Anatomy and Physiology

There are over 630 muscles in your body!

Anterior and posterior views of the human body showing the major muscles.

Here are seven of them:

• Masseter

The masseter runs from the temporal bone (that forms part of the sides and base of the skull) to the lower jaw (the mandible). It lifts the lower jaw, to close the mouth. The masseter is the strongest muscle in your body

• Biceps Brachii

The biceps brachii runs from the shoulder to the elbow.

The biceps brachii runs from the shoulder to the elbow. It is attached to the shoulder blade (the scapula), and extends along the front surface of the upper arm bone (the humerus). When the bicep contracts, the arm bends at the elbow. Notice that humerus sounds like humour – we call this area of the elbow the funny bone.

Nature of science

People who dissect animals (including humans) are called anatomist. For centuries, muscles have been given Latin names. The community of anatomists (scientists) all over the world all use Latin names when they are describing muscles.

• Deltoid

The deltoids are the triangular muscles of the shoulder. The strongest point is the central section, which raises the arm sideways. The front and back parts of the muscle twist the arm. Deltoid comes from the Greek word deltoids, meaning shaped like a (river) delta, which is triangular.

The deltoids are the triangular muscles of the shoulder and are used to both twist the arm and to raise it sideways

• Pectoralis Major (Yes the pecs!)

Thepectoralis major is a large, fan-shaped muscle. It covers much of the front upper chest, beginning at the breastbone (or sternum) including the second to the sixth ribs. From there, the pectoralis major attaches to the collar bone (or clavicle) and converges on the upper arm bone (or humerus), just below the shoulder. This muscle moves the arm across the body.

• Adductor Longus

The adductor longus is located on the inner thigh. Adduct means move, so this muscle allows the thigh bone (the femur) to move inward and to the side.

• Soleus

Located in the lower leg, the soleus runs from the lower leg bones (the tibia and fibula) to the heel (the calcaneus). The soleus muscle flexes the foot by moving the foot at the ankle. It also helps circulation by pumping blood back up towards the head.