus and drain: Superiorly → pterygoid plexus → retromandibular v → IJV Inferiorly → IJV  Innervation Pharyngeal Plexus Located over middle constrictor in retropharyngeal space Function: pharynx and soft palate ○ All motor for pharynx is vagus [X] except stylopharyngeus via branch of glossopharyngeal [IX] ○ All sensory via glosssopharyngeal [IX] except: Anterior/superior nasopharynx via maxillary x. [V2] Inferior laryngopharynx via internal branch of vagus [X] ○ Therefore: gag reflex = 9 in 10 out Formed by: ○ Pharyngeal branches [X] - major motor branch ○ External laryngeal n. [X] - from superior laryngeal branch ○ Pharyngeal branches [IX] ○ Cervical sympathetic ganglion  Laryngeal Muscles All innervated by vagus n. [X] Cricothyroid via external branch of superior laryngeal n. (of vagus n.) All others via recurrent laryngeal branch Cricothyroid Tense vocal l. Vocalis Relax vocal l. (runs adjacent Thyroarytenoids to vocal l.) Lateral cricoarytenoids Adduct arytenoids (closes Transverse arytenoids rima glottidis) Oblique arytenoids Posterior cricoarytenoids Abducts arytenoids (opens rima glottidis)  Neurovasculature Superior Branches Inferior Branches Arteries Superior laryngeal Inferior laryngeal (external carotid) (thyrocervical trunk) Veins Superior laryngeal Inferior laryngeal → superior thyroid → IJV → Inferior thyroid v. → brachiocephalic v. Lymph n. Superior deep cervical Inferior deep cervical Nerves Superior laryngeal Recurrent laryngeal (turning - External branch into inferior laryngeal) (All [X] Inferior constrictor of sensory below vocal branches) pharynx folds Cricothyroid m. motor to all other - Internal branch muscles sensory down to Travels around arch of vocal folds aorta (left) or under subclavian artery (right)  Neurovasculature Superior Branches Inferior Branches Arteries Superior laryngeal Inferior laryngeal (external carotid) (thyrocervical trunk) Veins Superior laryngeal Inferior laryngeal → superior thyroid → IJV → Inferior thyroid v. → brachiocephalic v. Lymph n. Superior deep cervical Inferior deep cervical Nerves Superior laryngeal Recurrent laryngeal (turning - External branch into inferior laryngeal) (All [X] Inferior constrictor of sensory below vocal branches) pharynx folds Cricothyroid m. motor to all other - Internal branch muscles sensory down to Travels around arch of vocal folds aorta (left) or under subclavian artery (right)  Thyroidectomy Structures at risk: External superior laryngeal n. → cricothyroid m. weak (usually tenses vocal cord) → weak voice, inability to sing, lower pitch Recurrent laryngeal n. During dissection of inferior thyroid a. → vocal cord toward miline ○ Unilateral → hoarse voice ○ Bilateral → airway obstruction and need for tracheostomy Parathyroid glands → hypocalcaemia Post thyroidectomy haemorrhage Thyroid is beneath deep cervical fascia and strap muscle layer Leads to increase in pressure on venous/lymphatic system → swelling of submucosa and airway obstruction Tx: open neck on ward to relieve pressure (need to cut through aforementioned layers)  Common Sites of Foreign Body Lodgement Piriform Fossa Vallecula On either side of laryngeal inlet Depression anterior to epiglottis Branches of internal laryngeal and recurrent laryngeal n. at risk Dehiscence of Killain Rima Glottidis Narrowest part of larynx Object or removal of object can damage vocal chords Pharyngeal Arches Skeletal tissue and cartilage Muscular derivative Innervation Vasculature Arch 1 Zygomatic bone, Muscles of Trigeminal nerve (CNV2 and Maxillary artery maxilla and mandible mastication V 3) Incus and malleus (upper inner ear bones) Arch 2 Lower part of inner ear bone Muscles of facial Facial nerve (CNVII) Stapedial artery → upper part of hyoid bone expression (embryo)/ Stapes caroticotympanic Styloid process These muscles are artery Stylohyoid ligament superior to muscles of Upper hyoid mastication as develop later and migrate after Arch 3 Lower part of hyoid bone Stylopharyngeus Glossopharyngeal nerve Common carotid muscle (CNIX) artery and 1st part of internal carotid) Pharyngeal Arches Skeletal tissue and Muscular derivative Innervation Vasculature cartilage Arch 4 & 6 Pharyngeal and Laryngeal muscles Branches of vagus nerve Arch 4 = right subclavian laryngeal Arch 4 = superior artery and aortic arch Merge to form cartilages laryngeal nerve thyroid and (cricothyroid Arch 6 = ductus arteriosus pharynx muscle) and pulmonary artery Arch 6 = recurrent laryngeal nerve (all other intrinsic laryngeal muscles) Arch 5 Disappears Forms gills but not in humans