The trapezius muscle originates at the base of the skull and attaches down into the middle and lower back. It is a long, trapezoid-shaped muscle that runs down the upper section of the spinal cord.

The angles of the trapezius fibers provide pull in different directions; up, down, and toward the center line of the body. The function of the latissimus dorsi is to pull the arm down toward the pelvis and to stabilize the body during many movements.

The trapezius muscle functions include shrugging up the shoulders, scapula adduction (a movement which brings the shoulder blades together), and scapula depression (pulling the shoulder blades down). This is the first layer of back muscles of which there are four.

The 2nd is the rhomboid minor and major which connect to the scapula and vertebrae of the spinal column.

The 3rd layer is the serratus posterior both superior and inferior muscles which are supportive of breathing.

The 4th layer is called the muscles of the back proper (musculi dosi proprii) which function to allow movement of the neck, spine, and body and are located along the whole spine.

Anatomy of the 1st layer of Back Muscles:

• Trapezius muscle origin is the occipital bone, protuberances of the neck, and thoracic vertebrae (to the 12th thoracic vertebrae included).

• Trapezius muscle attachment to the clavicle, scapula (acromion, ridge).

• Trapezius muscle function of shoulders elevating above level, scapula retraction to the spine.

• Latissimus Dorsi muscle origin hip bone, sacrum, thoracic, and lumbar vertebrae.

• Muscle attachment of latissimus dorsi to the humerus.

• Muscle function of latissimus dorsi is adduction, stretching arms backward.