Medical Science Optional daily answer writing practice for Civil service – Test Series April 29

1. Mucous membrane and its nerve supply:

The tongue is covered by a mucous membrane that is continuous with the mucous membrane of the floor of the mouth and the oropharynx. The mucous membrane of the tongue is divided into two regions: the anterior two-thirds and the posterior one-third. The anterior two-thirds of the tongue is covered by a stratified squamous epithelium that contains numerous papillae, which are small projections that give the tongue its rough texture. The posterior one-third of the tongue is covered by a lymphoid tissue known as the lingual tonsil.

The mucous membrane of the tongue is richly innervated by sensory fibers that are responsible for taste, touch, and temperature sensation. The anterior two-thirds of the tongue is supplied by the lingual nerve, which is a branch of the mandibular division of the trigeminal nerve (cranial nerve V). The posterior one-third of the tongue is supplied by the glossopharyngeal nerve (cranial nerve IX).

2. Muscles, movements produced by them and their nerve supply:

The tongue is composed of a group of intrinsic and extrinsic muscles that work together to produce a variety of movements. The intrinsic muscles are located entirely within the tongue and are responsible for changing the shape of the tongue. The extrinsic muscles are attached to the tongue and other structures in the head and neck, and are responsible for moving the tongue in different directions.

The intrinsic muscles of the tongue include the superior longitudinal, inferior longitudinal, transverse, and vertical muscles. These muscles are responsible for changing the shape of the tongue, such as curling, flattening, and narrowing.

The extrinsic muscles of the tongue include the genioglossus, hyoglossus, styloglossus, and palatoglossus muscles. The genioglossus muscle is the largest and most important extrinsic muscle of the tongue. It originates from the mandible and inserts into the tongue, and is responsible for protruding and retracting the tongue. The hyoglossus muscle originates from the hyoid bone and inserts into the tongue, and is responsible for depressing and retracting the tongue. The styloglossus muscle originates from the styloid process of the temporal bone and inserts into the tongue, and is responsible for elevating and retracting the tongue. The palatoglossus muscle originates from the soft palate and inserts into the tongue, and is responsible for elevating the back of the tongue.

The muscles of the tongue are supplied by the hypoglossal nerve (cranial nerve XII), which provides motor innervation to all of the intrinsic and extrinsic muscles of the tongue except for the palatoglossus muscle, which is supplied by the vagus nerve (cranial nerve X).

3. Lymphatic drainage:

The lymphatic drainage of the tongue is important for the removal of waste products and the immune response. The anterior two-thirds of the tongue drains into the submental and submandibular lymph nodes, while the posterior one-third of the tongue drains into the upper deep cervical lymph nodes.

4. Clinical anatomy:

The anatomy of the tongue is important for a variety of clinical applications, including speech therapy, dentistry, and oral surgery. Knowledge of the nerve supply to the tongue is important for diagnosing and treating conditions such as Bell’s palsy and trigeminal neuralgia. The lymphatic drainage of the tongue is important for the diagnosis and treatment of head and neck cancers. The extrinsic muscles of the tongue can be affected in conditions such as amyotrophic lateral sclerosis (ALS) and myasthenia gravis, which can lead to difficulties with speech and swallowing.