It is highly muscular organ on oral cavity. It lies partly in oral cavity and partly in pharynx. It functions are deglutition, taste and speech. The bones in which tongue is attached are hyoid, mandible, styloid process of temporal bone. The parts of tongue are as follow:
- Root
- dorsum
- inferior surface
- apex
Root of tongue is attached to hyoid and mandible, geniohyoid and mylohyoid inferiorly. Dorsum is postero-superior surface. The superior surface of tongue is divided by sulcus which is ‘v’ in shape and called sulcus terminalis. Sulcus terminalis divides tongue into pre-sulcal part and post-sulcul part.
Anterior part:
It is pre-sulcal part and lies in oral cavity. The foliate papillae lie on each side in front of palatoglossal arch. The mucosa of the anterior part of tongue is different in dorsal (superior) and ventral (inferior) part. The mucosa of the dorsal part is covered with filiform, fungiform and circumvallate papillae whereas mucosa of ventral surface is smooth and connected to floor of oral cavity by lingual frenulum. Plica fimbriata refers to the small folds in the membrane which are fringed mucosal ridge on the underside of tongue.
Posterior part:
It is the pharyngeal part of tongue which lies posterior to palatoglossal arches. This part does not contain papillae. The underlying lymphoid nodules are embedded in submucosa, which are collectively called lingual tonsils.
Tongue muscles:
Tongue has intrinsic muscles fibers which are aligned in vertical, horizontal, transverse fashion to provide the strength and greater range of motion.
Intrinsic muscles:
- superior longitudinal and inferior longitudinal: move up and down.
- transverse: narrows and lengthens.
- vertical: Flattens and depresses
Extrinsic muscles:
There are four pairs of extrinsic muscles in tongue.
- genioglossus: prevents tongue form falling
- hyoglossus: depress tongue up and back
- styloglossus: pull tongue up and back
- palatoglossus: pull tongue up and back
- chondroglossus (part of hyoglossus)
Vascular supply and lymphatic drainage
Arterial: Lingual artery (branch of external carotid artery) →
- dorsal lingual arteries
- Sublingual artery
- deep lingual artery
Venous: Lingual vein
Lymphatic drainage: Lymphatic drainage vessels of tongue can be divided into
- Marginal vessels
- Central vessels
- Dorsal vessels
Tip of the tongue drain into sub-mental lymph node. Anterior two third of tongue drains into submandibular lymph nodes. At the pharyngeal part of tongue, mucosa contains lymphoid follicle which are aggregated into groups, the lingual tonsils.
Innervation:
- Anterior to sulcus terminalis:
- Sensory innervation: Lingual nerve
- Motor innervation: hypoglossal nerve ( Palatogloss is supplied by pharyngeal plexus)
- Taste: chorda tympani
- Papillae: circumvallate, fungiform, filiform, foliate
Posterior to sulcus terminalis:
- Glossopharyngeal nerve
Autonomic nervous supply:
Chorda tympani which synapse with submandibular ganglion. Post ganglionic sympathetic supply by carotid plexus (fibers from cervical ganglion).
