Massage & Bodywork

January/February 2011

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functional anatomy BY CHRISTY CAEL SERRATUS ANTERIOR The serratus anterior is a broad muscle that lies between the scapula and thorax. Its fibers extend posteriorly and medially from a zigzagged origin on the lateral ribs before running deep to the scapula. The serratus anterior inserts on the undersurface of the medial border of the scapula, lying alongside the subscapularis and sharing an attachment with rhomboid major and minor. The serratus anterior has multiple functions Serratus Anterior Muscle SERRATUS ANTERIOR Attachments • Origin: Lateral surfaces of upper ribs 8 or 9 • Insertion: Anterior surface of medial border of the scapula Actions • Protracts, depresses, and upwardly rotates the scapula • Assists with forced inhalation when the scapula is fixed Innervation • Long thoracic nerve • C5–C7 in the body. Primarily, it works with the pectoralis minor and rhomboids to fix the scapula against the thorax, particularly when weight is supported on the arms or during pushing activities. This muscle also works with the trapezius to steer the glenoid fossa upward, maximizing range of motion when reaching overhead. Its function is critical to healthy scapulohumeral rhythm during movements such as reaching, throwing, and pushing. Scapulohumeral rhythm is the coordinated movement between the scapulothoracic and glenohumeral joints and requires balanced tissue mobility, proper muscle contraction sequencing, and functional strength in the neck and shoulder muscles. Additionally, the serratus anterior can be utilized for forceful inhalation along with the diaphragm, external intercostals, pectoralis minor, scalenes, and other muscles attaching to the thorax. It is recruited, for example, during the labored breathing commonly associated with exercise, but only if the medial border of the scapula is fixed to the rib cage. Dysfunction in the serratus anterior may result from prolonged positioning with the arms forward, a posture commonly utilized in activities of daily living, like computer earn CE hours at your convenience: abmp's online education center, www.abmp.com 87

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