Cranial nerves 2 Flashcards
Vestibular branch route
Semicircular canals, the saccule + utricle of inner ear -> vestibular ganglion -> vestibular nuclei in pons + medulla
CNVIII
Vestibulocochlear Nerve
sensory nerve
2 branches
Vestibular branch (carries impulses for equilibrium) and cochlear branch (Carries impulse for hearing)
Cochlear branch
Spiral organ (organ of corti) -> spiral ganglion -> auditory meatus -> medulla -> thalamus (medial genuculate nuclei, inferior colliculus midbrain) -> primary auditory area (41, 42)
Injury to vestibular branch
Vertigo - a subjective feeling that one’s own body or the environment is rotating
Ataxia - muscular incoordination
Nystagmus - involuntary rapid movement of the eyeball
Injury to cochlear branch
tinnitus - ringing in ears
Deafness
CN IX
Glossopharyngeal nerve
sensory, motor and autonomic
CN IX sensory
- Taste buds on posterior 1/3 of tongue
- Proprioceptors from some swallowing mm
- baroreceptors in carotid sinus that monitor BP
- Chemoreceptors
- External ear to convey touch, pain, heat and cold
- > superior and inferior ganglia -> jugular foramen -> medulla
CN IX motor
nuclei in medulla ->jugular foramen -> stylopharyngeus mm
CN IX Autonomic
inferior salivary nucleus in medulla ->otic ganglion -> parotid gland (facial nerve goes through but Glossopharyngeal innervates it)
Injury to CN IX
Dysphagia -difficult to swallow Aptyalia - no saliva Loss of sensation in throat Ageusia - no taste Glossopharyngeal neuralgia - posterior pharynx, tonsils, back of tongue, middle ear, can be triggered by chewing, swallowing, talking, sneezing, touching the tonsils an applicator
CN X
Vagus nerve
Autonomic
Motor and sensory
CN X sensory
Skin of external ear
a few taste buds in epiglottis and pharynx
proprioceptors in mm of neck and throat
baroreceptors and chemoreceptors
mainly from visceral sensory receptors in most organs of Thoracic and abdominal cavities that convey sensations (ie hunger, fullness, discomfort)
-> superior + inferior ganglia -> jugular foramen ->medulla
CNX motor
axons from medulla to jugular foremen -> pharynx, larynx, soft palate (swallowing, vocalization, coughing)
CNX autonomic
axons of autonomic motor neurons start in medulla and supply the lung, heart (cardiac), glands of the GI tract, smooth mm of respiratory passageways, esophagus, stomach, gallbladder, small intestine, most of large intestine
injury to CNX
vagal paralysis
dysphagia
tachycardia
CN XI
accessory nerve
motor nerve
CNXI motor
motor axons from anterior grey horn of first 5 segments of c/spine (C1-C5) -> Ascend through foramen magnum -> exit through jugular foramen -> SCM + trapezium
CN XI injury
Paralysis to SCM + Trapezius
CNXII
Hypoglossal nerve (motor)
CN XII motor
hypoglossal nucleus ->hypoglossal canal -> mm of tongue
Injury to CN XII
difficulty chewing
dysarthria (slur speech)
dysphagia (swallow)
the tongue, when protruded, curls toward the affected side and that side atrophies
Development of the nervous system
- begins in the 3rd week of gestation
- starts with a thickening of the ectoderm called the neural plate
- neural plate folds inward + forms a longitudinal groove, called the neural groove
- raised edges of neural plate are called neural folds
- as the whole thing grows it forms a tube (neural tube)
layers of walls of neural tube
- outer/marginal layer cells = white matter of nervous system
- middle/mantle layer cells = gray matter
- inner/ependymal layer cells = lining of central canal (spinal cord) and ventricles of brain
what is the mass of tissue between the neural tube and skin ectoderm?
Neural crest becomes posterior (dorsal) root ganglia of spinal nerves
- spinal nerves
- ganglia of cranial nerves
- cranial nerves
- ganglia of autonomic nervous system
- adrenal medulla
- meninges
