ANATOMY AND ANATOMY AND EMBRYOLOGY OF THE EMBRYOLOGY OF THE

PHARYNXPHARYNX

DEPT OF DEPT OF OTORHINOLARYNGOLOGYOTORHINOLARYNGOLOGY

J.J.M.M.CJ.J.M.M.CDAVANGEREDAVANGERE

EMBRYOLOGYEMBRYOLOGY

Components ofComponents of

branchial/pharyngeal branchial/pharyngeal apparatus:apparatus:

1)1) Pharyngeal archesPharyngeal arches

2)2) Pharyngeal Pharyngeal pouchespouches

3)3) Pharyngeal Pharyngeal clefts/groovesclefts/grooves

PHARYNGEAL (BRANCHIAL) PHARYNGEAL (BRANCHIAL) ARCHESARCHES

• Derived from neural crest cellsDerived from neural crest cells

• Resemble fish gills (branchia)Resemble fish gills (branchia)

• Begin to develop early in the 4Begin to develop early in the 4thth week week

• By end of 4By end of 4thth week, four pairs of arches are week, four pairs of arches are visible on the surface (not 5visible on the surface (not 5thth and 6 and 6thth ) and ) and a buccopharyngeal membrane ruptures a buccopharyngeal membrane ruptures forming communication between primitive forming communication between primitive oral cavity and foregut oral cavity and foregut

PHARYNGEAL ARCHES PHARYNGEAL ARCHES (CONT.)(CONT.)

• Contribute to the Contribute to the formation of the neck formation of the neck as well as the face.as well as the face.

• Visible structures at Visible structures at 42 weeks:42 weeks:

11stst arch: mandibular arch: mandibular prominence, maxillary prominence, maxillary prominences, and the prominences, and the frontonasal frontonasal prominenceprominence

PHARYNGEAL ARCHES PHARYNGEAL ARCHES (CONT.)(CONT.)

• Core of mesenchymal Core of mesenchymal tissue covered by surface tissue covered by surface ectoderm (outside) and ectoderm (outside) and by endodermal epithelium by endodermal epithelium (inside)(inside)

• Ectoderm -> skeletalEctoderm -> skeletal• Mesoderm -> muscles Mesoderm -> muscles

with accompanying nervewith accompanying nerve• Arterial component (aortic Arterial component (aortic

arches)arches)• Therefore, each arch Therefore, each arch

carries nerve, muscle, carries nerve, muscle, bone and blood supplybone and blood supply

FIRST PHARYNGEAL ARCHFIRST PHARYNGEAL ARCH

• Maxillary process (dorsal)Maxillary process (dorsal)– Premaxilla, maxilla, zygomatic bone, Premaxilla, maxilla, zygomatic bone,

portion of temporal boneportion of temporal bone

• Mandibular process (ventral)Mandibular process (ventral)– Contains Contains Meckel’s cartilage Meckel’s cartilage which which

disappears except for dorsal end disappears except for dorsal end (incus (incus & malleus)& malleus) and mandible and mandible

FIRST PHARYNGEAL ARCHFIRST PHARYNGEAL ARCH

• Muscles of mastication, digastric Muscles of mastication, digastric (ant belly), mylohyoid, tensor (ant belly), mylohyoid, tensor tympani and tensor palatinitympani and tensor palatini

• Therefore, the accompanying motor Therefore, the accompanying motor nerve is the mandibular branch of nerve is the mandibular branch of trigeminal (V2) and sensory are V1, trigeminal (V2) and sensory are V1, V2, and V3V2, and V3

• 11stst aortic arch practically disappears aortic arch practically disappears but forms the maxillary arterybut forms the maxillary artery

SECOND PHARYNGEAL ARCHSECOND PHARYNGEAL ARCH

• Reichert’s cartilage – Reichert’s cartilage – stapes, styloid stapes, styloid process, stylohyoid ligament, lesser horn process, stylohyoid ligament, lesser horn and upper part of the hyoidand upper part of the hyoid

