The Axilla

Question 1

What makes up the boundaries of the axilla?

Answer 1

Four walls:
Anterior: pectoralis major, pectoralis minor, and fascia
Posterior: scapula, subscapularis, teres major, and latissimus dorsi
Medial: Ribs 1-4, intercostal muscles, and serratus anterior
Lateral: intertubercular sulcus of the humerus

Base: axillary fossa (arm pit)

Apex: cervico-axillary canal

Question 2

What are the contents of the axilla?

Answer 2

Axillary artery 
Axillary vein
Axillary lymph nodes 
Brachial plexus
Short head of the bicep brachii 
Coracobrachialis 
Tendon of the long head of bicep brachii

Question 3

Where does the axillary artery begin and what are its 3 components?

Answer 3

Begins at rib 1 and continues until inferior borders of teres major

First part:
Superior thoracic artery: blood to subclavius, 1st and 2nd intercostal, serratus

Second part:
Throacoacromial:
Clavicular: supplies to sternoclavicular joint and subclavius
Acromial: supplies to deltoid
Deltoid: supplies to the deltoid
Pectoral: supples to the pectoral minor and part of pectoralis major
Lateral thoracic: supples to serratus anterior and lateral aspect of breast

Third part
Subscapular: supplies subscapularis muscle
Circumflex scapular: supplies posterior deltoid, teres minor, long head tri
Thoracodorsal: supplies latissimus dorsi
Anterior circumflex
Posterior circumflex

Question 4

Axillary vein

Answer 4

Union of the brachial (running medially) and cephalic vein (running laterally)

Question 5

Musculocutaneous

Answer 5

Branches form the lateral cord

Piecers through coracobrachialis and travels through bicep brachii and brachialis

Continues as lateral cutaneous nerve of forearm

Question 6

Median Nerve

Answer 6

Union of fibers from medial and lateral cords

Descends with brachial artery

Innervates muscles of the anterior forearm

Question 7

Ulnar nerve

Answer 7

Branches from the medial cord

Pass behind the medial epicondyle to enter forearm

Innervates flexor carpi ulnaris, flexor digitorum profundus, and intrinsic muscles of the hand

Question 8

Radial nerve

Answer 8

Branches from the posterior cord

Travels with deep brachial artery along radial groove

Innervates all muscles of posterior arm and the posterior lateral skin

Divides:
Superficial radial nerve: cutaneous innervation of the posterior forearm
Dee radial nerve: motor innervation of the posterior compartment

Question 9

Axillary nerve

Answer 9

Branches from the posterior cord

Innervates glenohumeral joint, teres minor, and deltoid muscle

Becomes the superior lateral brachial cutaneous nerve

Question 10

Nerves that arise from roots

Answer 10

Dorsal scapular:
From C5
Innervates rhomboids and levator scapulae

Long thoracic
From C5-C7
Innervates serratus anterior

1st intercostal nerve
From T1

Question 11

Nerves that arise from trunks

Answer 11

Nerve to subclavius
Arises from superior trunk
Innervates subclavius and sternoclavicular joint

Suprascapular
Arises from the superior trunk
Innervates superspinatus, infraspinatus, and glenohumeral joint

Question 12

Nerves from lateral cord

Answer 12

Lateral pectoral

Innervates pectoralis major and glenohumeral joint

Question 13

Nerves from medial cord

Answer 13

Medial pectoral
Innervates sternocostal pectoralis major and pectoralis minor

Medial cutaneous nerve of arm
Smalles nerve in brachial plexus
Innervates skin of medial arm

Medial cutaneous nerve of forearm
Innervates skin of medial side of the forearm

Question 14

Nerves arising from posterior cord

Answer 14

Upper subscapular
Innervates subscapularis

Lower subscapular
Innervates subscapularis and teres major

Thoracodorsal
Innervates latissimus dorsi

Question 15

Describe components of the subareolar lymphatic plexus

Answer 15

Laterally: axillary lymph nodes via the pectoral lymph nodes

Medially: parasternal lymph nodes

Inferiorly: abdominal lymph nodes