Tongue (part-1)

● Tongue is the muscular organ situated in the floor of the mouth

It has 2 surfaces

• Superior surface

• Inferior surface

● Superior surface is divided into 3 parts Anterior 2/3rd or oral part , posterior 1/3rd or pharyngeal part and base or root of the tongue

● Anterior 2/3rd and posterior 1/3rd are divided by V shaped sulcus terminalis, they are structurally and developmentally distinct.

● Inferior surface is covered by smooth mucous membrane. In midline a mucosal fold called frenulum connects tongue with floor of the mouth

● Lateral to frenulum deep lingual veins can be seen through mucosa lateral to lingual vein , mucosal fold called plica fimbriata is present

PAPILLAE OF TONGUE

Superior surface of tongue contains numerous papillae and have taste buds on their surface

Types of papillae

• Circumvalate papillae : present in front of sulcus terminalis , largest among papillae 8 to 12 in number

• Filliform papillae : Thin, long papillae with pointed ends. No taste buds. Identified by keratinization.

• Fungiform papillae: Slightly mushroom shaped , larger than Filliform papillae and present at apex of tongue and margins

• Foliate papillae : short vertical folds , present lateral to terminal sulcus and at margins

TASTE BUDS

Taste buds are sensory receptors for taste. Sensation of taste is called gustation.  Taste buds are located on surface of all papillae except Filliform papillae

Four taste sensation are sour, sweet, salty,  bitter and recently added is umami

MUSCLES OF TONGUE

● Intrinsic muscles: Main function is to alter the shape of the tongue ,they originate and insert within the tongue and no bony attachments.  ( 4) superior longitudinal,  inferior longitudinal,  vertical and transverse muscles

● Extrinsic muscles :  These muscles take origin from outside of the tongue and alter the shape as well.(4) Genioglossus, hyoglossus, styloglossus and palatoglossus

Superior longitudinal muscle: It lies just beneath dorsum of tongue. Action: It curls the tip upward and roll it posteriorly

Inferior longitudinal muscle : lies on each side lateral to the Genioglossus muscle. Action : To curl the tip of the tongue inferiorly

                                    

Transverse muscle: lies inferior to the superior longitudinal muscle and run from the septum to margins. Action : They narrow the tongue and increase the height

Vertical muscle: It lies inferolaterally to the Dorsum of tongue. Action : flattens the Dorsum

Genioglossus : origin- from superior mental spine and gets inserted into mucous membrane of tongue. It’s action is to protrude tongue, depress central part of tongue and increase the volume of sucking

Hyoglossus : origin- from greater horn and body of hyped bone and gets inserted to side of the tongue. It’s action is to depress side of the tongue assisting Genioglossus to enlarge the oral cavity

Styloglossus : origin- lower part of styloid process and upper part of stylohyoid ligament and inserts on side of the tongue. Action is to elevate and retract the tongue

Palatoglossus : origin- from soft palate and insertion lateral margin of tongue

♢ Styloglossus and palatoglossus attach the tongue Superiorly ,while Genioglossus and hyoglossus attached to the tongue inferiorly

♢ All the extrinsic and intrinsic muscles of tongue are supplied by hypoglossal nerve except palatoglossus supplied by vagus nerve

Reference: B.D chaurasia

One thought on “Tongue (part-1)

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