Nervous System - Spinal Nerves and Branches

Question 1

How many Spinal Nerves are there? How are they Named?

Answer 1

of Nerves
- 31 Pairs
Named
- Based on segment of spinal cord they leave the vertebral column at

Question 2

What is the Structure of the Spinal Nerve before it exits the Vertebral Canal?

Answer 2

• Ventral Root

- Dorsal Root

Question 3

What happens when the Dorsal and Ventral Root Join? What does this mean?

Answer 3

Joined

• This is what the Spinal Nerve
• It means Spinal Nerves are Mixed: have both Sensory and Motor Fibers

Question 4

What are the Spinal Nerves Split into After they leave the Vertebral Column?

Answer 4

• Ventral Rami

- Dorsal Rami

Question 5

Where does the Ventral Root come from and What does it carry?

Answer 5

• Arises from the Ventral Horn

- Carries Motor Fibers (efferent)

Question 6

Where does the Dorsal Root go and what does it carry?

Answer 6

• enters Dorsal Horn

- Carry Afferent (sensory) fibers

Question 7

What do Ventral Rami Form? Where? (3)

Answer 7

• Somatic Nerve Plexuses: Cervical, Lumbar, and Sacral Regions
• Intercostal Nerves: T1-T11
• Subcostal Nerve: T12

Question 8

What does the Dorsal Rami do?

Answer 8

• Supplies motor, visceral, and sensory nerves to the dorsal muscles of the back and the overlying skin

Question 9

What are paravertebral muscles? what supplies their nerves?

Answer 9

Paravertebral Muscles
- Muscles that lie close to the vertebral column
Supplies Nerves
- Dorsal Rami

Question 10

What are the 5 names for spinal nerves? how many of each?

Answer 10

• Cervical Spinal Nerves: C1-C8
• Thoracic Spinal Nerves: T1-T12
• Lumbar Spinal Nerves: L1-L5
• Sacral Spinal Nerves: S1-S5
• Coccygeal Spinal Nerves: Co

Question 11

What is a Dermatome?

Answer 11

• An area of skin that is innervated by a single spinal nerve or spinal cord segment

Question 12

What is a Myotome?

Answer 12

• A part of the skeletal muscle that is innervated by a single nerve or spinal cord segment

Question 13

What is the Cauda Equina? What does it do?

Answer 13

Cauda Equina
- The continuation of Dorsal and Ventral Roots in the vertebral column past the end of the Spinal Cord
Function
- supplies Spinal Nerves to the Lumbar, Sacral, and Coccygeal spinal segments

Question 14

What Spinal Nerves form the Cervical Plexus?

Answer 14

• Ventral Rami of C1-C4

Question 15

What Spinal Nerves form the Brachial Plexus?

Answer 15

• Ventral Rami of the C5-T1

Question 16

How do the Cervical Spinal Nerves exit the Lumbar Column?

Answer 16

• C1-C7: Exit through the vertebral canal above their corresponding cervical vertebrae
• C8: Exits Between the CVII and TI vertebrae

Question 17

How do the Thoracic Spinal Nerves exit the spinal column?

Answer 17

• T1-T12: exit through the lower corresponding vertebrae

Question 18

How do the Sacral Spinal Nerves exit the Vertebral Column?

Answer 18

• Through the corresponding sacral foramina

Question 19

What forms the Sacral Plexus? what else does it contribute to?

Answer 19

• Ventral Rami of L4-S4

- also contributes to the coccygeal plexus

Question 20

What forms the Lumbar Plexus? what else does it contribute to?

Answer 20

• Ventral Rami of the L1-L4

- Also contributes to the sacral plexus

Question 21

What forms the coccygeal plexus? what other spinal nerves contribute to this?

Answer 21

• The Single pair of Coccygeal spinal nerves

- The S4 and S5 spinal nerves contribute to it

Question 22

Where is the Cervical Plexus located?

Answer 22

• Deep to the Sternocleidomastoid Muscle

Question 23

What are the important branches of the Cervical Plexus? What kind of nerves do they provide and to where?

Answer 23

• Cutaneous Branch: sensory from ventral and lateral neck
• Ansa Cervicalis: Motor to Infrahyoid Muscles
• Phrenic Nerve: Motor to the Diaphragm

Question 24

What does the Brachial Plexus Supply?

Answer 24

• the upper limbs

Question 25

What is the Mnemonic for remembering the subdivisions of the Brachial Plexus?

