Spinal Cord

Question 1

Spinal cord function

Answer 1

Sends and receives signals between brain and rest of the body

Question 2

Structure of the spinal cord

Answer 2

Inner core of grey matter
H-shaped pillar with anterior and posterior grey columns
Contains a small central canal
Surrounded by an outer covering of white matter
Divided into anterior, lateral and posterior white columns

Question 3

Gray matter

Answer 3

The amount of gray matter present is related to the amount of muscle innervated at that level
Largest at cervical and lumbosacral region
Consists of a mixture of nerve cells, neuroglia and blood vessels

Question 4

Enlargements

Answer 4

Cervical enlargement - 4th cervical to 2nd thoracic segment

Lumbo-sacral enlargement - 2nd lumbar to 3rd sacral segment

Question 5

Describe the arrangement of spinal nerves

Answer 5

31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)

Attached by anterior/ventral (motor roots) and posterior/dorsal (sensory roots)

Each posterior nerve root processes a posterior root ganglion

Question 6

Ganglia

Answer 6

Clusters of nerve cell bodies that carry nerve signals to and from the CNS

Question 7

Sensory ganglia

Answer 7

Ovoid shape with an oval cell body

Question 8

Motor ganglia

Answer 8

Long chain in the spine from base of the skull to the tail, contain irregular shaped cell bodies

Question 9

Cauda equina

Answer 9

The collection of nerves at the end of the spinal cord

Question 10

Paraplegic (paralysis of the legs) - levels & symptoms

Answer 10

Thoracic, lumbar or sacral level

Limited mobility
Chronic pain
Reduced bowel & bladder function
Loss of sexual function
Loss of muscle tone in legs
Weight gain

Question 11

Quadriplegic - paralysis in all four limbs

Answer 11

Cervical level

Limited or complete absence of arm and hand function
Problems speaking, swallowing or breathing without assistance
Difficulty performing daily tasks, dressing and eating
Loss of muscle tone
Loss of bone density

Question 12

Levels of spinal cord injury

Answer 12

A - Complete injury
B - Sensory incomplete
C - Motor incomplete
D - Muscle function below level of injury
E - Normal

Question 13

PNS

Answer 13

Peripheral nerves are cranial and spinal nerves

Consists of parallel bundles of fibres that may be efferent or afferent axons

Surrounded by connective tissue sheaths

Question 14

Types of receptors

Answer 14

Skeletal muscle propioreceptors

Skin mechanoreceptors

Nociceptors thermoreceptors

Question 15

Role of Schwann cells

Answer 15

Produce myelin in PNS

Question 16

Describe a simple reflex arc

Answer 16

1. Stimulus
2. Receptor
3. Sensory neuron
4. CNS
5. Motor neuron
6. Effector
7. Response

Question 17

Importance of reflexes

Answer 17

Safeguard our bodies from injury caused by unexpected external and internal stimuli

Question 18

Stretch reflex

Answer 18

Monosynaptic

Most rapid

Simple reflex arc with a single synapse between the afferent and efferent neuron

Eg: patella reflex - muscle spindles

Question 19

What are muscle spindles

Answer 19

Muscle spindles are stretch detectors

They sense how much and how fast a muscle is lengthened or shortened

Question 20

Flexor withdrawal

Answer 20

Automatic response, withdrawing a limb from a painful stimulus

Intensity of reflex proportionate to intensity of stimulus

Polysynaptic reflex – uses interneurons

Question 21

Cross extensor reflex

Answer 21

Flexor contracts and extensor relaxes to withdraw foot

Extensor contracts and flexor relaxes in opposite leg to support weight

Question 22

Babinski reflexes

Answer 22

The plantar reflex (negative result) curling of the toes, is seen in healthy adults

The Babinski signs (positive result) occurs in the absence of curling toes. Normal in infants but pathological in adults

Question 23

Myotomes

Answer 23

C5 - shoulder abduction & external rotation, elbow flexion
C6 - wrist extension
C7 - elbow extension & wrist flexion
C8 - thumb extension & finger flexion
T1 - finger abduction
L1/L2 - hip flexion
L3 - knee extension
L4/L5 - ankle dorsiflexion
L5 - great toe extension
S1 - ankle plantar flexion
S4 - bladder & rectum motor supply