Tongue Anatomy and Function

• The tongue's primary composition is muscle
• The tongue is covered by a mucous membrane
• Small tissue nodules called papillae cover the tongue's upper surface
• Taste buds, located between the papillae, enable the sense of taste
• The tongue assists in chewing and swallowing, and it is important for speech

Tongue Composition

• The tongue comprises the root, body, and apex

Body

• Mostly mucous-covered muscles
• Bears taste buds

Median Lingual Sulcus

• A depression runs the length of the tongue's body
• Separates the tongue into two symmetrical halves

Sulcus Terminalis

• An inverted V-shaped depression
• Separates the tongue's base
• Topped by the foramen cecum

Root

• It connects the tongue to the mandible and hyoid bone
• It connects to the pharynx walls on each side

Epiglottis

• A movable plate
• Ensures that the larynx closes when swallowing to prevent food from entering the respiratory tract

Tongue Surface

• The upper surface (dorsum) is divided by the sulcus terminalis

Anterior 2/3 (oral part)

• Directed upwards towards the palate
• Includes papillae such as filiform, fungiform and circumvallate

Filiform Papillae

• Conical papillae with mechanical and tactile functions
• Create a rough surface for mastication

Fungiform Papillae

• Round, larger than filiform papillae
• Often contain taste buds

Circumvallate Papillae

• Dome-shaped structures
• Number varies from 8 to 12
• Situated on the dorsum, in front of the foramen cecum and sulcus terminalis
• Arranged in a row that runs backward and medially, meeting in the midline

Posterior 1/3 (pharyngeal part)

• Directed backward towards the pharynx
• Submucosa contains lymphoid tissue: the lingual tonsil

Lower Surface

• Shows the frenulum, deep lingual vein, and openings for the submandibular gland ducts and sublingual fold

Lymph Drainage

• Tip of the tongue drains to the submental lymph nodes
• Lateral parts drain to the submandibular lymph nodes
• Posterior part drains to the upper and middle deep cervical lymph nodes

Muscles of the Tongue

• Intrinsic muscles are confined to the tongue mass and have no bony attachments, consisting of longitudinal, transverse, and vertical fibers
• Intrinsic muscles alter the tongue's shape and affect speech
• Extrinsic muscles originate outside the tongue with attachments to it

Extrinsic Muscles

• Genioglossus: The largest muscle; protrudes the tongue's apex
• Hyoglossus: Depresses and retracts the tongue
• Styloglossus: Moves the tongue upward and backward
• Palatoglossus: Pulls the tongue's root upward and backward; closes the oropharyngeal isthmus and helps initiate swallowing
• Extrinsic muscles change the tongue's position

Nerve Supply to the Tongue

Sensory

• Anterior 2/3: General sensation via the lingual nerve (V), and taste sensation via the chorda tympani (VII)
• Posterior 1/3: General and taste sensation via the glossopharyngeal nerve (IX)

Motor

• All extrinsic and intrinsic muscles are controlled by the hypoglossal nerve (XII), except the palatoglossal muscle, which is controlled by the vagus nerve (X)

Blood Supply to the Tongue

• Lingual artery
• Tonsillar branch of the facial artery
• Ascending pharyngeal artery
• Veins drain to the IJV

Congenital Anomalies of the Tongue

• Macroglossia: An excessively large tongue may be present at birth due to inherited or congenital disorders, such as lymphangioma, Beckwith-Wiedemann Syndrome, or Down Syndrome; treatment involves surgical reduction
• Aglossia: Absence of the tongue at birth; may occur with other congenital defects involving limbs and craniofacial structures
• Bifid Tongue: Results from failure of the lingual swellings of the first pharyngeal arches to fuse, resulting in a split involving the tip or anterior two-thirds of the tongue
• Tongue-tie (Ankyloglossia): Caused by a short frenulum; treatment is unnecessary unless mastication or speech is impaired
• Excessive Length of Frenulum: May cause the tongue to fall back and occlude the pharynx, leading to suffocation

