Spinal nerves

Question 1

Nerve (2)

Answer 1

1) Found in PNS

2) Hundreds of thousands of axons wrapped together in connective tissue

Question 2

Dorsal ramus (3)

Answer 2

1) Serves dorsal trunk

2) Carries visceral motor, somatic motor, sensory information

3) Skin, muscles of back

Question 3

Ventral ramus (4)

Answer 3

1) Ventral trunk

2) Upper/lower limbs

3) Visceral motor, somatic motor

4) Body surface, body wall, limbs

Question 4

Plexus (2)

Answer 4

(1) Network of interconnecting nerves

2) Cervical, brachial, lumbar and sacral

Question 5

Dermatome (2)

Answer 5

(1) Region of skin that carries sensory information through a specific pair of spinal nerves

2) Include cervical, thoracic, lumbar, sacral

Question 6

Cervical plexus

Answer 6

Combination of the ventral rami of spinal nerves C1-C5

Question 7

Phrenic nerve (4)

Answer 7

1) Most important nerve of cervical plexus

2) Supplies motor and sensory fibers to diaphragm

3) Irritation of this nerve causes hiccups

4) Severing nerve would paralyze diaphragm, which would require a ventilator (mechanical respirator)

Question 8

“Three four five keeps the diaphragm alive”

Answer 8

Phrenic nerve in C3-C5 keeps diaphragm alive

Question 9

Ganglia (2)

Answer 9

1) Found in PNS

2) Clusters of nerve cell bodies in the PNS

Question 10

Spinal nerves (pairs, regions) (6)

Answer 10

1) 31 pairs total

2) Cervical - 8 pairs (C01-C08)

3) Thoracic - 12 pairs (T01-T12)

4) Lumbar - 5 pairs (L01-L05)

5) Sacral - 5 pairs (S01-S05)

6) Coccygeal - 1 pair

Question 11

Spinal nerve roots - names and operation

Answer 11

1) Dorsal root - axons of AFFERENT sensory neurons

2) Ventral root - Axons of EFFERENT motor neurons

3) Join together - ALL spinal nerves are mixed sensory and motor

Question 12

Afferent Signals

Answer 12

1) Received by spinal nerves

2) Signal passes through dorsal roots

3) Into spinal cord

4) Up to brain for processing

Question 13

Efferent signals (5)

Answer 13

1) Decision in the brain is made to move

2) Signal passes down the spinal cord

3) Out to the appropriate spinal level

4) Out the ventral root to destination

5) For voluntary motor contraction

Question 14

Brachial plexus components (4)

Answer 14

1) Ventral Rami of Spinal Nerves C5-T1

2) Roots combine to form three trunks:
a) superior
b) middle
c) inferior

Trunks form two divisions:
a) anterior
b) posterior

Divisions branch into three cords:
a) lateral
b) posterior
c) medial

Question 15

Axillary nerve (Brachial Plexus) (2)

Answer 15

1) Motor to three muscles:
a) Deltoid
b) Teres minor
c) Long head of the triceps brachii

2) Sensory information
a) from shoulder joint

Question 16

Radial nerve (Brachial Plexus) (2)

Answer 16

1) Motor to muscles:
a) Triceps brachii
b) 12 muscles of forearm for wrist and finger extension

2) Sensory information
a) Associated joints and overlying skin

Question 17

Median nerve (Brachial Plexus) (2)

Answer 17

1) Muscles:
a) Flexor muscles of the forearm
b) Thenar muscles (thumb)

2) Sensory information
a) Skin on digits 1-3 and 1/2 of digit 4

Question 18

Ulnar nerve (Brachial plexus) (2)

Answer 18

1) Muscles:
a) Flexor muscles of the forearm, wrist and hand

2) Sensory information
a) Skin on 1/2 of digit 4 and 5

Question 19

Musculocutaneous nerve (Brachial plexus) (2)

Answer 19

1) Muscles
a) Flexor muscles of elbow
b) Biceps brachii
c) Brachialis

2) Sensory
a) Skin on radial side of forearm

Question 20

Lumbar plexus (3)

Answer 20

1) Ventral rami of L1-L4

2) Anterior division

3) Posterior division

Question 21

Femoral nerve (Lumbar plexus) (2)

Answer 21

Muscles:
a) Hip flexors
b) Knee extensors

Sensation:
a) Skin on the anterior thigh

Question 22

Lateral femoral cutaneous nerve (Lumbar Plexus)

Answer 22

Sensation
a) Skin on anterior, lateral, posterior surfaces of thigh

Question 23

Saphenous nerve (Lumbar Plexus)

Answer 23

Sensation:
a) Skin from the medial surface of the leg

Question 24

Sacral Plexus (2)

Answer 24

1) Ventral rami of L4-S4

2) Sciatic nerve
a) Largest nerve in body
b) Inferior trunk, posterior surface of thigh

Question 25

Sciatic nerve branches

Answer 25

1) Common fibular (peroneal) nerve
a) Travels laterally

2) Tibial nerve
a) Travels along posterior surface of tibia