Shoulder

Question 1

Name the 6 muscles of the scapulohumeral group (Intrinsic shoulder muscles)

Answer 1

Deltoid, teres major, and the four rotator cuff muscles (supraspinatus, infraspinatus, supscapularis and teres minor).

Question 2

What are the attachments of the Deltoid muscle?

Answer 2

Originates from the scapula and clavicle, and attaches to the deltoid tuberosity on the lateral surface of the humerus.

Question 3

What nerve innervates the deltoid?

Answer 3

Axillary

Question 4

What are the actions of the deltoid?

Answer 4

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 5

Attachments of teres major

Answer 5

Originates from the posterior surface of the inferior angle of the scapula. It attaches to the intertubecular groove of the humerus.

Question 6

Innervation of teres major

Answer 6

Lower subscapular nerve.

Question 7

Actions of teres major

Answer 7

Adducts at the shoulder and medially rotates the arm.

Question 8

Supraspinatus - innervation & actions

Answer 8

Innervation: Suprascapular nerve.

Actions: Abducts the arm 0-15o, and assists deltoid for 15-90o

Question 9

Infraspinatus innervation and action

Answer 9

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

Question 10

Subscapularis - innervation & action

Answer 10

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

Question 11

Teres minor - innervation & action

Answer 11

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

Question 12

What are the two extrinsic muscles of the shoulder?

Answer 12

the trapezius and latissimus dorsi.

Question 13

What is the innervation of the trapezius?

Answer 13

Motor innervation is from the accessory nerve. It also receives proprioceptor fibres from C3 and C4 spinal nerves.

Question 14

Actions of the trapezius

Answer 14

The upper fibres of the trapezius elevates the scapula and rotates it during abduction of the arm.

The middle fibres retract the scapula and the lower fibres pull the scapula inferiorly.

Question 15

Latissimus dorsi innervation

Answer 15

Thoracodorsal nerve

Question 16

Actions of latissimus dorsi

Answer 16

Extends, adducts and medially rotates the upper limb

Question 17

What are the three deep extrinsic muscles of the shoulder?

Answer 17

Levator scapulae and the two rhomboids.

Question 18

Innervation and action of the levator scapulae

Answer 18

Dorsal scapula nerve - elevates

Question 19

Nerve innervation of rhomboids (minor and major)

Answer 19

Dorsal scapula nerve.

Question 20

Action of rhomboids

Answer 20

Retract and rotate scapular

Question 21

Differentiate between extrinsic and intrinsic muscles of the shoulder

Answer 21

Extrinsic - originate from the torso, and attach to the bones of the shoulder (clavicle, scapula or humerus).

Intrinsic – originate from the scapula and/or clavicle, and attach to the humerus.