Tongue Injuries

• Wounds & Lacerations from bites, accidents, or fits can cause severe bleeding (treated with sutures and hemostasis)
• Haematoma can cause respiratory obstruction if large (treated with tracheostomy or endotracheal intubation)

Tongue Ulcers

Aphthous Ulcers

• The most common type of mouth ulcer
• More common in women
• Typically first occurs between 10 and 40 years of age
• The cause is unknown
• If associated with systemic symptoms such as uveitis, genital ulcerations, conjunctivitis, arthritis, fever, or adenopathy, further investigation is needed

Types of Aphthous Ulcers

• Minor Ulcer: The most common type, less than 10 mm across, with typically one to five ulcers at a time, lasting 7-10 days and healing without scarring; not usually very painful
• Major Ulcer: Less common, also less than 10 mm across, but only one or two occur at a time, lasting from two weeks to several months, and healing with a scar; can be very painful
• Herpetiform Ulcer: Tiny, pinhead-sized ulcers (1-2 mm), with multiple ulcers that may join together, forming irregular shapes, lasting one week to two months

Treatment of Aphthous Ulcers

• Focuses on pain relief
• Promotes healing
• There is no cure
• Avoid spicy or acidic foods/drinks
• See a dentist for badly fitting dentures
• Use antiseptic mouthwash, steroid lozenges, anaesthetic oral gels, or alkaline lotions containing 2% sodium bicarbonate.

Dental Ulcers of the Tongue

• Caused by trauma from a broken tooth or poorly fitted dentures
• Occur on the side of the tongue near the offending tooth
• Appearance: small with a soft base
• Can be painful and tender, with enlarged draining lymph nodes
• Treatment: Remove the cause (offending tooth) and then use antiseptic mouthwash

Aetiology of Carcinoma of The Tongue

• More prevalent in males than females (M:F = 10:1)
• Typically occurs in individuals over 60 years old
• Predisposing factors include smoking, spirit consumption, spices, sepsis, and sharp teeth
• Predisposing lesions include leukoplakia, erythroplakia, tongue papilloma, chronic superficial glossitis, dental ulcers, and syphilis

Leukoplakia

• A white patch on the tongue that cannot be rubbed off
• Caused by excessive mucosal hyperkeratosis, which may involve dysplasia
• Can result from chronic irritation
• May resolve when irritation ceases, leaving a red glazed tongue
• Treatment involves surgical excision

Pathology of Carcinoma of The Tongue

• Site: Most commonly found on the margin of the anterior 2/3 (50%), less frequently on the posterior 1/3; rarely affects the tip

Grossly

• Ulcer with raised, everted edge, plus a necrotic floor, and an indurated base
• Plaque-like lesion
• Submucosal nodule
• Deep, indurated fissure
• Diffuse infiltration (wooden tongue)

Spread of Tongue Cancer

• Direct spread: To surrounding structures, such as the floor of the mouth and mandible for anterior tumors, or to the pharynx and tonsils for posterior tumors
• Lymphatic spread: Disseminates earlier than lip carcinoma; to the submental lymph nodes, and the upper deep cervical nodes.
• Blood spread: Rare, and usually occurs with posterior tumors

Investigations of Tongue Carcinoma

• Biopsy to examine any ulcer that resists treatment
• CT scan of the neck and mandible
• Fine needle aspiration cytology (FNAC) of the cervical lymph nodes
• Metastatic workup for distant spread

Complications of Tongue Carcinoma

• Recurrent inhalation bronchopneumonia
• Dysphagia
• Hemorrhage due to erosion of the lingual artery
• Suffocation due to edema of the glottis or lymph node compression
• Malignant cachexia

Treatment of Tongue Carcinoma

• Surgical excision with a 1.5 cm safety margin
• For anterior tumors, partial, hemi, or near-total glossectomy
• For posterior tumors, total glossectomy
• Neck dissection for lymph node involvement.
• COMMANDO operation for cases with invasion of the mandible
• Radiotherapy: either radium needles or external beam irradiation
• Chemotherapy may be used as adjuvant therapy.