Skeletal Muscle Examples

The bodies of living animals contain various types of muscles, all with distinct jobs. The three types are skeletal, smooth, and cardiac. Cardiac muscle makes up the heart and allows it to beat, and smooth muscle makes up the supporting structures of the blood vessels and digestive system.

Unlike smooth and cardiac muscle, skeletal muscle, also known as striated muscle, is voluntary muscle that move the bones and support the skeleton due to the intentional movement of the organism. Skeletal muscle is categorized as either superficial muscles, which are found close to the skin, or deep muscles, which are much deeper in the body.

There are 640 skeletal muscles, and with a few exceptions, they are found in pairs that combine the workload of their given tasks, such as one muscle that pulls up on the hand and another muscle that pushes back down.

1. Arms and Legs

As described, muscles in the arms and legs do their work in pairs. The biceps muscles, which are the ones on top of the upper arm that are often flexed to show strength, pull the hand towards the shoulder by contracting from the bend in the elbow. In order to straighten the arm, the triceps muscle-located on the back of the upper arm-contracts, pulling the arm straight again. This same process is repeated with the legs, in which the four quadrilateral muscles contract and bend the leg at the knee, and the hamstring muscles behind the upper leg contract to straighten the leg.

2. Abdomen and Back

There are multiple sets of skeletal muscles that run along the torso, both on the front and the back. The abdominal muscles-which are the external obliques, internal obliques, transversus abdominis, rectus abdominis, pyramidalis, cremasters, and quadratus lumborum muscles-contract to bend the body forward, and the back muscles-including the trapezius, latissimus dorsi, rhomboid major, rhomboid minor, and the levator scapulae-contract to help the person stand up or straighten.

3. The Head

The region that makes up the head and neck have numerous pairs of skeletal muscles which serve function in everything from opening and closing the eyelids to eating and speaking to turning the head. The scalp, eyes, nose, mouth, pharynx and larynx, and neck all have their own musculature, as well as the muscles that make up the face and support facial movement and expressions.