Question

Jean needs to have a tooth in her mandible filled. Her dentist injects a local anesthetic to block pain afferents in one of her cranial nerves. What cranial nerve does the dentist numb?

a. trigeminal
b. trochlear
c. glossopharyngeal
d. facial
e. hypoglossal

Answer 1

The trigeminal (option a) nerve is numbed by the dentist to prevent pain during a tooth filling procedure in the mandible. The local anesthetic, often lidocaine, is injected near the mandibular foramen to block nerve impulses that transmit sensation from the lower jaw.

Step-by-step explanation:

The cranial nerve that the dentist numbs to block pain afferents in the mandible for a tooth filling procedure is the trigeminal nerve. This nerve is responsible for sensation in the face and motor functions such as biting and chewing. It has three branches, and the mandibular branch is specifically targeted for dental procedures in the lower jaw. During the administration of local anesthetic, the dentist injects the anesthetic near the mandibular foramen, which is the point of entry for the sensory nerve that supplies the lower teeth.

Lidocaine, a common local anesthetic used in dental procedures, works by blocking voltage-gated sodium channels. The blockage of these channels prevents the generation and transmission of nerve impulses, resulting in numbness and the absence of pain. This process is necessary to conduct pain-free dental procedures like fillings, extractions, and other forms of oral surgery.