TONGUE

•  Tongue: a musclar structure in the oral cavity, divided in to 2 parts:

1.  Oral (pesulcal), movable part-the anterior 2\3 of the tongue 
2. Pharyngeal (postsulcal), nonmovable part-the posterior 1\3 of the tongue

• The sulcus terminalis, a V-shaped groove immediately posterior to the circumvallate papilla, separates the oral part from the pharyngeal part of the tongue
• The foramen cecum, which was the initial development site for the thyroid gland, is located at the tip (or angle) of the V.
• Median fibrous septum separates the tongue into halves 

 FUNCTIONS

• Mastication 
•  Taste
•  Talking
• Degultition

APPEARANE 

• The tongue typically is pink and and covered with numerous small bumps called papilla
• Change in color or texture may reflect health problems:

1. Leukoplakia
2. Squamous cell carcinoma
3. Nutritional deficiencies

• An unusual appearance of the tongue may represent a benign harmless condition:

1. Fissured toungue
2. Bkack hairy tongue
3. Geographic toungue

MUSCLE TYPES

• Extrinsic-move the tongue as an anatomic structure 
• Intrinsic-change the tongue's shape   

 

geographic tongue

hairy tongue 

fissured tongue

 

ORAL PART (PRESULCAL)
·         The oral part of the tongue is also known as the anterior 2\3 of the tongue ·         Develops from the 2 lateral lingual swelling and tuberculum impar of the 1st pharyngeal arch-thus mucosa is innervated by the nerve of the 1 st arch, which is the trigeminal nerve (lingual n.) ·         Has a dorsal and a ventral surface
Dorsal Surface
·         The mucosa is keratinized stratified squamous epithelium ·         Is bounded posteriorly by the sulcus terminalis
Structures	Comments
Median sulcus	A groove that travels anteriorly in the midline Represents the location of the median septum that divides the tongue in halves The septum is thicker posteriorly but thinner anteriorly
Papillae-there are 4 types of papillae on the dorsal surface of the tongue: ·         Filiform-lack tast buds Most numerous type of papillae Have thick keratin on epithelium ·         Fungiform-have taste buds that receive taste innervation from the facial nerve (chorda tympani branch) Scattered throughout the dorsum of the oral part Lack keratin on the epithelium ·         Foliate-have taste buds that receive taste innervation from the facial nerve (chorda tympani branch) Are located on the side of the tongue in 4 to 5 folds immediately anterior to the palatoglossal fold Lack keratin on the epithelium ·         Circumvallate-have taste buds that receive tast innervation from the glossopharyngeal nerve Generally a nonkeratinized epithelium Lie in a row immediately anterior to the sulcus terminalis	Papillae are raised projections that increase the surface area 5 basic types of taste are differentiated by the taste buds: ·         Bitter ·         Salt ·         Sweet ·         Sour ·         Umami
Glands	There are numerous mucous and serous glands on the dorsal surface

 

 

 

Ventral Surface
·         The mucosa is nonkeratinied stratified squamous epithelium
Structures	Comments
Lingual frenulum	A midline fold of tissue Connect the ventral surface of the tongue to the floor of the oral cavity
Sublingual papilla	A swelling on both sides of the lingual frenulum at the tongue base Marks the entrance of saliva from the submandibular glands into the oral cavity Continuous with the sublingual folds overlying the sublingual glands on the floor of the oral cavity
Plica fimbriata	Fimbriated folds Lateral to the lingual frenulum
Deep lingual veins	Can be observed through the mucosa between the plica fimbriata and the lingual frenulum

