spinal nerves and its plexus

Question 1

how many pairs of spinal nerves are there altogether ?

Answer 1

31

Question 2

where does spinal nerves supply to?

Answer 2

all parts of the body except head and some areas of the neck

Question 3

what are the region of spinal nerves?

Answer 3

8 cervical nerves
12 thoracic nerves
5 lumbar nerves 
5 sacral nerve 
1 coccygeal nerve

Question 4

what are the parts from the spinal cord ?

Answer 4

dorsal and ventral ramus

they both carry mixed sensory and motor fibers

Question 5

what does ventral plexus unite to form?

Answer 5

the spinal nerves from
C1-8
L1-5
S1-5
Co1 
unite and form plexus
carry sensory and motor fibres for the innervation of the kin and muscles of the limb and neck

Question 6

what are the 4 plexus it forms?

Answer 6

cervical
brachial
lumbar
sacral plexus

Question 7

which ventral rami does not form plexus ?

Answer 7

T1-T12

Question 8

what does the ventral rami of T2-11 form?

Answer 8

intercostal nerves
they supply the skin and muscles of the anterolateral thorax and abdominal wall
(2-7 supply the thorax and structures within it
7-11 are atypical anterior thoraco abdominal nerves

Question 9

what is ventral rami T12 ?

Answer 9

subcostal nerve

Question 10

where does the dorsal rami of spinal nerves supply?

Answer 10

posterior body trunk area with both motor and sensory fibers via several branches

Question 11

what is the cranial plexus formed by?

Answer 11

by the ventral rami of the upper 4 cerivical nerves (C1-C4)

Question 12

what is cervical plexus?

Answer 12

Transmit sensory impulses from the skin of neck,back of head and shoulder
Most are cutaneous nerves that supply only the skin
C1 has no sensory supply
C5 have little effect

Question 13

which plexus does phrenic nerve arise from?

Answer 13

cervical plexus

C3,4,5

Question 14

what is the function of phrenic nerve ?

Answer 14

Supplies both motor and sensory fibers to the diaphragm

Chief muscle that cause breathing movements

Question 15

what happen if the cervical plexus is damaged ?

Answer 15

Irritation of phrenic nerve : spasms of diaphragm or hiccups

Both phrenic nerve are destroyed, diaphragm is paralysed and respiratory arrest occurs (mechanical ventilators can keep victims alive)

Question 16

what is the function of Supraclavicular nerve ?

Answer 16

Supplies the skin of shoulder and clavicular region

Question 17

where is the Supraclavicular nerve found at ?

Answer 17

cervical plexus

C3,4

Question 18

some example of what is in cervical plexus

Answer 18

1. supraclavicular (3 and 4) they supply the skin of shoulder and clavicular region
2. phrenic (3,4,5) serves the diaphragm , motor function

Question 19

what is brachial plexus?

Answer 19

C5,6,7,8 and T1

Innervate upper limb
Can be palpated superior to the clavicle and lateral border of sternomastoid muscle

Question 20

what happens when the radial nerve is damaged ?

Answer 20

Unable to extend at the forearm, wrist and fingers.

Unopposed flexion of wrist occurs, known as wrist-drop.

Question 21

where is the radial nerve found at and what is its function?

Answer 21

brachial plexus C5-8
Triceps brachii muscle (forearm extension)
Wrist and finger extension too

Question 22

what is the function of axillary nerve?

Answer 22

Move deltoid, teres minor and tricep

C5,6

Question 23

what happens when the axillary nerve is damaged ?

Answer 23

Loss of movement or sensation in the shoulder.

Caused by
fracture of the humerus (upper arm bone),
pressure from casts or splints,
improper use of crutches.

Question 24

where is musculocutaneous nerve found at and what is its function?

Answer 24

brachial plexus C5-7

Anterior compartment of the arm: the coracobrachialis, biceps brachii, and brachialis.

Cutaneous innervation of the lateral forearm

Question 25

what will happen when the musculocutaneous nerve is damaged?

Answer 25

Loss of sensation in the skin on the front side of the forearm.

