Peripheral nerve innervation

Question 1

peripheral nerve lesion

Answer 1

Sensory &/or motor changes in a peripheral nerve distribution result

Question 2

spinal nerves

Answer 2

31 pairs of spinal nerves:
each divides into a dorsal & ventral ramus
31 pairs of dorsal rami remain segmental

Question 3

Dorsal rami:

Answer 3

innervate the skin & intrinsic muscles of the back

Question 4

PLEXUS

Answer 4

an intricate network/web latin = to plait

Question 5

cervical plexus:

Answer 5

C1-4 ventral rami

- phrenic nerve C3,4,5

Question 6

brachial plexus:

Answer 6

C5-T1 ventral rami
located in between the base of the neck and the axilla. On its way to the axilla it passes between the clavicle and 1st rib. Its branches supply the majority of muscles that move the upper limb & pectoral girdle.

Question 7

brachial plexus: RTDCB

Answer 7

Roots (5 - found at cervical Transverse processes )
Trunks (3) - between scalenes, superior, inferior, middle
Divisions (6) - trunk divides into anterior and posterior division. anterior divisions innervate anterior compartment - flxs and 3 posterior innervate posterior e.g extensors
Cords (3) - posterior cord (posterior structures), lateral cord, medial cord … named in reference to axillary artery
Branches - nerves, rami

Question 8

SUPRACLAVICULAR branches of brachial plexus - Arise from roots and trunks

Answer 8

branches arise from the roots (2 nerves) and trunks (1 nerve) of the brachial plexus.
dorsal scapular - C5
Long thoracic nerve - C5,6,7

Question 9

INFRACLAVICULAR branches of brachial plexus - Arise from trunks

Answer 9

Suprascapular - C5,6

Subclavian C5,6

Question 10

INFRACLAVICULAR BRANCHES

Answer 10

Arise from cords
• Lateral pectoral
Upper subscapular C5,6 
Thoracodorsal (Middle subscapular) C6,7,8
Lower subscapular C5,6
• Medial pectoral
• Medial brachial cutaneous
• Medial antebrachial cutaneous 
Axillary C5,6
Radial C5-C8 (T1) 
Musculocutaneous C5,6,7 
Median C5-T1
Ulnar C8, T1

Question 11

Axillary nerve

Answer 11

C5&6
Motor
Deltoid and Teres minor
Sensory
Patch over deltoid
• Quadrangular space = 1 bone, 3 muscles - could compromise axillary nerve and surgical head of humerus
• Anatomical neck of humerus

Question 12

Musculocutaneous nerve:

Answer 12

C5, 6, 7

- Continues as lateral cutaneous nerve of forearm

Question 13

Median nerve

Answer 13

(C5) C6-T1

Question 14

Ulnar nerve

Answer 14

C8-T1

Question 15

Thoracic ventral rami

Answer 15

form intercostal nerves

Question 16

Lumbar Plexus

Answer 16

(L1-L4, parts of T12): - exits the abdominopelvic cavity anteriorly
2 main branches exit pelvis anteriorly or medially
2 main branches:
1. Femoral nerve (L2-4)
travels under the inguinal ligament into the ‘femoral triangle’
2. Obturator nerve (L2-4
exits through obturator foramen

Question 17

Sacral plexus:

Answer 17

(L4-L5, S1-S4):
- exits the pelvic cavity posteriorly
Superior gluteal nerve (Gmed & min, TFL)
Inferior gluteal nerve (Gmax)
Sciatic nerve
1. Tibial nerve (L4-S3)
2. Common Fibular nerve (L4-S2)
3. Deep fibular nerve
4. Superficial fibular nerve
Pudendal nerve (supplies the perineum) S2,3,4

Question 18

Lumbosacral trunk:

Answer 18

L4-L5

connects lumbar & sacral plexuses

Question 19

Pudendal nerve

Answer 19

exits greater sciatic foramen and enters pelvic cavity to supply perineal cavity

Question 20

Deep fibular nerve

Answer 20

Anterior leg compartment

Question 21

Superficial fibular nerve

Answer 21

lateral leg compartment

Question 22

BRACH. PLEXUS: Root - DORSAL SCAPULA NERVE

Answer 22

ROOT
arising from the C5 ventral rami, piercing middle scalene.
- Levator scap, rhomboids

Question 23

BRACH. PLEXUS: Root - Long thoracic NERVE

Answer 23

Root
C5, 6 & 7 ventral rami and runs inferiorly over the serratus anterior.
serratus anterior

Question 24

The superior trunk - brachial plex.

Answer 24

The superior trunk forms from the merging of the C5 & C6 ventral rami. Therefore, the suprascapular nerve carries C5 & C6 axons.
suprascapular nerve C5,6 - supra and infraspinatus

Question 25

posterior cord

Answer 25

axillary
radial
upper subscap.
lower subscap.
thoracodorsal

Question 26

lat cord

Answer 26

lateral pectoral

musculocutaneous

Question 27

medial cord

Answer 27

medial pec.
med. brachial cutaneous (sensory only)
medial antebrachial cutaneous (sen. only)
Ulnar

Question 28

medial and lat cord

Answer 28

Median nerve