Chapter 11 - Motor Functioning

Question 1

main components of motor system

Answer 1

1. forebrain: responsible for initiating movement
2. brainstem: responsible for species-typical movement
3. spinal cord: responsible for executing movement

Question 2

brain regions assisting the motor system

Answer 2

• basal ganglia: in the forebrain, helps produce the appropriate amount of force
• cerebellum: in the brainstem, regulates timing and accuracy

Question 3

prefrontal cortex (PFC)

Answer 3

responsible for planning our behavior and setting our goals (e.g. deciding to return a book to the library)
- does not specify the precise movements to be made, just sets the goal
- sends instructions to the premotor cortex

Question 4

premotor cortex

Answer 4

responsible for organizing movement sequences and ensuring that the required body parts are coordinated (e.g. gripping the bike handlebar while pedalling)
- elicits whole body movements

Question 5

primary motor cortex (M1)

Answer 5

produces specific movements and executes the action

Question 6

brainstem

Answer 6

responsible for species-typical movements
- also important for standing upright, coordinating movements of the limbs, walking, swimming, etc.
- damage to the brainstem leads to locked-in syndrome and also cerebral palsy (CP)

Question 7

locked-in syndrome

Answer 7

the patient is conscious and awake but cannot move and communicate verbally because all voluntary muscles are paralyzed (except the eyes)

Question 8

spinal cord

Answer 8

the connection between the brain and the body
- contains complex motor programs based on reflexes: scratch reflex, knee-bending reflex, and walking reflex
- when the connection between the brain and the spinal cord is severed, spontaneous movements are still possible, but they are no longer guided and timed by the brain

Question 9

cut to cervical region of the spinal cord

Answer 9

causes paralysis and loss of sensation in the arms and legs
- called quadriplegia

Question 10

cut below the cervical region in the spinal cord

Answer 10

causes paralysis and loss of sensation in the legs and lower body
- called paraplegia

Question 11

movements spatially coded in a somatotropic arrangement

Answer 11

different parts of the motor cotex (M1) are responsible for the specific movements of different body parts (based on 2 principles)
- the relative sizes of body parts are disproportionate
- body parts are discontinuous

Question 12

disproportionate sizes of body parts

Answer 12

the M1 areas responsible for movement in the hands, fingers, lips, and tongues, are larger compared to M1 areas responsible for movement in other body parts
- the larger areas allow for more precise movement regulation
Penfield’s homunculus

Question 13

discontinuous body parts

Answer 13

the areas in M1 (and S1) are arranged differently from those of our body (e.g. the “hand” area in M1 lies above the “face” area)

Question 14

constraint-induced therapy

Answer 14

uses neural plasticity to treat stroke-induced paralysis

Question 15

motility is efferent

Answer 15

information goes from the brain (cortex) to the body (muscles)

Question 16

corticospinal tracts

Answer 16

the most important motor pathways (one on each side)
- originates in layer V of the motor cortex, continues to the ventral/anterior surface of the brainstem where it forms bumps or “pyramids” on both sides, and ends in the anterior horn of the spinal cord
- in the brainstem, some axons of the corticospinal tract cross to the contralateral side, while others remain on the same side

Question 17

neuromuscular junction

Answer 17

the efferent connection between motor neurons and muscle fibers
- main neurotransmitter is acetylcholine (released by motor neurons and attaches to specialized areas on muscles called end plates)

Question 18

basal ganglia

Answer 18

a collection of nuclei just beneath the cortex
- modulates the activity of cortical motor systems
- includes the caudate nucleus, putamen, globus pallidus, nucleus accumbens, subthalamic nucleus, and substantia nigra
- dopamine is the main neurotransmitter

Question 19

globus pallidus

Answer 19

• if it is excited, it inhibits the thalamus and blocks movement
• if it is inhibited, motor cortex circuits that include the thalamus can produce movement

Question 20

2 types of symptoms from damage to the basal ganglia

Answer 20

• hypokinetic symptoms
• hyperkinetic symptoms

Question 21

hypokinetic symptoms

Answer 21

(too little force)
- paucity of movement (rigidity) is involved in Parkinson’s disease, which is caused by a deficiency of dopamine in the substantia nigra, which makes it difficult to initiate movements

