Upper Extremity Muscles

Question 1

Deltoid

Answer 1

Innervation: Axillary nerve
Blood Supply: Posterior circumflex humeral artery,
deltoid branch of thoraco‐acromial
artery
Action: Clavicular part: flexes and medially
rotates arm
Acromial part: abducts arm beyond
initial 15 degrees done by
supraspinatus Spinal part: extends
and laterally rotates arm

Question 2

Infraspinatus

Answer 2

Innervation: Suprascapular nerve
Blood Supply: Suprascapular artery
Action: Lateral rotation of arm (with teres minor)

Question 3

Supraspinatus

Answer 3

Innervation: Suprascapular nerve
Blood Supply: Suprascapular artery
Action: Initiates arm abduction, acts with rotator cuff muscles

Question 4

Serratus Anterior

Answer 4

Innervation: Long thoracic nerve
Blood Supply: Lateral thoracic artery
Action: Protracts and rotates scapula and holds it against thoracic wall

Question 5

Subclavius

Answer 5

Innervation: Nerve to subclavius
Blood Supply: Clavicular branch of thoraco‐acromial artery
Action: Anchors and depresses clavicle

Question 6

Subscapularis

Answer 6

Innervation: Upper and lower subscapular nerves
Blood Supply: Subscapular artery, lateral thoracic
artery
Action: Medially rotates arm at shoulder and
adducts it, helps hold humeral head
in glenoid cavity

Question 7

Teres Major

Answer 7

Innervation: Lower subscapular nerve
Blood Supply: Circumflex scapular artery
Action: Adducts and medially rotates arm

Question 8

Teres Minor

Answer 8

Innervation: Axillary nerve
Blood Supply: Circumflex scapular artery
Action: Laterally rotates arm