Spinal Cord L2

Question 1

What are the 5 groups of vertebrae/nerves in the spinal cord and how many of each?

Answer 1

Cervical- 8
Thoracic- 12
Lumbar- 5
Sarcal- 5
Coccygeal- 1

Question 2

Where does the spinal cord itself end?

Answer 2

Lumbar region at L1-L2 at the conus medullaris (lower end of the spinal cord)

Question 3

What is the basic setup of the spinal cord?

Answer 3

Two roots coming in either side: Dorsal (with a ganglion) and ventral.
Circular, with an anterior median fissure on the front and a posterior median sulcus on the back.
Gray matter is ‘butterfly shaped’, and separated into 3 horns: anterior, posterior and lateral
Central canal is located in the middle of the gray commisure
The white on either side of the gray commisure are called the anterior and posterior white commisure.
Posteriorly, there are 2 pairs of white columns.
The outer pairs are the cuneate fasciculii (Present C1-T8)
The inner pairs are the gracile fasciculii
There are also two anterior spinothalamic tracts and two lateral corticospinal tracts

Question 4

What is a dermatome?

Answer 4

An area of skin supplied by a single spinal nerve

Question 5

What are the different types of receptors?

Answer 5

Encapsulated or free nerve ending receptors

Question 6

What are the types of encapsulated nerve endings and what do they do?

Answer 6

Meissner corpuscles: detect touch sensation

Pacinian corpuscles: detect pressure sensation

Question 7

What do the free nerve endings detect?

Answer 7

Pain and temperature sensations

Question 8

Which nerves out of encapsulated or free are myelinated?

Answer 8

The encapsulated ones are myelinated. They conduct their signals at approx. 50m/s-1 while free endings conduct at approx. 1m/s-1

Question 9

What type of neuron is myelinated in the spinal cord?

Answer 9

Pseudounipolar neurons

Question 10

What is discriminative vs non-discriminative sensation?

Answer 10

Discriminative means you can accurately determine where two different points of contact are. eg. touch and pressure (encapsulated nerve endings)
Non- discriminative means you can’t- you know a sensation is in an area, rather than a specific location. Eg. temperature. (free)

Question 11

Meninges

Answer 11

Three membrane layers that cover and protect your brain and spinal cord

Question 12

Pia Mater

Answer 12

The innermost layer of the meninges. The pial cellular layer firmly adheres to the surface of the spinal cord.

Question 13

Dura Mater

Answer 13

Dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system.

Question 14

Cauda Equina

Answer 14

The collection of nerves at the end of the spinal cord.

Question 15

Where is motor and sensory information carried?

Answer 15

Motor carried forward through ventral root

Sensory carried towards the back through the dorsal root

Question 16

Cervical enlargement

Answer 16

Area where the information goes to and from the arms

Question 17

Lumbar enlargement

Answer 17

Area of the spine where the information goes to and from the legs

Question 18

How does information about touch/pressure reach the spinal cord?

Answer 18

Stimulus applied to skin –> Encapsulated nerve ending receives it –> Forms a generator potential –> Conducted along myelinated axon –> Posterior root –> Cell body in posterior root ganglion –> (Posterior column) posterior gray horn (depending on whether it’s a spinal reflex)

Question 19

How does information about temperature/pain reach the spinal cord?

Answer 19

Stimulus –> free nerve ending receives it –> generator potential formed –> conducted along unmyelinated axon –> Posterior root –> Posterior root ganglion –> posterior gray horn

Question 20

Dorsal root ganglion

Answer 20

Bundle of cells bodies in dorsal root

Question 21

How does the sensory pseudounipolar neuron split?

Answer 21

One end goes to grey matter (synapses with other neurons) and the other to white matter (straight to the brain)

Question 22

What is convergence and what is its function?

Answer 22

1 sensory neuron picks up information from other neurons and then carries it to the brain. This reduces the spinal cord’s volume as fewer neurons enter the brain.

Question 23

Where is motor and sensory information carried?

Answer 23

Motor carried forward through the ventral root

Sensory carried towards the back through the dorsal root

Question 24

Where is white and grey matter located in the spinal cord?

Answer 24

White on the outside, grey on the inside.

Question 25

Where are opioid receptors located?

Answer 25

Dorsal gray root

Question 26

Where are cell bodies for upper motor neurons located?

Answer 26

Precentral gyri of the cerebral cortex

Question 27

Where are cell bodies of lower motor neurons located?

Answer 27

Anterior gray horns of the spinal cord

Question 28

Touch and pressure (and proprioception) information is sensed in the periphery by a ________, which
__ encapsulated. Information is then carried along a nerve, which __ covered in myelin, with a comparatively ____ conduction velocity of approximately __ m/s. The nerve fibre passes through the _______ root of the spinal nerve and into the spinal cord.

Answer 28

Touch and pressure (and proprioception) information is sensed in the periphery by a
receptor, which is encapsulated. Information is then carried along a nerve, which
is covered in myelin, with a comparatively
fast conduction velocity of approximately
50 m/s. The nerve fibre passes through the
dorsal root of the spinal nerve and into the spinal cord.

Question 29

Pain and temperature information is sensed in the periphery _____ , which ____ encapsulated. Information is then carried along a nerve, which ___
overed in myelin, with a comparatively ____ conduction velocity of approximately ___ m/s. The nerve fibre passes through the ___ root of the spinal nerve and into the spinal cord.

Answer 29

Pain and temperature information is sensed in the periphery by a free-nerve receptor/free nerve ending, which is not encapsulated. Information is then carried along a nerve, which is not covered in myelin, with a comparatively slow conduction velocity of approximately 1/one m/s. The nerve fibre passes through the dorsal root of the spinal nerve and into the spinal cord.