Question

a) identify muscles a and b.
b) which nerve supplies muscles a and b?
c) what is the action of these muscles?

Explanation:

• A) Muscle A is the temporalis muscle (a large, fan - shaped muscle covering the temporal bone). Muscle B is the masseter muscle (a thick, rectangular muscle located at the side of the face).
• B) Both the temporalis and masseter muscles are supplied by the mandibular branch of the trigeminal nerve (CN V3). The trigeminal nerve is the fifth cranial nerve, and its mandibular division provides motor innervation to the muscles of mastication.
• C) The main action of these muscles is mastication (chewing). The temporalis muscle elevates and retracts the mandible, while the masseter muscle elevates the mandible (closing the jaw).

Answer:

A. Muscle A: Temporalis; Muscle B: Masseter
B. Mandibular branch of the trigeminal nerve (CN V3)
C. Mastication (chewing); temporalis elevates and retracts the mandible, masseter elevates the mandible.