Muscles of Shoulder Joint

Question 1

Pectoralis Major

Answer 1

Origin: Clavicle, sternum, ribs 1 to 6
Insertion: Ant. surface of humerus
Action: Adduction, horizontal flex., med, rotation of shoulder joint

Question 2

Deltoids

Answer 2

Origin: Scapula and clavicle
Insertion: Lat. tub. of humerus
Action: Flex., horizontal flex., med. rotation of shoulder (ant. fibres). Abduction of shoulder (lat. fibres). Ext., horizontal ext., lat. rotation of shoulder (post. fibres)

Question 3

Latissimus Dorsi

Answer 3

Origin: T6 to T12, L1 to L5, iliac crest, lower 3 ribs
Insertion: Ant. surface of humerus
Action: Ext., adduction, med. rotation of shoulder

Question 4

Teres Major

Answer 4

Origin: Inf. angle of scapula
Insertion: Sup. and ant. surface of humerus
Action: Ext., adduction, med. rotation of shoulder