• Muscles include: stapedius, stylohyoid, Muscles include: stapedius, stylohyoid, digastric (post belly), auricular, and those digastric (post belly), auricular, and those of facial expressionof facial expression

• Facial nerve (CN VII)Facial nerve (CN VII)

• 22ndnd aortic arch – stapedial & hyoid arteries aortic arch – stapedial & hyoid arteries

THIRD PHARYNGEAL ARCHTHIRD PHARYNGEAL ARCH

• Cartilaginous contributions include greater Cartilaginous contributions include greater horn and lower part of hyoidhorn and lower part of hyoid

• Sole muscle: stylopharyngeusSole muscle: stylopharyngeus

• CN IX (Glossopharyngeal nerve)CN IX (Glossopharyngeal nerve)

• 33rdrd aortic arch (quite large): common aortic arch (quite large): common carotid, 1carotid, 1stst portion of internal carotid portion of internal carotid (remainder dorsal aorta), and external (remainder dorsal aorta), and external carotidcarotid

FOURTH & SIXTH PHARYNGEAL FOURTH & SIXTH PHARYNGEAL ARCHARCH

• Cartilaginous contributions to larynx derived from Cartilaginous contributions to larynx derived from fusion: thyroid, cricoid, arytenoid, corniculate, fusion: thyroid, cricoid, arytenoid, corniculate, and cuneiformand cuneiform

• Muscles of 4th: cricothyroid, levator palatini, and Muscles of 4th: cricothyroid, levator palatini, and pharyngeal constrictors are innervated by SLN pharyngeal constrictors are innervated by SLN (CN X)(CN X)

• Muscles of 6th: intrinsics of larynx are innervated Muscles of 6th: intrinsics of larynx are innervated by RLN (CN X)by RLN (CN X)

• 44thth aortic arch: L->arch of aorta & R->subclavian aortic arch: L->arch of aorta & R->subclavian• 66thth aortic arch: L & R pulmonary with ductus aortic arch: L & R pulmonary with ductus

arteriosus on leftarteriosus on left

ANATOMY OF THE PHARYNXANATOMY OF THE PHARYNX1.1. EPIGLOTTISEPIGLOTTIS

2.2. HYOID BONEHYOID BONE

3.3. ARYEPIGLOTTIC FOLDARYEPIGLOTTIC FOLD

4.4. VOCAL FOLDVOCAL FOLD

5.5. THYROID CARTILAGETHYROID CARTILAGE

6.6. CRICOID CARTILAGECRICOID CARTILAGE

7.7. OESOPHAGUSOESOPHAGUS

8.8. THYROID ISTHEMUSTHYROID ISTHEMUS

9.9. NASOPHARYNGEAL TONSILNASOPHARYNGEAL TONSIL

10.10. EUSTACHIAN TUBEEUSTACHIAN TUBE

11.11. SALPHINGOPHARYNGEAL SALPHINGOPHARYNGEAL FOLDFOLD

12.12. NASOPHARYNXNASOPHARYNX

13.13. PALATOGLOSSAL FOLDPALATOGLOSSAL FOLD

14.14. PALATINE TONSILPALATINE TONSIL

15.15. OROPHARYNXOROPHARYNX

16.16. PALATOPHARYNGEAL FOLDPALATOPHARYNGEAL FOLD

17.17. HYPOPHARYNXHYPOPHARYNX

ANATOMY (CONT…)ANATOMY (CONT…)

• It is a conical fibromuscular tube forming It is a conical fibromuscular tube forming upper part of air and food passage. It is upper part of air and food passage. It is 12-14 cm long. Extends from base of skull 12-14 cm long. Extends from base of skull to inferior border of cricoid cartilage to inferior border of cricoid cartilage anteriorly and inferior border of C6 anteriorly and inferior border of C6 posteriorlyposteriorly

