Lecture 33- Spinal Cord

Question 1

What are the two main functions of spinal cord?

Answer 1

provides a conduction pathway. Each column of white matter in the spinal cord contains bundles of axons (tracts).

Serves as an integration centre for spinal reflexes.

Question 2

What does the spinal cord extend from?

Answer 2

Foramen magnum of skull

Question 3

What prevents excessive movement of the spinal cord?

Answer 3

Fibrous extensions of the pia mater that anchor the spinal cord to the vertebral column and coccyx

Question 4

How many nerve pairs does spinal cord have?

Answer 4

31

Question 5

What divides the spinal cord into left and right halves?

Answer 5

Ventral (anterior) median fissure
Dorsal (posterior) median sulcus

Question 6

Central canal

Answer 6

Cerebrospinal fluid filled canal that runs the length of spinal cord at its centre

Question 7

What are Cervical and lumbar enlargements for?

Answer 7

the nerves that serve the limbs and a collection of nerve roots at the inferior end of the vertebral canal (cauda equina) that travel through the vertebral column to their intervertebral foramina

Question 8

Where is Grey mater of the cord?

Answer 8

At the core

Question 9

Where is white matter of the cord?

Answer 9

On the outside

Question 10

What do dorsal horns of grey matter contain?

Answer 10

Interneurons

Question 11

What to ventral horns of grey matter consist of?

Answer 11

Mostly cell bodies of somatic motor neurons

Question 12

In thoracic and superior lumbar regions….

Answer 12

there are also paired lateral horns that extend laterally between the dorsal and ventral horns, and contain cell bodies of autonomic motor neurons.

Question 13

Grey commissure

Answer 13

A bridge of grey matter that connects masses of grey matter on either side.

Question 14

Ventral roots

Answer 14

exit the spinal cord carrying axons of motor neurons, and join with dorsal roots entering the spinal cord from peripheral receptors from outside of the spine to form spinal nerves.

Dorsal root ganglia are the cell bodies of sensory neurons.

Question 15

What allows communication between the cord and brain?

Answer 15

White matter

Question 16

Localized damage to the spinal cord or it’s roots leads to…

Answer 16

Paralysis (loss of motor function)
Paresthesias (loss of sensory function)

Question 17

Severe damage to the ventral root or ventral horn results…

Answer 17

In flaccid paralysis

Question 18

When upper motor neurons of primary motor cortex are damaged….

Answer 18

Spastic paralysis occurs

Voluntary control over skeletal muscle is lost

Question 19

Damage to spinal cord occurs between….

Answer 19

T1 (first thoracic vertebra) and L1 (first lumbar vertebra)

Lower limbs affected
Paraplesia

Question 20

Damage in cervical region, what is affected?

Answer 20

All four limbs
Quadriplegia

Question 21

Spinal shock

Answer 21

Temporary loss of function caudal to the trauma

Question 22

Neuronal pathways

Answer 22

Carry sensory and motor information to and from the brain

Question 23

Function of Multineuron pathways

Answer 23

Cross from one side to the other (decussate)

Consist of a chain of two or three neurons

Exhibit somatotopy (a point-for-point relationship between an area of the body and a specific point in the central nervous system).

Question 24

Conduction pathway examples

Answer 24

Lateral spinothalamic tract:
• is located in the lateral column of white matter.
• begins in spinal cord.
• ends in thalamus.
• is a sensory (ascending) tract.

Anterior (ventral) corticospinal tract:
• is located in the anterior column of white matter.
• begins in cerebral cortex.
• ends in spinal cord.
• is a motor (descending) tract.

Question 25

Ascending pathways

Answer 25

conduct sensory impulses upward through a chain of three neurons.

Question 26

Conduction pathway neurons

Answer 26

First-order neuron conducts the sensory info from the receptor to the spinal cord or brain stem.

Second-order neuron conducts the impulse to the thalamus.

Third-order neuron conducts the impulse to the primary somatosensory cortex of the cerebrum.

Question 27

Nonspecific ascending pathways

Answer 27

receive input from many different types of sensory receptors, and make multiple synapses in the brain.

Question 28

Specific ascending pathways

Answer 28

mediate precise input from a single type of sensory receptor.

Question 29

Spinocerebellar tracts

Answer 29

convey information about muscle and tendon stretch to the cerebellum.

They are ipsilateral (don’t cross over) and only involve two neurons, not three.

Question 30

Descending pathways involve…

Answer 30

two neurons:
upper motor neurons
lower motor neurons that innervate skeletal muscle.

Question 31

Direct/pyramidal system

Answer 31

upper motor neurons from the cerebral cortex regulates fast, finely controlled or skilled movements.

Question 32

Indirect/extrapyramidal system

Answer 32

upper motor neurons from the brainstem regulate muscles for balance and coarse movements

Question 33

Naming conduction pathways

Answer 33

Location, from, to