MUSCLE ANATOMY – PECTORALIS MAJOR
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- UPPER CLAVICULAR
(1) Ab·duction
(2) Horizontal Ad·duction (Horizontal Flexion)
(3) Internal (Medial) Rotation
(4) Flexion - MIDDLE STERNAL
(1) Ad·duction
(2) Horizontal Ad·duction (Horizontal Flexion)
(3) Internal (Medial) Rotation
(4) Flexion - LOWER COSTAL
(1) Ad·duction
(2) Horizontal Ad·duction (Horizontal Flexion)
(3) Internal (Medial) Rotation
(4) Extension
LINK – Normal anatomy of the pectoralis major muscle. (a) The pectoralis major consists of a clavicular head (CH) and several sternal head segments (s1-s6). The proximal clavicular head attaches to the medial half of the clavicle, whereas the sternal head segments attach to the sternum, second to sixth costal cartilages, and aponeurosis of the external oblique muscle. The clavicular and sternal head tendons combine to form a U-shaped tendon laterally; this tendon consists of an anterior layer (AT) and posterior layer (PT). This common tendon inserts onto the humerus at the lateral lip of the bicipital groove. (b) Coronal T1-weighted MR image shows the clavicular (C) and sternal (S) heads and the deltopectoral groove (arrow). (c) Axial proton-density-weighted fat-saturated MR image shows the pectoralis major tendon attaching to the humerus (arrowheads). The cephalic vein is seen within the deltopectoral groove (arrow), and the pectoralis major muscle belly (PM) is seen in relation to the long head of the biceps tendon (LHB); short head of the biceps tendon (SHB); and deltoid (D), coracobrachialis (CB), pectoralis minor (PMin), teres major (TM), and serratus anterior (SA) muscles.
RADIO GRAPHICS .
– The pectoralis major muscle consists of clavicular (20%) and sternal heads (80%). The clavicular head is a single architectural segment that cannot be further divided. It’s within the clavicular lamina and arises from the medial half of the clavicle.
– The sternal head can be subdivided into 6 to 7 segments along individual fascial planes. The segments are within the abdominal and manubrial laminae and arise from the anterior manubrium, sternum, and second to sixth costal cartilages.
YOUTUBE VIDEOS
- NOTED ANATOMIST – GLENOHUMERAL JOINT .
(1) Pectoralis Major (2) Teres Major (3) Latissimus Dorsi - ANATOMY ZONE – PECTORALIS MAJOR .
- WEBSTER – LARGE SHOULDER MUSCLES – 11:40 .