Introduction The vagus nerve, also known as the 10th cranial nerve or CN X, is one of the longest and most complex nerves in the human body. It starts in the brainstem, travels through the neck, chest, and abdomen, and branches out to the heart, lungs, digestive tract, and even the tongue and ears. The…
Introduction The accessory nerve, also known as cranial nerve XI (CN XI), is one of the 12 cranial nerves in humans. It is considered a motor nerve and primarily innervates the sternocleidomastoid and trapezius muscles, which play crucial roles in head and shoulder movements. It has a cranial and a spinal component, though there is…
Introduction The glossopharyngeal nerve is also called the ninth cranial nerve (CN IX). It is one of the four cranial nerves, that perform sensory, motor, and parasympathetic functions. It starts from the medulla oblongata and ends in the pharynx. The glossopharyngeal nerve has multiple branches. The tympanic branch supplies the middle ear. The stylopharyngeal branch…
Introduction The vestibulocochlear nerve is also called cranial nerve eight (CN VIII). The vestibulocochlear nerve (CN VIII) connects the vestibular and cochlear nerves. It is situated within the internal auditory meatus (internal auditory canal). The cochlear nerve controls hearing, while the vestibular nerve controls balance and eye movements. CN VIII injuries are caused by pathological…
Introduction The abducens nerve, also known as the abducent nerve, controls the movement of the lateral rectus muscle, allowing your eye to rotate away from the centre of your body and look left or right. The 6th cranial nerve (CN VI) functions as the abducens. This nerve only has a motor function and not a…
Introduction The trigeminal nerve (CN V) is its fifth and largest cranial nerve. Its primary function is to provide sensory innervation to the face, which is divided into three major branches. The ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves are the three branches. The trigeminal ganglia, located within the Meckel’s cave of the middle…
Introduction The trochlear nerve, or fourth cranial nerve (CN IV), acts as one of the ocular motor nerves that regulate eye movement. As the only cranial nerve with a dorsal outflow from the brainstem, the trochlear nerve, despite being the smallest, has the longest intracranial path. It starts in the midbrain and travels laterally and…
Introduction The oculomotor nerve is the third cranial nerve (CN III), and its name indicates its function. The oculomotor nerve will innervate muscles that move the eye or its components, as implied by the name alone. The nerve’s ability to move makes it an effective indicator of brain injury. It is a mixed nerve with…
Introduction The optic nerve is the second cranial nerve (CN II) that transmits visual information. The optic nerve has only afferent (sensory) fibres and, like all cranial nerves, is paired. During embryogenesis, the optic nerve develops in the retina, exits the orbit via the optic canal, and travels throughout the central nervous system. The optic…
Introduction The first and smallest cranial nerve is the olfactory nerve. This nerve is one of two that do not connect to the brainstem. Your olfactory nerve anatomy is part of the central nervous system. The process begins in the brain and ends in the upper nose. It is also part of your autonomic nervous…
