Jan 30, 2011

Anatomy Basics: The Skeleton of the Back

The Back
As we move down from the neck, the next group of muscles we will look at we at will be those of the back. I find the back one of the more interesting yet difficult areas of the body to draw. There is so much happening in the back that it is easy to get lost in the forms of the muscles as they weave together to  create the large mass that is the back. Learning what muscles make those forms and how they move the body makes the process easier when translating what we see into a drawing.

Before we start looking the muscles we need to look at the skeletal structure that supports them.  

Today we will identify the major components that make up the skeleton of the torso as seen from the back.

The Back View of Skeleton 

To the right is a diagram that shows the bones that play a role in supporting the muscles of the back. These include:

  • Vertebral column (spine)
  • Clavicle (collar bone)
  • Scapula (shoulder blade)
  • Thoracic cage (ribcage)
  • Pelvis

Regions of Vertebrae
1. The Spine

The spine or vertebral column is made up of 24 individual bones called vertebrae, along with two sections of fused vertebrae called the sacrum and coccyx. The vertebral column is what houses the spinal cord and supports the neck, head, and torso when standing up.

The vertebrae of the spine are separated into three different regions that correspond to the neck, rib cage, and lower back. 

There are seven vertebrae in the neck. These are called the cervical vertebrae. When one twists his head to the side these vertebrae rotate and twist on top of each other.

The seventh cervical vertebrae makes a good reference point to align forms. This bone sits just above the ribcage and protrudes out just slightly. 

There are twelve vertebrae that correspond to the rib cage. These are the thoracic vertebrae, the ribs connect to the sides of these vertebrae and these also twist and bend to move the torso. 

The last five individual vertebrae found at the base of the spine are the lumbar vertebrae. These vertebrae twist when a person twists her torso to the side.

The sacrum is a group of fused vertebrae at the base of the vertebral column. The sacrum is what connects the spine to the pelvis. The coccyx is the last bone of the spinal column. Also called the tail bone, this bone is the small bone attached to the bottom of the sacrum.

The ribcage and scapula 
2. Rib Cage and Shoulder Blades

The ribcage or thoracic cage the is the group of rib bones that form a rounded cage around the heart, lungs, and other organs. The muscles of the upper torso attach to this. The ribcage protects the organs and flexes to allow for breathing and movement of the torso.

What is commonly called the shoulder blade is  a bone called the scapula. The scapula floats over the ribcage and meets the clavicle at the shoulder. The scapula assist in raising the arm up.

The pelvis
3. The Pelvis

Attached to the spine at the sacrum is the pelvis. The lower back muscles attach to the pelvis and assist in twisting from the hips.
In the next anatomy post we will start looking at how the muscles of the back attach to the skeleton. There will be some parts of the skeleton that we can use as reference points in order to understand how the muscle line up.
Richer, Paul and Hale, Robert Beverly, Artistic AnatomyWatson-Guptill publications, New York, 1971
Jeno Barcsay, Anatomy For The Artist, Barnes and Nobles Books, New York, 1995

Vertebral Column, http://en.wikipedia.org/wiki/Vertebral_column, Wikipedia, January 29, 2011
Pelvis, http://en.wikipedia.org/wiki/Pelvis, Wikipedia, January 29, 2011
Rib Cagehttp://en.wikipedia.org/wiki/Rib_cage, Wikipedia, January 29, 2011

Google Body, Google Labs, http://bodybrowser.googlelabs.com/ January 29, 2011