PH1124 - somatosensory and motor function Flashcards

1
Q

What is the role of a sensory pathway?

A

To conduct information about limb position and the sensations such as touch, temperature, pressure and pain.

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2
Q

What is the role of motor pathways?

A

Output from the spinal cord to the muscles ‘supervised’ by the descending brain pathways influenced by sensory inputs.

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3
Q

What is the role of the somatosensory pathways?

A

Process stimuli received from receptors within the skin muscles and joints.

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4
Q

What is the role of the viscerosensory pathways?

A

Process where stimuli received from the viscera (internal).

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5
Q

What is a neuron?

A
  • a nerve cell
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6
Q

What is a nerve fiber?

A

Refers to the axon and myelin sheath.

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7
Q

What is a nerve tract?

A

a bundle of nerve fibers in the central nervous system

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8
Q

What is a nerve?

A

One or more bundles of fibres that conveys impulses between the brain and spinal cord but also other parts of the body.

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9
Q

What are sensory receptors?

A

Nerve endings or specialised cells closely associated with nerve fibres.

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10
Q

what are the types of sensory receptors?

A
  • mechanoreceptors
  • chemoreceptors
  • thermoreceptors
  • photoreceptors
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11
Q

what is the mechanism from sensory receptor to the effector? (4)

A
  • sensory receptors responds to stimulus by producing a generator or receptor potential
  • sensory neuron (axon) conducts impulse from receptor to integrating centre
  • axon coducts impulses from integrating centre to effector (via motor neuron)
  • effector (muscle or gland) responds to motor nerve impulse
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12
Q

What are the 6 different receptors of the skin?

A
Free nerve endings.
Root hair plexus.
Tactile Merkel's disc.
Tactile Meissner's corpuscle.
Ruffini corpuscle.
Lamellated Pacinian corpuscle.
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13
Q

what are connected to Aβ fibres and what do they sense? (5)

A
  • sense touch, pressure and vibration
  • ruffini corpuscle
  • pacinian corpuscle
  • tactile meissner corpuscle
  • tactle merkel discs
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14
Q

what are connected to A fibres and what do they sense? (2)

A
  • sense movement of the hair follicle

- root hair plexus

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15
Q

what are connected to Aδ fibres and what do they sense? (2)

A
  • sense touch, pressure and pain

- free nerve endings

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16
Q

What is sensory transduction?

A

If a stimulus causes a change in a membrane potential high enough that it reaches the threshold and triggers an action potential,

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17
Q

How does the information from sensory receptors reach the brain?

A

Goes to the brain via ascending fibres primary than secondary afferent nerve fibres.

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18
Q

What is a dermatome?

A

an area of skin supplied by a single spinal nerve

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19
Q

What are proprioceptors?

A

Mechanoreceptors that detect the position or movement of a part of the body and help regulate movement.

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20
Q

What is a muscle spindle?

A

A type of proprioceptor parallel to the muscle that responds to a stretch and can cause contraction of the muscle.

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21
Q

How does the muscle spindle and golgi tendon organ work together?

A

The muscle spindle signals to contract if stretched and Golgi tendon organ responds to increases in muscle tension these signals act as a brake against excessive vigorous contraction by sending an impulse to the spinal cord where motor neurons are inhibited.

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22
Q

What is a somatic reflex?

A

Sensors detect external stimuli and sensory neurons sends an impulse to the spinal cord interneurons relay the information immediately back to the motor neurons which causes movement. It is an automatic involuntary consistent response.

23
Q

What is the reflex arc of the knee jerk stretch reflex?

A

It is initiated by the tapping of the tendon connected to the quad. Sensors detect sudden stretch in quad this information is conveyed to the spinal cord via sensory neuron the motor neurons then conveys a signal for the quad to contract jerking he leg forward.
The interneurons also in the spinal cord inhibit the motor neurons that supply the hamstring from contracting which would resist the action of the quad.

24
Q

What are the reflexes that infants have?

A

Grasp reflex then Babinski reflex and the rooting reflex.

25
Q

What is the grasp reflex?

A

Grasps any object that is placed in hands.

26
Q

What is the Babinski reflex?

