Tongue: Miscellaneous | Medical Science Optional Notes for UPSC PDF Download

Tongue-Development

The formation of the tongue commences in the fourth week of embryonic development through the emergence of a central swelling known as the tuberculum impar within the first pharyngeal arch.

By the fifth week, two additional lateral lingual swellings, one on the right side and one on the left, become evident on the first pharyngeal arch.

Rapid expansion of these lingual swellings occurs, enveloping the tuberculum impar and giving rise to the anterior portion of the tongue, which comprises two-thirds of its overall length. Simultaneously, during the fourth week, a midline swelling named the copula emerges from the second pharyngeal arch. Subsequently, in the fifth and sixth weeks, the copula is overtaken by a swelling originating from the third and fourth arches, primarily the third arch, known as the hypopharyngeal eminence. This growth contributes to the development of the posterior portion of the tongue, constituting the remaining one-third.

Tongue-Nerve supply

The innervation of the tongue involves various cranial nerve connections associated with muscles, oral mucosa, taste buds, and minor salivary glands. These connections include:

• Lingual branch of the trigeminal nerve (V)
• Chorda tympani branch of the facial nerve (VII)
• Glossopharyngeal nerve (IX)
• Motor components of innervated muscles through the hypoglossal nerve (XII).

The hypoglossal nerve (Cranial Nerve XII) supplies motor innervation to both intrinsic and extrinsic tongue muscles, enabling functions such as protrusion, retrusion, and alterations in the tongue's shape.

Tongue-Gross Anatomy

The organ responsible for deglutition, taste, and speech is divided by a V-shaped sulcus terminalis into two parts: an anterior, oral (presulcal) part facing upward, and a posterior, pharyngeal (postsulcal) part facing posteriorly. The root of the tongue is connected to both the hyoid bone and mandible.

Muscles of Tongue

The intrinsic muscles exclusively connect to various structures within the tongue. There are four sets of paired intrinsic muscles, named according to their directional orientation: the superior longitudinal, inferior longitudinal, transverse, and vertical muscles of the tongue. These muscles play a crucial role in influencing the shape and size of the tongue, as seen in activities like tongue rolling, and they contribute to functions such as speech, eating, and swallowing.

Motor innervation for the intrinsic muscles of the tongue is via the hypoglossal nerve(CNXII).

The hypoglossal nerve (Cranial Nerve XII) innervates all intrinsic and extrinsic muscles of the tongue, with the exception of palatoglossus, which receives its innervation from the vagus nerve (Cranial Nerve X).

Tongue-Blood supply

The primary blood supply to the tongue and the floor of the mouth comes from the lingual artery, originating from the anterior surface of the external carotid artery. The branches of the lingual artery create an extensive anastomotic network, providing blood to the musculature of the tongue and forming a dense submucosal plexus. The named branches of the lingual artery in the floor of the mouth include the dorsal lingual, sublingual, and deep lingual arteries.

Tongue- Repeats

Describe the nerve supply of tongue correlating it with its development. Add a note on its Blood supply and lymphatic drainage along with applied anatomy. (2011) Define tongue under the following subheadings: (2015)
(i) Mucous membrane and its nerve supply
(ii) Muscles, movements produced by them and their nerve supply
(iii) Lymphatic drainage
(iv) Clinical anatomy
Describe the developmental component and nerve supply of the tongue. (2017)