Shoulder Muscles

Question 1

What is the function of the deltoid? Give the innervation

Answer 1

Innervation: Axillary nerve.

Actions: The anterior fibres flex the arm at the shoulder, the posterior fibres extend the arm at the shoulder. The middle fibres are the major abductor of the arm – it takes over from the supraspinatus, which abducts the first 15 degrees.

Question 2

What is the function of the supraspinatus? Give the innervation

Answer 2

Innervation: Suprascapular nerve.
Actions: Abducts the arm 0-15o, and assists deltoid for 15-90o

Question 3

What is the function of the infraspinatus Give the innervation

Answer 3

Innervation: Suprascapular nerve.
Actions: Laterally rotates the arm.

Question 4

What is the function of the subscapularis? Give the innervation

Answer 4

Innervation: Upper and lower subscapular nerves.
Actions: Medially rotates the arm.

Question 5

What is the function of teres minor? Give the innervation

Answer 5

Innervation: Axillary nerve.
Actions: Laterally rotates the arm.