Axilla, Brachial Plexus, Anatomical Spaces, Brachium

Question 1

Axilla Walls

Answer 1

apex: “armpit”
base: skin
anterior wall: pectoralis major + minor
lateral wall: upper humerus
medial wall: serratus anterior, rib cage
posterior wall: latissimus dorsi, subscapularis, teres major

Question 2

Brachial Plexus

Answer 2

anterior/ventral rami of C5-T1

Question 3

RTDCB

Answer 3

r - rami
t - trunk (superior, midde, inferior)
d - dividions (3 anterior, 3 posterior)
c - cords (lateral, medial, posterior)
b - branches (5 terminal branches)

Question 4

Thoracic Outlet

Answer 4

• subclavian artery and vein travel out of thoracic outlet
• transitions to axillary artery and vein which travels alongside brachial plexus down the arm

Question 5

Thoracic Outlet Syndrome

Answer 5

• compression of nerves, arteries, or veins, in thoracic outlet region
• typically occurs via compression in space b/w clavicle and 1st rib, pec mionr, or presence of a cervical rib
• possible UE S/S = pain, weakness, numbness, muscle atrophy, swelling
  related to peripheral nerve distribution

Question 6

Quadrangular Space

Answer 6

• inferior margin of teres minor
• surgical neck of humerus
• superior margin of teres major
• lateral margin of triceps brachii (long head)
• contents = axillary nerve, posterior circumflex humeral artery and vein

Question 7

Triangular Space

Answer 7

• medial margin of triceps brachii (long head)
• superior margin of teres major
• inferior margin of teres minor
• contents = circumflex scapular artery and vein

Question 8

Triangular Interval

Answer 8

• lateral margin of triceps brachii (long head)
• shaft of humerus
• inferior margin of teres major
• contents = radial nerve, profunda brachii artery

Question 9

What is the only synovial joint articulation b/w the UE and axial skeleton?

Answer 9

sternoclavicular (SC) joint

Question 10

Anterior/Flexor Compartment of Brachium

Answer 10

• 3 muscles (biceps brachii, brachialis, coracobrachialis)
• brachial artery (main blood supply of UE)
• innervated by musculocutaneous nerve

Question 11

Who is the strongest elbow flexor?

Answer 11

brachialis

Question 12

Musculocutaneous Nerve

Answer 12

• from lateral cord … ventral rami C5, C6, C7
• motor innervation fo all muscles of anterior compartment of upper arm
• sensory innervation to skin of lateral forearm

Question 13

Posterior/Extensor Compartment of Brachium

Answer 13

• 1 muscle (triceps brachii)
• deep brachial artery (aka profunda brachii artery)
• innervated by radial nerve

Question 14

Who is the chief elbow extensor?

Answer 14

triceps brachii