Which of the following nerve supplies the sensory fibres to submandibular salivary gland ?
**Core Concept**
The question requires knowledge of the innervation of the submandibular salivary gland, specifically the sensory fibers. The submandibular gland receives both parasympathetic and sensory innervation from the facial nerve (cranial nerve VII) and sympathetic innervation from the superior cervical ganglion via the submandibular ganglion.
**Why the Correct Answer is Right**
The facial nerve (cranial nerve VII) provides the sensory innervation to the submandibular gland via the chorda tympani nerve, which joins the lingual nerve. The chorda tympani nerve contains taste fibers from the anterior two-thirds of the tongue and general sensory fibers from the submandibular gland. The general sensory fibers are responsible for conveying sensations such as touch, pressure, and temperature from the gland.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct nerve. While the glossopharyngeal nerve (cranial nerve IX) does provide sensory innervation to other structures in the head and neck, it is not responsible for the sensory innervation of the submandibular gland.
**Option B:** This option is incorrect because the vagus nerve (cranial nerve X) primarily provides parasympathetic innervation to the submandibular gland, not sensory innervation.
**Option C:** This option is incorrect because the trigeminal nerve (cranial nerve V) provides sensory innervation to the face, including the skin and muscles of mastication, but not specifically to the submandibular gland.
**Clinical Pearl / High-Yield Fact**
The chorda tympani nerve, a branch of the facial nerve, is a key structure in the innervation of the submandibular gland and carries both taste fibers from the anterior two-thirds of the tongue and general sensory fibers from the gland.
**Correct Answer: C. Trigeminal nerve (cranial nerve V) actually supplies the general sensation of the skin of the face including the area over the gland but the specific sensory innervation of the gland is from the chorda tympani nerve which is a branch of the facial nerve.