Ch. 11 - Somatosensation (FINAL)

Question 1

neuromuscular junctions: motor neurons layer

Answer 1

layer 4 CARRIES effector message to muscles

• high ACh: depolarization of muscle cells

Question 2

spinal cord: sections

Answer 2

1. cervical
   - head, neck, arms, hands.
   - C1/C2 sever: quadraplegia
2. thoracic (torso)
3. lumbar (hips and legs)
4. sacral (legs and feet)
5. coccygeal (tailbone)

Question 3

corticospinal tracts (2)

Answer 3

lateral: right side
anterior: body midline

Question 4

forebrain: basal ganglia and syndromes

Answer 4

LASHEY, 1950s.
force of movement
deep in white matter
made up of the striatum and globus pallidus
hyperkinetic syndrome: excessive/unwanted movement or dyskenesia
hypokinetic syndrome: insufficient movement or bradykinesia

Question 5

motor sequence : 3 steps

Answer 5

1. prefrontal cortex (what goal to select… grab? poke?)
2. pre-motor cortex
3. primary motor cortex/M1 (executes skilled movement)

Question 6

cerebellum: motor coordination

Answer 6

purkinje cells in hindbrain
timing and accuracy of movement
has correctional power over actions

Question 7

brainstem: motor organization

Answer 7

adaptive movements
species-typical (all members of a species have it)

Question 8

M1 organization (scientists)

Answer 8

Fritsch and Hitzig, 1870s
- discovery: M1 is contralateral
- performed neocortex stimulation of dogs on opposite sides

Penfield, 1930s
- discovery: homunculus and electrical mapping
- confirmed significance of M1 through electrical stimulation
- Graziano, 2009: same experiment but longer stimulation period

Nudo et al., 1996
- discovery: effectiveness of constraint induced therapy

Question 9

voluntary motor output: pathway

Answer 9

1. M1 layer 5
2. a) lateral corticospinal tract: contralateral
3. b) anterior horn on lateral neuron
4. c) limbs and digit control
5. a) anterior corticospinal tract: ipsilateral
6. b) anterior horn on medial neurons
7. c) trunk control

Question 10

somatosensation: skin types

Answer 10

hairy skin: dendrites are wrapped around hair follicles
glabrous skin: smooth, highly sensitive

Question 11

somatosensation: receptor types

Answer 11

nociception: irritation or damage, ligand gated channels to communicate chemical message, pain/itch/temperature

hapsis: pressure, touch, mechanical ion channels

propriception: muscle and joint movement, spatial awareness of body, location of limbs

Question 12

transduction (action potentials) somatosensory pathway

Answer 12

1. stimulus
   ** depolarization
2. posterior root ganglion
   ** action potentials
3. neurotransmitters at synapse
4. medulla
5. thalamus
6. S1

Question 13

vestibular system (ears)

Answer 13

semicircular canals: head rotation
otolith organs: tilt and gravitational orientation
- utricle and saccule

Question 14

semicircular canals

Answer 14

anterior duct: nodding
lateral duct: head shake
posterior duct: head tilt