Basic Classification of Back MusclesCredit: http://www.synergy-athletics.com/effective-strength-training/2-exercises-to-build-stubborn-shoulders-and-upper-back-muscle/
There are superficial back muscles which are found very close to the skin and they play a role in movement of shoulders as well as neck and the arms. The intermediate back muscles are found in between the superficial layer and deep muscles of the skin. Deeply placed are the deep muscles of the back which give the upright posture of the individual.Credit: http://perfectbodyrx.com/2010/11/04/tonights-epic-back-workout-routine/
Discussing the Sub-divisions of Back Muscles
The outermost superficial muscles are divided into four groups, each with a specific function. These include Trapezius, Latissimus dorsi, Rhomboid major and Rhomboid minor. Trapezius muscles are long and trapezoid in shape extending from the upper part of the spinal cord. They originate from the basement region of the skull and they function to bring about scapular elevation which is involved in upward movement of shoulder blades. They are also involved in scapular adduction which is involved in pulling of the shoulder blades together. They play a role in scapular depression which will facilitate downward movement of the shoulder blades. Rhomboid muscles are the channels through which the shoulders are connected to the vertebral column. They function to pull the entire scapula towards the vertebral column, squeezing the shoulder blades. Latissimus dorsi muscles are the strongest muscles of the back which function to stretch and rotate the arms during certain activities such as swimming. They are large and fan shaped which will help the individual to acquire several body positions. Latissimus muscles are joined to the upper parts of the humerus with fibers which runs down to the vertebral column and gets to the pelvic girdle.Credit: http://www.jimmythomas.com/training/members/linklowerback.htm
Spinal Erectors as Part of Back Muscles
This is a collection of muscles which function to offer support to the spinal cord. They are attached at one end to the vertebrae. The ribs and pelvis are attached to the other end. They allow for extension of the spine in addition to supporting it. They include longissimus, spinalis and iliocostalis muscles. Teres major has an origin at outer edges of the scapula and is attached to the humerus. It has a function is stabilizing the shoulder joint and works in combination with rotator cuff muscles to achieve this function. In combination with latissimus dorsi, they act to pull back the humerus. Rhomboid minor and Rhomboid major have their origin at the spinal column and are attached to the middle region of the scapula. Their names are based on their shapes which are rhomboid and the terms major and minor are symbolic of their relative sizes. Teres major controls the arm in a way that it pulls is to the back. It acts by pulling the humerus in a posterior direction.Credit: http://bestdumbbell.com/dumbbellexercises/20-exercises-for-muscles-of-the-chest-and-back.html
Location and Orientation of Back Muscles
Muscles are attached to the vertebral bones by tendons and they are specific in their attachment. Contraction or relaxation of the muscles will initiate the movement of the particular bones that are associated with the muscles. There are those muscles that are attached to specific parts such scapula and functions to move these parts. Back muscles are innervated by nerves which are well supplied along the vertebral column.