Weakened flexion at the shoulder and elbow.

Weakened rotation of the arm.

Question 26

where is the ulnar nerve found at and what is its function?

Answer 26

brachial plexus C8,T1

Stimulates muscles in the forearm, hand and fingers so you can:
Bend and straighten the pinky and ring fingers.
Grip and hold items.

Question 27

what happens when the ulnar nerve is damaged ?

Answer 27

Weakness, loss of coordination of the fingers.

Claw Like deformity of the hand and wrist.
Pain, numbness, decreased sensation, tingling, or burning sensation

Question 28

what happens when the median nerve is damaged ?

Answer 28

Compression of this nerve in the anterior wrist make it difficult to use pincer grasp (oppose thumb)
Carpal tunnel syndrome
To test: grip an object with his thumb and index finger and try to pull the object away.

Question 29

where is the median nerve found at and what is its function?

Answer 29

brachial plexus C5-8 and T1

Flexor muscles of the forearm and hand

Protonation of forearm
flexion, abduction, opposition, and extension of the thumb.

Sensory of skin of the lateral ⅔ of the hand , palm side and dorsum of fingers

Question 30

what are some examples of nerve in brachial plexus ?

Answer 30

1. radial nerve
2. musculocutaneous
3. ulnar nerve
4. median nerve
5. axillary nerve

Question 31

what is lumbar plexus ?

Answer 31

serve mainly the lower limb and also sends some branches to the abdomen and buttock

Question 32

what is lumbar plexus consist of?

Answer 32

spinal nerve L1-4

Question 33

what are some examples in lumbar plexus?

Answer 33

1. femoral nerve L2-4 , innervates anterior thigh muscles, quads which are thigh extensors and flexors
2. obturator (L2-4). motor to abduct muscles

Question 34

where can the femoral nerve be found and what is its function?

Answer 34

lumbar plexus L2-4

Innervate anterior thigh muscles, quads which are for hip flexors and knee extension

Question 35

where is the obturator nerve found at and what is its function?

Answer 35

lumbar plexus L2-4

Innervates the adductor muscles

Question 36

what is the sacral plexus?

Answer 36

they serve the buttock, lower limb, pelvic structures and perineum

Question 37

what nerves make up sacral plexus?

Answer 37

spinal nerves L4,5 S1-S4

Question 38

where is the Pudendal nerve found at and what is its function?

Answer 38

sacral plexus (S2-4)
Supplies most of skin and muscles of perineum

Question 39

what are some examples of the nerves in ?sacral plexus

Answer 39

1. sciatic nerve (tibial, L4-S3) (common fibular)
   - sensory, test leg and sole of feet
   - motor muscles to back of thigh, leg foot
2. pudendal (S2-4)
   - supplies most of skin and muscles of perinium, and external anal sphincter

Question 40

what does the sciatic nerve consist of?

Answer 40

tibial nerve

common fibular

Question 41

what happens when the tibial nerve is damaged ?

Answer 41

paralyzes the calf muscles, cannot plantar flex the foot , shuffling gait

Question 42

where is tibial nerve found at and what is its function?

Answer 42

L4,L5 and S1,2,3

Longest nerve in the body

Sensory: to posterior surface of leg and sole of foot
Motor: muscles to the back of leg (hamstrings)

Question 43

what is the Common fibular nerve ? where is it found at and what is its function?

Answer 43

sacral plexus L4,5 and S1,2

Sensory: anterior and lateral surface of the leg and dorsum of the foot
Motor : bicep femoris

Question 44

what are dermatome?

Answer 44

an area of skin in which sensory nerves derive from a single spinal nerve root
(C1 has no dermatome)
dermatome overlap so destruction of a single spinal nerve will not cause complete numbness

Question 45

what is the function of dermatome?

Answer 45

Helpful in evaluating and diagnosing conditions affecting the spine or nerve roots.
Experiencing symptoms along a specific dermatome can help inform doctors about which area of the spine may be affected.

Question 46

what is the lowest dermatome?

Answer 46

anterior trunk is T12

posterior trunk L5