Chorda

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Chorda filum Crouan

The topic "Chorda" can refer to different concepts depending on the context, such as "chorda tympani" in anatomy or "chorda" in a more general biological or historical context. Given the broad potential scope, I'll focus on the "chorda tympani" as it's a well-defined anatomical feature.

Chorda Tympani

The chorda tympani is a branch of the facial nerve (cranial nerve VII) that carries taste sensations from the anterior two-thirds of the tongue and supplies parasympathetic fibers to the submandibular gland and sublingual gland, which are salivary glands. The nerve is significant not only for its role in taste perception but also for its involvement in the regulation of salivation.

Anatomy

The chorda tympani nerve originates from the facial nerve just after it enters the petrous part of the temporal bone through the internal acoustic meatus. It travels through the middle ear, running between the ossicles, specifically between the malleus and the incus, and exits the middle ear cavity to join the lingual nerve (a branch of the mandibular nerve, which is part of the trigeminal nerve or cranial nerve V).

Function

The primary function of the chorda tympani includes the transmission of taste sensations from the anterior two-thirds of the tongue. These taste fibers are special visceral afferent fibers. Additionally, it carries parasympathetic preganglionic fibers to the submandibular ganglion, from where postganglionic fibers innervate the submandibular and sublingual glands, stimulating salivation.

Clinical Significance

Damage to the chorda tympani can result in a loss of taste sensation in the anterior two-thirds of the tongue and a decrease in salivary secretion. This can occur due to trauma, infection, or surgery involving the middle ear or the facial nerve. The nerve's proximity to the middle ear makes it particularly vulnerable during procedures such as tympanoplasty or mastoidectomy.

See Also

• Facial nerve
• Taste
• Salivary gland
• Tongue