Two studies of a nude man, standing in profile to the right, with his right arm cut off to show the muscles of the side; a scene of a horseman charging at a fleeing man with a shield; a note on the action of the shoulder muscles, and above, a slight sketch of the shoulder and raised arm of the central nude; to the right of the figures is a slight sketch of an arm, extended horizontally; on the extreme right, a man's left leg and hip, viewed in profile to the right.

The sketch of a skirmish at lower left relates the anatomical drawings directly to Leonardo’s work on the mural of the Battle of Anghiari (1503-6). To the right, the study of the inside of the left leg is shown as if the body had been cut down the middle; a circle behind the genitalia is presumably intended to represent the bladder. In the lower thigh, the contour of the vastus medialis muscle can be seen, and behind the patella is a curving ridge probably due to the underlying tendons of sartorius, gracilis, semitendinosus and semimembranosus. On the lower leg, the bulges of the gastrocnemius and soleus muscles can be distinguished.

Vertical lines travelling upwards from the heel and toe are connected with Leonardo’s studies of posture; another vertical line in the drawing at the centre of the sheet demonstrates the principal that, when standing upright, the head should be directly above the heel. A horizontal line on the same drawing, passing through the pubis and the greater trochanter of the femur, is at the mid-point of the body.

In the drawing to the left of this, the arm is again cut away to show the serratus anterior and external abdominal oblique muscles on the trunk. Five muscle bodies on the shoulder are labelled: a is the clavicular portion of pectoralis major, and b c d o are all portions of the deltoid, which Leonardo habitually treated as distinct fascicles. Leonardo attributed different actions to the various portions of the deltoid:

"The principal muscles of the shoulder are three, that is b c d; and there are two lateral ones which move it forwards and backwards: a moves it forwards and o pulls it backwards; and b c d upwards; upwards and forwards, a b c; upwards and backwards, c d o; downwards, its own weight is almost enough."

While it is true that the portions of the deltoid have different actions, they do not in themselves explain the many actions of the shoulder.

Text adapted from M. Clayton and R. Philo, Leonardo da Vinci: Anatomist, 2012, no. 23.