Exercise Phys 9: Balance and movement

Question 1

What does COG stand for and what is it?

Answer 1

Centre of gravity

The point of which mass is evenly distributed

Question 2

What is the line of gravity?

Answer 2

Vertical line which falls through the centre of gravity and the centre of support

Question 3

Sensory systems responsible for postural control?

Answer 3

Somatosensory
- information concerning relative position of body parts to support surface of eachother

Vestibular
- info dealing with gravitational, linear and angular accelerations of the head with respect to inertial space

Vision
- measures orientation of eyes and head in relation to surrounding objects

Question 4

Describe the function of the somatosensory system and what stimuli are involved

Answer 4

Detects touch, pain, pressure, temperature + experiences related to proprioception (muscle movement, joint position)

Moderates balance, proprioception

Question 5

What and where are proprioceptors in the human body?

Answer 5

Proprioceptors in

• skeletal striated muscles (muscle spindles)
• tendons (golgi tendon organs)
• fibrous capsules in joints

Question 6

Describe the leminiscal pathway (dorsal column) -> ascending/descending?

Answer 6

Proprioceptors -> (first order) afferent neuron
-> Dorsal root ganglion -> synapse at dorsal column nuclei

• > (second order) neuron - decussation of medial leminiscus - -> synapse at thalamus
• > (third order) neuron -> primary somatosensory cortex

Ascending pathway

Question 7

Role of the spino cerebellar tract in proprioception + movement? Pathway? Ascending or descending?

Answer 7

Proprioceptive input from joints, muscles, tendon etc.

Primary (afferent) neuron -> Spinal cord -> medulla oblongata -> (synapse)
-> secondary neuron -> pons -> cerebellum

Cerebellum used in learning -> important for muscle memory + learning of movements

Ascending pathway

Question 8

Role of the lateral corticol spinal tract? Controlled by what? ascending or descending?

Answer 8

Responsible for voltuntary movement -> speed/agility

• controlled by cortex

Descending pathway

Question 9

Role of the rubro-spinal tract? Controlled by what? ascending or descending?

Answer 9

Responsible for large muscle movement as well as fine muscle control
-> most likely upper limb control due to its termination in the cervical spinalcord

Controlled by midbrain

Descending pathway

Question 10

Role of the tecto-spinal tract?

Answer 10

coordination of head and eye movements

Question 11

Role of the reticulo-spinal tract?

Answer 11

automatic posture and gait related movements

Question 12

Parts of the vestibular system?

Answer 12

(3 canals)
Anterior verticle canal
horizontal canal
posterior verticle canal

(otolith organs)
Utricle
Saccule

cochlea

Question 13

vestibular organs responsible

head rotation? horizontal acceleration? verticle acceleration?

Answer 13

Rotation = semicircular canal;s

Linear acceleration
Horizontal = utricle
Verticle = saccule

Question 14

How do semicircular canals sense rotation?

Answer 14

inertia of Endolymph liquid produces a force across the cupula

• > displacement in opposite direction of movement
• > detection

Question 15

3 major vestibular reflexes?

Answer 15

Vestibulo-occular reflex
- keep eyes still in space when head moves

vestibulo-collic reflex
- keeps head still in space/level plane during walking(acts on neck muscles)

vestibulo-spinal reflex
- adjusts posture for rapid changes in position

Question 16

3 major vestibular reflexes?

Answer 16

Vestibulo-occular reflex
- keep eyes still in space when head moves by moving eyes opposite direction to head movement

vestibulo-collic reflex
- keeps head still in space/level plane during walking(acts on neck muscles)

vestibulo-spinal reflex
- adjusts posture for rapid changes in position