Muscle groups
Shoulder
Deltoid
The origin of the deltoid is at the clavicle.
The insertion of this muscle is at the lateral surface of the humerus.
The joint action occurs when the anterior fibres flex the shoulder and assist in horizontal flextion and medial rotation.
Pectoralis major
Origin - Clavical, sternum and cartilages of ribs from 1-6.
Insertion - Top of the humerus.
The joint crossed - Glenohumeral.
Joint actions - Shoulder horizontal flextion
- Shoulder adduction
- Shoulder medial rotation
Latissimus dorsi
Origin - thoracolumbar
Insertion - Top of the humerus
Joint crossed - Shoulder joint
Joint action - Origin fixed: adducts and extends the arm
Insertion fixed: tilts the pelvis forwards
Teres Major
Origin - Lateral border of the scapula near the inferior angle
Insertion - Humerus
Joint crossed - Shoulder joint
Joint action - Medial rotation, adduction and extension of the shoulder