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MuscleChestsuperficialDraft

Pectoralis majorMusculus pectoralis major

Large, fan-shaped chest muscle that flexes, adducts and medially rotates the arm.

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LatinMusculus pectoralis major
Origin
  • Clavicular head: anterior surface of the medial half of the clavicle
  • Sternocostal head: anterior surface of the sternum and the costal cartilages of the upper six ribs
  • Sternocostal head: aponeurosis of the external oblique muscle
Insertion
  • Lateral lip of the intertubercular (bicipital) groove of the humerus
Action
  • Whole muscle: adducts and medially rotates the arm
  • Clavicular head: flexes the arm
  • Sternocostal head: extends the arm from a flexed position; horizontally adducts the arm
NerveLateral and medial pectoral nerves (C5–T1 (clavicular head C5–C6; sternocostal head C7–T1))
NameLatin pectus, 'chest', and major, 'larger'.

Palpation

  1. Client supine with the arm resting by the side; stand beside the shoulder.
  2. Place a flat hand below the medial half of the clavicle and over the upper chest to feel the broad, flat muscle.
  3. Follow the fibres out to the front fold of the armpit (anterior axillary fold) and grasp the fold gently between thumb and fingers.
  4. Ask the client to press the arm in towards the body, or across the chest, against light resistance to feel the muscle contract.

Landmarks: Coracoid process

Pectoralis major forms the front wall of the armpit and most of the chest’s contour. Clients who sit at desks or drive for long periods often report tightness here, with the shoulders drawn forward. It is worked with the client supine, usually as part of an upper-limb or chest sequence, with draping and consent that suit the client.

Its two heads work differently. The clavicular head helps the anterior Deltoid bring the arm forward, while the sternocostal head pulls a raised arm down, alongside Latissimus dorsi. It covers Pectoralis minor, which runs deeper from the ribs up to the Coracoid process; press through pec major near the coracoid to reach it.

Techniques

  • Effleurage — Long, gliding strokes with the whole palm that spread the medium, warm the tissue and link the other strokes together.
  • Petrissage — Kneading strokes that compress, lift and squeeze the muscle away from the bone, working the tissue between the hands.
  • Compression — Pressing straight down into a muscle with the palm, fist or forearm, holding briefly, then releasing and moving on.
  • Passive stretching — The therapist gently moves a relaxed limb to lengthen a muscle to a point of mild stretch and holds it there, with no effort from the client.

Works with

  • Latissimus dorsi — Broad, flat, fan-shaped muscle of the lower and middle back that extends, adducts and medially rotates the arm.
  • Teres major — Thick, rounded muscle from the inferior angle of the scapula to the front of the humerus that pulls the arm down, back and inwards.
  • Subscapularis — Large, triangular rotator cuff muscle on the front of the scapula that medially rotates the arm and guards the front of the shoulder joint.
  • Deltoid — Thick, triangular muscle that caps the shoulder and is the main muscle for lifting the arm out to the side.

Opposes

  • Infraspinatus — Thick, flat rotator cuff muscle below the spine of the scapula that laterally rotates the arm and steadies the shoulder joint.
  • Teres minor — Narrow rotator cuff muscle along the lateral border of the scapula that laterally rotates the arm and stops the humerus riding upwards.
  • Rhomboid major — Diamond-shaped muscle between the spine and the shoulder blade that pulls the scapula towards the spine and holds it against the ribs.
  • Trapezius — Large diamond-shaped muscle of the upper back and neck that moves and stabilises the scapula.

Used in routines

Sources

  1. Wikipedia: Pectoralis major