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Basic Anatomy for the Artist

Lesson #8

In our first 7 lessons we examined the anterior aspect of the body. In these next few lesson we will look at the posterior aspect. If you are a sculptor or a serious student of figure painting, then these are the things you will need to learn in order to properly apply your craft.


THE MUSCLES OF THE LOWER LEG, POSTERIOR ASPECT

  The SOLEUS and the GASTROCNEMIUS are the two muscles whose forms can be seen on the back of the lower leg.

The SOLEUS lies beneath the gastrocnemius but the forms of its lateral and medial margins can be seen, especially on the lateral side of the leg. This is worth noting as the form on the lateral side is therefore different from the medial side. The soleus is a large flat muscle attached to the upper one-fourth and head of the fibula, to a fibrous band which stretches between fibula and tibia. It acts with the gastrocnemius. The tendon of the soleus joins that of the gastrocnemius to form the achilles tendon which inserts into the calcaneum (heel bone).

The GASTROCNEMIUS is the large superficial muscle which is responsible for the principle form on the back of the lower leg. It has two bellies and therefore two heads. These are tendinous attachments to the femur above it's medial and lateral condyles, and they are large and flat. They span the back of the knee joint. The two fleshy bellies end in one flat tendon which blends with the tendon of the soleus to form the achillies tendon. This tendon creates a straight, taut form from the calcaneum to the area of the muscle bundles. There is an apparent change of form in this region especially in athletic persons whose leg muscles are well developed. Also, the demarcation between the two bellies are often seen as an indentation.

The SOLEUS and the GASTROCNEMIUS are the chief plantar flexors of the foot. When their muscle bundles contract they bring the heel up and the sole of the foot (the plantar aspect) into view. They are the propulsive force in walking and jumping and will always be seen as thickened definite forms when the front part of the foot is pressed to the ground and the heel is raised.

Adding to the balk at the back of the leg are three deep muscles which arise from the tibia and fibula and whose tendons pass into the foot behind the medial malleolus, using it as a pulley. Their long narrow tendons can create forms here which is worth noting.


THE MUSCLES OF THE BACK

 

The two SACROSPINALES which attach to the sacrum and to the skull and to structures between these two points are the long unifying muscles for the action of the vertebral column. They are seen as long columns on either side of the vertebrae, and are particularly prominent in the lumbar area.

The sacrospinalis muscle has a large flat tendinous attachment to the sacrum and the posterior part of the iliac crest. The pair of tendons create here a large, flat triangular
form on the buttocks over the sacral region. The muscle splits into three parts in the lumbar region, called spinalis, longissimus and ilio-costo-cervicalis.

The spinalis is a small part attaching to the spines of the lumbar and thoracic vertebra.

The logissimus is attached to all the lumbar spines (5), all the thoracic spines (12) and to the lower ten ribs. Part continues to attach to the transverse processes of the second
to the sixth cervical vertebrae. Yet another part continues to the skull to insert into the posterior margin of the mastoid process. Longissimus ties together the skull, vertebrae, ribs, sacrum and pelvis, an incredible unifying design.

The ilio-costo-cervicalis is inserted into the ribs and into the transverse processes of the fourth to the sixth cervical vertebrae. By its attachment to all the ribs it integrates the whole rib cage with the actions of the spine.

When both the sacrospinales contract, the vertebral column is bent backward (extension of the vertebral column) and the long column of muscle will be seen mounding up over the midline especially in the lumbar region. When one of the pair contract, the trunk is bent laterally (to the side).

The Quadratus Lumborum is a short, thick column of muscle arising from the posterior part of the iliac crest and inserting into the transverse process of the lumbar vertebrae, and the twelfth rib. Its origin is wider than its insertion into the rib so its lateral border is at an angle. It's mass and power is added to the sacrospinalis.


See you next time!