A primer on anatomy - Part 3

The quadriceps are abbreviated to quads.

Exercises that train the quadriceps include squats, parallel-grip deadlift, and leg press.


The longest muscle in the body, which runs diagonally across the frontal thigh, from the proximal end of the tibia, to the outer edge of the pelvic girdle. The sartorius flexes the femur, and rotates the femur laterally.

A primer on anatomy

Some of the musculature shown on the right side of each anatomy chart is different from that shown on the left. This occurs where the outer layer of muscle has been omitted in order to show some of the deeper musculature.

A primer on anatomy

Drawings by Eleni lambrou, based on those of Chartex products, England.

Adductors, thigh

There are five major adductors of the femur, in the inner thigh: pectineus, adductor longus, adductor brevis, adductor magnus, and gracilis. They connect the pelvis to the femur, except for the gracilis that connects the pelvis to the tibia. They are responsible for adduction, flexion, and lateral rotation of the femur.

Squats, and the leg press, work the thigh adductors. A wider stance increases adductor involvement.


The muscular masses posterior to the pelvis formed by the three gluteal muscles (glutes): gluteus maximus, gluteus medius, and gluteus minimus. They extend (move rearward), rotate, and abduct the femur. (A group of six smaller muscles beneath the buttocks rotates the femur laterally.)

Exercises that train the buttocks include squats, deadlifts, and leg press.


The single name for three muscles — iliacus, psoas major, psoas minor — that fuse into a single tendon on the femur. These muscles originate on the pelvis or on some of the lower vertebrae, and are hidden from view. They flex the femur, and rotate it laterally. They are called the hip flexors. (Another hip flexor is the rectus femoris, of the quadriceps.)

The hip flexors are worked by most abdominal exercises.

Erector spinae

Large muscles of the vertebral column — the iliocostalis, longissimus, and spinalis groups — that stabilize the spine, extend it (arch the back), and move the spine from side to side. Some of the muscles produce rotation, too. They are abbreviated to erectors, and are also called the sacrospinalis.

Squats, deadlifts, and back extensions train the erector spinae.


Large muscle group deep to the erector spinae, from the sacrum to the neck, which extends and rotates the vertebral column.

The multifidus group is worked by the rotary torso, twisting crunch, and the same exercises that train the erector spinae.

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