Muscles of the Back and Shoulder

Question 1

Latissimus dorsi - name origin, insertion and actions

Answer 1

Origins: SP’s of T7-L5, posterior sacrum and iliac crest, TLF, lowest 3-4 ribs, inferior angle of scap
Insertion: bicipital groove
Actions: extension, adduction and medial rotation of shoulder

Question 2

Rhomboid major and minor - name origin, insertion and actions

Answer 2

Origin:
     - minor: SP's of C7-T1
     - major: SP's of T2-T5
Insertion: medial border of scapula
Actions: retraction, elevation and downward rotation of scapula

Question 3

Serratus anterior - name origin, insertion and actions

Answer 3

Origin: external surfaces of upper 8-9 ribs
Insertion: anterior surface of medial border of scapula
Actions: protraction, elevation, depression and upward rotation of scapula

Question 4

Teres major - name origin, insertion and actions

Answer 4

Origin: inferior lateral border of the scapula
Insertion: bicipital groove
Actions: extension, adduction and medial rotation of shoulder

Question 5

Teres minor (SITS) - name origin, insertion and actions

Answer 5

Origin: upper 2/3 of lateral border of scapula
Insertion: greater tubercle of humerus
Actions: lateral rotation of shoulder (stabilises humeral head)

Question 6

Supraspinatus (SITS) - name origin, insertion and actions

Answer 6

Origin: supraspinous fossa of the scapula
Insertion: greater tubercle of humerus
Actions: abduct the shoulder (stabilises humeral head)

Question 7

Infraspinatus (SITS) - name origin, insertion and actions

Answer 7

Origin: infraspinous fossa
Insertion: greater tubercle of humerus
Actions: lateral rotation of the shoulder (stabilises humeral head)

Question 8

Subscapularis (SITS) - name origin, insertion and actions

Answer 8

Origin: subscapular fossa of scapula
Insertion: lesser tubercle of humerus
Actions: medial rotation of shoulder (stabilises humeral head)

Question 9

Deltoid - name origin, insertion and actions

Answer 9

Origin: lateral 1/3 of clavicle, acromion and spine of scapula
Insertion: deltoid tuberosity of humerus
Actions:
- all fibres: abduction of the shoulder
- anterior fibres: flexion, medial rotation and horizontal adduction of the shoulder
- posterior fibres: extension, lateral rotation and horizontal abduction of shoulder

Question 10

Biceps brachii - name origin, insertion and actions

Answer 10

Origin:
- long head: supraglenoid tubercle of the scapula
- short head: coracoid process of scapula
Insertion: radial tuberosity, aponeurosis of the biceps brachii
Actions: flexion of the elbow, flexion of the shoulder and supination of the forearm

Question 11

Brachialis - name origin, insertion and actions

Answer 11

Origin: distal half of anterior humerus
Insertion: tuberosity and coronoid process of ulna
Actions: flexion of the elbow

Question 12

Triceps brachii - name origin, insertion and actions

Answer 12

Origin:
- long head: infraglenoid tubercle of scapula
- lateral head: posterior proximal half of the humerus
- medial head: posterior distal half of the humerus
Insertion: olecranon process of ulna
Actions:
- all heads: extension of elbow
- long heads: extension and adduction of the shoulder

Question 13

Brachioradialis - name origin, insertion and actions

Answer 13

Origin: proximal 2/3 of lateral supracondylar ridge of the humerus
Insertion: styloid process of the radius
Actions: flexion of the elbow, assists in pronation and supination of the forearm