Pectoral Region, Axilla, and the Brachial Plexus

Question 1

Pectoral fascia is continuous with…

Answer 1

Axillary fascia

Question 2

Clavipectoral fascia connects

Answer 2

Clavicle to floor of axilla

Question 3

Lymph drainage of UL

Answer 3

Lateral (humeral) nodes

Question 4

Pectoralis major function and innervation

Answer 4

Function: medial rotation, flexion
Innervation: medial/lateral pectoral nerve

Question 5

Pectoralis minor function and innervation

Answer 5

Function: depresses coracoid process
Innervation: medial/lateral pectoral nerve

Question 6

Boundaries of axilla

Answer 6

Anterior: pectoralis muscles
Posterior: subscapularis, teres major, & latissimus dorsi muscles
Medial: serratus anterior
Lateral: humerus

Question 7

Contents of axilla

Answer 7

Axillary artery, brachial plexus, axillary vein

Question 8

Brachial plexus has 5 roots

Answer 8

C5, C6, C7, C8, T1

Question 9

Brachial plexus has 3 trunks

Answer 9

Upper, lower, middle

Question 10

What comes off the upper trunk of the brachial plexus

Answer 10

Suprascapular nerve

Question 11

What goes right through the roots?

Answer 11

Long thoracic nerve (C5-C7)

Question 12

Brachial plexus has 3 cords

Answer 12

Medial, lateral, posterior

Question 13

How are the 3 cords named?

Answer 13

Position of the axillary artery

Question 14

Branch of lateral cord

Answer 14

Lateral pectoral nerve

Question 15

Branches of posterior cord (3)

Answer 15

Lower SC nerve, thoracodorsal nerve, upper SC nerve

Question 16

Branches of medial cord

Answer 16

Medial antebrachial nerve, medial brachial cutaneous nerve, medial pectoral nerve

Question 17

5 terminal branches of brachial plexus

Answer 17

Axillary nerve, musculocutaneous nerve, median nerve, radial nerve, ulnar nerve

Question 18

Myotome - shoulder adduction

Answer 18

C5-T1

Question 19

Myotome - shoulder abduction

Answer 19

C5-C6

Question 20

Myotome - Elbow flexion

Answer 20

C5-C6

Question 21

Myotome - Elbow extension

Answer 21

C6-C8

Question 22

Myotome - wrist flexion

Answer 22

C7

Question 23

Myotome - wrist extension

Answer 23

C6

Question 24

Finger flexion myotome

Answer 24

C8

Question 25

Finger abduction, adduction myotome

Answer 25

T1

Question 26

Finger extension myotome

Answer 26

C7

Question 27

Major lymph nodes

Answer 27

Axillary nodes
1. Anterior/pectoral -> directly drain the breast
2. Posterior/subscapular
3. Lateral (humeral)
4. Central nodes
5. Apical - terminal

Question 28

Biceps MSR

Answer 28

C5-6 -> musculocutaneous nerve

Question 29

Brachioradialis MSR

Answer 29

C5-C6 (radial nerve)

Question 30

Triceps MSR

Answer 30

C7-C8 (radial nerve)

Question 31

Lymphedema

Answer 31

an accumulation of lymph in the interstitial space of a tissue/region (i.e. it cannot be aspirated
or drained) resulting in swelling (of hand, forearm, etc.); commonly occurs in the upper extremity following
breast/axilla surgery with iatrogenic disruption of axillary lymph channels draining the upper limb

Question 32

Upper brachial plexus injury results in…

Answer 32

Erb-Duchenne palsy (Erb’s palsy)

Question 33

Erb-Duchenne’s palsy

Answer 33

Injury to C5 and C6 nerve roots or upper trunk of brachial plexus due to traction placed on the neck

Question 34

Sensory loss of Erb’s palsy

Answer 34

C5-C6 dermatome

Question 35

Waiter’s tip position (Erb’s palsy)

Answer 35

✓ adducted = abductors are paralyzed
✓ medially rotated = lateral rotators are paralyzed
✓ extended = elbow flexors are paralyzed
✓ wrist flexed = wrist extensors are paralyzed

Question 36

What can cause Erb’s palsy?

Answer 36

Widening the angle of separation, difficult fetal delivery, falling on shoulder and head simultaneously

Question 37

Lower brachial plexus injury

Answer 37

Klumpke’s palsy

Question 38

What can cause Klumpke’s palsy

Answer 38

Injury to C8, T1 nerve roots or lower trunk of brachial plexus
Catching one’s self in a hanging position while falling or difficult delivery of infant

Question 39

Symptoms of Klumpke’s palsy

Answer 39

Paralysis of hand muscles -> CLAW HAND
Sensory loss in C8-T1 dermatomes

Question 40

Axillary nerve injury (C5-C6)

Answer 40

Results in wasting of deltoid contour, weakness in shoulder abduction&raquo_space; flexion/extension of the arm, loss of cutaneous sensation over lower 1/2 of deltoid

Question 41

Radial nerve (C5-T1)

Answer 41

Injury to nerve as it exits the axilla or winds around the humerus in the “spiral” groove (midshaft humeral fracture), poor crutch placement, falling asleep with arm over back of chair (“Saturday night palsy”), downward dislocation of glenohumeral joint

Question 42

Radial nerve injury causes

Answer 42

Acute loss due to COMPLETE paralysis of all wrist extensors

Question 43

Axillary nerve injury (C5-C6)

Answer 43

Injury to nerve as it passes around the surgical neck of the humerus in quadrangular space,
occurs in downward glenohumeral dislocations, poor crutch placement, fracture of surgical neck
of humerus
• Results in wasting of deltoid contour, weakness in shoulder abduction&raquo_space; flexion/extension of
the arm, loss of cutaneous sensation over lower 1/2 of deltoid

Question 44

Parsonage-Turner Syndrome

Answer 44

a. acute brachial plexus neuritis; bilateral in 20% of pts
b. most commonly affects long thoracic nerve, musculocutaneous n and axillary nerve
c. etiologies: diabetes, lupus, viral infection, immunization

Question 45

Musculocutaneous spinal cord levels

Answer 45

C5, C6, C7

Question 46

Axillary spinal cord levels

Answer 46

C5, C6

Question 47

Median spinal nerve levels

Answer 47

C5-T1

Question 48

Radial spinal cord levels

Answer 48

C5-T1

Question 49

Ulnar spinal cord levels

Answer 49

C8, T1