The main human muscles are explained with origins, insertions, actions, exercises, stretching and more. Shoulder girdle, shoulder joint, arm and elbow muscles, knee joint, foot and ankle, hip and pelvic muscles are covered.
Skeletal muscles consist of a number of different parts which all contribute to the muscle contracting and towards growth, repair and protection of the muscle.
Muscle contractions occur every time we move. The muscle must contract in order to move the bone that it is attached to or to provide resistance against a force.
Shoulder girdle consists of the clavicle (collar bone) and the scapula (shoulder blade) which generally move together as a unit. Only the clavicle connects directly to the rest of the skeleton at the sternum bone. It is really only the scapula which moves from action of the muscles. The muscles of the shoulder girdle are serratus anterior, pectoralis minor, levator scapulae, rhomboids and trapezius.
The shoulder joint consists of the clavicle, scapula and humerus (upper arm bone). Due to the nature of the joint there is a huge range of movement or shoulder joint actions available. The muscles of the shoulder joint are the subscapularis, latissimus dorsi, infraspinatus, teres minor, teres major, supraspinatus, deltoid and pectoralis major (pec muscles).
The spine consists of 24 vertibrae, 7 cervical (neck), 12 thoracic (chest), 5 lumbar (lower back), 5 fused bones of the sacrum and 4 fused bones in the coccyx or tailbone. The main muscles involved in moving the spine and neck are the rectus abdominus, internal and external obliques, quadratus lumborum, multifidus, sternocleidomastoid and errector spinae.
The elbow joint is a simple hinge joint but most movements involving the elbow joint also involve the radioulna joint where the forearm bones (radius and ulna) join at the elbow joint. Muscles producing movements at the elbow and forearm are the triceps brachii, brachioradialis, brachialis, biceps brachii and the anconeus.
The knee joint consists of the femur (thigh bone), tibia and fibula with the patella or kneecap. Muscles producing joint actions at the knee joint are the quadriceps muscles (vastus medialis, vastus lateralis, vastus intermedius and rectus femoris at the front, with the hamstring muscles (semitendinosis, semimembranosus and biceps femoris) at the back along with the popliteus muscle.