Lecture 6 - Motor and Sensory Function

Question 1

Somatic Nervous system

Answer 1

• The somatic nervous system innervates the skeletal muscle (voluntary muscle)
• Somatic efferent nerve firing excites muscle activity
• Composed of somatic parts of the CNS and PNS

Question 2

Autonomic nervous system

Answer 2

• The autonomic nervous system innervates smooth muscle (involuntary) in the intestines, sweat, and salivary glands, myocardium and some endocrine glands
• Functions as a unit to maintain constancy in the internal environment

Question 3

Somatic sensory system

Answer 3

transmits sensations of touch, pain, temperature, and position from sensory receptors

Question 4

Somatic motor system

Answer 4

Innervates only skeletal muscle, stimulating voluntary and reflexive movement by causing the muscle to contract, as occurs in response to touching a hot flame

Question 5

Peripheral nerves

Answer 5

• A unique type of inert tissue in that they are not contractile tissue, but they are necessary for the normal functioning of voluntary muscle
• Can be sensory, motor, or mixed

Question 6

What is muscular weakness

Answer 6

Lack of muscle strength as a result of morphological factors, physiological, metabolic factors, or a lesion or disease of the muscle, its tendons, or the bony insertion

Question 7

What are the morphological factors of muscle weakness

Answer 7

• muscle cross-sectional area
• arrangement of muscle fibres
• fibre-type distribution
• fascicle length
• tendon stiffness

Question 8

What are ways to test muscle strength

Answer 8

• Single rep max
• MMT
• Hand help dynamometers
• Modified sphygmomanometer

Question 9

Motor impairment

Answer 9

Muscle weakness, if elicited, may be caused by:
- Upper motor neuron lesion
- A nerve root lesion
- Injury to a peripheral nerve
- Pathology at the neuromuscular junction

Question 10

Myotomes

Answer 10

• groups of muscles that are predominantly supplied by a single nerve root
• A lesion of a single nerve root is usually associated with paresis of the myotome

Question 11

Testing myotomes

Answer 11

• examiner should place the test joint(s) in a neutral or resting position and then apply a resisted isometric force
• The contraction should be held for at least 5 seconds and repeated 3 times to show if there is fatiguable weakness
• Positive findings indicate neurological impairment as opposed to muscle weakness

Question 12

Upper motor neuron syndrome

Answer 12

• includes lesions involving the cortical spinal pathways
• Levels of involvement include: cortex, internal capsule, brainstem, and spinal cord

Question 13

Lower motor neuron syndrome

Answer 13

Damage to the lower motor neuron cell bodies or their peripheral axons

Question 14

Negative features for upper motor neuron syndrome

Answer 14

• weakness
• slowness or movement
• impaired coordination

Question 15

Positive features for upper motor neuron syndrome

Answer 15

• spasticity
• hyperactive reflexes
• rigidity
• intentional tremors
• dystonia

Question 16

Negative features for lower motor neuron syndrome

Answer 16

• paresis
• Hyporeflexia
• rapid atrophy
• fatigue

Question 17

Positive features for lower motor neuron syndrome

Answer 17

• fasciculations (involuntary muscle contraction)
• spasms

Question 18

Sensation

Answer 18

• Sensation is the conscious perception of basic sensory input

Question 19

Sensibility

Answer 19

the neutral events occurring at the periphery nerve fibres. and nerve receptors

Question 20

Anterior spinothalamic tract

Answer 20

• type A alpha and C fibre
• small diameter, unmyelinated
• Discriminative aspects including location and intensity
• Light touch and pressure

Question 21

Anterior spinothalamic tract route

Answer 21

• Peripheral receptor
• enters the spinal cord
• synapses in the dorsal horn
• decussates (crosses) - can ascend a few levels prior to decussating
• travels up the spinothalamic tract (anterolateral pathway)
• synapses in the ventral posterior lateral nucleus ( thalamus)
• Terminates in tei primary somatosensory cortex

Question 22

Dorsal column - medial lemniscal pathway

Answer 22

• type a alpha and a beta
• large diameter, myelinated
• proprioception, vibration and fine touch

Question 23

Dorsal column - medial lemniscal pathway route

Answer 23

• peripheral receptor
• enters spinal cord and travels up the dorsal column
• synapses in the dorsal column nucleus (medulla)
• Decussates
• travels up the medial lemniscus pathway
• synapse in raw ventral posterior lateral nucleus (thalamus)
• terminates in the primary somatosensory cortex

Question 24

Lateral spinothalamic tract

Answer 24

• Type a alpha and type c
• pain and temperature

Question 25

Lateral spinothalamic tract route

Answer 25

The pathway crosses over at the level of the spinal cord, rather than in the brainstem like the dorsal column-medial lemniscal pathway

Question 26

Dermatome

Answer 26

- the area of skin supplies by a single nerve root - the area innervated by a nerve root is larger than that innervated by a puerperal nerve

Question 27

Peripheral cutaneous nerve

Answer 27

the subcutaneous tissue supply the skin

Question 28

Hyporeflexia

Answer 28

an absent or diminished response to tapping. It usually indicated a disease that involves one or more of the components of the neuron reflex arc

Question 29

Hyperreflexia

Answer 29

- hyperactive or repeating (clonic) reflexes - usually indicate an interruption of corticospinal and other descending pathways that influence the reflex arc due to a suprasegmental lesion, that is, a lesion above the level of the spinal reflex pathway

Question 30

Deep tendon reflexes

Answer 30

- results from sit,ulation of the stretch-sensitive IA afferents of the neuromuscular spindle producing muscle contraction via a monosynaptic pathway - tested by tapping sharply over the muscle tendon are increases in UMN syndrome and decreases in LMN syndrome

Question 31

What is the DTR grading

Answer 31

0 - Absent (areflexia) 1 - diminished (Hyporeflexia) 2 - Average 3 - exaggerated (brisk) 4 - clonus, very brisk (hyperreflexia)

Question 32

Proprioceptive reflexes

Answer 32

Clonus - extension of the wrist or dorsiflexion of the ankle - apply quick overpressure - positive sign includes more than 3 involuntary beats (1 or 2 beats is normal)

Question 33

Cutaneous reflexes

Answer 33

- light stroke applied to skin - the expected response is brief contraction of muscles innervated by the same spinal segments receiving the afferent inputs from the cutaneous receptors

Question 34

Babinski reflex

Answer 34

- Pathology: pyramidal tract lesion - Procedure: stroke lateral aspect of the sole of the foot - Positive: big toe extends and 4 lateral digits fan out - Normal: all toes flex Positive: corticospinal tract disruption (pyramidal)