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Extrinsic Chest Muscles

Thoracic Outlet – Functional Anatomy

The anatomy of thoracic outlet structures is complex in several ways. First, many of the bones are both origin and insertion for muscles. Second, several of the muscles have statistically significant variations in cadaver studies. Here, you will find a brief overview of Thoracic Outlet Syndrome followed by a walk-through of the structures from back …

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Extrinsic Chest Muscles – Functional Anatomy

The anatomy of the extrinsic chest muscles is more complicated than the first glance suggests. They originate on the front of the axial skeleton and insert on the upper extremity. Generally speaking, they protract the scapula and draw the humerus toward the midline. This arrangement gets a little more complicated with the pectoralis major. The …

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Subclavius- Functional Anatomy

The subclavius is a short, thick triangular muscle along the inferior aspect of the clavicle. Origin – first rib Insertion – medial clavicle. Function – lowers clavicle. The origin is a flat tendon that attaches on the first rib, near the sternal cartilage. It gradually transitions to muscle fibers. The insertion is a tendon that …

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Serratus Anterior – Functional Anatomy

Overview The serratus anterior has complex and variable anatomy. It is a broad, flat muscle with multiple bellies. It usually has eight sections, connecting the scapula’s vertebral border to each of the first eight ribs. Therefore, this structure makes it an extrinsic chest muscle. It is on the lateral trunk, under the scapula, extending like …

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Pectoralis Minor – Functional Anatomy

Pectoralis minor is a fan-shaped muscle in the front of the shoulder that secures the lateral angle of the scapula to the rib cage. Superficially, it is covered by the pectoralis major. Brief Anatomy Overview Origin ribs 3-5 Insertion coracoid process of the scapula Function protracts scapula depresses scapula Assists in labored breathing Innervation medial pectoral nerve …

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Pectoralis Major – Functional Anatomy

Dissection studies show that the pectoralis major varies dramatically. There are commonly 2-5 laminates, sometimes 6 or 7, and sometimes the entire pectoralis is missing (Poland Syndrome). Also, the overlap of sections varies among studies. The variation illustrated here is common and I used it because, well, it was fun to illustrate and shows how differently …

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