Difference between revisions of "Tongue - Anatomy & Physiology"

Revision as of 16:07, 1 July 2008

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Introduction

The tongue (lingua) occupies the ventral aspect of the oral cavity and oropharynx. Itis involved with grooming, lapping, prehension and manipultaing food in oral cavity. It is also involved in the deglutition reflex and vocalisation.

The tongue is capable of vigerous and precise movements due to the apex being free of attachments to the oral cavity.

Functional Anatomy

Skeletal muscle dorsally

Structural fat surrounded by cartilagenous sheath forming lyssa (canids only) ventrally

Attached root and body with a free apex

Frenulum (fold of mucosa) attaches the body of the tongue to the floor of the oral cavity

Root of tongue attached to hyoid bone

In the horse and dog the tongue is 'u' shaped, becoming broader towards the tip. The furrow in the centre of the canid tongue is called the median sulcus.

In the ox, sheep and pig the tongue if 'v' shaped with a pointed apex. The tonus linguae is a swelling across the tongue laterally which pushes food against the hard palate.

Muscles

Intrinsic Muscles

The dorsal and ventral longitudinal

Transverse and vertical bundles

Extrinsic Muscles

Styloglossus

   -Origin: Hyoid apparatus (stylohyoid)
   -Retracts and elevates tongue

Genioglossus

   -Origin: Incisive part of mandible
   -Protrudes and depressed tongue

Hyoglossus

   -Origin: Hyoid apparatus (basihyoid)
   -Retracts and depresses tongue

Geniohyoideus

   -Origin: Incisive part of mandible
   -Insertion: Body of hyoid
   -Lies below the tongue (not within it)
   -Draws the hyoid and therefore the tongue forward

Innervation

All muscles moving the tongue are innervated by the hypoglossal nerve (CN XII)

Rostral 2/3 of tongue is innervated by the lingual branch of trigeminal (CN V) which is sensory supplying temperature, touch and pain. The Chorda tympani of facial (CN VII) supplies the taste.

The caudal 1/3 of tongue is innervated by the glossopharyngeal (CN IX) providing motor function for taste.

Histology

Stratified squamous epithelium

Lingual glands

Mucosal covering tightly adheres to the contact surface

Degree of keratinisation depends on diet

Less keratinisation on ventral surface and sides of tongue

Covered by papillae (taste buds)for protection and taste

Papillae are specialised projections of the mucosa

Some papillae have taste buds others are mechanical to roughen surface of tongue

Types of Papillae

Conical

   -Not in horses
   -Caudal 1/3 of tongue
   -Point caudally
   -No taste buds
   -Thick epithelium

Foliate

   -8 to 12 papillae in group, one either side of tongue midline
   -Stratified squamous epithelium
   -Caudal 1/3 of tongue
   -Taste buds present

Vallate

   -3 to 6
   -Often secondary papillae in taste buds
   -Broad glands
   -Caudal 1/3 of tongue
   -Taste buds present

Fungiform

   -Red dots on tongue surface
   -Keratinised, stratified squamous epithelium
   -Blood vessels
   -Loss of heat via panting in dogs
   -Rostral 2/3 of tongue
   -Taste buds present

Filoform

   -Most numerous
   -Points caudally
   -No taste buds
   -Smallest
   -Thick epithelium
   -Very prominent in cat
   -Rostral 2/3 of tongue

Taste Buds

Also found on the soft palate and pharynx (but sparsely distributed)

Constant cell turnover

Flat, think cells

Taste hairs (microvilli) pointing though taste pore

Nerves transduce chemical signals into nervous signals

Species Differences

Dog has stretch receptors in the tongue

Dog uses the tongue to lose heat by panting

Ruminant tongue is heavily keratinised with long papillae for eating (protective surface)

