Term
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Definition
brain started as a tube that folded in on itself
formed 12 specialized regions |
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Term
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Definition
- 12 pairs innervate certain area of head/body
- e. n has 1+ unique func (taste, smell, hearing, balance, vision)
- e. has motor (efferent) or sensory (afferent) axons, or both
- considered part of the PNS |
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Term
| nerve cell bodies for somatic motor fibers in cranial nn |
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Definition
- found within nuclei (clusters of gray matter/nerve cell bodies) in the brain itself. - These are considered lower motor neurons with the nerve cell bodies IN the CNS
-w/ Nerve there are many nuclei in the brain where info come from or goes to
-Some of the cranial nerves have somatic motor fiber --> ultimate synapse is on a piece of striated muscle. These fibers are found in the brain itself |
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Term
| nerve cell bodies for somatic sensory fibers in cranial nn (not special senses) |
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Definition
- in ganglia outside the CNS.
- These are like the sensory neurons in the spinal cord with the nerve cell body in the dorsal root ganglia |
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Term
Sensory and motor func
(DONT REALLY NEED TO KNOW THIS) |
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Definition
GS = general somatic
* general somatic (EX: spinal nn)
GSA = gs afferent
* sensory (EX: pain, temp to face)
GSE = gs efferent
* motor (EX: musc for cheewing or facial move
SSA = special somatic afferent
* carry sensory fibers w/ special afferent func (EX: vision, hearing, balance)
SVA = special visceral afferent
* other type of sensory n (EX: taste and smell)
SVE = special visceral efferent
* innervaate musc of larynx, pharynx, part of esophagus to control swalowing and resp
GVE = general visceral effernt
* motor fibers from the autonomic )parasymp) NS that innervate smooth musc (EX: innervation of gut by vagus n) |
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Term
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Definition
Olfactory
- chemoreceptors in nasal mucosa that detect odors and trasmit sensory info to axons of CN 1
- nucleus for this n is found in olfactory bulb and anterior olfactory nucleus in forebrain |
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Term
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Definition
- Light entering the retina activates photoreceptors which generate
action potentials that are relayed via retinal ganglion cells which form the axons in
the optic nerves.
- The optic nerves from each eye converge at the optic chiasm,
there is some decussation (amount is species dependent), and then optic tracts
are formed by the continuation of the axons.
- The entire optic nerve and retina are
actually part of the CNS – they are evolutionary modifications of a primitive tract
rather than an actual peripheral nerve
- cell body of neurons in the retina: ganglion cells
- axons finish in both brainstem and thalamus:
*2 types of fibers: conscious and unconscious |
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Term
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Definition
1) 80 % of fibers fuel cortex
- concious, reponse and vision path; thalamus (end)
- concious fibers go to the LGN --> back into occipital cortex through optic radiations
- The fibres for conscious perception of vision synapse in the Lateral Geniculate
Nucleus (LGN).
- The postsynaptic fibres form the optic radiation to the visual cortex
(located in the occipital region of the brain).
2) 20% go to the midbrain and tell pupil to adjust diameter
- subconscious; reflex pathway, mesencephalon (end)
- The fibres for unconscious responses to visual stimuli (pupils) pass to the Pretectal Area.
- move to part of the brain called the pretectal (midbrain) |
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Term
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Definition
| Originates from nuclei in the rostral (anterior) ventral area of the midbrain (there are 2 nuclei on each side, 1 for eye movement, 1 for iris constriction). |
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Term
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Definition
Trochlear n
Nucleus for CN IV is located caudally in the
mesencephalon (midbrain |
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Term
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Definition
Trigeminal N
the nuclei (motor and sensory) are located in the
pons. Sensory component has three branches. Ophthalmic
branch innervates the ocular region and the medial canthi.
Maxillary branch innervates the nasal region and lateral
canthi. Mandibular branch innervates the buccal area.
Sensory component has a large ganglion called the
Trigeminal or Gasserian ganglion which contains primary
nerve cell bodies for the sensory component of the nerve. |
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Term
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Definition
Motor for masticatory muscles:
– Mandibular branch
Sensory for different regions of the face:
– Mandibular branch
– Maxillary branch
– Ophthalmic branch |
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Term
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Definition
1) Palpebral reflex : Stimulate the medial canthus
(ophthalmic branch) and lateral canthus (maxillary branch) or skin over mandible (mandibular branch) and look for a blink in response (normal).
2) Stimulate nasal septal mucosa : use a cotton bud to touch the nasal mucosa on each side of the nasal septum (maxillary branch), and observe for symmetry of response (normal = symmetrical response). |
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Term
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Definition
abducens n
Nucleus is located in the dorsal medulla
(brainstem) |
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Term
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Definition
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Term
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Definition
Multiple specific nuclei are in medulla.
Innervation to the muscles and glands of the face: eyelids,lips, etc. Sensory fibres from tongue. |
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Term
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Definition
vestibulochoclear
- The vestibular portion consists of the vestibular nerve and the four vestibular nuclei in the brainstem (medulla).
- They are responsible for the normal posture and
coordination of the eyes, head, neck, trunk, and limbs.
- Vestibular information is projected to CN III, IV, and VI via the medial longitudinal fasciculus (MLF), and also to the cerebellum.
- The cochlear nerve travels together with the vestibular portion of CN VIII to the medulla.
- Vestibular receptors located in inner ear
*Sense head movement and changes in head position
- Information transmitted to vestibular nuclei in medulla and cerebellum |
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Term
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Definition
glossopharyngeal n
The glossopharyngeal nuclei in the ventrolateral aspect of the
medulla. Fibres run to pharynx and caudal tongue. |
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Term
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Definition
vagus n
Large nerve with multiple nuclei in medulla. Runs through
vagosympathetic trunk to heart, lungs, viscera |
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Term
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Definition
accessory n
Originates from ventral roots of cervical segments and enters
the skull through the foramen magnum before exiting
through a foramen. Muscles innervated support the neck
laterally along with the muscles innervated by C1-C4 |
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Term
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Definition
| Originates in hypoglossal nucleus in medulla. |
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Term
| optic nerve visual system |
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Definition
* Fibers from the medial (nasal) portion
of the retina decussate
* Fibers from the lateral(temporal) portion of the retina
stay on same side
*photoreceptors pick up signal --> APs generated by retinal ganglion (AP generated b/c chemical rxns between light and chemical)
*if you shine a light in the eye, you can map where in the retina the lesion is. or even further back in the optic n |
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Term
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Definition
# varies by species
proportion of crossover at chiasm:
HUMAN = 50%
CAT= 66%
DOG= 75%
HORSE, COW, SHEEP = 80-90% |
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Term
| Pupillary Light Reflex (PLR) |
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Definition
Direct PLR:
- Shine light into the eye and observe for pupillary constriction in same eye.
- Abnormal result is lack of constriction in response to the light.
- This also tests the oculomotor nerve, CN III.
Indirect (Consensual) PLR:
- Shine light into one eye, and observe the other
eye for pupillary constriction.
- Abnormal result is lack of constriction.
- This also tests the oculomotor nerve, CN III. |
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Term
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Definition
Pupillary light reflex (PLR)
-shine light in eyes. iris should dilate
Menace response
-cover one eye, add threat to other. animal should blink
Palpebral reflex
-touch eye and face in various places. animal should respond w/ blink / musc twitching
Palpebral closure
- brush finger across the palpebral
commissure. observe how tightly the animal is able to close its eye.
Oculocephalic reflex
-tests vestib syst. move head from side to side. should see normal nystagmus (coordinated eye movements)
Oculocardiac reflex
-pressure on the eyeballs results in a
decreased heart rate. |
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