Chapter 4: MOTOR PHYSIOLOGY

Question 1

Anterior to the central cortical sulcus

Answer 1

Brodmann Area 4 and 6

Question 2

Primarily involved with discrete voluntary movements

More than ½ is concerned with controlling muscles of the hands and speech

Answer 2

Primary Motor Cortex (Area 4)

Question 3

Nerve signals generated cause much more complex patterns of movement

Answer 3

Premotor Area (Area 6)

Question 4

Most important output pathway from the motor cortex

Answer 4

CORTICOSPINAL (PYRAMID) TRACT

Question 5

giant pyramidal cells that are only found in the motor cortex.

Answer 5

BETZ CELLS

Question 6

Cross at the lower brain stem and follows a course adjacent to the corticospinal tract

Answer 6

RUBROSPINAL TRACT

Question 7

Serves as an accessory route for transmission of relatively discrete signals from the motor cortex to the spinal cord

Answer 7

RUBROSPINAL TRACT

Question 8

communicates closely with the motor cortex through the corticorubral tract

Located: mesencephalon

Answer 8

RED NUCLEUS

Question 9

it has 2 types: Pontine reticulospinal tract & Medullary reticulospinal tract

Answer 9

RETICULOSPINAL TRACT

Question 10

excites the anti-gravity muscles of the body

Answer 10

PONTINE RETICULOSPINAL TRACT

Question 11

inhibits the anti-gravity muscles of the body

Answer 11

MEDULLARY RETICULOSPINAL TRACT

Question 12

Selectively control the excitatory signals to the different anti-gravity muscles to maintain equilibrium

Answer 12

VESTIBULOSPINAL TRACT

Question 13

Give rise to the nerve fibers that leave the cord by way of the anterior roots, and directly innervate the skeletal muscle fibers.

Answer 13

ANTERIOR MOTOR NEURONS

Question 14

It gives rise to large A alpha motor fibers.

It goes directly to the extrafusal muscle fibers

Answer 14

ALPHA MOTOR NEURONS

Question 15

It gives rise to A gamma motor fibers

It go directly to the intrafusal muscle fibers

Answer 15

GAMMA MOTOR NEURONS

Question 16

Signals from spinal nerves terminate first to the interneurons where they are processed and combine with the other signals from other tracts or nerves and converge in the anterior motor neurons

Answer 16

INTERNEURONS

Question 17

muscle is stretched suddenly, excitation of the spindles causes?

sudden muscle streched = ?

Answer 17

REFLEX CONTRACTION

sudden muscle streched = REFLEX CONTRACTION

Question 18

Lengthening the whole muscle stretches the mid portion of the spindle and, therefore, excites the receptor.

Answer 18

MUSCLE SPINDLE

Question 19

Even if the length of the entire muscle does not change, contraction of the end portions of the spindle’s in trafusal fibers stretches the midportion of the spindle and therefore excites the receptor.

Answer 19

MUSCLE SPINDLE

Question 20

helps control muscle tension. Specifically:

1. It provides a negative feedback mechanism that prevents the development of too much tension on the muscle.
2. Lengthening reaction: sudden reaction in the spinal cord that causes instantaneous relaxation of the entire muscle.
3. Equalize contractile forces of the separate muscle fibers.

Answer 20

GTO (GOLGI TENDON ORGANS)

Question 21

When a stretch reflex excites one muscle, it often simultaneously inhibits the antagonist muscles

Answer 21

RECIPROCAL INHIBITION

Question 22

Neuronal circuit that causes this reciprocal relation

Answer 22

RECIPROCAL INNERVENTION

Question 23

Simplest manifestation of muscle spindle function.

Answer 23

MUSCLE STRETCH REFLEX

Question 24

Any type of sensory stimulus from a limb is likely to cause the flexor muscles of the limb to contract, thereby withdrawing the limb from the object

Answer 24

Flexor Withdrawal Reflex

Question 25

Painful stimulus is applied to the hand; as a result, the flexor muscles of the upper arm become excited

Answer 25

Flexor Withdrawal Reflex

Painful stimulus applied –> flexor muscle excites –> flexor withdrawal

Question 26

Signals from sensory nerves cross to the opposite side of the cord to excite extensor muscles

Answer 26

Crossed Extensor Reflex

Question 27

After a stimulus elicits a flexor reflex in one limb, the opposite limb begins to extend

Answer 27

Crossed Extensor Reflex

Question 28

Tract that excites and inhibits the anti-gravity muscles of the body

Answer 28

RETICULOSPINAL TRACT

Question 29

Pressure on the foot pad causes the limb to extend against the pressure applied to the foot

Answer 29

Positive Supporting Reaction

Question 30

When laid on one side, it will make uncoordinated movements to try to raise itself to standing position

Answer 30

Cord “Righting” Reflexes

Question 31

Rhythmical stepping movements of one limb → flexion followed by extension
*
Reciprocal stepping of opposite limb → forward movement of one limb causes the other to move backwards
*
Diagonal stepping (mark time reflex

Answer 31

Stepping Reflexes

Question 32

Position sense → allows one to find the exact point of irritation
*
To-and fro scratching movement

Answer 32

Scratch Reflex