The muscles in the shoulder attach the upper extremity to the thoracic cage and clavicle. They include the pectoralis major, pectoralis minor, serratus anterior, and subclavius. They receive their nerve supply from branches of the brachial plexus. The pectoralis major covers the anterior part of the thoracic cage and consists of three heads. The pectoralis major originates from the medial half of the clavicle, sternum, rib cartilages 1-6, and the anterior layer of the rectus sheath.
The rotator cuff is one of the most important stabilizing muscles in the shoulder. It anchors the anterior labrum and serves as a primary restraint on anterior translation. However, a tear in the labral tissue can result in instability in the shoulder. This is a serious problem that needs urgent attention and can be treated by arthroscopic surgery.
The stabilizer muscles help coordinate movement and prevent injury to the shoulder. These muscles are relatively short, but they do contract significantly when acting as stabilizers. This is why they often get overlooked, but they are incredibly important to exercise and fitness.
Effector muscles in the shoulder respond to motor neurones and are involved in movements of the arm. They include the biceps and triceps. When biceps contract, they pull on the radius and straighten the arm, while triceps contract and pull on the ulna.
The rotator cuff muscles originate from the scapula and insert on the head of the humerus. They control lateral and vertical movement of the humerus relative to the scapula. In addition, the teres minor is responsible for external rotation of the arm. The other muscles of the shoulder originate from the spine and rib cage and insert on the scapula and humerus. They are divided into two layers, the deep layer and the superficial layer. The deep layer includes the subclavius and teres minor, while the latter layer comprises the pectoralis major. Pectoralis major attaches to the clavicle, sternum, and upper ribs.
The pectoral muscles in the shoulder play an important role in shoulder mobility and functionality. The pectoralis major, or large, is the largest muscle in the pectoral girdle and attaches to the ribs. It aids in protraction of the shoulders and helps stabilize the shoulder complex. It also helps in raising the ribs during inspiration.
The pectoralis major muscle is divided into two main heads, called the sternal and clavicular. Both of these muscles are located behind the sternocostal joint and cross the humerus bone. The sternal head of the pectoralis major muscle is thick and fan-shaped, while the clavicular head is broad and triangular in shape.
The rotator cuff is a group of muscles that supports the shoulder joint. When these muscles become weak, they can cause pain or restrict motion in the shoulder. Fortunately, this issue can be treated in a variety of ways. If you suffer from shoulder pain, consult your doctor.
The rotator cuff consists of four muscles that arise on the scapula and insert into the proximal humerus. These muscles provide stability to the ball and socket joint, control arm rotation and raise and lower the shoulder. These muscles also have tendons that surround the humerus, providing an outer cloak that protects the humeral head. The subscapularis muscle is located at the front of the shoulder blade and acts to rotate the arm inward and contributes to the stability of the shoulder joint.