Wk 11.1 Motor and Somatosensory

Question 1

What are motor and someatosensory systems?

Answer 1

-Motor systems are descending pathways.
-Comes from the brain and travels downwards to the muscles

-Somatosensory takes sensory like touch or temperature receptors & sends to the cortex by ascending pathways

Question 2

Information on motor reflexes?

Answer 2

-Motor reflex is independent no help from the CNS

• It is couples a sensory input to motor output

-Involuntary, but CNS inputs can influence the way it works

Question 3

What are motor reflexes important for?

Answer 3

-Important for:
Fine control of muscle tension,

Protective (eg., nocioceptive
withdrawal)

Prevent overstretch of muscle- motor reflex to detect can help protect muscles

Balance and maintenance of posture (allpart of ‘position sense’) (Vestibular)

Question 4

What are the two types of motor reflexes and their information about them?

Answer 4

-Muscle spindle and Inverse myotactic

-Muscle spindle is couple simply
*Monosynaptic (one sensory neuron to one motor neuron)
*Regulate muscle length by –ve feedback
*Length detected by muscle spindle- crucial for proprioception

Inverse myotactic
* dysynaptic ( connection 2 neurons in the pathway)
*activated when muscle becomes over-tensioned- *automatically inhibits α-motorneurone
*tension detected by Golgi Tendon Organ

Question 5

What test can be used to test reflexes?

Answer 5

Reflex hammer to knee
Apply stretch by hitting the tendon causing the tendon to be elongated and the muscle are pulled

Question 6

1. What does muscle spinde meausure?
2. What are e.g of afferent intrsfusal sensory neurones?

Answer 6

1. Length and rate of change of muslce fibres

2.Ia- monitor rapid (phasic) muscle contraction
*II static- maintaining muscle tension

Question 7

What the function of the cerebellar?

Answer 7

‐ Balancing responses to environment

‐ Adjusting performance to feedback from evolving movement

‐ Organizing complex movement patterns

‐ Automatic and other ‘housekeeping’ functions (eg, regulation of posture and balance, eye movements, etc)

‐ Predictable neurological responses to dysfunction of cerebellum and /or associated pathways…?

Question 8

What is the Pontocerebellum and Spino/vestibulocerebellum role?

Answer 8

-Pontocerebellum –Planning and ongoingControl of movement

-Spino/vestibulocerebellum –Control of balance and eye movements, etc

Question 9

What is the cortical control of the movement functions?

Answer 9

*Primary (M1) main outputs to spinal motor systems for generating voluntary movements.

• SMA associated with internal planning of movements, especially complex sequences
• PMA associated with movements guided by sensory cues (eg vision, touch and hearing

Question 10

How doe sthe corticospinal pathway work ?

Answer 10

• Arises from the motor cortex, SMA,Premotor area
• Descends laterally and medially
• Projects to contralateral lower-MNs and spinal interneurones
• Newly learnt and ‘automatic’ movements -Lateral: limbs and hands- Anterior: trunk, shoulders and neck

*Direct corticomotoneuronal projections to distal hand muscles (single projection fromcortex)

• Corticobulbar fibres also descend here, but serve cranial nerve nuclei.
• Damage causes serious voluntary motor deficits