Muscles

1-We have four groups.

2-Anterior group:

-Formed from biceps and brachialis.

Above the elbow the radial nerve (arrow) lies between the brachioradialis (Brd) and brachialis muscles (Br) and is typically outlined by a small layer of fat on axial T1-weighted images. The biceps (B) and extensor carpi radialis longus (ECRL)muscles are also indicated.

3-Posterior group:

-Formed from triceps and anconeus.

Normal triceps muscle and tendon. A, Sagittal T1-weighted MR image shows the triceps muscle (M) and its tendon (white arrows) inserting on the olecranon (O). Fat (F) is present in the olecranon fossa. The box delineates the field of view in the corresponding sonographic image.

4-Medial groups=flexors muscles arises from medial condyle as common tendon= pronator teres and palmaris longus and flexors.

5-Lateral groups=extensors muscles arise from lateral epicondyle
as common tendon.