Arm/Shoulder/Forearm Muscles

1. Arm/Shoulder/Forearm Muscles Alex Day January 2010

2. Arm/Shoulder Muscles

3. Biceps Brachii The biceps has several functions, the most important being to rotate the forearm and to flex the elbow. The biceps is tri-articulate, meaning that it works across three joints. Proximal radioulnar joint – Humeroulnar joint – (Elbow) Glenohumeral joint – (Shoulder)

4. Brachialis A muscle in the upper arm that flexes the elbow joint. It lies just deep of the biceps brachii, and is a synergist that assists the biceps brachii in flexing at the elbow. The brachialis is the strongest flexor of the elbow.

5. Deltoid -The muscle forming the rounded contour of the shoulder. -An important function of the deltoid in humans is stopping : preventing the dislocation of the humeral head when a person carries heavy loads. 1.The anterior fibers are involved in shoulder abduction when the shoulder is externally rotated. 2. The posterior fibers are strongly involved in transverse extension 3. The lateral fibers are involved in shoulder abduction when the shoulder is internally rotated, are involved in shoulder flexion when the shoulder is internally rotated, and are involved in shoulder transverse abduction (shoulder externally rotated)

6. Arm/Forearm Muscles

7. Triceps Brachii The large muscle on the back of the human upper limb. It is the muscle principally responsible for extension of the elbow joint (i.e. straightening of the arm). 1.The three heads have the following names and origins: The "Long head": infraglenoid tubercle of the scapula. 2. The "Lateral head": posterior shaft of the humerus, lateral and superior to the radial (spiral) groove. 3. The "Medial head": posterior shaft of the humerus, medial and inferior to the radial (spiral) groove

8. Flexor Carpi Radialis Amuscle of the human forearm that acts to flex and abduct the hand.

9. Flexor Carpi Ulnaris -A muscle of the human forearm that acts to flex and adduct the hand. -Flexor carpiulnaris muscle arises by two heads - humeral and ulnar

10. Flexor DigitorumSuperficialis An extrinsic flexor muscle of the fingers at the proximal interphalangeal joints. -The muscle has two classically described heads - the humeroulnar and radial. The primary function of flexor digitorumsuperficialis is flexion of the middle phalanges of the fingers at the proximal interphalangeal joints, however under continued action it also flexes the metacarpophalangeal joints and wrist joint.

11. Extensor Carpi Radialis It is one of the five main muscles that control movements at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone (metacarpal of the index finger).

12. Extensor Digitorum a muscle of the posterior forearm present in humans and other animals. It extends the medial four digits of the hand. -It divides below into four tendons -The tendons then diverge on the back of the hand, and are inserted into the middle and distal phalanges