anatomy & physiology of pharynx

Anatomy of PharynxDr. B. Arvind Sangavi

M.S.(ENT)Associate ProfessorDept of ENT & HNS

RIMS

PharynxPharynx is a conical fibromuscular tube

forming upper part of aero-digestive tract12-14 cms, extends from base of skull to

lower border of cricoid cartilage (C6).Width is 3.5 cms at base & 1.5 cms at

pharyyngo-oesophageal junction, which is the narrowest part in GIT.

Mucous membranePharyngeal aponeurosis / Pharyngobasilar fascia

Muscular coatBuccopharyngeal fasciaCiliated columnar in nasopharynx &

stratified squamous in rest of pharynx

Killian’s dehiscenceInferior constrictor muscle- thyropharyngeus –oblique fibres

cricopharyngeus – transverse fibresPotential gap- Killian’s Dehiscence“Gateway of tears” – perforation can occur at

this site during oesophagoscopy.Pharyngeal pouch- herniation of pharyngeal

mucosa

Waldeyer’s RingSubepithelial layer of lymphoid tissueNasopharyngeal tonsil/adenoidsPalatine tonsilTubal tonsilLateral pharyngeal bandsNodules-posterior pharyngeal wall

Pharyngeal SpacesRetropharyngeal space- from base

of skull to bifurcation of trachea between buccopharyngeal fascia & prevertebral fascia. Divided by median raphe into two (space of Gillette)

Prevertebral space - between vertebral bodies & prevertebral fascia, extends from base of skull to coccyx

Parapharyngeal spaceMedial: buccopharyngeal fascia covering

constrictorsPosterior: prevertebral fasciaLateral: medial pterygoid muscle,

mandible.Styloid complex- divides into anterior &

posterior compartment. Antr- tonsillar fossa medially & pterygoid

muscle laterally Postr- pharyngeal wall med & parotid

laterally. Carotid art, jugular vein, IX, X, XI, XII CN, & nodes

PharynxNasopharynx, Oropharynx & HypopharynxNasopharynxEpipharynx: from base of skull to plane

passing through hard palateRoof: basisphenoid & basiocciputPosterior wall: atlas vertebra with musclesFloor: anteriorly soft palate & posteriorly

communicates with the oropharynx through nasopharyngeal isthmus

Lateral wall: E.tube 1.25cms behind IT Torus tubaris- elevation behind tubal opening Fossa of Rosenmuller- site for origin of

Nasopharyngeal Carcinoma Salpingopharyngeal foldTubal tonsil: part of Waldeyer’s ring

Adenoids-Nasopharyngeal tonsil upto12 years, later atrophies

Nasopharyngeal bursaEpithelial lined median recess within adenoids

Extends from pharyngeal mucosa to basiocciput

Represents attachment of notochord to pharyngeal entoderm during embryonic life

Infection – persistent postnasal discharge

Thornwaldt’s disease- abscess

Rathke’s pouch: remniscent of buccal mucosal invagination,forming antr lobe of pituitary. Craniopharyngioma may arise from this site

Sinus of Morgagni: space between base of skull & upper free border of superior constrictor . E.tube, tensor veli palatine, levator veli paltine enters along with ascending palatine artery br of facial artery

Passavant’s ridge: mucosa ridge raised by palatopharyngeus. Deglutition, cuts off NP from OP

Lined by pseudostratified ciliated columnar epithelium

Lymphatics drain into upper deep cervical nodes either directly or thro’ retro/parapharyngeal nodes

FunctionsConduit of humidified air into larynx/tracheaVentilates ME thro’ E.tube, equalizes air

pressure.Cuts off oropahrynx during deglutition, vomiting,

speechResonating chamberDrainage channel for mucous secreted by nasal

glands

Oropharynx Extends from plane of hard palate above to plane of

hyoid bone belowCommunicates with oral cavity thro’ oropharyngeal

isthmus.Posterior wall: related to retropharyngeal space, C2-C3Anterior wall: above opens into oral cavity, & below

related to base of tongue, lingual tonsil, valleculaeLateral wall: anterior & posterior pillars, faucial tonsilLower limit is by upper border of epiglottis &

pharyngoepiglottic folds

Lymphatics drain into upper jugular chain-JD nodes, also to retro & para pharyngeal nodes.

FunctionsConduit for passage of air & foodPharyngeal phase of deglutitionVocal tract for certain speech soundsTaste sensation-BOT, soft palate, pillars,

PP wallLocal defence & immunity at entrance of

aerodigestive tract- Waldeyer’s ring

Hypopharynx (Laryngopharynx)It lies behind & sides of larynxExtends from plane passing from hyoid

bone to lower border of cricoid cartilage, (C3-C6).

Three regions: Pyriform sinus, post cricoid region & posterior pharyngeal wall.

Pyriform fossa: either side of larynx. Internal laryngeal nerve runs submucosally in lat wall, cause referred pain in carcinoma

Post-cricoid region: cricoid lamina, site for carcinoma in pt’s with Plummer-Vinson syndrome

Posterior pharyngeal wall: from level of hyoid bone to crcoarytenoid joint.

Lymphatic drainage: upper jugular chain, parapharyngeal nodes, supraclavicular.

Functions:Conduit for air & food, Vocal tract resonanceTakes part in deglutitionFailure of cricopharyngeal sphincter to relax

when pharyngeal muscles contract- hypopharyngeal diverticulum

Structures passing throughAbove superior constrictorE.tube, tensor palati, levator palati musclesPalatine br ascending pharyngeal arteryBetween superior & middle constrictorStylopharyngeus muscle, glossopharyngeal nBetween middle & inferior constrictorInternal laryngeal n, superior laryngeal vessels.Below inferior constrictorRecurrent laryngeal nerve, inferior laryngeal

art

Blood supply: branches of external carotid artAscending pharyngeal, Dorsal lingual arteryAscending palatine & tonsillar arteryBranches of internal maxillary arteryNerve supply: pharyngeal plexus formed byPharyngeal br of vagus & glossopharyngealPharyngeal br of superior cervical

sympathetic ganglionVagal fibres are motor, glossopharyngeal is

sensory & sympathetic is vasomotor

Functions of PharynxDeglutitionProtection from aspirationPart of respiratory & food passageSpeech adds resonance to the voiceWaldeyer’s ring is involvedTaste sensationMucous from respiratory tract is

swallowedE.tube ventilates & drains the middle ear

cleft

Thank You..