Sport Science: Muscle Origin and Insertion

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Deltoid

In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder. Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central nervous system. * Origin: upper clavicle, scapula * Insertion: upper humerus

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Trapezius
The superior or upper fibers of the trapezius arise from the external occipital protuberance, the medial third of the superior nuchal line of the occipital bone (both in the back of the head), and the ligamentum nuchae.
The middle fibers of the trapezius arise from the spinous process of the seventh cervical (both in the back of the neck), and the spinous processes of the first, second, and third thoracic vertebrae. They are inserted into the medial margin of the acromion, and into the superior lip of the posterior border of the spine of the scapula.
The inferior or lower fibers of the trapezius arise from the spinous processes of the remaining thoracic vertebrae. From this origin they proceed upward and laterally to converge near the scapula and end in an aponeurosis, which glides over the smooth triangular surface on the medial end of the spine.
Origin: vertebrae
Insertion: clavicle, scapula
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Pectoralis Major

Origin: clavicle, sternum
Insertion: humerus

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Lattisimus Dorsi
It is the larger, flat, dorso-lateral muscle on the trunk, posterior to the arm, and partly covered by the trapezius on its median dorsal region.
The latissimus dorsi is responsible for extension, adduction, transverse extension also known as horizontal abduction, flexion from an extended position, and (medial) internal rotation of the shoulder joint. It also has a synergistic role