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Terminal
- 0
- General somatic sensory from nasal mucosa
- Lacking in Agnathans, constant in everyone else
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Olfactory
- 1
- Special somatic sensory from nasal sac
- cell bodies located in nasal epithelium in vertebrates with vomeronasal organs, olfactory branches to form vomeronasal nerves.
-
Optic
- 2
- Technically a brain tract rather than a nerve.
- special somatic sensory from retina to optic lobes.
- below mammals, much decussation (the crossing of the midline of the brain or spinal cord by neuron tracts)
- in mammals, not all fibers decussate
-
Oculomotor
- 3
- general visceral motor (ciliary branch of oculomotor), somatic motor, proprioceptive somatic sensory (may travel in trigeminal)
- travels to and from extrinsic eye muscles (those that move the eyeball) that develop from the first somite ( dorsal rectus, medial rectus, ventral rectus, ventral oblique)
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Trochlear
- 4
- Innervates extrinsic muscles of eye that develop from the second somite ( which is only one, the dorsal ( = superior) oblique)
- somatic motor function
-
Trigeminal
- 5
- named because it is 3-branched
- Mandibular Branch - special visceral motor to first branchial arch derivatives
- Ophthalmic and infraorbital branches - general somatic sensory from face
-
Abducens
- 6
- last ocular muscle arises from 3rd somite, abducens is somatic motor to it.
- has some proprioceptive fibers in lower vertebrates
-
Facial
- 7
- special visceral motor to hyoid muscles of second visceral arch.
- becomes a motor nerve to facial muscles of mammals.
- general and special visceral sensory from oral cavity and pharynx.
- special somatic sensory from surface of the body.
-
Auditory
- 8
- a general term, called statoacoustic in fishes and vestibulocochlea in mammals.
- special somatic sensory neurons from the ear.
-
Glossopharyngeal
- 9
- special visceral motor to muscles of third branchial arch.
- contains general and special visceral sensory nerves from the first gill pouch and back of pharynx.
- in fishes may return fibers from part of the lateral line.
-
Vagus (Wandering)
- 10
- special visceral motor to muscles of branchial arches 4-7; general special sensory from pharynx and gill pouches.
- accessory branch - special visceral motor to cucullaris muscle of pectoral girdle in fishes.
- intestinal branch - general visceral motor and sensory to and from abdominal viscera.
-
Spinal Accessory
- 11
- special visceral motor to derivatives of the cucullaris (Muscles of the shoulders)
-
Hypoglossal
- 12
- somatic motor to the base of the tongue, innervates tounge muscles.
- occipital nerves - homolog of the hypoglossal in syclostomes and fishes ( in which it is called the hypobranchial)
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