Axilla & Brachial Plexus

Question 1

Boundaries of Axilla

Answer 1

1. Superiorly by the clavicle, the scapula, and the 1st rib
2. Inferiorly by the skin at the lower borders of the pectoralis major and the teres
   major/latissimus dorsi
3. Anteriorly by pectoral muscles
4. Posteriorly by the subscapularis
5. Medially by the serratus anterior
6. Laterally by the humerus

Question 2

Contents of Axilla

Answer 2

B. Contents

1. Brachial plexus
2. Axillary fat and fascia
3. Axillary vessels and branches
4. Axillary lymph nodes

Question 3

What roots does the BP come from

Answer 3

C5, C6, C7, T1

Question 4

How are spinal roots named as they come out of vertebrae?

Answer 4

C1 - C7 come out above respective vertebrae
C8 comes out above T1, there is no C8 vertebrae
T1 and onward come out below respective vertebrae

Question 5

What are the segments of the Brachial Plexus

Answer 5

“Real teachers drink cold beer”
Roots, trunks, divisions, cords, branches
Anterior Rami of C5-8 & T1

Question 6

What is another name for the middle subscapular nerve?

Answer 6

Thoracodorsal nerve

Question 7

What artery does the radial nerve travel with?

Answer 7

Deep brachial or profundi brachial artery

Question 8

Damage to what nerve results in carpal tunnel?

Answer 8

Median Nerve

Question 9

What nerves come from the lateral cord?

Answer 9

DS - dorsal scapular
SUBc - subclavius
SUP - suprascapular  
LP - lateral pectoral 
LT - long thoracic - from roots of C6-7

Question 10

What nerves come from the posterior cord?

Answer 10

L - lower subscapular
M - middle subscapular - also known as the thoracodorsal which goes to the lat
U - upper subscapular

Question 11

What nerves come from the medial cord?

Answer 11

MAC - medial antibrachial cutaneous
MBC - medial brachial cutaneous
MP - medial pectoral

Question 12

What nerves come from the “M/W”?

Answer 12

MAR-MU
M - musculocutaneous 
A - axillary 
R - radial 
M - medial 
U - ulnar

Question 13

What does the musculocutaneous nerve pierce?

Answer 13

Corachobrachealis.

Also innervates brachealis, and biceps.

Question 14

What does median nerve do in upper arm?

Answer 14

Nothing

Question 15

Branches of the axillary artery?

Answer 15

Screw The Lawyer, Save A Patient
S - Superior thoracic
T - thoracic acromial 
L - lateral thoracic 
S - subscapular - largest branch 
A - anterior circumflex humeral
P - posterior circumflex humeral

Question 16

Where do dorsal ramii go?

Answer 16

To the true back muscles

Question 17

Where does the subscapular nerve pass?

Answer 17

Under the transverse scapular ligament. Army over…navy under

Question 18

What provides sensation to the thumb?

Answer 18

C6 root

Question 19

What other nerve does C5 contribute to?

Answer 19

Phrenic Nerve

Question 20

Where do the trunks of the BP lie?

Answer 20

Between the scalene muscles medial to the midpoint of the clavicle

Question 21

Where do the BP divisions Lie?

Answer 21

Posterior to clavicle MP adjacent to third part of subclavian artery and beginning of axillary artery

Question 22

Where do the BP cords lie?

Answer 22

Extend laterally from clavicle midpoint to inferomedial aspect of coracoid process on the scapula

Question 23

Erb’s Palsy

Answer 23

Upper trunk injury
Effects suprascapular, musculocutaneous, and axillary nerves
Lose ability to laterally rotate leaving you in tip taking position

Question 24

Klumpke’s Palsy

Answer 24

Lower trunk injury - also called “TOTAL PAW”
If you pull on a babies are in general or in trying to deliver you can rip the lower trunk
“Klumpke the Monkey” - Makes your fingers permanently flexed

Question 25

Ulnar Claw

Answer 25

Caused by distal ulnar lesion paralyzing two medial lumbricals

Question 26

Pope’s blessing / Benedictine sign

Answer 26

Looks same as Ulnar Claw but only evident when making fist

Due to median nerve injury paralyzing lateral 2 lumbricals and weakening FDS

Question 27

MARMU mnemonic

Answer 27

3 Musketeers assassinated 5 rats, 5 mice, and 2 Unicorns