MR imaging assessment of the pectoralis major myotendinous unit: An MR imaging-anatomic correlative study with surgical correlation

OBJECTIVE. MR imaging is the optimal imaging technique to study the normal and abnormal conditions of the pectoralis major muscle and tendon unit. The purpose of this study was to use MR imaging to provide an anatomic survey of the normal pectoralis major tendon and its insertion and to compare thes e findings with surgically proven cases of rupture. CONCLUSION. MR imaging shows the normal pectoralis major myotendinous unit has low signal intensity on both T1- and T2-weighted images. Reliable anato mic landmarks for visualization and examination of injuries to the muscle a nd myotendinous unit include the quadrilateral space, or the origin of the lateral head of the triceps, as the superior boundary and the deltoid tuber osity as the inferior boundary of the intact tendon of insertion. Failure t o visualize a normal insertion within these boundaries should prompt a dedi cated search by the radiologist for rupture and retraction of the tendon me dially.