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Pharynx: Fri, Oct 6


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Pharynx: Intro
*12-15 cm tube
*begins at base of skull adn extends to junction with esophagus (inferior border of cricoid cartilage
*5cm wide superiorly
*1.5cm wide inferiorly-narrowed part of GI tract
*mixture of air and food in upper part of pharynx
Walls of Pharynx:
1. mucosa
2. submucosa: (pharyngobasilar fascia); deep to tonsil
3. muscular layer: inner longitudinal and outer circular
4. palatine tonsil: lies in mucosa
5. buccopharyngeal fascial layer-posterior to pharyngeal muscles
6. retropharyngeal space-posterior to buccopharygeal fascia
Subdivisions of Pharynx:
1. nasopharynx: posterior nasal aperture or choanae is opening from nasal cavity
*extends from base of skull to tip, inferior end of soft palate (uvula)
2. oropharynx: runs from uvula to tip end of epiglottis
3. larygopharynx: from epiglottis to inferior border of cricoid cartilage (C6 vertebrae)
1. choanae
2. pharyngeal tonsil-on superior aspect of posterior wall
3. ostium (1.5cm from inferior conchal bone) and opening of eustachian tube
4. torus tubarius: swelling produced by medial portion of eustachian tube
5. salpingopharyngeal fold: extends down from torus tubarius into pharynx
6. pharyngeal recess: cleft where cancers form
7. parapharyngeal space: lateral to recess, where infections from teeth can spread
8. pharyngeal isthmus: bridge between naso- adn oro- pharnyx's
9. levator palatini
10. tensor palatini: anterolateral to levator
**CC: both muscles elevate and pull soft palate posteriorly to close off nasopharynx from oropharynx during 2nd stage of deglutition (involuntary)
Eustachian tube:
**conduit connecting nasdopharynx to middle ear
**purpose to equalize pressure on either side of tympanic membrane
**also conduit for bacteria
**cartilaginous (medial 2/3) and bony (lateral 1/3)portions
**not a complete ring but is completed by membrane

**CC: 1) Valsalva maneuver-equalizes pressure (holding nose and blowing with mouth closed); 2) otitis media (middle ear infection): more common in children b/c eustachian tube is shorter, wider and more horizontal
Soft Palate:
1. uvula- appendage hanging down to separate naso- and oro- pharynx's
2. made of glands, minor salivary glands
3. five muscles in posterior aspect:
a) tensor palatini
b) levator palatini
c) palatoglossus
d) palatopharyngeus
e) muscularis uvuli: cause rolling "r" in spanish
**bound by soft palate superiorly, base of tongue inferiorly, arches laterally
1. palatoglossus muscle: short and brief, deep to fold and anterior to palatine tonsilar bed
2. pharyngobasilar fascia lies over tonsil bed; used as lateral boundary for tonsilectomies
3. throat, or fauces, lies between palato- glossal and pharyngeal folds
4. superior constrictor muscle: forms bed of tonsil
5. palatoglossal muscle
6. palatopharyngeus muscle
7. epiglottic folds: lie between epiglottis and tongue
Innervation and Blood supply:
1. paratonsillar (external palatine) vein
**CC: bleeding after tonsilectomy usually from paratonsillar vein

2. tonsillar branch of facial artery (main supply): 5 arteries of tonsillar bed

1. glossopharyngeal: only nerve to tonsillar bed-supplies taste and sensation to posterior 1/3 of tongue; can be found in gap between middle and superior constrictors (as well as stylohyoid lig and stylopharyngeus
2. lingual nerve-may be sacrificed in tonsillectomies

*CC: surgeon can go through thin superior constrictor and nick coiled ICA
1. aditus: opening of larynx-marked laterally by aryepiglottic folds
2. bulge for cricoid cartilage and piriform recess, a mucosal fold covering internal laryngeal nerve
Muscles of Pharynx:
3 Inner Longitudinal:
1. salpingopharyngeus-most superior
2. palatopharyngeus
3. stylopharyngeus-upper fibers external to pharynx
*muscles blend together and attach inferiorly into wall of pharynx and superior-posterior aspects of thyroid cartilage
**contraction of longitudinal muscles widens adn shortens pharynx as it receives bolus of food