PHARYNGEAL PART(POSTSULCAL)
·           The pharyngeal part of the tongue is also known as the posterior 1\3 of the tongue ·         Develops from the hypobranchial eminence of the 3rd pharyngeal arch-thus mucosa is innervated by the nerve of the 3rd arch (the glossopharyngeal nerve) ·         The area immediately posterior to the palatoglossal folds (alsa called the anterior pillar of the fauces) is the oropharynx ·         Has a dorsal surface only ·         Does not possess any papilla
Dorsal Surface
·         The mucosa is nonkeratinized stratified squamous epitheelium
Structures	Comments
Lingual tonsils	Large nodules of lymphatic tissue Cover the pharyngeal surface of the tongue
Glosseoepiglottic folds	Mucous membrane of nonkeratinized stratified squamous epithelium from the pharyngeal  part and lateral wall of pharynx that reflects onto the anterior epiglottis, forming: ·         Median glossoepiglottic fold ·         2 lateral glossoepiglorric folds The median glossoepiglottic fold is bordered by a depression on each side: ·         Vallecula Connect the posterior portion of the pharyngeal part of the tongue with the epiglottis of the larynx

Muscle	Origin	Insertion	Action	Nerve	Comment
Genioglossus	Superior genial tubercle of the mandible	Superior fibers fan into the entire ventral surface of the tongue while intermixing with the (intrinsic muscles) Intermediate fibers fan posteriorly in attach to the posterior tongue Inferior fibers insert into the body of the hyoid via an aponeurosis	Protrusion of the tongue Bilaterally-the 2 muscles will depress the central Portion of the tongue, which makes the dorsal surface concave Unilaterally-makes the tongue deviate to the contralateral side	Hypoglossal n.	The lingual a. is located between the genioglossus and hyoglossus mm.
Hyoglossus	Greater cornu and anterior portion of the body of the hyoid	Lateral portion of the tongue between the styloglossus m. and the interior longitudinal m.	Depresses the tongue		The lingual n., hypoglossal n., and submandibular duct are located on the lateral surface of the hyoglossus m. Some authors describe the chondroglossus asa separate muscle or as part of the hyoglossus
Styloglossus	Anterolateral portion near the apex of the styloid process Stylomandibular ligament	Longitudinal portion inserts into the dorsolateral part of the tongue to intermix with the inferior longitudinal m. Oblique portion inserts into the dorsolateral portion of the tongue to intermix with the hyoglossus m.	Retrusion of the tongue Elevation of the tongue		Smallest of the extrinsic tongue muscles
Palatoglossus	Palatine aponeurosis (oral surface)	Lateral side of the tongue where some fibers intermix with the transverse m. and some along the dorsal surface of the tongue	Elevation of the root of the tongue Narrows the oropharyngeal isthmus for deglutition	Pharyngeal plexus (the motor portion of this plexus is formed by the pharyngeal branch of the vagus n.)	Grouped as either an extrinsic tongue muscle of the tongue or a muscle of the soft palate

Muscle	Origin	Insertion	Actions	Nerve	Comment
Superior longitudinal	Median septum Submucous layer near epiglottis	Lingual margins	Shortens Curls the tongue’s apex and lateral margins upward, which makes the dorsal surface concae	Hypoglossal n.	Located immediately deep to the mucous membrane of the tongue’s dorsal surface
Inferior longitudinal	Root of the tongue Body of the hyoid	Apex of the tongue	Shortens Curls the tongue’s apex downward, which makes the dorsal surface convex		Runs the length of the tongue between the hyoglossus and genioglossus mm.
Transverse	Median septum	Fibrous tissue in the submucosa of the lingual margins Some fibers intermix with palatoglossus	Narrows lengthens		Runs the width of the tongue
Vertical	Submucosa of dorsal surface of tongue	Submucosa of ventral surface of tongue	BROADENS Flattens		Runs from the dorsal to the ventral tongue surface

TYPES OF SENSORY NERVE SUPPLY
Type	Function	Nerves
General somatic afferent (GSA)	Pain, temperature, discriminative touch	Trigeminal (via lingual), glossopharyngeal, and vagus (via internal laryngeal), to innervate the mucosa
Special visceral afferent (SVA)	Taste	Facial (via chorda tympani), glossopharyngeal, and vagus (via internal laryngeal), to innervate the tast buds