• Widest portion (5cm) at hyoidWidest portion (5cm) at hyoid• Narrowest portion (1.5cm) at caudal endNarrowest portion (1.5cm) at caudal end• Divided into 3 parts: nasopharynx, Divided into 3 parts: nasopharynx,

oropharynx, and laryngo(hypo)pharynxoropharynx, and laryngo(hypo)pharynx

NASOPHARYNX/ NASOPHARYNX/ EPIPHARYNXEPIPHARYNX• Anterior: choana (posterior nasal aperture)Anterior: choana (posterior nasal aperture)• Posterior: pharyngobasilar membrane, Posterior: pharyngobasilar membrane,

superior constrictor muscle, arch of atlas superior constrictor muscle, arch of atlas covered by prevertebral muscle and fascia.covered by prevertebral muscle and fascia.

• Superior: basi-occiput and basi-sphenoid.Superior: basi-occiput and basi-sphenoid.• Inferior: soft palate (Anteriorly) deficient Inferior: soft palate (Anteriorly) deficient

posteriorly-nasopharyngeal isthmus.posteriorly-nasopharyngeal isthmus.• Lateral :pharyngeal opening of eustachian Lateral :pharyngeal opening of eustachian

tube situated 1.25 cm behind the posterior tube situated 1.25 cm behind the posterior end of inferior turbinate, bounded by end of inferior turbinate, bounded by torus torus tubaristubaris. above and behind the tubal . above and behind the tubal elevation is a recess- elevation is a recess- fossa of Rosenmullerfossa of Rosenmuller..

NASOPHARYNX/ NASOPHARYNX/ EPIPHARYNXEPIPHARYNX

STRUCTURES OF PHARYNGEAL STRUCTURES OF PHARYNGEAL WALLWALL

1.1. Mucus membrane-ciliated columnar in Mucus membrane-ciliated columnar in nasopharyx and stratified squamous in nasopharyx and stratified squamous in other areas.other areas.

2.2. Pharyngeal aponeurosis ( pharyngo-Pharyngeal aponeurosis ( pharyngo-basilar fascia)basilar fascia)

3.3. Muscular coat-external layer contains Muscular coat-external layer contains superior , middle, inferior constrictors. superior , middle, inferior constrictors. Internal layer-stylopharyngeus, Internal layer-stylopharyngeus, salpingopharyngeus, palatoparyngeus.salpingopharyngeus, palatoparyngeus.

4.4. Buccopharyngeal fascia.Buccopharyngeal fascia.

KILLIAN’S DEHISCENCEKILLIAN’S DEHISCENCE• Inferior constrictor muscle has two Inferior constrictor muscle has two

parts -thyropharyngeus with oblique parts -thyropharyngeus with oblique fibres and cricopharyngeus with fibres and cricopharyngeus with transverse fibres. A potential gap transverse fibres. A potential gap between these two parts is called between these two parts is called killian’s dehiscencekillian’s dehiscence. Also called . Also called “gateway of tears” as perforation can “gateway of tears” as perforation can occur during esophagoscopy. This is occur during esophagoscopy. This is also the site of mucosal herniation in also the site of mucosal herniation in case of pharyngeal pouch.case of pharyngeal pouch.

NASOPHARYNGEAL TONSILNASOPHARYNGEAL TONSIL

• Tonsil Tonsil - It is a sub epithelial collection of - It is a sub epithelial collection of lymphoid tissue at the junction of roof and lymphoid tissue at the junction of roof and posterior wall of nasopharynx. it increases in posterior wall of nasopharynx. it increases in size up to 6 yrs and then gradually atrophies.size up to 6 yrs and then gradually atrophies.

• Bursa Bursa - epithelial lined median recess found - epithelial lined median recess found within the adenoid mass and extends from within the adenoid mass and extends from pharyngeal mucosa to periosteum of pharyngeal mucosa to periosteum of basiocciput. It represents attachment of basiocciput. It represents attachment of notochord to the pharyngeal endoderm notochord to the pharyngeal endoderm during embryonic life. Sometimes an abscess during embryonic life. Sometimes an abscess can form in the bursa -can form in the bursa -Thornwald’s disease.Thornwald’s disease.