Cat has long papillae for grooming so tongue is rough

Ox has lenticular papillae which are hard and horny due to heavy keratinisation

Most of the papillae in the pig are soft, long and directed caudally

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+<big><center>[[Alimentary - Anatomy & Physiology|'''BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY''']]</center></big>
 ==Introduction==
-The tongue (lingua) occupies the ventral aspect of the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Oropharynx - Anatomy & Physiology|oropharynx]]. It is involved with grooming, lapping, prehension and manipulating food in the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]. It is also involved in the [[Deglutition|deglutition]] reflex and vocalisation. The tongue is capable of vigorous and precise movements due to the apex being free of attachments to the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]].
+The tongue (lingua) occupies the ventral aspect of the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]]. Itis involved with grooming, lapping, prehension and manipultaing food in [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]. It is also involved in the [[Deglutition|deglutition]] reflex and vocalisation.
-[[Image:Tongue Anatomy Cow.jpg|thumb|right|250px|Tongue Anatomy (Cow) - Copyright Nottingham 2008]]
+The tongue is capable of vigerous and precise movements due to the apex being free of attachments to the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]].
+==Functional Anatomy==
+*Skeletal muscle dorsally
+*Structural fat surrounded by cartilagenous sheath forming lyssa (canids only) ventrally
-==Structure and Function==
+*Attached root and body with a free apex
-The tongue is skeletal muscle dorsally and structural fat surrounded by a cartilagenous sheath forming lyssa (canids only) ventrally. It has an attached root and body with a free apex. The '''frenulum''' (fold of mucosa) attaches the body of the tongue to the floor of the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]. The root of tongue is attached to the [[Hyoid Apparatus - Anatomy & Physiology|hyoid bone]]. In the horse and dog, the tongue is 'u' shaped, becoming broader towards the tip. The furrow in the centre of the canid tongue is called the '''median sulcus'''. In the ox, sheep and pig the tongue is 'v' shaped with a pointed apex. The '''torus linguae''' is a swelling across the tongue laterally which pushes food against the [[Hard Palate|hard palate]].
+*Frenulum (fold of mucosa) attaches the body of the tongue to the floor of the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]
-[[Image:Tongue Anatomy Cow2.jpg|thumb|right|250px|Tongue Anatomy (Cow) - Copyright Nottingham 2008]]
-==Muscles==
+*Root of tongue attached to hyoid bone
-[[Image:Tongue Venous Drainage.jpg|thumb|right|250px|Venous Drainage of the Tongue - Copyright Prof. Pat Mccarthy]]
-===Intrinsic Muscles===
+*In the horse and dog the tongue is 'u' shaped, becoming broader towards the tip. The furrow in the centre of the canid tongue is called the median sulcus.
-Intrinsic muscles include the dorsal and ventral longitudinal muscles and the transverse and vertical bundles.
+*In the ox, sheep and pig the tongue if 'v' shaped with a pointed apex. The tonus linguae is a swelling across the tongue laterally which pushes food against the [[Hard Palate - Anatomy & Physiology|hard palate]].
-===Extrinsic Muscles===
-The extrinsic muscles include:
+==Muscles==
-'''Styloglossus'''
+'''Intrinsic Muscles'''
-Its origin is at the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]] (stylohyoid) and it retracts and elevates the tongue.
+*The dorsal and ventral longitudinal
-'''Genioglossus'''
+* Transverse and vertical bundles
-The origin is at the incisive part of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It protrudes and depressed the tongue.
+'''Extrinsic Muscles'''
-'''Hyoglossus'''
+*Styloglossus
+    -Origin: Hyoid apparatus (stylohyoid)
+    -Retracts and elevates tongue
-The origin is at the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]] (basihyoid). It retracts and depresses the tongue.
+*Genioglossus
+    -Origin: Incisive part of mandible
