Tongue Anatomy: Oral & Dental Sciences

• The tongue and taste: Oral & Dental Sciences.
• The Greek word "Glossus" is where the word tongue comes from.

GDC ILOS

• Describe dental, oral, craniofacial, and general anatomy and their application to patient management.
• Describe physiology and its application to patient management.

Related topics

• Epithelium
• Muscles
• Floor of the mouth
• Regional anatomy
• Oral Mucosa

Aim

• Overview the structure, functions, and variations in appearance of the tongue.

Learning Outcomes

• Describe the structures and functions of the tongue and taste buds.
• Describe tongue muscles (intrinsic and extrinsic), including nerve innovation and blood supply.
• Describe how the sensation of taste is created.
• Recognize variations in the tongue's appearance in health and disease.
• The tongue is a moveable muscular organ.
• The tongue includes a root, body, and tip (apex), featuring a curved dorsal surface and an inferior ventral surface.

Functions of the tongue

• Mastication
• Taste
• Swallowing
• Oral Hygiene
• Speech
• Kissing
• Sensitivity
• Suckling
• Defense

Structures of the tongue

• Epiglottis
• Palatine Tonsil
• Lingual Tonsil
• Sulcus Terminalis
• Dorsum/Dorsal surface
• Lateral border
• Ventral surface
• Lingual Papillae
• Apex (tip)
• Median Lingual Sulcus
• Root/Base (Posterior 1/3)
• Body (Anterior 2/3)

Dorsum

• The dorsum is divided into anterior two-thirds (oral/body) and posterior one-third (pharyngeal/base).
• The dorsum is separated by the sulcus terminalis (a triangle-shaped landmark) and foramen caecum.

Ventral Surface

• The ventral surface is covered during the ‘FOM and Palate’ lecture.
• This surface features deep lingual veins and plicae fimbriate (fimbriated fold).

Lateral Border

• The main features of the lateral border are the ridges comprised of foliate papillae.

Types of Lingual Papillae

• Filiform are one of the four types of lingual papillae located on the dorsum of the tongue.
• Fungiform are one of the four types of lingual papillae located on the dorsum of the tongue.
• Circumvallate are one of the four types of lingual papillae located on the dorsum of the tongue.
• Foliate are one of the four types of lingual papillae located on the dorsum of the tongue.

Taste Buds

• Taste buds are barrel-shaped organs composed of 30-80 spindle-shaped cells.
• These cells extend from the basement membrane to the epithelial surface of the lingual papillae.
• Fungiform, foliate, and circumvallate lingual papillae are associated with taste buds.
• Taste bud cells turnover is rapid, approximately 10 days.

Taste bud cell types

• Supporting cells support the taste bud and are located on the outer portion.
• Taste cells are Located in the central portion of the taste bud.
• The taste pore is an opening existing in the most superficial portion of the taste bud.
• Superficial taste receptors contact dissolved food molecules at the taste pore, producing a taste sensation.
• Taste cells are associated with sensory neuron processes in the inferior portion of the taste bud.
• Taste cells receive messages of taste sensation through receptors; the nerve sends messages to the central nervous system, where the taste is identified.

Taste (Gustation)

• Sweet, umami or low salt indicates foods rich in nutrients.
• Bitter, sour, or highly salty indicates potentially toxic or spoiling foods.
• Taste starts digestion and links to the other four senses: sight, smell and the sounds prepare the body by increasing saliva production.
• Touch allows the body to know the appropriate saliva.
• Saliva is needed to experience taste, substances can only be tasted in solution.

Muscles of the tongue

• Extrinsic muscles originate outside the tongue and insert into it.
• Intrinsic muscles are contained entirely within the tongue.

Extrinsic Muscles

• Genioglossus origin is the superior genial tubercle (on the inferior aspect of the mandible).
• Genioglossus inserts into the whole surface of the tongue and pulls the tongue forward to protrude from the mouth and depress to form a concavity on its dorsal surface
• Hyoglossus origin is the hyoid bone and inserts into the ventral side of the tongue to Depresses the tongue and assists in retraction
• Palatoglossus lies within the palatoglossal arch.
• Palatoglossus originates in the aponeurosis of the soft palate.
• Palatoglossus insertion is on the side of the tongue and blends with the intrinsic muscles to lift the tongue, closing off the mouth from the pharynx.
• Styloglossus origin is a short muscle originating at the styloid process.
• Styloglossus blends with the inferior longitudinal muscle and the hyoglossus and draws the tongue upwards and backwards.

Intrinsic Muscles

• These muscles alter the shape of the tongue.
• The superior longitudinal muscle originates in the sub mucosa of the posterior portion of the tongue.
• The superior longitudinal muscle inserts into the apex and anterolateral margins of the tongue.
• The superior longitudinal muscle Shortens the tongue and turns the tip and the sides upwards.
• The inferior longitudinal muscle originates in the root of the tongue and the hyoid bone.
• The inferior longitudinal muscle inserts into the apex of the tongue to Shortens the tongue and pulls the tip and sides downwards.
• The vertical muscle originates in the root of the tongue and genioglossus muscle and lingual aponeurosis to flatten and broaden the tongue.
• The transverse muscle originates in fibres in the median lingual septum and passes laterally to insert into the side of the tongue to narrow and lengthen the tongue.

Nerve Innervation

• The tongue has a sensory and a motor nerve supply.
• Posterior 1/3 of the tongue: Glossopharyngeal Nerve (IX) provides sensory and taste.
• Anterior 2/3 of the tongue: Lingual nerve (Trigeminal Nerve V) provides sensory.
• Chorda Tympani (Facial nerve VII) & Lingual nerve provides taste.
• Hypoglossal nerve (XII) provides motor supply, except for the Palatoglossus, which the Vagus nerve (X) supplies.

Blood Supply

• Blood reaches the tongue via the lingual artery, which is a branch of the external carotid artery.
• The tongue drains principally through the lingual vein

Abnormal Tongue Appearance

Geographic Tongue

• This is a benign condition caused by inflammation.
• It presents as smooth irregular red patches and white wavy lines, which may change position.
• Its appearance is likened to a map - hence the name 'geographic' .
• No treatment is required, but advise to avoid acidic and spicy foods to reduce soreness.

Glossitis

• Inflammation causes swelling, redness, and changes in the surface texture.
• It can be categorized into acute, chronic, atrophic, and median rhomboid.
• Several causes, including anaemia, celiac disease, trauma, and allergic reaction.

Piercings

• Tongue piercings are the most popular oral piercing.
• They may impact oral hygiene and the integrity of the teeth.

Black Hairy Tongue

• This includes Overgrowth of cells creating elongated papillae.
• Trapped food, bacteria, and yeast that causes discolouration.
• Smoking, antibiotics, and radiotherapy can contribute to the appearance.
• Treatment involves cleaning the tongue surface with a toothbrush or tongue scraper and changing lifestyles.

Squamous Cell Carcinoma

• Squamous cell carcinomas (SCC) make up 95% of oropharyngeal cancers.
• The posterior lateral border or ventral surface of the tongue is the most common site (40%).