TUBAL TONSIL AND SINUS OF TUBAL TONSIL AND SINUS OF MORGAGNIMORGAGNI

• Tubal tonsil-Collection of subepithelial Tubal tonsil-Collection of subepithelial lymphoid tissue situated at the tubal lymphoid tissue situated at the tubal elevation. It is continuous with elevation. It is continuous with nasopharyngeal tonsil forms a part of nasopharyngeal tonsil forms a part of waldeyar’s ring.waldeyar’s ring.

• Sinus of Morgagni - space between Sinus of Morgagni - space between the base of the skull and free upper the base of the skull and free upper border of superior constrictor muscle. border of superior constrictor muscle. Eustachian tube, levator veli palatine, Eustachian tube, levator veli palatine, tensor veli palatine and ascending tensor veli palatine and ascending pharyngeal artery passes through it.pharyngeal artery passes through it.

PASSAVANT’S RIDGEPASSAVANT’S RIDGE• It is a mucosal ridge raised by fibres It is a mucosal ridge raised by fibres

of palato-pharyngeus. It encircles the of palato-pharyngeus. It encircles the posterior and lateral walls of posterior and lateral walls of nasopharyngeal isthmus. Soft palate nasopharyngeal isthmus. Soft palate during contraction, makes firm during contraction, makes firm contact with this ridge to cut off contact with this ridge to cut off nasopharynx from the oropharynx nasopharynx from the oropharynx during deglutition or speech.during deglutition or speech.

WALDEYER’S RINGWALDEYER’S RING• Scattered subepithelial lymphoid Scattered subepithelial lymphoid

aggregates in and around pharynx are aggregates in and around pharynx are collectively called waldeyer’s ringcollectively called waldeyer’s ring

• It consists of inner ring and outer ringIt consists of inner ring and outer ring• Inner ringInner ring: nasopharyngeal tonsil, palatine : nasopharyngeal tonsil, palatine

tonsil, lingual tonsil, tubal tonsil, lateral tonsil, lingual tonsil, tubal tonsil, lateral pharyngeal bands, nodules in posterior pharyngeal bands, nodules in posterior pharyngeal wallpharyngeal wall

• Outer ringOuter ring: lymph nodes at : lymph nodes at retropharyngeal, styloid, lateral retropharyngeal, styloid, lateral pharyngeal, behind sternomastoid, at pharyngeal, behind sternomastoid, at bifurcation of common carotid, in front of bifurcation of common carotid, in front of sternomastoid, at angle of jaw, at hyoid sternomastoid, at angle of jaw, at hyoid and subhyoidand subhyoid

WALDEYER’S RINGWALDEYER’S RING

FUNCTIONS OF FUNCTIONS OF NASOPHARYNXNASOPHARYNX1.1. Conduit for air.Conduit for air.2.2. Ventilation of middle ear and Ventilation of middle ear and

equalize pressure.equalize pressure.3.3. With passavant’s ridge to cut off With passavant’s ridge to cut off

nasopharynx from oropharynx.nasopharynx from oropharynx.4.4. Resonating chamber during voice Resonating chamber during voice

production.production.5.5. Drainage channel for secretion Drainage channel for secretion

drainage from nose.drainage from nose.

OROPHARYNXOROPHARYNX

• Extends from plane of hard palate above Extends from plane of hard palate above to plane of hyoid bone below.to plane of hyoid bone below.

• Anterior: oropharynx communicates with Anterior: oropharynx communicates with oral cavity,oral cavity,

• Posterior: related to retropharyngeal space Posterior: related to retropharyngeal space opposite C2-3, superior constrictor through opposite C2-3, superior constrictor through oropharyngeal isthmus.oropharyngeal isthmus.