Outer Circular Layer:
1. superior constrictor: attaches anteriorly to pterygomandibular raphe and bone at either end-medial pterygoid plate (hamulus) and mandibular part, just posterior to mylohyoid line
2. middle constrictor: arises from stylohyoid lig, lesser horn of hyoid, and superior border of greater horn of hyoid
3. inferior constrictor: arises from thyroid and cricoid cartilages; has 2 portions: oblique thyropharyngeus and horizontal cricopharyngeus
**contract in sequence to force bolus of food down esophagus
*have common posterior attachment: midline raphe
1. between skull and superior constrictor: pharyngobasilar muscle pierced by auditory tube and levator palatini; ascending palatine br of facial artery an dascending pharyngeal artery pass over gap
2. between superior and middle constrictors: stylohyoid lig, stylopharyngeus, and CNIX
3. between middle and inferior constrictors: thyrohyoid membrane pierced by internal laryngeal nerve and superior laryngeal artery

**CC: in between thyropharyngeus and cricopharyngeus is thinnest layer of GI tract: Killian's Dehiscence-a pharyngeal diverticulum can occur b/c area of least resistance
Nerves of Pharynx:
1. V2: pharyngeal br of V2 supplies some afferent fibers to upper part of pharynx just superior to ostium of auditory tube
2. CNIX: afferent fibers to area from just superior to ostium to termination of pharynx
3. CNX: internal laryngeal branches supply some of pharynx

A. Pharyngeal plexus:
*lies on posterior aspect of middle constrictor
1. CNX (SVE) fibers are motor to most muscles of pharynx
2. CNIX: sensory to most of pharynx
3. CNIX: motor branch (SVE) supplies stylopharyngeus
4. sympathetics: from pharyngeal branches of sympathetic trunk

*note: internal laryngeal pierces region of piriform recess
*recurrent laryngeal passes between cricopharyngeaus and muscle of esophagus
*recurrent becomes inferior laryngeal where thyroid cartilage junctions with cricoid cartliage
Blood Supply:
ECA gives off 8 branches:
1. Superior thyroid
2. Ascending pharyngeal
3. Lingual
4. Facial
5. Occipital (posteriorA)
6. Posterior auricular (posterior)
7. Superficial temporal (terminal)
8. Maxillary (terminal)

**CCA bifurcates at superior level of thyroid cartilage
**termination of ECA into 2 branches is at level of neck of mandible

A. carotid sinus: dilatoin in distal portion of CCA and initial portion of ICA (baroreceptors)
*CC: if pressed, stimulates increase pressure and results bradycardia, resulting in reducing pulse rate and possibly fainting.
*could also break off calcified cholesterol, resulting in stroke

B. carotid body: is a chemoreceptor in bifurcation of CCA

1. pharyngeal veins drain into pharyngeal plexus of veins, which typically drains into IJV, BUT can drain into facial of lingual
1. superifial nodes in head and face take shape of collar
2. superficial cervical
3. deep cervical (deep to SCM)
*omohyoid crosses IJV and divides deep cervical into superior and inferior sets
4. pharynx drains to deep cervical (retropharyngeal)
5. palatine tonsil drains into jugulodigastric node (deep cervical)

**superficial lymphatic drainage of head and neck all drain into deep cervical, which in turn drain to jugular trunk.
a. left side: thoracic duct
b. right sidea: right lymph duct
Lymphoid tissue:
**adenoids: when pharyngeal tonsil is enlarged
**may be collection of lymphoid tissue at opening of eustachian tube. if enlarged due to infection, plugs up nasopharyngeal opening (middle ear infection)
**additional tissue in palatine and lingual tonsils
**Waldeyer's Ring: ring of tissue guarding the orifices of pharynx

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