Back muscles

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The back is a wide flat part on our dorsal side extending from the base of neck to end of spine. The backbone i.e. the vertebral column is not one single long bone. In adults it is a series of 26 bones attached to each other. The total number of vertebrae in children is 33. Each small bone that makes the backbone is called a vertebra. Between two successive vertebrae is a cushioning disc, the intervertebral disc. The back is held upright by muscles, tendons and ligaments attached to the backbone.

The spine with its vertebrae separated by intervertebral discs gives our back strength coupled with flexibility. Muscles at the back effect various types of movements. Thus the back appearing so broad and rigid like a plank is a dynamic structure.

Some of the major muscles at our backside are - (1) The Trapezius is a muscle of shoulder blade but two of these muscles form a diamond like shape and cover upper back. Fibers of the trapezius have an origin from the base of skull and first neck vertebra upto the last i.e. 12 th thoracic vertebra. It is inserted on collar bone, and on shoulder blade. The trapezius moves collar bone and steadies or moves the shoulder blade. (2) Latissimus dorsi - the broad fanlike muscles in middle portion of back. They originate in last 6 thoracic vertebrae and 5 lumbar vertebrae. The lumbar region is between the ribs and the hip bones. These muscles end up on the arm bone and bring arm near the body or can take it away as well as can move shoulders downward and backward. These muscles can also rotate arm. (3) Erector Spinae Muscles - This is a group of muscles or a muscle complex. It is a large mass composed of muscles and tendons. It spans from the neck to small of back that is almost entire length of the back. The erector spinae has three different layers of fibers. (3.1) The iliocostalis or lateral layer, (3.2) The longissimus or middle layer and (3.3) The spinalis or medial layer.

Together all these layers of the erector spinae extend the trunk. (4) Rhomboides major and minor - These two muscles extend from the medial margin of shoulder blade to the backbone. They help in bringing about movement of the scapula i.e. the shoulder blade. Here is a site for taking a close look at the muscles of our back http://www.bartleby.com/107/illus389.html
 

The copyright of the article Back muscles in Human Anatomy is owned by Narayan Dattatray Wadadekar. Permission to republish Back muscles in print or online must be granted by the author in writing.