Anatomy of pharynx

ANATOMY OF PHARYNX

KEERTHI NS2010 BATCH

An overviewPharynx is a conical

fibromuscular tube forming the upper part of air and food passages

12-14cm longWidth :3.5cm at base; 1.5cm at

pharyngo-oesophageal junction

PHARYNX

Division of Pharynx

a)Base of skull(basioociput and basi sphenoid) soft palate

b)Plane of hard palate hyoid bone

c) Hyoid bone lower border of cricoid cartilage

STRUCTURE OF PHARYNGEAL WALL

From outwards:a)Mucus membraneb)Pharyngeal

aponeurosis c)Muscular coat d)Buccopharyngeal

fascia

Mucus membrane• Pseudostratified ciliated

columnar(in nasopharynx)• Stratified squamous epithelium

Pharyngeal aponeurosis• Pharyngobosilar fascia• Fibrous layer lining muscular coat

Muscular coat• Longitudinal muscles(internal

layer) • Constrictors

Buccopharyngeal fascia• Covers pharynx externally • Pharyngeal plexus of nerves

Pharyngeal Muscles

Stylopharyngeus

• O:medial aspect of styloid process

• Gap between middle and superior constrictor

• NS: glossopharyngeal

Palatopharyngeus

• O: upper surface of palatine aponeurosis as 2 fasiculi

• Moves along inner aspect of the constrictor

• NS: pharyngael plexus

Salpingopharyngeus

• O: cartilage of the auditory tube near the pharyngeal opening of it.

LONGITUDINAL MUSCLES

All the 3 are inserted as a conjoint sheet at the post border of thyroid cartilage and lat aspect of epiglottis

Constrictors

Lies in wall of nasopharynx and oropharynx Wide originPost border of med pterygoid plate

&pterygoid hamulusPterygomandibular raphaePost end of mylohyoid line Mucus membrane on side of tongue

Lower part covered by middle constrictor.

Superior Constrictor

Middle Constrictor

HypopharynxO: lower part of stylohyoid ligament lesser and greater cornu of hyoid

Inferiorly overlapped by inferior constrictor.

Inferior Constrictor

Thickest of the 3Thyropharyngeus obliquely displaced O:oblique line of thyroid cartilage inferior cornu of thyroid

Cricopharyngeus transversly displaced O: ant part of cricoid cartilage between attachment of cricothyroid and articulation of inferior cornu

Cricopharyngeus

Muscles of 2 sides act as a sphincterFunction– prevent the entry of air in

to the oesophagus in the interval between swallowing

So sphincter relaxes during swallowing

Contracts between the acts of swallowing.

All of the fibres get inserted into the median fibrous raphae

Extending from Pharyngeal tubercle

oesophagus

Constrictors

Killian’s DehiscencePotential gap b/w weak area of pharyngeal wall

Gateway of Tear perforation can occur at this site during oesophagostomy.

Killian’s Dehiscence

PHARYNGEAL SPACES2 potential spaces in relation to pharynx:Retropharyngeal space:

Situated behind pharynxExtends from base of skull to the bifurcation of

tracheaParapharyngeal space:

Situated on the side of pharynxContains carotid vessels, jugular veins, last

four cranial nerves & cervical sympathetic chain

Pharngeal Plexus of NervesAlmost all of the nerve supply to the pharynx, whether motor or sensory, is derived from the pharyngeal plexus

Formed by the pharyngeal branches of the glossopharyngeal and vagus nerves with contributions from the superior cervical sympathetic ganglion.

The pharyngeal branch of the vagus supplies all the muscles of the pharynx

Excluding stylopharyngeus, which is supplied by the glossopharyngeal nerve

NASOPHARNX / EPIPHARYNX

RoofPost

wallFloor Ant

wall Lat

wall

Nasopharynx Uppermost part Behind nasal cavitiesExtents:Base of skull to soft palateRoof:Basisphenoid and

basiocciputPosterior wall:Arch of atlas vertebraPre vertebral musclesFascia

Nasopharynx (contd)

Floor:Ant:soft palatePost: deficit(nasopharyngeal

isthumus)Ant wall:Posterior nasal apertures or

choanaePosterior ends of nasal

turbinates and meatus are seen

Nasopharynx (contd)Lat wall:Presents pharyngeal opening of eustachian

tube situated 1.25cm behind the posterior end of inferior turbinate

Bounded above and behind by an elevation called TORUS TUBARIUS raised by the cartilage of the tube.◦ Above and behind the tubal elevation is a recess

called fossa of Rosenmuller-commonest site for origin of carcinoma.

◦ Salpingopharyngeal fold-A ridge extending from lower end of the TT to the lateral pharyngeal wall;raised by salpingopharyngeus

NASOPHARYNGEAL TONSIL(ADENOIDS)Subepithelial collection of

lymphoid tissue.At the junction of roof and

posterior wall of nasopharynx.Causes the overlying mucous

membrane to be thrown into radiating folds.

Increases in size up to the age of six years and then gradually disappears.

