Muscles of the shoulder region

Question 1

What are the extrinsic muscles of the shoulder?

Answer 1

Trapezius
Latissimus dorsi
Levator scapulae
Rhomboid major
Rhomboid minor

Question 2

Which extrinsic muscles are located superficially?

Answer 2

Trapezius

Latissimus dorsi

Question 3

Which extrinsic muscles are located deeply?

Answer 3

Levator scapulae
Rhomboid major
Rhomboid minor

Question 4

Trapezius

Answer 4

O: External occipital protuberance (of the skull), ligament nuchae, spinous process of C7-T12

I: Clavicle, acromion and spine of scapula

I: Spinal accessory nerve (cranial nerve IX) and proprioceptors from C3+C4

A: Elevate scapula and rotate during abduction of arm above 90° (upper fibres), retract the scapula (middle fibres), pull scapula inferiorly (lower fibres)

Question 5

Latissimus Dorsi

Answer 5

O: Spinous processes of T6-T12, iliac crest, thoracolumbar fascia and inferior three ribs

I: Fibres converge into a tendon inserting to intertubercular sulcus of the humerus

I: Thoracodorsal nerve

A: Extends, abducts and medially rotates the upper limb

Question 6

Levator Scapulae

Answer 6

O: transverse processes of C1-C4 vertebrae

I: Medial border of the scapula

I: Dorsal scapular nerve

A: Elevates the scapula

Question 7

Rhomboid Minor

Answer 7

O: Spinous processes of C7-T1 vertebrae

I: Medial border of the scapula

I: Dorsal scapular nerve

A: Retracts the scapula and rotates the medial border (helps return to anatomical position after abduction of arm above 90°)

(located superior to rhomboid major)

Question 8

Rhomboid Major

Answer 8

O: Spinous processes of T2-T5 vertebrae

I: Medial border of the scapula

I: Dorsal scapular nerve

A: Retracts the scapula and rotates the medial border (helps return to anatomical position after abduction of arm above 90°)

Question 9

What are the 6 intrinsic muscles of the shoulder?

Answer 9

Deltoid
Teres major
Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 10

Deltoid (also in S6)

Answer 10

O: Anterior border and upper surface of the lateral third of clavicle

I: Deltoid tuberosity of the humerus

I: Axillary nerve

A:

• Anterior = flexion and medial rotation of the arm
• Middle fibres = abduct the arm from 15-90°
• Posterior fibres = extend and laterally rotate the arm

Question 11

Teres major

Answer 11

O: Posterior surface of the inferior angle of the scapula

I: Medial lip of the intertubercular groove of the humerus

I: Lower subscapularis nerve

A: Adducts and extends the arm (and medial rotation)

Question 12

Supraspinatus

Answer 12

O: Supraspinous fossa of the scapula

I: Greater tubercle of the humerus

I: Suprascapular nerve

A: Abducts the arm from 0-15° and assist deltoid to abduct 15-90°

Question 13

Infraspinatus

Answer 13

O: Infraspinous fossa of the scapula

I: Greater tubercle of the humerus

I: Suprascapular nerve

A: lateral rotation of the arm

Question 14

Subscapularis

Answer 14

O: Subscapular fossa

I: Lesser tubercle of the humerus

I: Upper and lower subscapular nerve

A: medial rotation of the arm

Question 15

Teres minor

Answer 15

O: Posterior surface of the scapula

I: Greater tubercle of the humerus

I: Axillary nerve

A: Lateral rotation of the arm