TONGUE

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Anatomy and Physiology of Tongue

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TONGUE:

TONGUE Guided By: From: Dr. Nagaraj Yogendra prakash M.S. (Ayu) IIIrd B.A.M.S

PowerPoint Presentation:

Anatomy Of Tongue

CONTENTS :

CONTENTS Introduction Parts of Tongue Muscles of tongue Intrinsic muscles Extrinsic muscles Attachment Blood supply Nerve supply Lymphatic drainage

Introduction:

Introduction Voluntary muscular structure Occupies floor of mouth 3 inch long. Superior surface consist of stratified squamous epithelium with numerous papillae contains sensory receptors for the sense of taste in taste bud.

Parts of the Tongue:

Parts of the Tongue Root Located between the hyoid bone and mandible. Dorsal portion sits in the oropharynx. Attaches the tongue to roof of the mouth. Body Makes up the anterior two-thirds of the tongue. Rough surface due to the lingual papillae. Surrounded by anterior and lateral teeth. Mobile portion of the tongue. Apex Also known as the tip, is the anterior one-third of the anterior tongue surface. Rests against the incisor teeth. Highly mobile.

Surface of the Tongue:

Surface of the Tongue The top of the tongue (superior surface) has a V-shaped line known as the terminal sulcus that divides the tongue into the anterior and posterior surfaces. The anterior surface is made up of the apex at the tip and body. The posterior surface is made up entirely of the root. The inferior surface of the tongue (underside)  is also made up of the body and apex.

MUSCLES OF TONGUE A median fibrous septum divides the tongue into Rt. & Lt. halves. Each half contains 4 intrinsic & extrinsic muscles.:

MUSCLES OF TONGUE A median fibrous septum divides the tongue into Rt. & Lt. halves. Each half contains 4 intrinsic & extrinsic muscles. Intrinsic muscles Extrinsic muscles Superior longitudinal Inferior longitudinal Transverse Vertical Genioglossus Hypoglossus Styoglossus Palatoglossus

INTRINSIC MUSCLES:

INTRINSIC MUSCLES Occupy the upper part of tongue and attached to the submucous fibrous layer and to median fibrous septum. Alter the shape of tongue. 4 in no. they are 1. Superior longitudinal 2. Inferior longitudinal 3. Transverse 4. Vertical

PowerPoint Presentation:

Superior longitudinal- beneath the mucous membrane. Shortens the tongue. Make dorsum concave. Inferior longitudinal- Lying close to inferior surface of tongue between genioglossus and hypoglossus. Shortens the tongue. Makes its dorsum convex. Transverse- Extend from median septum to the margins. Makes the tongue narrow and elongated. Vertical- Found at the borders of anterior part of tongue it make tongue broad & flattened.

EXTRINSIC MUSCLES:

EXTRINSIC MUSCLES 4 in no. they are 1. Genioglossus 2.Hyoglossus 3. Palatoglossus 4. Styoglossus Connect to the tongue to mandible by Genioglossus, hyoid bone via Hyoglossus, Styloid process viz. Styloglossus and palate via Palatoglossus .

Genioglossus-:

Genioglossus- Fan shaped, form main bulk of tongue. Origin - Upper genial tubercle of mandible which run backward. Inserted- Upper fiber--tip-retracted the tip of tongue Middle fiber-dorsum-depress tongue Lower fiber- hyoid bone- pull posterior part of tongue forward and protrude out.

Hyoglossus- :

Hyoglossus- Origin - Whole length of greater cornua and lateral part of body of hyoid bone. Fibers run upward and forwards. Insertion - Side of tongue between Styloglossus and inferior longitudinal muscle of tongue. Action - depresses tongue makes dorsum convex retracts and protruded tongue.

Palatoglossus-:

Palatoglossus- Origin- Oral surface of palatine aponeurosis. Insertion - Descends in the Palatoglossus arch to the side of tongue at junction of its oral and pharyngeal parts. Action - Pulls up the root of tongue, approximates the Palatoglossus arches and thus closes the oropharyngeal isthmus.

Styoglossus-:

Styoglossus- Shortest and smallest Origin- Styloid process of temporal bone Insertion- Tip and sides of tongue Action- Retraction and elevation of tongue

Blood supply:

Blood supply External carotid artery- lingual branch Lingual vein- joins to internal jugular vein Root of tongue- tonsillar and ascending pharyngeal arteries.

Nerve supply of muscles-:

Nerve supply of muscles- Four extrinsic and 3 intrinsic muscles of tongue are supplied by IX C.N. Only palatoglossus supplied by vago-accessory complex.