+    -Protrudes and depressed tongue
-'''Geniohyoideus'''
+*Hyoglossus
+    -Origin: Hyoid apparatus (basihyoid)
+    -Retracts and depresses tongue
-It originates at the incisive part of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] and the insertion site is the body of the [[Hyoid Apparatus - Anatomy & Physiology|hyoid]]. It lies below the tongue (not within it) and draws the [[Hyoid Apparatus - Anatomy & Physiology|hyoid]] and therefore the tongue forward.
+*Geniohyoideus
+    -Origin: Incisive part of mandible
+    -Insertion: Body of hyoid
+    -Lies below the tongue (not within it)
+    -Draws the hyoid and therefore the tongue forward
-[[Image:Tongue Muscles Drawing.jpg|thumb|right|250px|Drawing of the Extrinsic Muscles of the Tongue - Copyright nabrown]]
 ==Innervation==
-All muscles moving the tongue are innervated by the hypoglossal nerve ([[Cranial Nerves - Anatomy & Physiology|CN XII]]). The rostral 2/3 of the tongue is innervated by the sensory lingual branch of the trigeminal ([[Cranial Nerves - Anatomy & Physiology|CN V]]) transmitting temperature, touch and pain sensation. The chorda tympani of the facial nerve ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) transmits the taste. The caudal 1/3 of the tongue is innervated by the glossopharyngeal ([[Cranial Nerves - Anatomy & Physiology|CN IX]]) providing sensory function for taste.
+*All muscles moving the tongue are innervated by the hypoglossal nerve (CN XII)
+*Rostral 2/3 of tongue is innervated by the lingual branch of trigeminal (CN V) which is sensory supplying temperature, touch and pain. The Chorda tympani of facial (CN VII) supplies the taste.
+*The caudal 1/3 of tongue is innervated by the glossopharyngeal (CN IX) providing motor function for taste.
-==Vasculature==
-The main blood supply to the tongue is via the '''lingual artery''', a branch of the external carotid artery. A secondary blood supply to the tongue is provided via the tonsillar branch of the facial artery and the ascending pharyngeal artery.
 ==Histology==
-[[Image:Tongue Histology Cat.jpg|thumb|right|250px|Tongue Histology (Cat) - Copyright RVC 2008]]
-The tongue consists of stratified squamous epithelium. There are [[Lingual Gland - Anatomy & Physiology|lingual]] glands and a mucosal covering tightly adheres to the contact surface. The degree of keratinisation depends on the diet. There is less keratinisation on the ventral surface and sides of tongue. It is covered by papillae for protection and taste. Papillae are specialised projections of the mucosa. Some papillae have taste buds, others are mechanical to roughen the surface of the tongue.
+*Stratified squamous epithelium
-==Types of Papillae==
+*Lingual glands
-===Conical===
+*Mucosal covering tightly adheres to the contact surface
-Conical papillae are not found in horses. They are present in the caudal 1/3 of the tongue. They point caudally and have no taste buds. There is a thick epithelium.
-[[Image:Foliate_Papillae_Cat.jpg|thumb|right|250px|Foliate Papillae (Cat) - Copyright RVC 2008]]
+*Degree of keratinisation depends on diet
-===Foliate===
+*Less keratinisation on ventral surface and sides of tongue
-Eight to twelve papillae in parallel folds, one either side of the tongue midline. Consists of a stratified squamous epithelium, present in the caudal third of the tongue. There are taste buds, glands and lymphatics present.
-===Vallate===
+*Covered by papillae (taste buds)for protection and taste
-[[Image:Circumvallate Papillae.jpg|thumb|right|250px|Circumvallate Papillae (Goat) - Copyright RVC 2008]]
-There are three to six, often secondary papillae in taste buds. There are broad glands in the caudal 1/3 of tongue. Taste buds and lymphatics are present.
-===Fungiform===
+*Papillae are specialised projections of the mucosa
-They form the red dots on tongue surface and consist of keratinised, stratified squamous epithelium and blood vessels. They are involved in loss of heat via panting in dogs. They are present in the rostral 2/3 of the tongue and contain taste buds.
-[[Image:Filoform Papillae Histology.jpg|thumb|right|250px|Filoform Papillae Histology (Cat) - Copyright RVC 2008]]