Question 22

hyperkinetic symptoms

Answer 22

(too much force)
- excessive involuntary movements are involved in Huntington’s disease
- here cells of the putamen and caudate nucleus are damaged, causing sudden and exaggerated movements
- tourette syndrome, which involves excessive involuntary movements, is another disorder that is linked to damage to the putamen and caudate nucleus

Question 23

cerebellum

Answer 23

allows us to get to know movements and remember how to perform them
- can be divided into 3 areas (the base, medial part, and lateral parts)
- contributes to the timing and accurate execution of movements
- if the cerebellum is damaged, the ability to correct errors by comparing the intended and actual movement is reduced

Question 24

the base of the cerebellum (flocculus)

Answer 24

controls eye movements and balance, in cooperation with the vestibular system in the middle ear

Question 25

medial part of the cerebellum

Answer 25

support movements in the face and trunk

Question 26

lateral parts of the cerebellum

Answer 26

support movements of the limbs, hands, feet, and digits

Question 27

somatosensory system

Answer 27

ensures that we feel everything, from pain to movement of the joints

Question 28

2 types of skin

Answer 28

• hairy skin (e.g. arms, legs, back)
• glabrous skin (e.g. tongue, lips, hand palms); most sensitive

Question 29

somato sensory receptors

Answer 29

classified into 3 groups
- nociception (irritation)
- hapsis (pressure)
- proprioception (body awareness)

Question 30

nociception

Answer 30

the perception of pain, temperature, and itch
- when the nerve endings are irritated or damaged, a chemical is released, causing an action potential

Question 31

hapsis

Answer 31

the ability to distinguish objects by touch
- this is the perception of light touch or pressure

Question 32

proprioception

Answer 32

the perception of body location and movement
- the nerve endings are sensitive to muscle extension and the movement of joints

Question 33

rapidly adapting receptors

Answer 33

activate neurons when stimulation starts and when it ends

Question 34

slowly adapting receptors

Answer 34

activate neurons if a sensory event is present, they detect if an event is still ongoing

Question 35

projection from the somatosensory system to the cortex

Answer 35

takes place via the thalamus
- when the axons of somatosensory neurons enter the CNS, they split, forming 2 pathways

Question 36

posterior spinothalamic tract

Answer 36

formed by haptic and proprioceptive axons which lie in the posterior part of the spinal cord
- carries fine touch and pressure fibres

Question 37

anterior/ventral spinothalamic tract

Answer 37

formed by the nociceptive axons transmitting their information to the neurons in the grey matter on the dorsal side of the spine, from where the axons of these neurons cross to the contralateral ventral side of the spinal cord

Question 38

monosynaptic reflex

Answer 38

is a reflex caused by a direct connection between a sensory and motor neuron (knee-jerk reflex)
- cortex is not involved
- fast reflex (approximately 30 ms)
- function is mainly protective

Question 39

pain gating theory

Answer 39

tries to find an explanation for the phenomenon that you can reduce acute pain by rubbing the sore spot
- haptic and proprioceptive fibres and nociceptive fibres synapse with the same interneuron having opposite effects (stimulation vs inhibition)

Question 40

referred pain

Answer 40

occurs when pain that arises from an internal organ (e.g. the heart) is felt on the body surface (e.g. the left shoulder)
- happens because internal organs and body surface receptors share the same pathway to the cortex

Question 41

organ of balance

Answer 41

in the inner ear, near the cochlea
- consists of 2 groups of receptors: semi-circular canals and otolith organs

Question 42

semi-circular canals

Answer 42

• one for each direction
• each canal is filled with fluid (endolymph) and contains hair cells
• movement of the head makes the cilia on the hair cells move, which leads to action potentials

Question 43

otolith organs

Answer 43

• consist of utricle and saccule
• these receptors detect gravity (tilt) and linear acceleration
• utricle and saccule also contain hair cells, but in a jelly-like substance (otoconia), which bends when the head moves up or down, which in turn causes action potentials

Question 44

2 main areas of the somatosensory cortex

Answer 44

• primary somatosensory cortex
• secondary somatosensory cortex

Question 45

primary somatosensory cortex

Answer 45

receives sensory information from the body through the thalamus (sensory relay station)

Question 46

secondary somatosensory cortex

Answer 46

receives sensory information from the primary somatosensory cortex and from the visual and auditory cortexes