TONGUE

Tongue

• derived from 1st-4th branchial arches

• manipulates food for chewing and swallowing

• contains no bony supports for the muscles– the extrinsic muscles of the tongue anchor the tongue firmly

to surrounding bones and prevent the mythical possibility of 'swallowing' the tongue

• sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move

Anatomy

• made mainly of skeletal muscle

• dorsum – oral part (anterior two-thirds

of the tongue) that lies mostly in the mouth

– pharyngeal part (posterior third of the tongue), which faces backward to the oropharynx

– separated by a V-shaped groove, which marks the sulcus terminalis

Anatomy

Normal name Anatomical name Adjective

Tongue tip Apex Apical

Tongue blade Lamina Laminal

Tongue dorsum Dorsum Dorsal

Tongue root Radix Radical

Tongue body Corpus Corporeal

Muscle From Nerve Function

Genio-glossus

mandible

hypoglossal nerve

protrudes the tongue as well as depressing its center.

Hyo-glosus

hyoid bone

hypoglossal nerve

depresses the tongue.

Stylo-glossus

styloid process

hypoglossal nerve

elevates and retracts the tongue.

Palato-glossus

palatine aponeurosis

pharyngeal branch of vagus nerve

depresses the soft palate, moves the palatoglossal fold towards the midline, and elevates the back of the tongue.

Extrinsic Muscles of the Tongue

Intrinsic Muscles of the Tongue

• superior longitudinal muscle: assists in retraction of, or deviates the tip of the tongue– originates near the epiglottis, the hyoid bone, from the median

fibrous septum

• inferior longitudinal muscle: lines the sides of the tongue, and is joined to the styloglossus muscle

• verticalis muscle: joins the superior and inferior longitudinal muscles

• transversus muscle: divides the tongue at the middle

Pappilae

• The oral part of the tongue is covered with small bumpy projections called papillae. There are four types of papillae:

– filiform (thread-shape)– fungiform (mushroom-shape)– circumvallate (ringed-circle)– foliate (leaf-shape)

• All papillae except the filiform have taste buds on their surface

Blood Supply

• primarily from the lingual artery, a branch of the external carotid artery.

• secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery

Nerve Supply

• Motor innervation: hypoglossal nerve – the palatoglossal muscle is innervated by the pharyngeal

branch of vagus nerve

• Sensory Innervation– somatic sensations: lingual nerve, a major branch of the

mandibular nerve; also carries general sensation from areas of the oral mucosa and gingiva of the lower teeth.

– taste sensation: facial nerve via the chorda tympani; also carries parasympathetic fibers from the facial nerve to the submandibular ganglion

– posterior one-third of the tounge: glossopharyngeal nerve

Function

• assists in forming the sounds of speech

• it is the primary organ of taste– much of the surface of

the tongue is covered in taste buds