Lymphatic drainage-:

Lymphatic drainage- Tip of tongue- Drains bilaterally to the sub mental nodes. Remaining part- Ant. Rt. & lt. 2/3 drains unilaterally to the submandibular nodes. Few central lymphatics drains bilaterally to same nodes Post. 1/3 drains bilaterally to the jugulo-omohyoid nodes.

PHYSIOLOGY OF TONGUE:

PHYSIOLOGY OF TONGUE

CONTENTS…:

CONTENTS… Taste buds Location Structure Papillae Types of papillae Physiology of taste Neural pathways for taste Function of tongue

Taste Bud:

Taste Bud Taste buds are sensory organs that are found on your tongue and allow you to experience tastes that are sweet, salty, sour, and bitter The sense of taste called gustation. 10,000 taste buds are present in its papilla. A papilla contains few to 100 taste buds.

Location of Taste Buds:

Location of Taste Buds Taste buds contains sensory receptors found in the papillae of tongue and widely distributed in the epithelium of tongue, soft palate, pharynx and epiglottis.

Structure of Taste Buds:

Structure of Taste Buds Oval barrel shape 70um*50um. Life span- 10 days Having opening called taste pores Composed of 5-15 gustatory receptors cell, 40 supporting cells or subtentacular cell and 15-20 transitional cells.

Electron microscopic structure of taste buds:

Electron microscopic structure of taste buds

Papillae :

Papillae The majority of taste buds on the tongue sit on raised protrusions of the tongue surface called papillae.

Types of papillae:

Types of papillae

Fungiform papillae:

Fungiform papillae As the name suggests, these are slightly mushroom-shaped if looked at in longitudinal section. These are present mostly at the apex (tip) of the tongue, as well as at the sides. Innervated by facial nerve.

Filiform papillae:

Filiform papillae These are thin, long papillae. "V"-shaped cones That don't contain taste buds but are the most numerous. These papillae are mechanical and not involved in gustation . They are characterized by increased keratinization .

Foliate papillae:

Foliate papillae Foliate papillae are short vertical folds found on the lateral margins of the tongue. They are occasionally Misdiagnosed as tumors or inflammatory disease. They are usually bilaterally symmetrical. Sometimes they appear small and inconspicuous, whereas they may be prominent. Lingual tonsils are found immediately beneath the foliate papillae and, when hyperplastic , cause a prominence of the papillae.

Circumvallate papillae or vallate p.:

Circumvallate papillae or vallate p. 10 to 14 in no. Present at the back of the oral part of the tongue. They are arranged in a circular-shaped row just in front of the sulcus terminalis of the tongue. They are associated with ducts of Von Ebner's glands. innervated by the glossopharyngeal nerve.

Cont… :

Cont… It is generally accepted that there are four taste sensations, recently a fifth basic taste has been added: Sweet, sour, salty, bitter and the recently added umami (used in Asian kitchens produced by monosodium glutamate). Salts, sweet, sour and umami tastes causes depolarization of the taste cells. Although different mechanisms are applied. Bitter causes an internal release of Ca2+, no external Ca2+ is required.

Physiology of Taste:

Physiology of Taste The gustation involves stimulation of chemoreceptors by dissolved chemicals. The sensory receptors are stimulated by chemicals that enter the pores dissolved in saliva. Nerve impulses are generated and conducted along the glossopharyngeal from post.1/3rd, facial from ant. 2/3 tongue and vagus nerves from pharyngeal wall before synapsing in medulla and thalamus. Their final destination is the taste area in the parietal lobe of the cerebral cortex where taste is perceived.

Neural pathways for taste-:

Neural pathways for taste- The primary sensory neurons carrying taste sensation from taste buds are located in geniculate ganglion , superior petrosal ganglion and inferior ganglion ( ganglion nodosum) of facial glossopharyngeal and vagus nerves respectively. The peripheral processes of these cells connect with the taste buds, while central processes end in nucleus tractus solitarius (NTS).

Conti…..:

Conti….. The secondary order sensory neurons arise from nucleus tractus solitarius, cross the midline, turn upwards to join the medial lemniscus and terminate in the posteroventral nucleus of thalamus. The third order sensory neurons arise from posteroventral nucleus of thalamus and project in the inferior part of the post central gyrus of the parietal lobe of the brain, the taste area of the cerebral cortex.

Function of Tongue:

Function of Tongue Mastication Deglutition Speech Taste

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