The Cranial Nerves & Topography
The cranial nerve nuclei follow a logical plan of spatial organization within the brain stem. Cranial Nerves VIII-XII are located in the medulla and are associated with the balance and hearing (VIII), oropharyngeal cavity (IX), viscera (X), neck and shoulder muscles (XI) and tongue (XII) respectively. Cranial nerves V and VII are found in the pons and are associated with facial sensation and musculature. Cranial nerves II, IV and VI are found in the mibrain and control eye movements. Cranial nerves I and II are situated in the forebrain and convey olfactory and visual information to the thalamus and ventral telencephalon respectively.
The Optic Nerve (II) rods and cones encode brightness and form information that is used to compute object speed and distance.
The Oculomotor Nerve (III) projects to all extraocular muscles except the superior oblique (IV) and lateral rectus (abducens VI)
The Trochlear Nerve (IV) lower motoneurons projecting to superior oblique muscles
The Abducens Nerve (VI) lower motoneurons innervating lateral rectus muscles.
The Facial Nerve (VII), the motor nucleus of VII is a mixed nerve, innervates muscles of facial expression. The movement of stapes for activation of middle ear reflexes that regulate reflex responses that reduce the loudness of potentially damaging sounds. The elevation of the hyoid has a role in controlling the pitch of speech.
The Vestibulocochlear nerve (VIII) (Note: the only purely sensory cranial nerve subserving two modalities); the vestibular nuclei receive input from vestibular hair cells via vestibular ganglion cells for equilibrium analysis and project to the forebrain, the oculomotor system and the spinal cord. The cochlear nuclei receive input from spiral ganglion cells that innervate cochlear hair cells.
The Glossopharyngeal nerve (IX), the solitary nucleus is recipient of pain, touch and temperature from these receptors on the posterior one-third of the tongue, via the petrosal ganglion. The spinal trigeminal nucleus, general somatic afferents, pain and temperature from skin around the ear through the jugular ganglion of IX. The inferior salvatory nucleus parasympathetic motor supply to the parotid salivary gland. The nucleus ambiguus; motor neurons controlling pharyngeal muscle.
Vagus nerve (X) spinal trigeminal nucleus, touch pain and temperature from skin of ear and external auditory meatus. Solitary nucleus, touch pain and temperature from larynx, pharynx and thoracic and abdominal viscera via the inferior ganglion of X. Nucleus ambiguus, motor to larynx and pharynx and to branchial arch muscles. Dorsal motor nucleus supplies thoracic and abdominal viscera via preganglionic neurons situated near the target organs. solitary nucleus.
Spinal Accessory Nerve (XI) control of sternocleidomastoid and trapezius muscles
Hypoglossal Nerve (XII), hypoglossal nucleus contains lower motoneurons innervating the tongue
The Oculomotor Nerve (III) projects to all extraocular muscles except the superior oblique (IV) and lateral rectus (abducens VI)
The Trochlear Nerve (IV) lower motoneurons projecting to superior oblique muscles
The Abducens Nerve (VI) lower motoneurons innervating lateral rectus muscles.
The Facial Nerve (VII), the motor nucleus of VII is a mixed nerve, innervates muscles of facial expression. The movement of stapes for activation of middle ear reflexes that regulate reflex responses that reduce the loudness of potentially damaging sounds. The elevation of the hyoid has a role in controlling the pitch of speech.
The Vestibulocochlear nerve (VIII) (Note: the only purely sensory cranial nerve subserving two modalities); the vestibular nuclei receive input from vestibular hair cells via vestibular ganglion cells for equilibrium analysis and project to the forebrain, the oculomotor system and the spinal cord. The cochlear nuclei receive input from spiral ganglion cells that innervate cochlear hair cells.
The Glossopharyngeal nerve (IX), the solitary nucleus is recipient of pain, touch and temperature from these receptors on the posterior one-third of the tongue, via the petrosal ganglion. The spinal trigeminal nucleus, general somatic afferents, pain and temperature from skin around the ear through the jugular ganglion of IX. The inferior salvatory nucleus parasympathetic motor supply to the parotid salivary gland. The nucleus ambiguus; motor neurons controlling pharyngeal muscle.
Vagus nerve (X) spinal trigeminal nucleus, touch pain and temperature from skin of ear and external auditory meatus. Solitary nucleus, touch pain and temperature from larynx, pharynx and thoracic and abdominal viscera via the inferior ganglion of X. Nucleus ambiguus, motor to larynx and pharynx and to branchial arch muscles. Dorsal motor nucleus supplies thoracic and abdominal viscera via preganglionic neurons situated near the target organs. solitary nucleus.
Spinal Accessory Nerve (XI) control of sternocleidomastoid and trapezius muscles
Hypoglossal Nerve (XII), hypoglossal nucleus contains lower motoneurons innervating the tongue
Olfactory Nerve (I)
Optic Nerve (II) Visual Evoked Potentials
Oculomotor Nerve (III) Visual Evoked Potentials
Trochlear Nerve (IV) Superior Oblique Muscles
Trigeminal Nerve (V) Buccinator Muscles
Abducens Nerve (VI) Lateral Rectus Muscles
Facial Nerve (VII) Five Branches of the Facial Nerve
(Frontalis, Obicularis Oculi, Nasalis/Zygomatic, Orbicularis Oris, Platysma)
Vestibulocochlear Nerve (VIII) Auditory Brain Stem Response
Glossopharyngeal Nerve (IX) Posterior Tongue
Vagus Nerve (X) Recurrent Laryngeal Nerve
Spinal Accessory Nerve (XI) Trapezius
Hypoglossal Nerve (XII) Tongue
Optic Nerve (II) Visual Evoked Potentials
Oculomotor Nerve (III) Visual Evoked Potentials
Trochlear Nerve (IV) Superior Oblique Muscles
Trigeminal Nerve (V) Buccinator Muscles
Abducens Nerve (VI) Lateral Rectus Muscles
Facial Nerve (VII) Five Branches of the Facial Nerve
(Frontalis, Obicularis Oculi, Nasalis/Zygomatic, Orbicularis Oris, Platysma)
Vestibulocochlear Nerve (VIII) Auditory Brain Stem Response
Glossopharyngeal Nerve (IX) Posterior Tongue
Vagus Nerve (X) Recurrent Laryngeal Nerve
Spinal Accessory Nerve (XI) Trapezius
Hypoglossal Nerve (XII) Tongue