Posterior Trunk: Origin, Insertion, and Action

Question 1

Supraspinatus

Answer 1

Origin: Suprapinatus fossa
Insertion: superior aspect of the greater tubercle of the humerus
Action: abduction of shoulder/arm

Question 2

Infraspinatus

Answer 2

Origin: infraspinatus fossa
Insertion: middle portion of greater tubercle
Action: lateral rotation of arm/shoulder

Question 3

Subscapularis

Answer 3

Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Action: medial rotation of shoulder/arm

Question 4

Teres Major

Answer 4

Origin:lower lateral border/inferior angle of the scapula
Insertion:medial lip of intertubicular groove of humerus
Action: adduction; assists in medial rotation; works with shoulder extension

Question 5

Teres Minor

Answer 5

Origin: medical aspect of the lateral border of the scapula
Insertion: inferior aspect of the greater tubercle of humerus
Action: lateral rotation of shoulder/arm

Question 6

Rhomboid Major

Answer 6

Origin:spinous processes of T2-T5
Insertion: medial border of scapula
Action: retract and elevate scapula

Question 7

Rhomboid Minor

Answer 7

Origin:spinous process of C7-T1
Insertion: superior aspect of medial border of scapula
Action: retract and elevate scapula

Question 8

Latissmus Dorsi

Answer 8

Origin: spinous process of T7-L5; iliac crest; inferior angle of scapula; ribs 9/10-12
Insertion: floor of the intertubicular groove
Action: medially rotates arm/shoulder; adduction of arm; extends arm

Question 9

Triceps

Answer 9

Origin: longhead=infraglenoid tubercle of scapula; middle=dorsal surface of humerus; lateral head=distal surface of the humerus
Insertion: olecranon process of ulna
Action: extend the elbow and help extend shoulder

Question 10

Deltoid

Answer 10

Origin:ant=lateral 3rd of clavicle, middle=acromion, post= spine of scapula
Insertion: deltoid tuberosity
Action: abduction, shoulder flection, shoulder extension

Question 11

Trapezius

Answer 11

Origin: sup= external occipital protuberance; middle: spinous process of C7-T3
Insertion:sup= lateral 3rd of clavicle; retraction; elevation and depression of scapula; extending of neck