PHARYNGEAL POUCHES

TONGUE, THYROID

Dr. G.Prabavathy

Assistant Professor

Pharyngea

l

apparatus

OBJECTIVES

Pharyngeal pouches – derivatives

Development of tongue

Development of thyroid

Pharyngeal arches

Pharyngeal clefts

Pharyngeal pouches

Pharyngeal membranes

PHARYNGEAL APPARATUS

Pharyngeal arch Nerves

First arch Maxillary and Mandibular

nerves

Chorda tympani nerve

Second arch Facial nerve

Third arch Glossopharyngeal nerve

Fourth arch Superior laryngeal branch

of vagus

Sixth arch Recurrent laryngeal branch

of vagus

DERIVATIVES OF PHARYNGEAL ARCHES

Nerves of the pharyngeal arches

MUSCLES OF PHARYNGEAL

ARCHES

Pharyngea

l arch

Muscles

First arch Muscles of Mastication (Temporalis,

Masseter, Medial and Lateral Pterygoid)

Anterior belly of digastric, Mylohyoid,

Tensor tympani & tensor veli palatini

Second arch Muscles of facial expression, posterior belly

of digastric, stylohyoid, stapedius

Third arch Stylopharyngeus

Fourth arch Cricothyroid, levator palati, contrictor of

pharynx and intrinsic muscles of larynx Sixth arch

SKELETAL ELEMENT OF PHARYNGEAL

ARCHES

Pharynge

al arch

Skeleton Ligaments

First arch

(Meckes’s

cartilage)

Malleus, and Incus

Premaxilla, maxilla

,zygomatic bone, part of

temporal bone, mandible,

Anterior ligament of

malleus

Sphenomandibular

ligament

Second arch

(Reichert’s cartilage)

Stapes, styloid process,

Smaller cornu of hyoid bone,

superior surface of body of the

hyoid bone

Stylohyoid ligament

Third arch Greater cornu and lower part

of body of hyoid bone

Fourth arch Laryngeal cartilages (thyroid,

cricoid, arytenoids,

corniculate, cuneiform) Sixth arch

PHARNYGEAL POUCHES

PHARNYGEAL POUCHES Four pairs of pouches – evaginations of endoderm,

lining between two arches

FIRST PHARYNGEAL POUCH

First pharyngeal pouch – tubotympanic recess

Distal part of tubotympanic recess – middle ear

cavity and mastoid antrum

Proximal part – eustachian/auditory tube

SECOND PHARYNGEAL POUCH • Endoderm proliferates to Form solid buds, central core

of these buds breaks down to form Tonsillar crypts

• Part of this pouch remains as intratonsillar crypt

(crypta magna)

THIRD PHARYNGEAL POUCH

Dorsal bulbar part – parathyroid III or inferior

parathyroid gland

Ventral tubular part - thymus

FOURTH PHARYNGEAL POUCH

Dorsal bulbar part – superior parathyroid gland IV

Fifth pouch incorporated with fourth pouch – caudal

pharyngeal complex – para follicular cells or c cells

SUMMARY

Pharyngeal arches – five in number, present in lateral wall and floor of the primitive pharynx

Pharyngeal clefts- four in number, present externally between the arches, lined by ectoderm

Pharyngeal pouches – four in number, present internally between the two pharyngeal arches, lined by the endoderm

Pharyngeal membranes – four in number and located between adjacent arches

TONGUE

THYROID GLAND

TONGUE

• Muscular organ located in the oral

cavity.

• Consists of connective tissue and

interlacing skeletal muscle fibres

• Covered by surface elevations

called papillae

i. Fungiform papillae

ii. Filliform papillae

iii. Circumvallate papillae

iv. Foliate papillae

TONGUE

Circumvallate

papillae

Filliform

Fungiform

Anterior 2/3rd

Posterior

1/3rd

Posterior

most part

V shaped

sulcus

terminalis

Tongue develops in the floor of developing mouth from

first, second, third and fourth pharyngeal arches

Tuberculum impar – small median swelling develops

cranial to foramen caecum

Lingual swelling – two lateral oval swellings on each

side of tuberculum impar

Hypobrachial eminence (Copula of His) – large

median swelling develops in relation to second, third

and fourth pharyngeal arches

DEVELOPMENT OF VARIOUS PARTS OF

TONGUE

Two lateral lingual swelling overgrow tuberculum impar and merge

with each other – anterior two- third of tongue

Cranial part of hypobrachial eminence – posterior one-third of

tongue including circumvallate papillae

Caudal part of hypobrachial eminence – posterior most part of the

tongue and epiglottis

GROWTH OF THIRD ARCH OVER SECOND ARCH

MUSCLES OF THE TONGUE

Develops from myoblasts that migrate into

developing tongue from occipital myotomes

CORRELATION OF NERVE SUPPLY OF TONGUE WITH ITS

DEVELOPMENT

SEPARATION OF TONGUE FROM FLOOR OF

MOUTH

Separation of tongue from the floor of the mouth

by deepening of linguogingival sulci

ANAMOLIES OF TONGUE

TONGUE TIE(Ankyloglossia)

Due to frenulum of tongue extends to the tip of the

tongue, thus preventing its protrusion and causing

difficulty in speech

BIFID TONGUE MACROGLOSSIA

CONGENITAL ANOMALIES

FISSURED TONGUE

THYROID GLAND

THYROID GLAND

• Highly vascular

endocrine gland

• Two lobes connected by

isthmus

Thyroid gland develop during third week of IUL as

endodermal thickening- diverticulum

thyroglossal duct

PATH OF THYROGLOSSAL DUCT

HISTOGENESIS OF THYROID GLAND

Parafollicular cells (C

cells) – neural crest of caudal

pharyngeal complex

I Anomalies of position of thyroid:

Lingual thyroid – 10%

Sublingual thyroid

Intrathoracic thyroid

II Ectopid thyroid:

Larynx

Trachea

Esophagus

Pericardium

Pleura

Ovaries

CONGENITAL ANOMALIES

Lingual thyroid

THYROGLOSSAL CYST:

May form anywhere along the course

of the Thyroglossal duct.

Persistense of a part of thyroglossal

duct turned into a cyst called

Thyroglossal Cyst.

always formed in the midline of the

front the Neck and observed by the age

of 5 years.

Cyst Ruptures-Fistula.

CONGENITAL ANOMALIES

PYRAMIDAL LOBE

ACCESSORY LOBE

1. parathyroid gland arises from

A) 1st and 2nd pharyngeal pouch

B) 3rd and 4th pharyngeal pouch

C) 5th and 6th pharyngeal arch

D) 3rd and 4th pharyngeal arch

2. nerve of III pharyngeal arch supplies

A)cricothyroid

B)stylopharyngeus

C)stapedius

D)stylohyoid

3.All the muscles of tongue are supplied by

A) Facial nerve

B) lingual nerve

C) Hypoglossal nerve

D) Occipital nerve

Enumerate the Derivatives of second pharyngeal

arch

Name the Derivatives of first pharyngeal arch

Development oy hyoid bone [apr 2002]

Explain Cervical sinus

Development of parathyroid [dec 2010]

Thyroglossal duct [dec 2011]

Explain the Development of thyroid gland

Brief account of Development of tongue