Postural Control & Locomotion pp

Question 1

Ventromedial P/W’s

Answer 1

Both lateral vestibulospinal tract & reticulospinal tract
extend length of spinal cord. Facilitate motor neurons of extensor muscle.
Extensor drive cause of decerebrate posturing

Question 2

Medial Vestibulospinal Tract

Answer 2

Only descends as far as upper thoracic cord

FX: is mediation of reflex head movements in response to vestibular stimuli.

Question 3

Reticulospinal System

Answer 3

Role in anticipatory postural adjustmants to prepare cortical controlled movements
Activating locomotion & controlling its speed

Question 4

Colliculospinal Tract

Answer 4

aka TECTOSPINAL Tract
Origin in superior colliculus & projects to the cervical S.C.
Major output to S.C via reticular formation

Question 5

Posture

Answer 5

Overall position of the body & limbs relative to each other & orientation of body & limbs in space

Question 6

FX of Postural Adjustments

Answer 6

Support head & body against gravity & external forces
Keep center of gravity & balance over base of support

Question 7

Sensory influences on postural control

Answer 7

Vision
Vestibular
Somatosensation

Question 8

Visual Kinesthesis

Answer 8

Dependent on internal sensors & external stimuli

Normal sway but increases in swinging room

Question 9

Feeling of visual kinesthesis

Answer 9

Compelling feeling of body movement when large part of a persons visual field is moving
ex. IMAX

Question 10

Vection

Answer 10

Is the perception of self motion induce by visual stimuli

Vestibular system is to suppress the sense of self generated movement

Question 11

Postural Reflexes

Answer 11

Head position
Visual input
Vestibular input via vestibulocollic
Neck reflexes acting on muscles
Proprioceptive input from neck muscle spindles

Question 12

Decerebrate posture problem

Answer 12

Upper pontine damage

Question 13

Decorticate postures problem

Answer 13

Upper midbrain damage

Question 14

Decerebrate posturing

Answer 14

Lesions caudal to red nucleus but rostral to the lateral vestibular nucleus.
Patient extensions of both arms & legs w/ arching of back & dorsiflexion of head & feet plantar flexed

Question 15

Decorticate rigidity

Answer 15

Lesion is in a supratentorial, causes central herniation the patient will switch to decerebrate posturing

Question 16

Postural Stability in Humans

Answer 16

Maintained by continuously monitoring posture & making appropriate adjustment
Increasing or decreasing the strength of reflexes

Question 17

Control of locomotion

Answer 17

Spinal cord contains stepping pattern generators for each limb
Oscillatory - alternating flexion & extension during locomotion

Question 18

Gamma Rigidity

Answer 18

gMN are excited enough will cause contraction of intrafusal fibers which stimulates 1a afferents from the muscle spindle loop to aMN cause contraction of muscle

Question 19

Decerebrate rigidity

Answer 19

Through gamma loop
Posterior roots cut loses its hypertonus
Interferes w/ 1a activates extensor aMN

Question 20

Dorsal Rhizotomy

Answer 20

Child w/ cerebral palsy
Excessive spasticity in his legs, can be decreased by cutting some rootlets
Decreasing effect of gamma loop