Cranial and Spinal Nerves Flashcards
1
Q
Cranial nerves
A
- 12 paired nerves primarily serve the head neck except vagus nerve
- vagus nerve extends to thoracic and abdominal cavities
- some are primarily motor in composition, some are primarily sensory, and some include both
2
Q
Olfactory nerve (I)
A
- nerve fibres running from olfactory cavity to olfactory bulbs (fibres run through ethmoid bone)
- broken noses can result in a loss of smell
- olfactory bulb narrows into the olfactory tract
3
Q
Optic nerve (II)
A
-fibres originate in receptors of the retina (passing through the optic canal of the orbit)
-optic nerves converge to form optic chiasma
-fibres partially cross over
(damage past this point results in loss of the opposite side of the visual field)
-optic tracts enter the thalamus (from thalamus, messages passed to the visual cortex
4
Q
Vagus nerve (X)
A
- “wanderer”
- most motor fibres are part of the parasympathetic division (regulate thoracic, abdominal organ activity)
- sensory impulses from the thoracic and abdominal regions (includes fibres from BP receptor, peripheral chemoreceptors near the aorta)
- and some sensory impulses from the neck region (taste buds on epiglottis, stretch receptors from larynx and pharynx)
5
Q
Spinal nerves
A
- all mixed in function
- 31 paired nerves: (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal, named after the region of the cord they arise)
- dorsal root: sensory fibres entering the CNS
- ventral root: motor fibres exiting the CNS
- dorsal and ventral root join into spinal nerve before leaving the vertebral canal
6
Q
Spinal nerve and plexuses
A
- after exiting the vertebral canal, spinal nerves split into branches (dorsal and ventral rami)
- fibres from different nerves may join up in plexuses
- plexus branches contain fibres from several spinal nerves
- fibres from each nerve travel through the periphery in a number of ways
- creates redundancy in muscle control, allowing muscles to be functional even if one nerve is damaged