GENERAL SENSORY INNERVATION (GENERAL SOMATIC AFFERENT)
Nerve	Source	Course
Lingual	Mandibular division of the trigeminal n.	Lies inferior to the lateral pterygoid m. amd medial and anterior to the inferior alveolar nn. Within the infratemporal fossa Chorda tympani branch of the facial n. joins its posterior part Lingual n. passes between the medial pterygoid m. and the ramus of the mandible to pass obliquely, entering the oral cavity bounded by the superior pharyngeal constrictor m., the medial pterygoid, and the mandible Enters the oral cavity lying along the lingual tuberosity of the mandible The submandibular ganglion is supended from the lingual n. at the posterior border of the hyoglossus m. Continues anteriorly and passes onto the lateral surface of the hypoglossus Passes from the lateral side inferiorly and medial to the submandibular duct to reach the mucosa of the tongue Supplies GSA fibers to the epithelium and papillae of the tongue’s anterior 2\3, mucosa along the floor of the oral cavity (linguoalveolar ridge), and gingiva on the lingual aspect of the mandibular teeth
Glossopharyngeal	Arises as a cranial nerve from the medulla oblongata	Passes through the jugular foramen with the vagus and accessory nn. Within the foramen, it passes between the internal carotid a. and the internal jugular v. Continues inferiorly and posteriorly relative to the stylopharyngeus m. Passes anteriorly with the stylopharyngeus m. and travels between the superior and middle constrictor mm. to beome located by the palatine tonsils Small lingual branches distribute GSA fibers to the epithelium of the tongue’s posterior 1\3, in addition to the fauces
Internal laryngeal	Superior laryngeal branch of the vagus n.	Vagus n. branches from the medulla oblongata and passes through the jugular for amen with the glossopharyngeal and accessory nn. Within the foramen, it passes between the internal carotid a. and the internal jugular v. A series of nerves branch from the vagus in the neck, including the superior laryngeal n., which travels inferiorly posterior to the internal carotid a. on the side of the pharynx and divides into the internal and external laryngeal nn. The internal laryngeal n. passes inferior to the larynx and passes through the thyrohyoid membrane with the superior laryngeal vv. Distributes GSA fibers to the tongue’s base at the epiglottic region and the mucous membranes of the larynx as far inferiorly as the false vocal folds

SPECIAL SENSORY INNERVATION (SPECIAL VISCERAL AFFERENT)
Nerve	Source	Course
Chorda tympani	Facial n. in the tympanic cavity	Carries preganglionic parasympathetic fibers to the submandibular ganglion and tast fibers to the anterior 2\3 of the tongue Passes anteriorly to enter the tympanic cavity and lies along the tympanic membrane and malleus until exiting the petrotympanic fissure Joins the posterior border of the lingual n. Lingual n. is distributed to the anterior 2\3 of the tongue, and the SVA fibers from the chorda tympani travel to the taste buds in this region
Glossopharyngeal	Arises as a cranial nerve from the medulla oblongata	Passes through the jugular foramen with the vagus and accessory nn. Within the foramen, it passes between the internal carotid a. and the internal jugular v. Continues inferiorly and travels posterior to the stylopharyngeus m. Passes anteriorly with the stylopharyngeus m. and travels between the superior and middle constrictor mm., to be located by the palatine tonsils Small lingual branches distribute SVA fibers to the taste buds in the mucous membrane of the tongue’s posterior 1\3 and the circumvallate papilla
Internal laryngeal	Superior laryngeal branch of the vagus n.	Vagus n. branches from the medulla oblongata and passes through the jugular foramen with the glossopharyngeal and accessory nn. Within the foramen, it passes between the internal carotid a. and the internal jugular v. A series of nerves branch from the vagus in the neck, including the superior laryngeal n., which travels inferiorly posterior to the internal carotid on the side of the pharynx and divides into the internal and external laryngeal nn. The internal laryngeal n. passes inferior to the larynx and passes through the thyrohyoid membrane with the superior laryngeal vv. Distrbutes SVA fibers to the taste buds scattered at the base of the tongue at the epiglottic region

