Pectoralis major

You have big muscles on your chest.

These are called chest muscles. They are thick and shaped like a fan. They sit right under your breast.

These muscles help you move your arms. They help you lift a child. They help you throw a ball. They even help you pull your arms in close. These muscles keep your arm attached to your body. They help you stay strong every day.

The pectoralis major is a large muscle in your chest.

Many people call it the "pecs" or the chest muscle. It is thick and shaped like a fan or a triangle. This muscle sits right under the breast. It lies on top of another muscle called the pectoralis minor.

This muscle connects to many parts of your body. It starts at your collarbone and your breastbone. It also connects to your ribs and your belly muscles. All these parts meet at a flat tendon. This tendon attaches to your upper arm bone, called the humerus.

The pectoralis major helps you move your arm in many ways. The top part helps you lift your arm up. This is what you do when you throw a ball. The bottom part helps you pull your arm toward your body. It also helps you turn your arm inward. This happens when you do arm-wrestling. The muscle also helps keep your arm attached to your trunk.

The pectoralis major is a thick, fan-shaped muscle in the human chest.

It makes up most of the chest muscles and sits just under the breast. Many people call it the "pecs" or simply the chest muscle. It lies on top of a smaller muscle called the pectoralis minor. This muscle is very important for moving your upper body. It helps keep your arm attached to your main trunk.

This muscle works by connecting many different body parts together. It starts at the clavicle, which is your collarbone, and the sternum, or breastbone. It also attaches to the cartilages of your true ribs and your abdominal muscles. All these fibers pull together toward a flat tendon. This tendon is about 5 cm wide. It attaches to a specific spot on your humerus, which is your upper arm bone.

Moving your arm requires different parts of this muscle to work. The clavicular head is the part near your collarbone. It helps with flexion, which is lifting your arm up like throwing a ball. The sternocostal head is the part near your breastbone. This part helps with adduction, which means pulling your arm toward your body. Together, they also help with internal rotation. This is the inward turning motion used in arm-wrestling.

Your brain controls this muscle through two main nerves. These are the medial pectoral nerve and the lateral pectoral nerve. These nerves carry signals from the brachial plexus to make the muscle move. The muscle also sends sensory information back to your brain. This information travels through the spinal cord to a part of the brain called the thalamus. The thalamus acts like a gateway to the cortex. It helps you feel pressure and know where your arm is located.

Sometimes, people are born with different muscle shapes. A rare condition called Poland syndrome means the muscle is missing on one side. This can make moving the arm much harder. Most people have healthy muscles, but athletes can sometimes get injuries. A tear can happen during heavy lifting, like a bench press.

If a tear is serious, doctors may use surgery to fix it. Most people recover well with physical therapy after a few months.

The pectoralis major is a thick, fan-shaped muscle located in the human chest. It is the largest and most superficial muscle in the chest area. Because of its size and position, people often call it the "pecs" or the chest muscle. This muscle sits directly above a smaller muscle called the pectoralis minor. It is essential for many movements of the upper body. It plays a major role in keeping the arm attached to the main trunk of the body.

The structure of the pectoralis major is quite complex due to its wide origin. It begins at several different points on the skeleton. These include the anterior surface of the sternal half of the clavicle, or collarbone. It also attaches to the sternum, which is the breastbone. The muscle fibers arise from the costal cartilages of the true ribs. Some fibers even come from the aponeurosis of the abdominal external oblique muscle. These many fibers all converge toward a single insertion point. They end in a flat tendon that is about 5 cm in breadth. This tendon inserts into the lateral lip of the bicipital groove on the humerus.

The tendon of the pectoralis major actually consists of two layers, or laminae. The anterior lamina is the thicker layer. It receives the fibers from the clavicle and the uppermost part of the sternum. The posterior lamina is located behind the first layer. It receives the majority of the sternal fibers and the deep fibers from the costal cartilages. Because of how these fibers attach, the tendon often appears to be twisted. The posterior lamina reaches higher on the humerus than the anterior one. It also provides an expansion that covers the intertubercular groove of the humerus. This expansion blends with the capsule of the shoulder joint.

This muscle performs different tasks depending on which part is working. The clavicular head is the part near the collarbone. It is responsible for flexion, which is the movement of lifting the arm forward. It also helps with horizontal adduction and inward rotation of the humerus. The sternocostal head is the part near the breastbone. This part helps with adduction, which is pulling the arm toward the center of the body. Together, the muscle performs four primary actions. These include flexion, adduction, medial rotation, and pulling the scapula forward and downward.

The central nervous system controls this muscle through dual motor innervation. The medial pectoral nerve and the lateral pectoral nerve both provide signals to make the muscle move. The clavicular head receives signals from the C5 and C6 nerve roots. The sternal head receives signals from the C7, C8, and T1 nerve roots. Sensory information travels in the opposite direction. This feedback includes information about pressure and proprioception, which is the sense of muscle position. This data travels through the spinal cord to the medulla. From there, it moves to the thalamus, which acts as a gateway to the cortex. The brain then processes this information in the parietal lobe.

Most people are born with a standard muscle structure, but there are variations. Some people have different attachment points on their ribs or sternum. A rare congenital condition is called Poland syndrome. In this condition, the pectoralis major is missing on one side of the body. This can also involve the absence of the breast in females. Other rare variations include the sternalis muscle or the chondroepitrochlearis. While these variations are interesting, they can change how easily a person moves their arm. In Poland syndrome, other muscles like the latissimus dorsi may try to help with movement.

Injuries to the pectoralis major can be serious, especially for athletes. Tears often happen at the musculotendinous junction, where the muscle meets the tendon. These injuries are frequently caused by violent, eccentric contractions. This is a type of movement where the muscle is stretched while it is trying to contract. This often happens during heavy lifting, such as the bench press. Men in contact sports or weightlifting are more susceptible to these tears. Women are generally less susceptible due to greater muscular elasticity and larger tendon diameters.

If a person suffers a high-grade tear, they may need surgical repair to keep their muscle function. Doctors use ultrasound or MRI to find the exact location and extent of the tear. After surgery, the arm is usually kept still in a sling for six to eight weeks. Following this, physical therapy is introduced for about six months. Most patients can return to their normal activities within six months to a year. While they may have slightly reduced strength, most people are very satisfied with their recovery.