Sternalis Muscle Profile: A Cadaveric Study

Abstract

Background: Sternalis muscle is an additional muscle of anterior chest wall present in the superficial plane occasionally. It can be unilateral or bilateral. It is attached below to ribs or costal cartilages and above to the upper part of sternum. Its fibres may fuse with pectoralis major, sternocleidomastoid muscle or external oblique aponeurosis. Purpose of study: To study the profile of sternalis muscle in cadavers. Material and methods: During a time period of ten years, 50 adult cadavers were dissected in the dissection hall of Anatomy department of Maharaja Agrasen Medical College, Agroha. During the dissection of anterior chest wall a bilateral strap like muscle was found in one male cadaver. Morphometry of this muscle was done. The nature of muscle fibres, length, distance from the midline and angle with the midline was measured. Results: Bilateral sternalis muscle was found in one male cadaver. It was extending from the fifth rib 3 cm lateral to the lateral border of sternum to the sternal angle on both the sides. Lower part of the muscle was fleshy while its upper part was tendinous. On the right side, its tendon was bifurcating into medial and lateral lamina in the upper part of the muscle. The fleshy part of the muscle was 8 cm, medial lamina 4.5 cm and lateral lamina was 3 cm in length. On the left side, muscle was 13 cm in length with a single tendon. Conclusion: The early detection is essential in regular mammogram screening to differentiate it from the malignant lesions. This muscle is a matter of interest for anatomists, radiologists and surgeons for doing surgeries on anterior chest wall. KEYWORDS: Mammography, lamina, Pectoralis major muscle, Sternalis muscle, Sternocleidomastoid muscle, Sternum.