Mar 20, 2026 · Human muscle system, the muscles of the human body that work the skeletal system, that are under voluntary control, and that are concerned with movement, posture, and balance. …

Mar 1, 2026 · Heart, organ that serves as a pump to circulate the blood. It may be as simple as a straight tube, as in spiders and annelid worms, or as complex as the four-chambered double pump …

Mar 20, 2026 · Human muscle system - Shoulder Muscles, Joints, Movements: The shoulder is a complex ball-and-socket joint comprising the head of the humerus, the clavicle (collarbone), and the …

Mar 20, 2026 · Human muscle system - Abdominal Muscles, Anatomy, Function: There are three muscular layers of the abdominal wall, with a fourth layer in the middle anterior region. The fourth …

Apr 17, 2026 · Muscle, contractile tissue found in animals, the function of which is to produce motion. Muscle cells fuel their action by converting chemical energy in the form of adenosine triphosphate …

Mar 31, 2026 · Skeletal muscle fibres are bound together by connective tissue and communicate with nerves and blood vessels. For more information on the structure and function of skeletal muscle, see …

Cardiac muscle, in vertebrates, one of three major muscle types, found only in the heart. Cardiac muscle possesses contractile units known as sarcomeres and exhibits rhythmic contractions. The rhythmic …

Mar 21, 2026 · Human eye, specialized sense organ in humans that is capable of receiving visual images, which are relayed to the brain. The anatomy of the eye includes auxiliary structures, such as …

Mar 23, 2026 · The human body is the physical substance of the human organism. Characteristic of the vertebrate form, the human body has an internal skeleton with a backbone, and, as with the …

Apr 16, 2026 · Stomach, saclike expansion of the digestive system, between the esophagus and the small intestine; it is located in the anterior portion of the abdominal cavity in most vertebrates. The …