Final answer:
The boundaries of sensory innervation from Cranial Nerve V's GSA fibers encompass the entire face and are divided among the three divisions of the nerve: V1 (Ophthalmic), V2 (Maxillary), and V3 (Mandibular), each innervating specific regions of the face and head.
Step-by-step explanation:
The boundaries of sensory innervation from the General Somatic Afferent (GSA) fibers of Cranial Nerve V (CN V) are delineated by its three divisions: V1 (Ophthalmic division), V2 (Maxillary division), and V3 (Mandibular division). These three divisions are responsible for conveying the general somatic senses from the head to the brain.
V1 (Ophthalmic division) provides sensory innervation to areas such as the forehead, scalp, upper eyelid, cornea, and nose. V2 (Maxillary division) innervates the lower eyelid, upper lip, cheek, nasal mucosa, maxillary sinus, and upper teeth. Lastly, V3 (Mandibular division) supplies sensation to the lower lip, lower teeth, chin, jaw, the anterior two-thirds of the tongue (not taste), and the temporal region.
Each of these divisions is involved in specific sensory tests, and damage to these areas may reveal deficits in adjacent regions of the brain stem. Additionally, the trigeminal nerve plays a critical role in general senses and is commonly evaluated during a cranial nerve exam.