Model Answer
0 min readIntroduction
The tongue is a muscular hydrogel organ in the oral cavity, crucial for taste, speech, and swallowing. Its complex anatomy reflects its diverse functions. It’s composed of skeletal muscle covered by a mucous membrane. Understanding the tongue’s structure is fundamental to diagnosing and treating various oral and systemic conditions. This answer will comprehensively describe the tongue under the specified subheadings, providing a detailed anatomical overview relevant to medical practice. The tongue’s development is closely linked to the branchial arches, influencing its nerve supply and muscular arrangement.
(i) Mucous Membrane and its Nerve Supply
The mucous membrane covering the tongue is stratified squamous epithelium, adapted for protection against abrasion during speech and food manipulation. It’s divided into two parts: the dorsal surface and the ventral surface.
- Dorsal Surface: Characterized by numerous papillae – filiform, fungiform, foliate, and circumvallate. Filiform papillae are the most numerous and provide texture for taste. Fungiform papillae contain taste buds. Foliate papillae are located on the lateral borders, and circumvallate papillae are arranged in a V-shape at the posterior aspect.
- Ventral Surface: Smoother and thinner, with prominent superficial veins. The frenulum linguae, a fold of mucous membrane, connects the tongue to the floor of the mouth.
Nerve Supply: The anterior two-thirds of the tongue receives sensory innervation from the chorda tympani branch of the facial nerve (VII), which mediates taste sensation, and the lingual nerve, a branch of the trigeminal nerve (V3), for general sensation. The posterior one-third receives sensory innervation from the glossopharyngeal nerve (IX), also carrying taste sensation. The epiglottis and root of the tongue are innervated by the vagus nerve (X).
(ii) Muscles, Movements Produced by Them and their Nerve Supply
The tongue is composed of intrinsic and extrinsic muscles.
- Intrinsic Muscles: These muscles alter the shape of the tongue.
- Superior Longitudinal: Shortens the tongue and curves its tip upwards. (Innervated by hypoglossal nerve (XII))
- Inferior Longitudinal: Shortens the tongue and depresses its tip. (Innervated by hypoglossal nerve (XII))
- Transverse: Narrows and elongates the tongue. (Innervated by hypoglossal nerve (XII))
- Verticalis: Flattens and broadens the tongue. (Innervated by hypoglossal nerve (XII))
- Extrinsic Muscles: These muscles alter the position of the tongue.
- Genioglossus: Protrudes the tongue, depresses the central part, and retracts the sides. (Innervated by hypoglossal nerve (XII))
- Hyoglossus: Depresses and retracts the tongue. (Innervated by vagus nerve (X))
- Styloglossus: Retracts and elevates the tongue. (Innervated by vagus nerve (X))
- Palatoglossus: Elevates the posterior part of the tongue and depresses the soft palate. (Innervated by vagus nerve (X))
Movements: Protrusion, retraction, elevation, depression, curling, and flattening.
(iii) Lymphatic Drainage
The lymphatic drainage of the tongue is complex and clinically significant due to the potential for cancer metastasis.
- Dorsal Surface: Drains to the submandibular and deep cervical lymph nodes.
- Lateral Surfaces: Drains to the submandibular and deep cervical lymph nodes.
- Tip: Drains to the submental lymph nodes.
- Root: Drains to the deep cervical lymph nodes.
The deep cervical lymph nodes are further divided into superior, middle, and inferior groups. The lymphatic vessels follow the arteries.
(iv) Clinical Anatomy
Several clinical conditions relate to the anatomy of the tongue.
- Geographic Tongue: Characterized by irregular, map-like patches on the dorsal surface, representing areas of papillary atrophy.
- Black Hairy Tongue: Caused by keratin accumulation on the filiform papillae, often associated with poor oral hygiene and antibiotic use.
- Oral Cancer: Squamous cell carcinoma is the most common malignancy of the tongue, often occurring on the lateral borders. Early detection and treatment are crucial.
- Glossitis: Inflammation of the tongue, which can be caused by various factors, including infection, trauma, and nutritional deficiencies.
- Frenulum Linguae Anomalies: A short frenulum can restrict tongue movement (tongue-tie), affecting speech and feeding.
Knowledge of the nerve supply is vital during surgical procedures to avoid iatrogenic nerve damage. The lymphatic drainage pattern is crucial for staging and treating oral cancers.
Conclusion
The tongue’s anatomy is intricately linked to its diverse functions, ranging from taste and speech to swallowing and overall oral health. A thorough understanding of its mucosal membrane, muscular structure, lymphatic drainage, and clinical implications is essential for medical professionals. Recognizing the potential for various pathologies and the importance of early diagnosis and intervention are paramount in ensuring optimal patient care. Further research into the regenerative capabilities of the tongue may offer novel therapeutic approaches in the future.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.