• Superior: soft palateSuperior: soft palate• Inferior: base of tongue, lingual tonsils, Inferior: base of tongue, lingual tonsils,

valleculae, superior epiglottis.valleculae, superior epiglottis.• Laterally: palatoglossal (Anteriorly) and Laterally: palatoglossal (Anteriorly) and

palatopharyngeal arches (posteriorly), palatopharyngeal arches (posteriorly), palatine (faucial) tonsilpalatine (faucial) tonsil

OROPHARYNXOROPHARYNX

FUNCTIONS OF OROPHARYNXFUNCTIONS OF OROPHARYNX

1.1. Conduit for passage of food and air.Conduit for passage of food and air.

2.2. Pharyngeal phase of deglutition.Pharyngeal phase of deglutition.

3.3. Vocal tract for certain speech Vocal tract for certain speech sounds.sounds.

4.4. Appreciation of taste.Appreciation of taste.

5.5. Local defense and immunity.Local defense and immunity.

HYPOPHARYNXHYPOPHARYNX

• Lowest part of larynx, Lies posterior and Lowest part of larynx, Lies posterior and partly on sides of the larynx. lies opposite partly on sides of the larynx. lies opposite C3-6C3-6

• Superior: superior border of epiglottis and Superior: superior border of epiglottis and pharyngoepiglottic folds (plane passing pharyngoepiglottic folds (plane passing through body of hyoid bone)through body of hyoid bone)

• Inferior: inferior border of the cricoidInferior: inferior border of the cricoid• Posterior/lateral: middle & inferior Posterior/lateral: middle & inferior

constrictors, bodies of C3-C6constrictors, bodies of C3-C6• Anterior: laryngeal inletAnterior: laryngeal inlet• Subdivided into three regions-pyriform Subdivided into three regions-pyriform

sinus (fossa), post cricoid region, posterior sinus (fossa), post cricoid region, posterior pharyngeal wall.pharyngeal wall.

PYRIFORM SINUSPYRIFORM SINUS• Lies on either side of larynx and extends Lies on either side of larynx and extends

from pharyngoepiglottic fold to the upper from pharyngoepiglottic fold to the upper end of esophagus.end of esophagus.

• boundaries:boundaries: -laterally: thyrohyoid membrane and -laterally: thyrohyoid membrane and

thyroid cartilage.thyroid cartilage. -medially: aryepiglottic fold, posterolateral -medially: aryepiglottic fold, posterolateral

surface of arytenoid, cricoid cartilage.surface of arytenoid, cricoid cartilage.• Internal laryngeal nerve passes Internal laryngeal nerve passes

submucosally in lateral wall of sinus so submucosally in lateral wall of sinus so easily accessible for local anaesthesia. In easily accessible for local anaesthesia. In carcinoma of pyriform sinus this nerve carcinoma of pyriform sinus this nerve causes referred otalgia.causes referred otalgia.

PHARYNGEAL MUSCLESPHARYNGEAL MUSCLES

PHARYNGEAL MUSCLES AND PHARYNGEAL MUSCLES AND NERVE SUPPLY.NERVE SUPPLY.

• External circular and internal longitudinal External circular and internal longitudinal (opposite in remainder of GI tract)(opposite in remainder of GI tract)

• External: 3 constrictors (CN XI via X and External: 3 constrictors (CN XI via X and ELN/RLN for middle and inferior) function ELN/RLN for middle and inferior) function to constrict wall of pharynx during swallowto constrict wall of pharynx during swallow

• Internal: palatopharyngeus and Internal: palatopharyngeus and salpingopharyngeus (CN XI via X) and salpingopharyngeus (CN XI via X) and stylopharyngeus (CN IX) act to elevate stylopharyngeus (CN IX) act to elevate pharynx and larynx during speech/swallowpharynx and larynx during speech/swallow

