Brachial Plexus

Question 1

What is the brachial plexus?

Answer 1

Collection of anterior/ventral rami of spinal nerves coming together to form a set of peripheral nerves

Question 2

What muscles are supplied by the brachial plexus?

Answer 2

Shoulder girdle + upper limbs muscles

Question 3

Where does the brachial plexus supply sensation to?

Answer 3

Upper limbs

Question 4

Location of brachial plexus

Answer 4

Axilla + neck

Question 5

Colloquial term for axilla

Answer 5

Armpits

Question 6

Mnemonic for remembering part of brachial plexus

Answer 6

Remember To Drink Cold Beer

Roots Trunks Divisions Cords Branches

Question 7

Which spinal nerves are in the brachial plexus?

Answer 7

C5-T1

Question 8

Origin + roots of long thoracic nerve

Answer 8

C5, C6, C7
From anterior rami of spinal nerves (roots)

Question 9

What does damage to the long thoracic nerve cause?

Answer 9

Winged scapula

Question 10

What are the trunks of the brachial plexus?

Answer 10

Superior
Middle
Inferior

Question 11

Roots of the superior trunk of brachial plexus

Answer 11

C5, C6

Question 12

Roots of the middle trunk of brachial plexus

Answer 12

C7

Question 13

Roots of the inferior trunk of brachial plexus

Answer 13

C8, T1

Question 14

What does the anterior division of the superior trunk branch into in the brachial plexus?

Answer 14

Lateral cord

Question 15

What does the posterior division of the superior trunk branch into in the brachial plexus?

Answer 15

Posterior cord

Question 16

What does the anterior division of the middle trunk branch into in the brachial plexus?

Answer 16

Lateral cord

Question 17

What does the posterior division of the middle trunk branch into in the brachial plexus?

Answer 17

Posterior cord

Question 18

What does the anterior division of the inferior trunk branch into in the brachial plexus?

Answer 18

Medial cord

Question 19

What does the posterior division of the inferior trunk branch into in the brachial plexus?

Answer 19

Posterior cord

Question 20

What branches off the lateral cord in the brachial plexus?

Answer 20

Musculocutanoeus nerve
Median nerve

(Lateral pectoral nerve)

Question 21

Origin + roots of lateral pectoral nerve

Answer 21

C5, C6, C7
From lateral cord

Question 22

What branches off the medial cord in the brachial plexus?

Answer 22

Median nerve
Ulnar nerve

(Medial pectoral nerve)

Question 23

Origin + roots of medial pectoral nerve

Answer 23

C8, T1
From medial cord

Question 24

What branches from the posterior cord of the brachial plexus?

Answer 24

Axillary nerve
Radial nerve

Question 25

Where does the musculocutaneous nerve branch from?

Answer 25

Lateral cord

Question 26

Where does the axillary nerve branch from?

Answer 26

Posterior cord

Question 27

Where does the radial nerve branch from?

Answer 27

Posterior cord

Question 28

Where does the median nerve branch from?

Answer 28

Lateral + medial cord

Question 29

Where does the ulnar nerve branch from?

Answer 29

Medial cord

Question 30

Origin + roots of musculocutaneous nerve

Answer 30

C5, C6, C7 From lateral cord Three musketeers

Question 31

Origin + roots of axillary nerve

Answer 31

C5, C6 From posterior cord Assassinated

Question 32

Origin + roots of median nerve

Answer 32

C5, C6, C7, C8, T1 From lateral + medial cord Five mice

Question 33

Origin + roots of radial nerve

Answer 33

C5, C6, C7, C8, T1 From posterior cord Five rats

Question 34

Origin + roots of ulnar nerve

Answer 34

C8, T1 From medial cord Two unicorns

Question 35

Motor function of musclocutaneous nerve

Answer 35

**Anterior arm** - biceps brachii - brachialis -coracobranchialis

Question 36

Sensory function of musclocutaneous nerve

Answer 36

Becomes lateral cutaneous nerve of forearm Lateral forearm

Question 37

Motor function of axillary nerve

Answer 37

**Shoulder muscles** - deltoid - teres minor

Question 38

Sensory function of axillary nerve

Answer 38

Lateral aspect of superior arm *’regimental badge area’*

Question 39

Motor function of median nerve

Answer 39

Anterior forearm Thenar muscles

Question 40

Sensory function of median nerve

Answer 40

Radial 3 1/2 digits of palmar hand + tips of those fingers on dorsum of hand Thumb, pointer + 1/2 middle

Question 41

Motor function of radial nerve

Answer 41

**Posterior arm + forearm**

Question 42

Sensory function of radial nerve

Answer 42

4 branches Posterior arm Forearm Dorsum of hand - radial 3 1/2 digits NOT fingertips

Question 43

Motor function of ulnar nerve

Answer 43

Flexor carpi ulnaris Flexor digitorum profundus Intrinsic muscles of hand (*not LOAF*)

Question 44

Sensory function of ulnar nerve

Answer 44

Ulnar 1 1/2 digits of hand - plantar + dorsum Little + 1/2 ring

Question 45

What does an upper brachial plexus injury affect?

Answer 45

Superior trunk C5 + C6 nerve roots

Question 46

Mechanism of an upper brachial plexus injury

Answer 46

- Fall onto neck > excess lateral flexion - Obstetric complication > shoulder dystocia

Question 47

Presentation of upper brachial plexus injury Name for this position

Answer 47

Arm -ADducted + internally rotated Elbow - extended + pronated Wrist - flexed **Waiters Tip Position**

Question 48

Reason for Waiters Tip Position in Erb’s Palsy

Answer 48

C5 + C6 nerve roots affected C5 - shoulder ABduction + external rotation C6 - elbow flexion, rust extension + supination Opposite of these myotomes occur in presentation

Question 49

Another name for upper brachial plexus injury

Answer 49

Erb’s palsy

Question 50

Another name for lower brachial plexus injury

Answer 50

Klumpke’s palsy

Question 51

What does a lower brachial plexus injury affect?

Answer 51

Inferior trunk C8 + T1 nerve roots

Question 52

Mechanism of lower brachial plexus injury

Answer 52

- Falling out of a tree + grabbing a branch - Obstetrics complication > delivery with arm pulled

Question 53

Presentation of Klumpke’s palsy Name for this position

Answer 53

- Hyperextension of metacarpophalangeal joints - Flexion of interphalangeal joints - ABduction of thumb **Claw hand**

Question 54

Reason for Claw hand in Klumpke’s palsy

Answer 54

C8 + T1 nerve roots affected C8 - finger flexion + extension + thumbs extension T1 - finger ADduction + ABduction

Question 55

List the peripheral nerves in the brachial plexus

Answer 55

Musculocutaneous Axillary Radial Median Ulnar

Question 56

What are the roots of the brachial plexus formed by?

Answer 56

Anterior rami of spinal nerves C5-T1

Question 57

What are the cords of the brachial plexus? What are they named relative to?

Answer 57

Lateral, posterior + medial cords Named by their relative position to the axillary artery

Question 58

Way to orientate yourself when looking at brachial plexus prosection

Answer 58

Look for **M shape** Made of musculocutaneous, median + ulnar nerve Superficial to axillary artery

Question 59

What is the M shape of the brachial plexus peripheral nerves made of?

Answer 59

Musculocutaneous Median Ulnar