1. Development of Palate & Tongue
Dr. Saleem Shaikh

2. Introduction
The formation of palate and tongue is a complex and interrelated process.
The formation of lip takes place by the fusion of maxillary process with the frontonasal process
The maxillary process also extends backwards on either side of the stomatodeum
From each maxillary process a plate like shelf extends mesially. This is called as palatal process.
At this stage, there are three components which make up the palate -
Frontonasal process – primitive palate (premaxilla)
The two palatal shelves

4. The two palatal shelves initially grow downwards (vertically) and after sometime, these two processes swing upwards to become horizontal.
The process first fuses with the frontonasal process, then the two processes fuse with each other to form the roof of the oral cavity and separate the nasal cavity from the oral cavity.
The fusion starts anteriorly and progresses posteriorly.
The medial edges of the palate also fuse with the free lower edge of the nasal septum, this separates the nasal cavity into two parts.

6. Once the fusion of the palatal shelves is complete, the anterior part undergoes ossification to form the hard palate.
The part of the palate which is derived from the frontonasal process forms the premaxilla, which carries the incisors.
Defective fusion of the various components of the palate gives rise to various forms of cleft palate

7. Development of Tongue

8. Development of Tongue
The tongue is one of the most important organ in the oral cavity.
The tongue develops in relation to the pharyngeal arches in the floor of the mouth.
The pharyngeal arches arises as a mesodermal thikenings in the lateral wall of the foregut and it grows to meet the corresponding arch on the other side.
The medial most part of the mandibular arch proliferate to form two lingual swellings, on either side of the midline
A median swelling also appears between the two lingual swellings – this is known as “ Tuberculum Impar”

9. Another midline swellings are seen in relation to the midline of the second third and fourth arches. This swelling is known as the “ Hypobranchial eminence”
This eminence divides into two parts –
Cranial - second and third
Caudal – fourth

11. The anterior two third of the tongue is formed by fusion of the
Two lingual swellings and tuberculum impar. The tuberculum impar regresses as the development proceeds and most part of the developed anterior tongue is made up of the two lingual swellings
The posterior one third of the tongue is derived from the cranial part of the hypobranchial eminence. (the third arch mesoderm grows over the second arch )
The posterior most part of the tongue is formed by the caudal part of the hypobranchial eminence.

12. Nerve supply of the anterior two third of the tongue –
Lingual branch of the mandibular nerve – sensory
Chorda tympany branch of facial nerve – taste
Posterior one third of the tongue is supplied by the glossopharyngeal nerve
Posterior most part of the tongue is supplied by Superior laryngeal nerve.
The muscles of the tongue are supplied by the hypoglossal nerve.