Nerve Plexuses

Question 1

Through which root do sensory signals/information go through?

Answer 1

The dorsal root to the spinal cord.

Question 2

Through which root do motor signals leave the spinal cord?

Answer 2

The ventral root of the spinal cord.

Question 3

Plexuses are networks of nerves originating from ______________ of the spinal nerves.

Answer 3

Ventral rami.

Question 4

How many nerve plexuses are there?

Answer 4

Four nerve plexuses.

Question 5

What are the nerve plexuses?

Answer 5

1. Cervical Plexus
2. Brachial Plexus
3. Lumbar Plexus
4. Sacral Plexus

Question 6

Which two plexuses are sometimes combined and what are they called?

Answer 6

The Lumbar and Sacral plexuses are sometimes combined to form the lumbosacral plexus.

Question 7

What vertebrae does the Cervical plexus span?

Answer 7

C1-C4, C5

Question 8

What vertebrae does the Brachial plexus span?

Answer 8

C5-T1

Question 9

What vertebrae does the Lumbar plexus span?

Answer 9

T12-L4

Question 10

What vertebrae does the Sacral plexus span?

Answer 10

L4-S4

Question 11

All plexuses have?

Answer 11

Both sensory and motor nerves.

Question 12

List the Cervical plexus nerves.

Answer 12

LGTAPSNC
Large gorillas take a piss so newts care.
- Lesser Occipital Nerve
- Great Auricular Nerve
- Transverse Cervical Nerve
- Ansa Cervicalis
- Phrenic Nerve
- Supraclavicular Nerve
- Nerve to Rhomboids and Serratus
- Cranial Nerves

Question 13

What is special about the cervical plexus?

Answer 13

Has nerves that contribute to cranial nerves.

Question 14

What is the organization of the brachial plexus?

Answer 14

Branching off the spinal cord:
- Ventral rami (roots)
- Trunks (superior, middle, and inferior)
- Divisions (anterior and posterior)
- Cords (Posterior, lateral, and medial)
- Nerves

Question 15

All of the nerves of the Brachial Plexus have both _____ and ______ ______.

Answer 15

Sensory and motor nerves. (Specifically within each nerve)

Question 16

List the Brachial Plexus Nerves.

Answer 16

MAMRU
My aunt makes rainbow undies.
- Musculocutaneous Nerve
- Axillary Nerve
- Median Nerve
- Radial Nerve
- Ulnar Nerve

Question 17

Nerves in the Brachial Plexus (other)

Answer 17

• Nerve to subclavius
• Dorsal scapular nerve
• Long thoracic nerve
• Suprascapular nerve
• Pectoral nerves (medial and lateral)
• Subscapular nerves
• Thoracodorsal nerve

Question 18

Clinical applications associated with the Brachial plexus?

Answer 18

Radial nerve damage/compression “wrist drop”
Median nerve issues- wasting of thumb side muscles
Due to pressure/compression

Question 19

List the Lumbar plexus nerves.

Answer 19

IILGFO
iil getthe fuck out
- Iliohypogastric Nerve
- Ilio-inguinal Nerve
- Lateral femoral cutaneous Nerve
- Genitofemoral Nerve
- Femoral Nerve
- Obturator Nerve

Question 20

List the Sacral plexus nerves.

Answer 20

PPISS
- Posterior fermoral cutaneous Nerve
- Pudendal Nerve
- Inferior gluteal Nerve
- Sciatic Nerve
- Superior gluteal Nerve

Question 21

Which nerve is the largest in the body?

Answer 21

Sciatic Nerve.

Question 22

What does the Sciatic nerve branch into?

Answer 22

The tibial and fibular nerves (motor and sensory nerves for the leg, ankle, and foot).

Question 23

What causes sciatica?

Answer 23

Compression of the sciatic nerve from the piriformis can cause sciatica.

Question 24

What are dermatomes?

Answer 24

Specific regions of skin that are supplied by certain spinal sensory nerves. There can be significant overlap between adjacent dermatomes.

Question 25

Shingles

Answer 25

The rash and pain from shingles typically follow the pattern of the dermatome corresponding to the affected nerve. Each spinal nerve innervates a specific area of the skin, so shingles affects the area served by the reactivated nerve.

Question 26

What is a reflex?

Answer 26

An immediate involuntary motor response.

Question 27

What is a reflex arc?

Answer 27

The neural wiring of a single reflex. Begins at a sensory receptor and ends at a peripheral effector.

Question 28

Is conscious control needed for a reflex arc?

Answer 28

No.

Question 29

Describe the steps of a reflex arc.

Answer 29

1. Stimulation and activation of receptor (hand hits a thumbtack) 2. Activation of a sensory neuron, which sends signal through dorsal root to spinal cord. 3. Excitatory neuron relays sensation to the brain and motor neuron is stimulated. 4. Information processing in CNS leads to the activation of a motor neuron (after signal leaves from ventral root). 5. Response by effector (pull arm away).

Question 30

Describe the steps of a stretch reflex.

Answer 30

1. Stimulus activates receptor. Muscle spindle fibers are stretched. 2. Activation of a sensory neuron. 3. Information processing in CNS (no interneuron). 4. Activation of a motor neuron. 5. Response by effector. Muscle contracts.

Question 31

What is an example of a stretch reflex?

Answer 31

Knee-jerk reflex. The patellar reflex is controlled by muscle spindles in the quadriceps fermoris. The stimulus is a reflex hammer tappung the muscle tendon, stretching the spindle fibers. This results in a sudden increase in the activity of the sensory neurons, which synapse on spinal motor neurons. An action potential is propagated to motor units in the quadriceps femoris. This leads to contraction of the stretched muscle, causing a reflexive kick.