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Pectoralis major muscle

The pectoralis major is a large, fan-shaped superficial muscle located in the anterior chest wall. It plays a vital role in upper limb movement and the biomechanics of the shoulder joint. The muscle is easily palpable and forms the bulk of the chest musculature, contributing significantly to the contour of the anterior thoracic wall. Its importance extends to clinical, radiological, and surgical domains.

Synonyms

  • Pectoralis major

  • Greater pectoral muscle

  • Pec major

Function

  • Adduction of the humerus

  • Medial (internal) rotation of the humerus

  • Flexion of the humerus (clavicular head)

  • Assists in deep inspiration by expanding the thorax when the arms are fixed

Origin

  • Clavicular head: Anterior surface of the medial half of the clavicle

  • Sternocostal head: Anterior surface of the sternum, upper six costal cartilages, and aponeurosis of the external oblique muscle

Insertion

  • Lateral lip of the bicipital (intertubercular) groove of the humerus

Nerve Supply

  • Lateral pectoral nerve (C5-C7)

  • Medial pectoral nerve (C8, T1)

Arterial Supply

  • Pectoral branch of the thoracoacromial artery

  • Lateral thoracic artery

  • Perforating branches of the internal thoracic artery

Venous Drainage

  • Corresponding veins drain into the cephalic vein and axillary vein

MRI Appearance

  • T1-weighted: Muscle appears intermediate to low signal intensity

  • T2-weighted: Muscle shows intermediate signal, with higher signal seen in areas of edema or injury

  • STIR (Short Tau Inversion Recovery): Muscle shows low signal intensity in healthy tissue; hyperintensity is seen if there is edema, inflammation, or acute injury.

CT Appearance

  • Homogeneous soft tissue density

  • Appears as a well-defined muscle mass in the anterior chest wall

MRI images

Pectoralis Major Muscle Anatomy AXIAL MRI IMAGE

MRI image

Pectoralis major muscle anatomy MRI coronal image -img-00000-00000

CT images

Pectoralis major muscle anatomy CT axial image -img-00000-00000

CT images

Pectoralis major muscle anatomy CT axial image -img-00000-00000_00001

MRI image

Pectoralis major muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Pectoralis major muscle sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Pectoralis major muscle axial shoulder ct