Unit III: The Nervous System (Spine, Nerves and Reflexes)

Question 1

Where does the spinal cord begin and end?

Answer 1

Begins at the base of the brain and goes down to T12.

Question 2

Cervical and Lumbosacral enlargements

Answer 2

Cervical supplies to the shoulder and upper limbs.
Lumbosacral innervates structures of the pelvis and lower limbs.

Question 3

Conus Medullaris

Answer 3

Lower end of the spinal cord tappers off around the lumbar vertebrae. Between L1 and L2.

Question 4

Causa Equina (L2 to S5)

Answer 4

A bundle of nerves at the end of the spinal cord that resembles a horse’s tail.

Question 5

Meninges of the Spinal Cord

Answer 5

Protection of the spinal cord (similar to the brain). Specialized membranes surrounding the spinal cord, provide the necessary physical stability and shock absorption.

Question 6

Epidural Space

Answer 6

Adipose tissue between vertebra and dura mater

Question 7

Subarachnoid Space

Answer 7

Filled with cerebrospinal fluid between the arachnoid membrane and the outer surface of the pia mater.

Question 8

Spinal Tap/Lumbar Puncture

Answer 8

The withdrawal of CSF with the insertion of a needle into the subarachnoid space in the inferior lumbar region.

Question 9

Gray Matter in the Spinal Cord

Answer 9

Mostly cell bodies, the butterfly shape in the middle of the spinal cord.

Question 10

Posterior (dorsal horns)

Answer 10

Interneurons are found here

Question 11

Anterior (ventral) horns

Answer 11

Cell bodies of motor neurons

Question 12

Lateral horns

Answer 12

Sympathetic neurons

Question 13

What runs through the central canal?

Answer 13

CSF

Question 14

Posterior (dorsal) root

Answer 14

brings sensory information into the spinal cord.

Question 15

Anterior (ventral) root

Answer 15

Axons of motor neurons that extend into the peripheral to control somatic and visceral effectors

Question 16

What are the function of the spinal nerves?

Answer 16

Allow communication with the peripheral organs.

posterior and anterior roots fuse into a spinal nerve

Question 17

Tract

Answer 17

A bundle of axons in the CNS that is somewhat uniform in diameter, myelination, and propagation speed.

Question 18

Ascending Tracts

Answer 18

Carry sensory information toward the brain.

Question 19

Descending Tracts

Answer 19

Convey motor commands to the spinal cord.

Question 20

How many columns can white matter be divided in?

Answer 20

3. posterior, anterior and lateral.

Question 21

Posterior Column

Answer 21

Between the posteior horns and median sulcus.
Ascending Tracts

Question 22

Anterior Tract

Answer 22

Between the anterior horn and anterior median fissure.
Ascending and descending*

Question 23

Lateral Column

Answer 23

Between the anterior and posterior columns on each side.
**Ascending and descending. **

Question 24

How many pair of spinal nerves are there?

Answer 24

31.

Question 25

Do sensory nerve fibers enter the ventral side of the dorsal side of the spinal cord?

Answer 25

Sensory nerve fibers enter the dorsal side of the spinal cord (afferent)

Question 26

Do motor nerves leave from the ventral or dorsal side of the spinal cord?

Answer 26

Motor nerves leave from the ventral side (efferent)

Question 27

Posterior (dorsal) rami

Answer 27

Serve the skin and muscles of the posterior trunk.

Question 28

Anterior (Ventral) Rami

Answer 28

T2-T12 forms intercostal nerves- serve muscles between the ribs, skin, and muscles of the anterior and lateral trunk.

Question 29

Cervical Plexus C1-C5

Answer 29

Serves the diaphragm and muscles of the shoulder and neck. Phrenic Nerve

Question 30

Phrenic Nerve

Answer 30

The major nerve of the cervical plexus, supplies the diaphragm, a key breathing muscle. If damaged this can result in death due to respiratory paralysis.

Question 31

Brachial Plexus (C5-C8 and T1)

Answer 31

Nerves that innervate the upper limb and pectoral girdle. Axillary, radial, median, ulnar.

Question 32

What results from radial nerve damage?

Answer 32

Wrist drop or inability to extend hand at the wrist.

Question 33

What results from median nerve damage?

Answer 33

Inability to pick up small objects.

Question 34

What results from ulnar nerve damage?

Answer 34

Claw hand or inability to spread fingers apart.

Question 35

Lumbar Plexus

Answer 35

L1-L4 Major nerves, femoral, and obturator

Question 36

Sacral Plexus

Answer 36

L4-S4 Sciatic nerve Tibial and common fibular (peroneal)

Question 37

What results from tibial and common fibular damage?

Answer 37

Inability to extend the hip and flex the knee. Sciatica

Question 38

What is a dermatome?

Answer 38

Area of the skin is innervated by the cutaneous branches of a single spinal nerve. All spinal nerves expect **C1**

Question 39

What is the clinical importance of dermatomes?

Answer 39

Damage or infection. Shingles!

Question 40

What are reflexes?

Answer 40

They are rapid, predictable motor responses to a stimulus.

Question 41

How are reflexes classified?

Answer 41

Innate vs. Acquired Response Complexity of circuit Processing site.

Question 42

Innate vs. Acquired

Answer 42

innate- genetically determined Acquired- with time, these reflexes are learned.

Question 43

monosynaptic vs. polysynaptic

Answer 43

mono- one synapse poly- more than two synapses

Question 44

What is a reflex arc?

Answer 44

Direct route from a sensory neuron to an interneuron to an effector

Question 45

What are the five components of a reflex?

Answer 45

Receptor, sensory neuron, integration center, motor neuron, effector

Question 46

What type of reflex in the plantar reflex?

Answer 46

Monosynaptic

Question 47

Babindki's Sign

Answer 47

Abnormal plantar reflex where the great toe dorsiflexes (flexes upward) and the smaller toes fan laterally.

Question 48

Paralysis

Answer 48

Loss of motor function

Question 49

Flaccid Paralysis

Answer 49

Severe damage to the ventral root. Motor nerve impulses do not reach muscles. NO VOLUNTARY MOVEMENT POSSIBLE. Muscles begin to **atrophy**

Question 50

Spastic Paralysis

Answer 50

Occurs when the spinal cord is cut crosswise (transected) or crushed. Affected muscles stay healthy because they are still stimulated by reflex arcs and movement occurs. Movements are involuntary.

Question 51

Paraplegia

Answer 51

Transaction between T1 and L1. **only legs are affected**

Question 52

Quadriplegia

Answer 52

Transaction just below C5 **All limbs are affected**

Question 53

Death

Answer 53

Transaction above C3 **Respiratory paralysis** Phrenic Nerve!!!!