Epithelial lined median recess found within adenoid massExtends from pharyngeal mucus to periosteum of basiocciput.Represents the attachment of notochord to pharyngeal endoderm during embryonic developmentInfected pharyngeal bursitis post nasal discharge or crustingAbscess in the bursa:Thornwaldt’s disease

Nasopharyngeal Bursa

Rathke’s Pouch

Clinically represented-A dimple above the adenoids

Reminiscent of buccal mucosal invagination to form the anterior lobe of pituitary

Carcinopharyngoima may arise

Tubal tonsilCollection of subepithelial

lymphoid tissueSit. at tubal elevationContinuous with adenoid tissue

and forms a part of Waldeyer’s ring.

CA:When enlarged due to infection,

it causes eustachian tube occlusion.

Sinus of Morgagni:space b/w base of skull & upper free border of sup. constrictor

Pierced by: Eustachian tube Levator veli

palatini Tensor veli

palatini Ascending

palatine artery

FOSSA OF ROSENMULLER

Pharyngeal recessCommonest site of nasopharyngeal

carcinomaMalignant growth may infilterate

adjacent structures

Brain Soft palate Auditory tube nasal cavity

Passavant’s Ridge

A mucosal ridge raised by fibres of palatopharyngeus.

Forms a ring around post and lat walls of nasopharyngeal isthmus.

When soft palate is elevated the muscle band appear as a ridge Passavant’s ridge

During act of swallowing palate and the ridge approximated.

Lymphatic DrainageUpper deep cervical nodes

Retropharyngeal nodesParapharyngeal nodes

Spinal accessory chain of nodes in the posterior triangle of the neck.

FunctionsActs as a conduit for air;b/w nose and

larynx.Ventilates midle ear through eustachian

tube and equalises air pressure on both sides of TM.

Cuts off nasopharynx from oropharynx with the help of Passavant’s ridge.

Acts as a resonating chamber for voice production

Acts as a drainage channel for mucus secreted by nasal and nasopharyngeal glands

OROPHARYNX

Boundaries • Roof • Post wall• Ant wall• Floor • Lat wall

Oropharynx Extends from the plane of hard palate

to the plane of hyoid bone. Lies opposite to the oral cavity, Through oropharyngeal isthmus,it

communicates with oral cavity.

OROPHARYNGEAL ISTHMUS-boundaries.Soft palate above.Upper surface of tongue below.Palatoglossal arch on either sides.

Boundaries of oropharynxPosterior wall Related to retropharyngeal space.Lies opposite the second and upper part

of third cervical vertebrae.Anterior wallDeficient aboveBelow,it presents:

◦Base of the tongue , posterior to circumvallate papillae

◦Lingual tonsils◦Valleculae

Valleculae Cup shaped depressions Lying b/w the base of the tongue

and anterior surface of epiglottis.Bounded medially by the median

glossoepiglottic fold Laterally by pharyngoepiglottic

fold

Boundaries of oropharynx [cont…]Lateral wall presents:

◦Palatine tonsil◦Anterior pillar:palatoglossus muscle◦Posterior pillar: palatopharyngeus

muscleTonsillar fossaA triangular depression b/w the

anterior and the posterior pillars.Lodges palatine tonsils

Lymphatic DrainageUpper jugular chainjugulo-digastric nodes

◦Retropharyngeal and parapharyngeal nodesPosterior cervical group

Function

Conduit passage for air and foodHelps in pharyngeal phase of deglutitionForms part of vocal tracthelp in speechHelps in appreciation of tasteProvide local immunity and defense against

harmful intruders

Laryngopharynx / Hypopharynx

Lowest part of pharynxAbove oropharynx

Below oesophagus

Ant laryngeal cavityLaryngeal inlet

Clinically

Pyriform sinus Post-cricoid Post-pharyngeal (fossa) region wall

Pyriform sinus / fossaBoundariesLat:thyrohyoid memb & thyroid cartilageMed:aryepiglottic fold, postero lateral

surfaces of arytenoid and crocoid cartilage

Forms lateral channel for foodSmuggler’ fossaForeign bodies may get lodged here

Internal laryngeal nerve in submucosa of lateral wall; easily accessible for LA

CA: pain is referred to ear in Ca of pyriform sinus

Pyriform sinus / fossa

ExtentPharyngoeppiglottic fold to upper end of oesophagus

Post-cricoid region

Part of:Ant wall of

laryngopharynx between upper and lower border of cricoid lamina

CA:Commonest site

for carcinoma in females suffering from Plummer-Wilson syndrome

Post-Pharyngeal Wall

EXTENTS FROM:Hyoid bone to the level

of cricoarytenoid joint

Function

Common pathway for air and foodHelp in deglutitionProvides a vocal tract for resonance of certain speech sounds.

Lymphatic Drainage

Pyriform sinus drains intoupper jugular chain

Rich lymphatics high frequency of nodal metastasis in carcinoma of this regionPost cricoid parapharyngeal nodesPost wall parapharyngeal nodes or

lateral pharyngeal nodes

Waldeyer’s RingA ring composed of MALT at

beginning of food and air passage.

Produce B and T lymphocytesLocal defenseAlso produce lymphocytes to

send to other lymph nodes.

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