Welcome to Monday muscle of the week this week we are looking at the Pectoralis Major and Pectoralis Minor
The pectoralis minor is a muscle that becomes easily shortened and tight due to many factors, including rounded shoulder posture, glenohumeral joint dysfunction, breathing dysfunction, and a variety of compensation patterns. The pectoralis minor is a downward rotator of the scapula and oftentimes involved in glenohumeral dysfunction. The pectoralis minor is also an internal rotator of the humerus.
3rd to 5th ribs near their costal cartilages
Medial border and superior surface of coracoid process of scapula
Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall
The pectoralis minor has two main functions. On one hand, it pulls the scapulaanteriorly and inferiorly toward the ribs (abduction and depression respectively). This leads to a dorsomedial movement of the inferior angle of the scapula. This movement is both helpful when retracting the elevated arm and as well as moving the arm posteriorly behind the back. On the other hand, the pectoralis minor elevates the third to fifth ribs (given a fixed scapula) and expands the ribcage. By those means, it can also serve as an accessory muscle during inspiration.
Along with the pectoralis minor, the pectoralis major forms the anterior wall of the axilla.
Clavicular head: medial half or two- thirds of front of clavicle, Sternocostal portion: front of manubrium and body of sternum. Upper six costal cartilages. Rectus sheath.
Adducts and medially rotates humerus.Clavicular portion: flexes and medially rotates shoulder joint, and horizontally adducts humerus toward opposite shoulder. Sternocostal portion: obliquely adducts humerus toward opposite hip.
Pectoralis major is one of the main climbing muscles, pulling the body up to the fixed arm.
BASIC FUNCTIONAL MOVEMENT
Clavicular portion: brings arm forward and across body, e.g. asin applying deodorant to opposite armpit.Sternocostal portion: pulling something down from above, e.g. a rope in bell ringing.
REFERRED PAIN PATTERNS
Clavicular portion: local pain, radiating to anterior deltoid and long head of biceps brachii area. Sternal portion: “acute” back pain into anterior chest wall in a 10–20 cm patch of diffuse pain around medial border of upper extremity. Stronger pain below medial epicondyle in a 5 cm patch, diffuse pain into 4th and 5th digits.
Costal portion: 5th and 6th ribs leads to severe cardiac referral (even at night). Intense breastpain (10–15 cm patch). Diffuse radiations into axillary tail, and into axilla.
Poor posture while sitting, round- shouldered postures, heavy lifting, chilling of muscle in air conditioning, immobilization of shoulder or arm in cast or sling, anxiety and poor breathing, sports overload (e.g. weight training, rowing, boxing, push-ups).