Axilla and Arm

Question 1

What is the innervation of pectoralis major and minor?

Answer 1

Major = medial and lateral pectoral nerves
Minor = medial pectoral nerve

Question 2

What is the action of pectorlais major?

Answer 2

Flexion of extended arm
Extension of flexed arm
Medial rotation

Question 3

What is the action of serratus anterior?

Answer 3

Protraction and rotation of scapula

Question 4

What causes winging of the scapula, and what effect does it have?

Answer 4

Damage to long thoracic nerve

Inferior angle / medial border of scapula elevate away from thoracic wall

Question 5

What structures form the 4 borders of the axilla?

Answer 5

Anterior:
pec major + minor
clavicopectoral fossa
subclavius

Medial:
thoracic wall
serratus anterior

Lateral:
intertubercular sulcus

Posterior:
subscapularis
teres major
latissimus dorsi
long head of tricps brachii

Question 6

What is contained within the neurovascular bundle of the axilla?

Answer 6

Brachial plexus
Axillary artery
Axillary vein

Question 7

Lymph nodes in the axilla drain 75% of the lymph from the breast. What is the clinical significance of this?

Answer 7

Patient may develop pitting oedema after mastectomy or nodal clearance

Question 8

Describe the cause, underlying pathology, and presentation of a patient with Erb’s palsy.

Answer 8

Cause: excessive increase in angle between neck and shoulder as a result of difficult birth or trauma to shoulder. Causes nerve roots to stretch. Damage to upper parts of brachial plexus.
Underlying pathology: Paralysis to supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, delotid and teres minor.
Presentation: arms hang limply, medially rotated (waiter’s tip position)

Question 9

Describe the cause, underlying pathology, and presentation of a patient with Klumpke’s palsy.

Answer 9

Causes: excessive abduction - damage to lower parts of brachial plexus.
Underlying pathology: Affects nerves derived from T1 - Ulnar and median nerves. Paralysis of all small hand muscles.
Presentation: Hand has clawed appearance. Loss of sensation along medial arm.

Question 10

Which artery is the axillary artery a continuation of, and which artery does is become?

Answer 10

Subclavian

Brachial

Question 11

Where do the anterior and posterior circumflex humeral arteries arise and where do they anastomose?

Answer 11

Arise inferior to pectoralis minor, anastamose around the surgical neck of the humerus via the quadrilateral space

Question 12

Which 3 muscles are flexors of the forearm

Answer 12

Biceps brachii
Brachialis
Coracobrachialis

Question 13

What is the common nerve supply to the flexors of the forearm?

Answer 13

Musculocutaneous

Question 14

Which artery supplies the anterior compartment of the forearm?

Answer 14

Brachial artery. Continues distally to elbow where it bifurcates into radial and ulnar arteries.

Question 15

Which artery supplies the posterior compartment of the forearm?

Answer 15

Profunda brachii

Question 16

What is the innervation of triceps brachii?

Answer 16

Radial nerve

Question 17

What is a Colle’s fracture?

Answer 17

Fracture of distal radius. Characteristic posterior displacement of the wrist to give ‘fork like’ appearance.

Question 18

What structure prevents hyperextension at the elbow?

Answer 18

Olecranon process

Question 19

What is a supracondylar fracture? Which artery is vulnerable and what problem may this cause?

Answer 19

Fracture of the distal humerus, just above the epicondyles. Common in children. Result of a fall on a hyperextended elbow. Brachial artery is at risk - circulation to foremarm is lost, which can lead to compartment syndrome.

Question 20

What structure is likely to be fractured if a person falls directly onto their elbow?

Answer 20

Olecranon