Nerve	Sorce	Course
Hypoglossal	Arises as a series of rootlets from the medulla oblongata and passes through the hypoglossal canal	Travels inferiorly and is located between the internal carotid a. and the internal jugular v. Passes anteriorly as it wraps around the occipital a. Passes superficial to the external carotid and the loop pf the lingual a. in its anterior path Passes deep to the posterior belly of the digastric and the stylohyoid m. and lies superficial to the hyoglossus m. with the accompanying vein of the hypoglossal n. Passes deep to mylohyoid m. and continues anteriory in the genioglossus m. Muscular branches supply: ·         All intrinsic tongue muscles ·         Hyoglossus m. ·         Styloglossus m. ·         Genioglossus m.
Pharyngeal  plexus	Pharyngeal plexus (the motor portion of this plexus is formed by the pharyngeal branch of the vagus n.)	Arises from the upper part of the inferior ganglion of the vagus n. Lies along the upper border of the middle constrictor m., where it forms the pharyngeal plexus Motor branches from the plexus are distributed to the muscles of the pharynx and soft palate (with the exception of the tensor veli palatine m.) It the tongue, it innervates: ·         Palatoglossus m

Artery	Source	Course
Lingual	External carotid a. within the carotid triangle	Passes superiorly and medially (obliquely) toward the greater cornu of the hyoid bone and makes a loop by passing anteriorly and inferiorly while traveling superficial to the middle constrictor m. While forming a loop, the artery is crossed superficially by the hypoglossal n. Passes deep to the posterior belly of the digastric m. and the stylohyoid m. as it travels anteriorly, where it gives off a suprahyoid branch that travels on the superior surface of the hyoid bone, supplying the muscles in that area The lingual a. passes deep to the hyoglossus m. and travels anteriorly betweem it and the genioglossus m. After passing deep to the hyoglossus, 2 to 3 small dorsal lingual aa. Are given off at the posterior border of the hyoglossus. The lingual a. continues to pass anteriorly and gives off the sublingual branch at the anterior border of the hyoglossus The deep lingual a., the terminal branch or continuation of the lingual a. once the sublingual a. is given off, travels superiorly to reach the tongue’s vental surface
Dorsal lingual	Lingual	After passing deep to the hyoglossus, 2 to 3 small dorsal lingual aa. Are given off at the posterior border of the hyoglossus; they pass in a superior direction to the posterior 1\3 of the dorsum of the tongue and provide vascular supply to the mucous membrane in this region, the palatoglossal arch, the palatine tonsil, the epiglottis, and the surrounding soft palate
Deep lingual		The deep lingual a., the terminal branch or continuation of the lingual a. once the sublingual a. is given off, travels superiorly to reach the tongue’s ventral surface Located between the inferior longitudinal m. of the tongue and the mucous membrane, the deep lingual a. is accompanied by branches of the lingual n., and it anastomoses with its counterpart from the other side
Sublingual		The sublingual branch arises at the anterior border of the hyoglossus The sublingual a. passes anteriorly between the genioglossus and mylohyoid mm. to the sublingual gland and provides vascular supply to the gland and the muscles and mucosa in the area Typically has 2 branches of significance: ·         Branch that passes mylohyoid to anastomose with submental a. ·         Branch that passes deep to the gingiva to anastomose with branch from contralateral side ·         At this anastomosis, typically 1 branch (although may be multiple branches) arises to enter a small lingual foramen superior to the genial tubercles in the posterior midline
Submental	A branch of the facial a. from the external carotid a.	Given off at the submandibular gland, travels anteriorly superficial to the mylohyoid m. Anastomoses with a branch from the sublingual branch of the lingual a. to help supply the tongue
Tonsillar		While ascending superiorly along the lateral side of the pharynx, it passes into and supplies the superior constrictor m. until reaching the palatine tonsil and root of the tongue
Ascending pharyngeal	External carotid a.	The smallest branch arising from the external carotid a. Ascends superiorly between the lateral aspect of the pharynx and the internal carotid a. Has branches supplying the palatine tonsil that anastomose with tonsillar branch of facial and dorsal lingual branches at root of the tongue

