FIG 1.

Trigeminal nerve, associated nuclei, and major branches. Sagittal graphic (A) shows the major branches of the trigeminal nerve (CN V), including the preganglionic or cisternal segment (black straight arrow), trigeminal ganglion (black arrowhead) in the trigeminal cave, ophthalmic division (white straight arrow, CN V1) entering the orbit via the superior orbital fissure, maxillary division (white arrowhead, CN V2) exiting at the foramen rotundum, and mandibular division (white curved arrow, CN V3) exiting the skull base at the foramen ovale before transiting the infrazygomatic masticator space. Sagittal graphic (B) highlights the brain stem nuclei of the trigeminal nerve, including the mesencephalic nucleus (orange shading, black straight arrow), main sensory nucleus (blue shading, black arrowhead), spinal nucleus (pink shading, white straight arrow), and motor nucleus (green shading, white arrowhead). Axial graphic (C) demonstrates the course of the trigeminal nerves, including the preganglionic segments (black straight arrows), trigeminal ganglia (black arrowheads), ophthalmic divisions (white straight arrows, CN V1), maxillary divisions (white arrowheads, CN V2), and mandibular divisions (white curved arrows, CN V3), as well as the sensory (blue shading, black curved arrows) and motor (green shading, black dashed arrows) nuclei. Axial graphic (D) shows the relationship of the auriculotemporal nerve (black straight arrow), a complex branch of the mandibular nerve (black arrowhead, CN V3) that transits the infrazygomatic masticator space and parotid space, serving as an extracranial “bridge” linking CN V3 and the intraparotid facial nerve (white straight arrow, CN VII). Graphics are reproduced with permission from Imaging Anatomy: Brain and Spine and Specialty Imaging: Head and Neck Cancer. Copyright Elsevier.