A

stroke sole of the foot upward, toward the great toe

27
Q

What is the rooting reflex?

A

Brushing an infant’s cheek will cause the baby to turn in that direction and suck.

28
Q

Where is the motor cortex located?

A

Anterior to central sulcus located in the frontal lobe

29
Q

Where is the somatosensory cortex located?

A

Posterior to central sulcus in the parietal lobe.

30
Q

What is the function of the primary motor cortex?

A

allows conscious control of precise, skilled, voluntary movements

31
Q

What is the function of the primary somatosensory cortex?

A

Receives sensory input from the different sensory fields.

32
Q

What are the 2 afferent somatosensory pathways to the brain?

A

Dorsal column leminscal for fine touch, vibration and position and the spinothalamic for crude touch temperature and pain.

33
Q

There are 3 neurons that are involve in the somatosensory pathways to the brain where do they synapse and terminate?

A

The first synapses in the spinal cord the second synapses in the thalamus. The pathway crosses the midline in the medulla oblongata and terminates in the somatosensory cortex.

34
Q

What are the 2 motor pathways and where do they synapse and terminate?

A

Dorsolateral corticospinal tract which goes to the peripheries (toes) and the ventromedial corticospinal tract which goes to shoulder neck and trunk. 2 neurons which synapse in the spinal cord and terminate at the neuromuscular junction with muscle.

35
Q

What can the prmary motor cortex also do?

A
Controls movement in conjunction with other brain areas including:
Prefrontal cortex.
Premotor cortex.
Basal ganglia.
Cerebellum.
Supplementary motor cortex.
36
Q

What is the function of the prefrontal cortex?

A

Responds to light noises and other sensory signals. As well as calculating predictable out comes of actions and plans movement accordingly.

37
Q

Premotor cortex functions?

A

Active during preparation for movement and receives information about a target in space.
Integrate information about position and posture of the body and organises the direction of movement.

38
Q

What is the function of the supplementary motor cortex?

A

Is important for organising a rapid sequence of movements.

39
Q

What is the function of the posterior parietal cortex?

A

Contributes visual information.

40
Q

What is the role of the cerebellum?

A

It coordinates voluntary, motor movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity.

41
Q

What will damage to the cerebellum cause?

A

Issue with rapid movement and aim/timing.

Examples include clapping hands, speaking and writing as well as postural impairment and tremor.

42
Q

What is the cerebellar cortex?

A

outer layer of gray matter

43
Q

What are the 3 parts of the basal ganglia?

A

Putamen, Caudate nucleus and Globus pallidus.

44
Q

What is the role of the basal ganglia?

A

Function in control of voluntary movement.

45
Q

What is the role of the frontal lobe?

A

Decision making, planning, problem solving and thinking.

46
Q

What are the symptoms of brain tumour affecting the frontal lobe?

A

Personality change especially with increased aggression and apathy, difficulty planning or organising as well as difficulties in walking, speaking and a weakness on the side of the face or body.

47
Q

What is the role of the parietal lobe?

A

Perception and integration of sensory information like touch pressure and pain. A well as number representation and coordinating our movements in response to objects in the environment (near space and distant space).

48
Q

What are the symptoms of brain tumour affecting the parietal lobe?

A

Loss of sensation in part of the body normally on one side so will not respond to sound gesture or touch.

Difficulty speaking or understanding and problems with reading/writing.

49
Q

What is the role of the occipital lobe?

A

Primary visual area of the brain.

50
Q

What are the symptoms of brain tumours affecting the occipital lobe?

A

Blindness in one eye or both.

51
Q

What are the functions of the temporal lobe?

A

Recognition, perception, understanding language, emotional reactions, associated cognitive disorders.

52
Q

What ae the symptoms of brain tumours affecting the temporal lobe?

A

Fits.
Short term memory problems.
Inability to recall words.

53
Q

What is the function of the cerebellum?

A

Coordination of voluntary movement, balance, reflex memory, timing, posture and sequence learning

54
Q

What are the symptoms of brain tumours affecting the cerebellum?

A

Problems with balance and coordination, intention tremor, abnormal eye movements and dizziness, as well as problems with coordination of limbs.