Vein	Course
Lingual	Receives tributaries from the deep lingual vv. On the ventral surface, and the dorsal lingual vv. From the dorsal surface Passes with the lingual a., deep to the hyoglossus m., and ends in the internal jugular v. The vena comitans nervi hypoglossi, or accompanying vein of the hypoglossal n., begins at the tongue’s apex and may either join the lingual v. or accompany the hypoglossal n. and enter the commen facial v., which empties into the internal jugular
Submental	Anastomoses with the branches of the lingual v. Parallels the submental a. on the superficial surface of the mylohyoid m. and ends in the facial v.

ANKYLOGLOSSIA

• Ankyloglossia: condition in which the lingual frenulum is restricted because of an increase in tissue, leading to reduced tongue mobility
• Also known as tongue-tie

PRESENTATIONS

• Tongue may not be capable of protrusion beyond the incisors
• Tongue may not be capable of touching the palate 
• Tongue may have a V-shaped notch at its tip or may appear bilobed on protrusion

COMPLICATIONS

• Causes problems for babies who breastfeed
• If the tongue cannot clear the oral cavity of food, caries, periodontal disease, and halitosis can rresult
• If condition is severe, can cause a speech impediment

TREATMENT

• If necessary, the lingual frenulum may be cut (frenectomy)

HYPOGLOSSAL NERVE  PARALYSIS 

• Hypoglossal nerve lesions paralyze the tongue on 1 side 
• On protrusion, the tongue deviates to the ipsilateral (same) or contralateral side, depending on the lesion site

LOWER MOTOR NEURON LESION

• Lesions to the hypoglossal nerve cause paralysis on the ipsilateral side:

1. Tongue deviates to the paralyzed side on protrusion (the paralyzed muscles will lag, causing the tip to deviate)
2. Musculature atrophies on the paralyzed side 
3. Tongue fasciculations occure on the paralyzed side 

Example: With a neck wound that cuts the right hypoglossal nerve, the tongue deviates to the right on protrusion, and the right half of the tongue will later demonstrate atrophy and fasciculations

UPPER MOTOR NEURON LESION

• Causes paralysis on the contralateral side:

1. Tongue deviates to the side opposite the lesion
2.  Musculature atrophies on side opposite the lesion

Example: After a stroke on the right side of the brain that affects the right upper motor neurons, the tongue deviates to the left on protrusion, and the left half of the tongue will atrophy

SQUAMOUS CELL CARCINOMA

• Squamous cell carcinoma accounts for most cancers of the oral cavity 
• In the tonge, usually located on the anterolateral aspect
• Alcohol and tobacco use are risk factors
• Premalignant lesion, such as erythroplasia and leukoplakia, should be identified, because early diagnosis and treatment are paramount for long-term survival
• Radiographic imaging helps reveal the tumor's extent and location 
• Staging of the tumor guides prognosis

TREATMENT

• Excision or radiation therapy, or possibly in combination with chemotherapy
• If lesion is detected early, excision may suffice 
• With later tumor stages, a 2nd primary squamous cell carcinoma must be excluded

LEUKOPLAKIA

• Leukoplakia: a commen premalignant condition of the oral cavity involving the formation of white spots on the mucous membranes of the tongue and inside the mouth 
• Hairy leukoplakia is a type observed in persons with compromised immune systems
• Risk factors:

1. Tobacco use
2. Alcohol use
3. Human immunodeficiency virus (HIV) infection
4. Epstein-Barr virus infection

• Although a precancerous lesion, it may not progress to oral cancer