Enumerate the derivatives of first branchial arch. What are the head and neck structure which develop from 3rd pharyngeal arch and pouch?

In the early embryo, the fore-gut develops between the brain above and the primitive heart below.

The mouth is separated from the pharynx by the buccopharyngeal membrane which disappears around the end of 3rd week when a series of arches appears in the wall of pharynx. These arches are formed by mesodermal condensations and are known as the branchial arches.The arches fuse ventrally, thus forming u-shaped structures which support the pharynx. Initially there are 6 of these arches, but the 5th is vestigial and rapidly disappear.

There are 4  branchial pouches internally, 4 branchial grooves externally. These separate the remaining five branchial arches.

Each branchial pouch is lined by endoderm and branchial grooves by endoderm. These pouches and grooves are separated by a thin layer of mesoderm. If this endoderm, mesoderm & ectoderm layers break down a branchial fistula is formed.


A central core of cartilage develop in each arch and muscles differentiate from the surrounding mesoderm.
Each arch is supplied by Cranial Nerve and by an artery.


1st Branchial arch –

  • Maxilla, Incus, Malleus, Anterior ligament of malleus, sphenomandibular ligament, Mandible
  • Muscles- Muscles of mastication
  • Nerve- Mandibular Branch of the Trigeminal Nerve
  • Artery- Maxillary artery


2nd Branchial arch-

  • Stapes, styloid process, stylohyoid ligament, lesser cornua and upper part of the body of the hyoid bone.
  • Muscles of facial expression, Posterior belly of Diagastric
  • Stylohyoid muscle
  • Auricles muscles stapedius muscles
  • Nerve- Facial
  • Artery- 2nd aortic arch Rarely persist as stapedial


3rd Branchial arch

  • Greater cornua and lower part of the body of the hyoid bone
  • Muscles- Stylopharyngeus
  • Nerve- Glossopharyngeal Nerve
  • Artery – 3rd aortic artery which persist as part of the Internal Carotid Artery


4th Branchial arch

  • Thyroid and epiglottis
  • Muscles- cricothyroid, all  muscles of palate except tensor veli palatini
  • Artery- left aorta, Rt- subclavian artery


5th Brachial arch

  • Cricoid, Arytenoid, corniculate, cuneiform
  • Muscles:  All muscles of pharynx except cricothyroid
  • Artery- Pulmonary



1ST Branchial Pouch:

Growth laterally to form: The Eustachian tube and the middle ear.

2nd Branchial Groove:

Deepens to form (only Dorsal part) External auditory meatus and remaining disappear but if it persist collaural fistula is formed.



Number of tubercles appear at the dorsal each of the first and 2nd branchial arches. These tubercles surrounds the dorsal end of the 1st groove which is to be form the External Auditory Canal.


2nd /3rd /4th  Branchial pouches and grooves

2nd pouch –Dorsal part contribute to middle ear

ventral part – supra tonsillar fossa.

Externally 2nd Branchial arch grow caudally and covers over 3rd 4th 6th arch

3rd pouch –Dorsal part Inferior parathyroid gland

Ventral part- Thymic part

Deep pit/sinus lined by ectoderm. Its lip fuse and ectoderm lining cystic space is produced which disappear later.


Brancial arches








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