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A primer on anatomy - Part 1

To understand the muscle involvement in each exercise you need at least a rudimentary knowledge of the names and functions of the main muscles of the human body, as outlined in this chapter. Most of the deep, hidden muscles have been excluded, however, because of the complexity of the entire system. For example, there are many deep muscles in the back, between and around the vertebrae.

But first you need to know the basics of the skeleton.

The skeletal system

The bones comprise the framework to which the muscles are attached. There are 206 bones in the human body, including 28 in the skull. These are arranged into a cranial group (eight bones), facial group (14 bones), and the three tiny bones in each ear (the auditory ossicles).

The skeleton is divided into two regions: The axial skeleton consists of 80 bones and is comprised of the skull, spine, and thorax (ribs and sternum). The appendicular skeleton consists of 126 bones and is comprised of the shoulder girdle, pelvis, and limbs.

Most of the bones of the skeleton are joined to one another by movable joints, or articulations.

A primer on anatomy

A primer on anatomy

Drawings by Darwen and Vally Hennings, from HUMAN ANATOMY AND PHYSIOLOGY (1989, Harcourt Brace Jovanovich), by Anthony J. Gaudin, and Kenneth C. Jones.

The toes (14 phalanges) articulate with the five metatarsals (the framework of the instep), which articulate with the tarsus (seven tarsal bones of the ankle, including the calcaneus, or heel bone). The talus — uppermost tarsal — is the primary bone of the ankle joint. The ankle joint articulates with the distal ends of the fibula and tibia (shinbone).

The proximal ends of the fibula and tibia articulate with the distal end of the femur (thighbone), at the knee.

The proximal end of the femur articulates with the pelvic girdle (hip bones), which in turn articulates solidly with the sacrum of the vertebral column. The pelvic girdle supports the weight of the upper body, and distributes it to the lower limbs.

The torso is connected to the vertebral column through the rib cage (12 pairs of ribs, and the sternum).

The vertebral column has 33 or 34 bones in a child, but because of fusions that occur later in the lower spine, there are usually 26 separate bones in the adult vertebral column. The skull is attached to the top of the vertebral column at the first vertebra, called the atlas.

Above and to the rear of the rib cage, are the pectoral or shoulder girdles (a clavicle or collar bone, and a scapula or shoulder blade, for each girdle).

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