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Anatomy Encyclopedia Entry 1777866545

** The **Pectoralis Major** is a large, fan-shaped muscle in the chest that plays a crucial role in movements of the shoulder joint. ## Overview The **Pectoralis Major** is a complex muscle located in the chest, responsible for a wide range of movements in the shoulder joint. It is one of the largest muscles in the human body, consisting of two parts: the **Clavicular Pectoralis** and the **Sternal Pectoralis**. The **Pectoralis Major** is a vital component of the **Anterior Axial Skeleton**, working in conjunction with other muscles to facilitate movements such as flexion, extension, and rotation of the shoulder joint. This muscle is also essential for maintaining posture and stability in the upper body. The **Pectoralis Major** is a **Striated Muscle**, composed of **Fast-Twitch Fibers**, which enable rapid contractions and powerful movements. The muscle is innervated by the **Lateral Pectoral Nerve** and the **Medial Pectoral Nerve**, both of which originate from the **Brachial Plexus**. The **Pectoralis Major** receives its blood supply from the **Pectoral Branch of the Axillary Artery** and the **Thoracoacromial Artery**. ## History/Background The study of the **Pectoralis Major** dates back to ancient civilizations, with early anatomists such as **Galen** and **Andreas Vesalius** providing detailed descriptions of the muscle's structure and function. In the 19th century, the discovery of the **Pectoral Nerves** by **Charles Bell** and **William Sharpey** significantly advanced our understanding of the muscle's innervation. Modern anatomy has further refined our knowledge of the **Pectoralis Major**, with the development of advanced imaging techniques such as **MRI** and **CT Scans**. ## Key Information The **Pectoralis Major** is a **Bipennate Muscle**, consisting of two parts: the **Clavicular Pectoralis** and the **Sternal Pectoralis**. The **Clavicular Pectoralis** originates from the **Clavicle** and the **Costal Cartilages**, while the **Sternal Pectoralis** originates from the **Sternum** and the **Costal Cartilages**. The muscle inserts into the **Humerus**, specifically at the **Greater Tubercle**. The **Pectoralis Major** is responsible for a wide range of movements, including: * **Flexion** of the shoulder joint * **Extension** of the shoulder joint * **Adduction** of the shoulder joint * **Rotation** of the shoulder joint ## Significance The **Pectoralis Major** plays a crucial role in maintaining posture and stability in the upper body. Damage to the muscle, such as **Pectoralis Major Rupture**, can result in significant disability and impairment. Understanding the anatomy and function of the **Pectoralis Major** is essential for **Physical Therapists**, **Athletic Trainers**, and **Surgeons** who work with patients with shoulder injuries or disorders. INFOBOX: - **Name:** Pectoralis Major - **Type:** Muscle - **Date:** Ancient civilizations (Galen, Andreas Vesalius) - **Location:** Chest - **Known For:** Facilitating movements of the shoulder joint TAGS: **Anatomy**, **Muscle**, **Shoulder Joint**, **Pectoral Nerves**, **Galen**, **Andreas Vesalius**, **Charles Bell**, **William Sharpey**, **MRI**, **CT Scans**