Muscles of Upper limb

Question 1

What muscles act accessory muscles of respiration

Answer 1

Pectoralis major, minor, serratus anterior
(increases vol. of thoracic cavity)

Question 2

Important landmark of Brachial plexus

Answer 2

Coracobrachialis

Question 3

Muscles in Pectoral Region

Answer 3

Pectoralis Major (superficial)
Pectoralis Minor (deep to ↑)
Serratus Anterior (deep to ↑)
Subclavius

Question 4

O, I, A, Inv for Pectoralis Major

Answer 4

O: Sternal head, Clavicular head
I: Intertubercular sulcus
A: Arm adduction, medial rotation, draw scapula anteroinferiorly
Inv: Lateral (C5-7) & Medial pectoral nerves (C8-T1)

Question 5

O, I, A, Inv for Pectoralis Minor

Answer 5

O: 3’rd-5th ribs
I: Coracoid process
A: Draw scapula anteroinferiorly (stabilises)
Ins: Medial pectoral nerve (C8-T1)

Question 6

O, I, A, Inv for Serratus anterior

Answer 6

O: 1’st-8th ribs
I: Scapula
A: Rotates scapula (arm raised above 90°)
Inv: Long thoracic nerve (C5-7)

Question 7

O, I, A, Inv for Subclavius

Answer 7

O: 1’st rib
I: Clavicle
A: Anchors clavicle
Inv: Nerve to subclavius

Question 8

O, I, A, Inv for Coracobrachialis

Answer 8

O: Coracoid process
Insertion: Humerus
A: Elbow flexion, weak adduction
Inv: Musculocutaneous nerve (C5-7)

Question 9

O, I, A, Inv for Deltoid

Answer 9

O: Clavicle, Scapula
I: Deltoid tuberosity
A: (Ant.) Arm flexion, medial rotation, (Mid.) abduction (15-90°), (Post.) Arm extension, lateral rotation
Inv: Axillary nerve (C5, C6)

Question 10

What happens when the long thoracic nerve is damaged and what are the causes of this

Answer 10

Serratus anterior is paralysed.
Winged scapula deformity -medial border of the scapula is no longer held against the chest wall and protrudes posteriorly
Cause: Trauma
e.g.) Surgical trauma: Mastectomy with axillary clearance
Blunt trauma: Sudden depression of the shoulder girdle

Question 11

The axillary borders

Answer 11

Apex: Lateral border of the first rib
Base: Axillary fascia
Lateral wall: Intertubercular sulcus of the humerus
Medial wall: Serratus anterior, ribs, intercostal muscles
Anterior wall: Pectoralis major, minor, subclavius
Posterior wall: Subscapularis, teres major, latissimus dorsi

Question 12

Contents of the axilla

Answer 12

Axillary artery
Axillary vein
Cords of the brachial plexus
Intercostobrachial nerve
Axillary lymph node

Question 13

Three routes by which structures leave the axilla

Answer 13

1. Inferiorly and laterally, into the upper limb
2. Quadrangular space (axillary nerve, posterior circumflex artery pass)
3. Clavipectoral triangle (cephalic vein enters, medial & lateral pectoral nerves leave)

Question 14

Lymph nodes of the axilla

Answer 14

A nterior (pectoral) group
P osterior (subscapular) group
I nfraclavicular (deltopectoral) group
C entral group
A pical group
L ateral group

Question 15

Causes of Axillary lymphadenopathy

Answer 15

Infection of upper limb (causes lymphangitis)
Infection of the pectoral region & breast
Metastases from breast cancer
Leukaemia/lymphoma
Metastases from malignant melanoma in upper limb

Question 16

What nerves are at risk of damage during axillary lymph node dissection

Answer 16

Thoracic nerve
Thoracodorsal nerve (supply to latissimus dorsi)

Question 17

The five main vessels that the arterial supplied to the upper limb

Answer 17

Subclavian artery
Axillary artery
Brachial artery
Radial artery
Ulnar artery

Question 18

Main branches of the Axillary artery

Answer 18

First part (proximal to pectoralis minor):
Superior thoracic artery

Second part (posterior to pectoralis minor):
Thoracoacromial artery, Lateral thoracic artery

Third part (distal to pectoralis minor):
Subcapsular artery, anterior&posterior circumflex humeral artery

Question 19

What does the anterior and posterior circumflex humeral arteries form

Answer 19

Anastomotic network
(can be damaged in fractures of this region)

Question 20

Where is the second most common site for avascular necrosis to occur

Answer 20

Head of humerus

Question 21

Main branches of the Axillary vein

Answer 21

First part (above pectoralis minor): Cephalic vein

Second part (posterior to pectoralis minor):
Thoracoacromial vein, Lateral thoracic vein

Third part (distal to pectoralis minor):
Subcapsular vein, anterior&posterior circumflex humeral vein

Question 22

Where does the axillary vein drain deoxygenated blood from

Answer 22

Arm
Axilla
Superolateral chest wall