Head and Neck Anatomy (5th copy) PDF

Upper Respiratory Tract and Pharynx The Connected Bits Nasal sinuses drain into the nasal cavity Middle ear is connected to the nasopharynx via the eustachian tube Oral cavity and nasal cavity are separ...

Upper Respiratory Tract and Pharynx The Connected Bits Nasal sinuses drain into the nasal cavity Middle ear is connected to the nasopharynx via the eustachian tube Oral cavity and nasal cavity are separated by the hard and soft palate Pharynx → Oesophagus (C3-4) ○ Nasopharynx - from nasal cavity via choanae ○ Oropharynx - from oral cavity via palatoglossal folds Larynx → trachea (C3-4)  Ear Relations: Nasal cavity - pharyngotympanic tube External - external acoustic meatus Cranial cavity - temporal bone (internal acoustic meatus) The Ear Split into external/outer ear, middle ear, and inner ear Bony part is part of temporal bone Brief overview of function: Sound is trapped by external ear and travels through external acoustic meatus Sound waves move the tympanic membrane (ear drum) which is attached to the ossicles (malleus, incus, stapes) in the middle ear, which functions to amplify the sound The stapes is attached to the inner ear and moves fluid in the cochlea which is detected by the vestibulocochlea nearve [VII] The semicircular canals in the inner ear also has fluid which has functions in balance - and is the reason why you are dizzy  External Ear Consists of auricle and external acoustic meatus (from concha to tympanic membrane/ear drum) Skin cancers often present at the helix. Darwin’s tubercle is normal. Auricle Helix (w/ crux) + antihelix (w/ crura) Tragus + antitragus with intertragic notch in between Fossas - triangular and scaphoid Lobule and concha 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 - Where? Situated between the external ear and inner ear in an air-filled mucous membrane lined space in the temporal bone Consists of the tympanic cavity (directly next to the tympanic membrane) and the epitympanic recess (superiorly) Communicates with Looking from the side into the ear ○ The mastoid area (posteriorly) which consists of mastoid air cells via the (lateral view) mastoid antrum - this is part of the temporal bone. Because the mucous membranes are continuous, infections can spread from the middle ear to the mastoid process ○ The nasopharynx (anteriorly and medially) via the pharyngotympanic (eustachian) tube - this is why you can make your ears pop by blocking your nose and blowing out air. It functions to equalize pressure across the tympanic membrane Surrounded by cartilage and tensor veli palatini muscle (which contracts when you swallow) - opening up the tube Looking in from the front (anterior view) 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 - Contents Auditory Ossicles Malleus, incus and stapes form an osseous chain from the tympanic membrane to the oval window of the internal ear Malleus ○ Handle - attached to the tympanic membrane and tensor tympani m. ○ Lateral process - anterior/posterior malleolar folds of tympanic membrane ○ Anterior process - anterior wall via a ligament ○ Head - articulates with incus Incus ○ Body - articulates with head of malleus ○ Long limb with a lenticular process - articulates with head of stapes ○ Short limb - ligament to upper posterior wall of middle ear Stapes ○ 2 limbs attach to oval base which articulates with oval window on labyrinth wall ○ Associated with stapedius muscle Middle Ear - Contents Muscles - modulates movement during transmission of vibrations Tensor tympani - attached to handle of malleus to tense tympanic membrane (branch of V3) Stapedius - from mastoid wall to neck of stapes - pulls stapes posteriorly to prevent excessive oscillation in response to loud noises (VII) (lateral view) Middle Ear - The Room (learn) Lateral view looking into the ear (so that tympanic membrane is removed and the back = the wall between middle/internal ear)  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 Otitis Media Definition Infection of middle ear Epi Common in infants and small children (6-24M) - eustachian tube is more horizontal, shorter, has less cartilage and is more patent + immunological immaturity Pathophys Viruses (RSV) most common - also S. pneumoniae, H. influenzae, Moraxella catarrhaxillis Ascending infection often 2˚ to URTI Inflammation and swelling of mucous membrane of tympanic cavity causes partial or complete pharyngotympanic tube blockage Sx Fever, lethargy, irritability Earache, ear discharge ± hearing loss, bulging ear drum Usually self-resolving, symptoms last