Answer 25

``` Read That Daunting Cadaver Book ```

Question 26

What are the important branches of the Brachial Plexus? (4)

Answer 26

- Musculocutaneous - Median - Ulna - Radial

Question 27

Where does the Musculocutaneous branch of the Brachial Plexus provide motor nerves to and receive sensory nerves from?

Answer 27

- Motor: the Muscles of the anterior compartment of the arm | - Sensory: From the lateral side of the arm

Question 28

Where does the Median Branch of the Brachial Plexus send motor nerves and receive sensory nerves from?

Answer 28

- Motor: to (almost) all muscles of the anterior Forearm and some of the muscles of the hand - Sensory: From the skin of the lateral palm (thumb side) and the lateral 3 1/2 fingers

Question 29

Where does the Ulnar Branch of the Brachial Plexus supply motor nerves? where does it receive sensory nerves from?

Answer 29

Motor: Some muscles in the anterior forearm, most intrinsic muscles of the hand Sensory: From the medial third of the palmar and dorsal aspect of the hand / and medial 1 1/2 fingers.

Question 30

Where does the Radial Branch of the Brachial Plexus send motor nerves to and receive sensory nerves from?

Answer 30

Motor: To the posterior compartment of the arm and the forearm Sensory: from the skin of the posterior arm and forearm / lateral 2/3rds of back of hand

Question 31

What Spinal Nerves make up the Roots of the Brachial Plexus?

Answer 31

- C5-T1 (neck region)

Question 32

How do the Roots of the Brachial Plexus differentiate into the Trunks?

Answer 32

- Upper: C5 & C6 - Middle: C7 - Lower: C8-T1

Question 33

What divides into anterior and posterior axilla (divisions) in the Brachial Plexus?

Answer 33

- The Trunks

Question 34

What divides into anterior and posterior divisions in the Brachial Plexus?

Answer 34

- The Trunks

Question 35

What are the names of the 3 Cords in the Brachial Plexus?

Answer 35

- Lateral - Medial - Posterior

Question 36

What forms the Lumbar Plexus?

Answer 36

- The Ventral Rami of Spinal Nerves L1-L4

Question 37

What are the Important branches of the Lumbar Plexus?

Answer 37

- Lateral Femoral Cutaneous - Femoral - Obturator

Question 38

What does the Lateral Femoral Cutaneous branch of the Lumbar Plexus do?

Answer 38

- Sensory: Receives senses from the lateral side of the thigh

Question 39

What type of nerve is the Femoral Branch of the Lumbar Plexus? what do they do?

Answer 39

- Motor: to muscles of the anterior compartment of the thigh and iliacus muscle - Sensory: from anterior and medial thigh and medial aspect of the leg and foot

Question 40

What type of nerve is the Obturator Branch of the Lumbar Plexus? what does it do?

Answer 40

Mixed - Motor: to muscles of the medial compartment of the thigh - Sensory: From the skin of the medial side of thigh

Question 41

What forms the Sacral Plexus?

Answer 41

- The Roots of L4-Co Spinal Nerves

Question 42

What are the Important Branches of the Sacral Plexus?

Answer 42

- Superior Gluteal - Inferior Gluteal - Sciatic Nerve - Pudendal

Question 43

What does the Superior Gluteal Branch of the Sacral Plexus do?

Answer 43

- Motor: To some of the gluteal muscles (pure motor)

Question 44

What does the Inferior Gluteal Branch of the Sacral Plexus do?

Answer 44

- Motor: to the Gluteus Maximus (motor)

Question 45

What are the two divisions of the Sciatic Nerve Branch of the Sacral Plexus?

Answer 45

- Anterior Division | - Posterior Division

Question 46

Where does the tibial and common fibular division of the Siatic Nerve come from?

Answer 46

- Tibial: the Anterior division | - Common Fibular: The Posterior Division

Question 47

What does the Tibial Nerve of the Sciatic Nerve do?

Answer 47

- Motor: to most muscles of the posterior thigh, all posterior muscles of the leg, and all muscles of the plantar aspect of the foot - Sensory: from posterior aspect of the leg and the entire plantar aspect of the foot

Question 48

What does the Common Fibular division of the Sciatic Nerve do?

Answer 48

- Motor: to muscles of the anterior and lateral compartmetns of the leg and some muscles on the dorsum of the foot - Sensory: from the skin on the lateral side of the leg and the dorsum of the foot

Question 49

What does the Pudendal Branch of the Sacral Plexus do?

Answer 49

- Motor: to muscles of the perineum | - Sensory: from skin of the perineum