+*Some papillae have taste buds others are mechanical to roughen surface of tongue
-===Filiform===
-Filiform papillae are the most numerous and point caudally. There are no taste buds, glands or lymphatics. They are the smallest and consist of a thick keratin on stratified squamous epithelium. They are very prominent in cat and are present in the rostral 2/3 of the tongue.
-==[[Gustatory System - Anatomy & Physiology|Taste Buds]]==
+===Types of Papillae===
+*Conical
+    -Not in horses
+    -Caudal 1/3 of tongue
+    -Point caudally
+    -No taste buds
+    -Thick epithelium
+*Foliate
+    -8 to 12 papillae in group, one either side of tongue midline
+    -Stratified squamous epithelium
+    -Caudal 1/3 of tongue
+    -Taste buds present
+*Vallate
+    -3 to 6
+    -Often secondary papillae in taste buds
+    -Broad glands
+    -Caudal 1/3 of tongue
+    -Taste buds present
+*Fungiform
+    -Red dots on tongue surface
+    -Keratinised, stratified squamous epithelium
+    -Blood vessels
+    -Loss of heat via panting in dogs
+    -Rostral 2/3 of tongue
+    -Taste buds present
+*Filoform
+    -Most numerous
+    -Points caudally
+    -No taste buds
+    -Smallest
+    -Thick epithelium
+    -Very prominent in cat
+    -Rostral 2/3 of tongue
+==Taste Buds==
+*Also found on the [[Soft Palate - Anatomy & Physiology|soft palate]] and pharynx (but sparsely distributed)
+*Constant cell turnover
+*Flat, think cells
+*Taste hairs (microvilli) pointing though taste pore
+*Nerves transduce chemical signals into nervous signals
-Also found on the [[Soft Palate|soft palate]] and the [[Pharynx - Anatomy & Physiology|pharynx]] (but sparsely distributed). There is a constant cell turnover, with flat, thick cells. There are taste hairs (microvilli) pointing through the taste pore. Nerves transduce chemical signals into nervous signals.
 ==Species Differences==
-[[Image:Pig Tongue.jpg|thumb|right|250px|''Pig Tongue'' <br> Pollo 2007, WikiMedia Commons]]
-===Canine===
-There are stretch receptors in the tongue and they use the tongue to lose heat by panting.
-===Ruminant===
-The tongue is heavily keratinised with long papillae for eating (protective surface). The ox has lenticular papillae which are hard and horny due to heavy keratinisation.
-===Feline===
+*Dog has stretch receptors in the tongue
-Feline species have long papillae for grooming, so their tongue is rough.
-===Porcine===
+*Dog uses the tongue to lose heat by panting
-Most of the papillae are soft, long and directed caudally.
-===[[Avian Tongue - Anatomy & Physiology|Avian]] ===
+*Ruminant tongue is heavily keratinised with long papillae for eating (protective surface)
-The avian tongue contains a bone and is mainly used for manipulation of food rather than vocalisation like in mammals. Parrots use the tongue to produce human sounds (see [[Syrinx - Anatomy & Physiology#Species differences|species differences in syrinx]])
-==Links==
+*Cat has long papillae for grooming so tongue is rough
-Click here for [[Tongue - Pathology|pathology of the tongue]] information.
+*Ox has lenticular papillae which are hard and horny due to heavy keratinisation
-<br>
-{{Learning
-|flashcards= [[Tongue Anatomy & Physiology Flashcards]]<br>[[Facial_Muscles_-_Musculoskeletal_-_Flashcards|Facial Muscles]]
-|powerpoints= [[Oral Cavity Histology resource|Histology of the oral cavity, see part 1 for the tongue]]
-|videos = [[Video: Ventral muscles of the head potcast|Ventral muscles of the head potcast]]<br>[[Video: Lateral surface of the head of the dog potcast|Lateral surface of the head of the dog potcast]]<br>[[Video: Lateral surface and sagittal section of the head of a sheep|Lateral surface and sagittal section of the head of a sheep]]<br>[[Video: Lateral surface of the head of the dog potcast 5|Lateral surface of the head of the dog potcast 5]]
-|OVAM = [http://www.onlineveterinaryanatomy.net/content/cat-tongue Image - Cat Tongue]
-|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis00702.asp Macroglossia]
-}}
-==Webinars==
+*Most of the papillae in the pig are soft, long and directed caudally
-<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
-[[Category:Oral Cavity - Anatomy & Physiology]]