Brachial Plexus

Question 1

What is the brachial plexus?

Answer 1

A spaghetti-like network of nerves in the axilla that controls movement and sensation in the upper extremity

Question 2

Draw the brachial plexus.

Answer 2

Question 3

What does MARMU stand for?

Answer 3

Musculocutaneous Nerve

Axillary Nerve

Radial Nerve

Medial Nerve

Ulnar Nerve

Question 4

Describe how the name of the subclavian artery changes as it moves towards the brachial plexus.

Answer 4

It starts as the subclavian artery until it crosses the 1st rib, where it then becomes the axillary artery until it crosses the teres major where it becomes the brachial artery.

THEY ARE ALL THE SAME ARTERY TUBE

Question 5

What is the largest artery coming off of the axillary artery?

Answer 5

Subscapular Artery

Question 6

What is the largest nerve off the brachial plexus?

Answer 6

Radial Nerve

Question 7

Describe how the brachial plexus is divided into sections.

Answer 7

Roots

Trunks

Divisions

Cords

Branches

“Real teachers drink cold beer.”

Question 8

What nerves are found in the roots of the brachial plexus?

Answer 8

Dorsal Scapular

Long Thoracic

Question 9

What nerves are found in the trunks of the brachial plexus?

Answer 9

Subclavian

Suprascapular

Question 10

What nerves are found in the divisions of the brachial plexus?

Answer 10

None

Question 11

What nerves are found in the cords of the brachial plexus?

Answer 11

Superior: Lateral Pectoral

Middle: Lower Subscapular, Middle Subscapular (thoracodorsal) and Upper Subscapular

Inferior: Medial Antebrachial Cutaneous, Medial Brachial Cutaneous and Medial Pectoral

Question 12

What nerves are found in the branches of the brachial plexus?

Answer 12

Musculocutaneous

Axillary

Radial

Medial

Ulnar

Question 13

What does the musculocutaneous nerve innervate?

Answer 13

Short head of the biceps

Brachialis

Coracobrachialis

“BBC”

Question 14

What is the middle subscapular nerve also known as?

Answer 14

Thoracodorsal Nerve

Question 15

What does the long thoracic nerve innervate?

Answer 15

Serratus Anterior

Question 16

What does the dorsal scapular nerve innervate?

Answer 16

Rhomboids and levator scapulae

Question 17

What does the suprascapular nerve innervate?

Answer 17

Supraspinatus and infraspinatus

Question 18

What does the subclavian nerve innervate?

Answer 18

Subclavius

Question 19

What does the lateral pectoral nerve innervate?

Answer 19

One of the two nerves innervating the pectoralis major

Question 20

What does the medial pectoral nerve innervate?

Answer 20

The pectoralis major and minor

Question 21

What does the upper subscapular nerve innervate?

Answer 21

One of the nerves that innervates the subscapularis muscle

Question 22

What does the lower subscapular nerve innervate?

Answer 22

One of the nerves that innervates the subscapularis muscle and the teres major

Question 23

What does the middle subscapular (thoracodorsal) nerve innervate?

Answer 23

Latissimus dorsi

Question 24

What does upper root damage cause?

Answer 24

Erb’s Palsy - results in the “tipper’s hand”

Question 25

What does lower root damage cause? What may look like lower root damage but actually is not?

Answer 25

Klumpke's Palsy - manifests as a claw hand True claw is caused by a lower root injury that results in damage to the radial, median and ulnar branches True ulnar claw is caused by distal damage to the ulnar nerve and NOT damage to the root which paralyzes the median 2 lumbricals responsible for moving the ring finger and the pinky

Question 26

Describe the "pope's blessing" and its difference from the true ulnar claw.

Answer 26

Both look the same but the "pope's blessing" is only seen in active flexion while the true ulnar claw is seen passively. The "pope's blessing" is caused by median nerve damage rather than ulnar nerve damage. The problem in this case is flexion of the lateral fingers, not the ring finger and the pinky but the index and middle fingers.

Question 27

What are the contributions of the musculocutaneous nerve?

Answer 27

C5, C6 and C7 Three musketeers

Question 28

What are the contributions of the axillary nerve?

Answer 28

C5 and C6 Assassinated

Question 29

What are the contributions of the radial nerve?

Answer 29

C5, C6, C7, C8 and T1 Five Rats

Question 30

What are the contributions of the median nerve?

Answer 30

C5, C6, C7, C8 and T1 Five mice

Question 31

What are the contributions of the ulnar nerve?

Answer 31

C8 and T1 Two unicorns

Question 32

What would injury to the inferior trunk affect?

Answer 32

The inferior trunk is C8 and T1 so it would affect the ulnar nerve.

Question 33

What would injury to the middle trunk affect?

Answer 33

The middle trunk is C7 so it would affect the middle finger, however there are no no nerve branches that arise directly from the middle trunk and isolated middle trunk injury is rare.

Question 34

What would injury to the superior trunk affect?

Answer 34

The superior trunk is C5 and C6 so it would affect all muscles with C5-C6 innervation and the index finger and the thumb.

Question 35

Which is the brachial plexus largely made up of, dorsal or ventral rami?

Answer 35

Ventral Rami