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BIOL 2P95 (35)

Pharynx I

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Dirk De Clercq

Basicranium and Pharynx I. Basicranium a. Bones i. Occipital, temporals, sphenoid, vomer, palatines, & maxillae ii. Also parts of parietals and zygomatics are visible b. Foramina & Structures Passing through them i. Incisive foramen—nasopalatine n., sphenopalatine a. ii. Palatine Foramina—greater/lesser palatine nn. & vessels iii. Foramen Ovale—CN V3 (and sometimes lesser petrosal n.) iv. Foramen Lacerum—covered w/ cartilage; int. carotid passes superiorly; jxn of occipital, sphenoid, and temporal bones v. Foramen Spinosum—middle meningeal vessels; meningeal br. of CN V3 vi. Carotid Canal—internal carotids; carotid plexus (sympathetic) vii. Jugular Foramen—CNs IX, X, XI, internal jugular veins viii. Stylomastoid Foramen—CN VII ix. Foramen Magnum—spinal cord, vertebral aa., spinal accessory nn. x. Hypoglossal Canal (foramen)—CN XII xi. Condylar Canal (fossa)—emissary vv. From sigmoid sinus; meningeal br. of occipital a.; holes are variable xii. Mastoid Foramina—emissary v. from sigmoid sinus; holes are variable c. Other structures i. Choane—mark boundary between nasal cavity and nasopharynx ii. Medial/lateral pterygoid plates of sphenoid—insertion for pterygoid mm. & tensor veli palatine iii. Hamulus of medial ptergoid plate—pulley for tensor veli palatine iv. Articular tubercle & mandibular fossa—form TMJ v. Pharyngeal Tubercle—where pharynx attaches to occipital bone ant. to foramen magnum vi. Styloid process—3 muscles & 2 ligaments attach here vii. Auditory tube & EAM viii. Mastoid Processes—hollow and full of air cells ix. Occipital condyles x. External Occipital Protuberance—inion II. Pharynx a. Definition: a fibromuscular tube running from base of skull to inferior border of cricoid cartilage i. Common route for food and air ii. Five layers: mucosa, submucosa, fibrous fascia (pharyngofacial fascia), muscular layer, loose connective fascia (buccopharyngeal fascia) b. Divisions i. Nasopharynx—posterior extension of nasal cavity superior to soft palate; 1. extends from choanae (internal nares) to soft palate 2. contains pharyngeal tonsils (adenoids) & opening to auditory tubes (pharygotympanic) ii. Oropharynx—continuous with oral cavity 1. extends from soft palate to epiglottis 2. contains palatoglossal & palatopharyngeal arches & palatine tonsils iii. Laryngopharynx—posterior to larynx 1. extends from epiglottis to the lower border of the cricoid cartilage 2. contains aditus (inlet) of larynx & piriform recesses 3. continuous with esophagus c. Muscles i. External: three constrictors (sphincters); all insert into median raphe; have gaps laterally but overlap slightly on posterior aspect 1. Superior Constrictor—from pterygomandibular raphe &pterygoid hamulus to median raphe and pharyngeal tubercle 2. Middle constrictor—from hyoid bone & inf. end of stylohyoid lig. To median raphe 3. Inferior Constrictor—from thyroid and cricoid cartilages to median raphe ii. Internal (longintudinal) 1. Stylopharyngeus—from styloid process to thyroid cartilage (starts externally but becomes internal) 2. Palatopharyngeus—from palate to thyroid cartilage & side of pharynx 3. Salpingopharyngeus—from auditory tube to pharynx d. Innervation i. Pharyngeal Plexus—supplies most innervation to pharynx; composed of CN IX (sensory), CN X (motor) & sympathetics from superior cervical plexus ii. Exceptions 1. Stylopharyngeus—motor innervation by CN IX (only muscle inn) 2. Nasopharynx—sensory supplied by CN V instead of CN IX e. Structures Passing between Pharyngeal Muscles i. Between skull & superior constrictor—levator veli palatine & auditory tube ii. Between superior & middle constrictors—stylopharyngeus m, CN IX, & stylohyoid ligament iii. Between middle & inferior constrictors—internal laryngeal n & superior laryngeal vessels iv. Below inferior constrictor—inferior laryngeal a & recurrent laryngeal n. III. Nasal Cavity & Paranasal Sinuses a. Function: i. Transmit, warm, filter, & humidify air ii. Olfaction via CN I iii. Resonating chambers—nose and paranasal sinuses affect voice sound voice b. Innervation 1+2 i. Sensory—CN V (mucosa) ii. Parasympathetic—CN VII (mucosal secretions via paranasal sinuses & nasolacrimal duct)
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