• CN V supplies nasopharynxCN V supplies nasopharynx

PHARYNGEAL PHARYNGEAL MUSCLES(CONT…)MUSCLES(CONT…)

• Tensor veli palatini (V3) tenses soft Tensor veli palatini (V3) tenses soft palate & opens ET during palate & opens ET during yawn/swallowyawn/swallow

• Levator veli palatini (CN XI via X) Levator veli palatini (CN XI via X) elevates palate during swallow/yawnelevates palate during swallow/yawn

• Palatoglossus (CN XI via X) Palatoglossus (CN XI via X) approximates tongue and soft palateapproximates tongue and soft palate

PHARYNGEAL MUSCLESPHARYNGEAL MUSCLES

PHARYNGEAL LYMPHATIC PHARYNGEAL LYMPHATIC DRAINAGEDRAINAGE

• Oral cavityOral cavity– Submandibular, upper Submandibular, upper

deep cervicaldeep cervical• Oro/hypopharynx Oro/hypopharynx

– Upper deep cervical, Upper deep cervical, retropharyngeal, retropharyngeal, parapharyngeal, parapharyngeal, posterior cervicalposterior cervical

• Nasopharynx Nasopharynx – Upper deep cervical Upper deep cervical

either directly or either directly or indirectly through indirectly through retropharyngeal and retropharyngeal and parapharyngeal LNparapharyngeal LN

PHARYNGEAL VESSELSPHARYNGEAL VESSELS

BLOOD SUPPLY BLOOD SUPPLY

• Blood supply is by branches of Blood supply is by branches of external carotid arteryexternal carotid artery

1.1. Ascending pharyngeal. AAscending pharyngeal. A

2.2. Ascending palatine branch of facial. Ascending palatine branch of facial. AA

3.3. Lingual. ALingual. A

4.4. Superior thyroid. ASuperior thyroid. A

VENOUS DRAINAGEVENOUS DRAINAGE

• The veins form the pharyngeal The veins form the pharyngeal plexus which drains into common plexus which drains into common facial vein and internal jugular veinfacial vein and internal jugular vein

PARAPHARYNGEAL SPACEPARAPHARYNGEAL SPACE• Pyramidal in shape with its base at the Pyramidal in shape with its base at the

base of skull and apex at the hyoid bonebase of skull and apex at the hyoid bone• Boundaries: Boundaries: a)a) Superior: base of skullSuperior: base of skullb)b) Inferior: mediastinumInferior: mediastinumc)c) Medial: buccopharyngeal fascia, Medial: buccopharyngeal fascia,

prevertebral muscle and fasciaprevertebral muscle and fasciad)d) Lateral: ramus of mandible, deep surface Lateral: ramus of mandible, deep surface

of parotid, medial pterygoid muscleof parotid, medial pterygoid muscle• Contents: carotid artery, jugular vein, CN Contents: carotid artery, jugular vein, CN

ix, x, xi, xii, cervical sympathetic trunk, ix, x, xi, xii, cervical sympathetic trunk, deep cervical lymph nodesdeep cervical lymph nodes

PARAPHARYNGEAL SPACEPARAPHARYNGEAL SPACE

RETROPHARYNGEAL SPACERETROPHARYNGEAL SPACE(GILLETTE’S SPACE)(GILLETTE’S SPACE)

• Space lies behind the pharynx, divided Space lies behind the pharynx, divided by a median partition into right and left by a median partition into right and left compartmentcompartment

• Boundaries:Boundaries:

a)a) Anteriorly: buccopharyngeal fasciaAnteriorly: buccopharyngeal fascia

b)b) Posteriorly: prevertebral fasciaPosteriorly: prevertebral fascia

c)c) Superior extent: base of skullSuperior extent: base of skull

d)d) Inferior: bifurcation of tracheaInferior: bifurcation of trachea

• Contents: retropharyngeal lymph nodes Contents: retropharyngeal lymph nodes which usually disappear at 3-4 years of which usually disappear at 3-4 years of age.age.