Mkgrady8 Neuro 1 Intro To Long Tracts Of The Cns

Front 1

what are the 2 major afferent tracts and what info do they send

Back 1

afferent aka ascending aka sensory; dorsal columns= discriminatory touch, vibration, and proprioception (position sense); anterolater or spinothalamic (spine to thalamus)= pain and temp and crude touch

Front 2

what is the major efferent tract and what does it send

Back 2

efferent aka descending aka motor; corticospinal (cortex to spine)= fine voluntary motor control

Front 3

talk me through the path of vibration picked up in the finger

Back 3

pseudounipolar nerve picks it up --> dorsal root --> dorsal root ganglion where its cell body is (fasiculus cuneatus b/c finger) --> ascends to nucleus cuneatus (1st synaptic contact) at level of the CAUDAL MEDULLA and crosses to other side of the medulla HERE (KEEP IN MIND THIS LOCATION FOR IF THERE IS AN INJURY) --> ascends in medial lemniscus --> synaptic contact at thalamus (ventral posterior lateral nucleus) --> 3rd order neuron goes to correct area of cerebrum on post central gyrus (the primary somatosensory cortex)

Front 4

talk me through the path of pain picked up in the finger

Back 4

picked up by a pseudounipolar neuron --> dorsal root --> synapses in the dorsal horn then immediately crosses over to the contralateral side of the spinal cord --> spinothalamic tract in anterolateral pathway that ascends the neural axis (spine) all the way up to the thalamus where it synapses on the ventral posterior lateral nucleus of the thalamus --> 3rd order neuron goes to post central gyrus (primary somatosensory cortex)

Front 5

talk me through the path of a signal to move a muscle

Back 5

cell body in precentral gyrus sends an signal down an axon in the corona radiata (white matter) through the posterior limb of the internal capsule through the middle portion of the cerebral peduncle then through the basis pontis then through the pyramids (medulla) then across the pyramidal decussation (so crosses to contralateral side at the level of the medulla at CERVICOMEDULLARY JUNCTION aka foramen magnum (slightly inferior to the caudal medulla crossing)) then down the spinal cord in the lateral corticospinal tract and leaves the spinal cord at the correct level

Front 6

summary: white matter is what and grey matter is what

Back 6

white matter= axons/dendrites of nerve cells; grey matter= cell bodies/somas of nerve cells

Front 7

summary: descending corticospinal (CST) tracts cross to the contralateral side at

Back 7

the caudal medulla (responsible for voluntary movement)

Front 8

summary: ascending anterolateral tracts cross

Back 8

when they enter the spinal cord to the opposite side of the body; responsible for pain, temp, and crude touch sensations

Front 9

summary: ascending dorsal columns cross

Back 9

just rostral to the CST in the caudal medulla; responsible for proprioception, vibration, and discriminative tough

Front 10

summary: at the level of the caudal medulla what is crossed

Back 10

everything is crossed

Front 11

summary: in order to ID the site of the lesion you will rely on what

Back 11

CN nerve deficits which is why you have to know the CNs very well

Front 12

summary: to ID medulla on cross section what do you look for

Back 12

inferior olivary nucleus (squiggles)

Front 13

summary: to ID pons on cross section what do you look for

Back 13

huge pontine fibers and nuclei and descending CST

Front 14

summary: to ID midbrain on cross section what do you look for

Back 14

cerebral aqueduct and red nucleus