sensory information (dickinson 1-3) Flashcards
(23 cards)
two pathways for sensory information to travel
spinal cord/brainstem - reflex arc
ascending pathways to the cerebrum/cerebellum
which modalities travel via the DCML pathway
touch/pressure
pain (pinprick)
temperature
conscious proprioception (TL only)
travels to cerebrum
which modalities travel via the ascending reticular formation
visceral pain
travels to cerebrum and cerebellum
which modalities travel via spinocerebellar tracts
proprioception
- muscle spindles
- golgi tendon organs
travels primarily to cerebellum but some info. gets sent to cerebrum
stimulus intensity
summation
- temporal
- spatial
adaptation
tonic: on all of the time, adapt slowly
phasic: detect changes, adapt quickly
most voluntary movement stimulates which type of efferent motor neuron
gamma
alpha motor neuron
stimulates contraction of extrafusal muscle fibers
gamma motor neuron
stimulates contraction of the ends of intrafusal muscle fibers (muscle spindles)
1a afferent
muscle spindle receptor neuron
annulospiral receptor
- detects stretch of the muscle spindle
(stretch due to extrafusal stretch or due to gamma neuron firing)
reflex arc stimulates the alpha motor neuron causes muscle contraction, lessens stretch
sends info. to brain
describe the DCML pathway
N1: pseudounipolar neuron senses stimulus and travels to the medulla without decussating
N2: cuneate nucleus (TL) or gracile nucleus (PL) begins on the ipsilateral side and decussates before travelling to the thalamus
N3: cell body in thalamus to the cerebrum
- somatotopic organization
describe the spinomedullothalamic pathway
conscious proprioception in pelvic limb
N1: pseudounipolar neuron that synapses in dorsal horn of spinal cord
N2: dorsal horn of spinal cord to ipsilateral medulla
N3: decussates from ipsilateral medulla to contralateral thalamus
N4: thalamus to cerebrun
describe the spinocervicothalamic pathway
carnivores only
N1: pseudounipolar neuron that synapses in the dorsal horn of spinal cord
N2: decussates at the level of the cervical vertebrae and travels to the contralateral ventrocaudolateral nucleus of the thalamus
N3: thalamus to the cerebrum
what does a tendon tap test
transient stretch of the muscle
- tests the reflex pathway beginning with muscle spindles
muscle spindles allow for…
- smooth muscle control
- stabilization of movement and posture
- feedback sets muscle tone
RAS
reticular activating system
diffuse throughout the brainstem
maintains cerebral awareness (mentation)
RAS function
- modulates muscle tone and stretch reflexes
- influences motor activity
- modulates vital reflexes and visceral pain sensation
sensory nucleus of trigeminal
runs entire length of brainstem
primary afferents
- enter nucleus via trigeminal ganglion
secondary afferents
- decussate and ascend the trigeminothalamic pathway
tertiary afferents
- relays info to the cortex
nucleus of the solitary tract
taste afferents (7, 9, 10)
secondary neuron
- thalamus some contralateral but mainly ipsilateral
tertiary neuron
- thalamus to the cortex
corneal reflex
CN 5 …
sensory nucleus …
motor nucleus of CN 7 (2 synapses) …
facial nerve …
blink
salivary reflex
CN 9 …
nucleus of solitary tract …
parasympathetic nucleus of CN 9 …
otic ganglion …
CN 9 …
salivation
gag reflex
CN 9 CN10 …
nucleus of solitary tract …
nucleus ambiguous (2 synapses) …
CN 9 CN 10 …
gag
3 things that indicate a central lesion rather than a peripheral lesion
- change in mentation
- long tract signs
- multiple CNs affected
