There are over 600 muscles within the human body, narrowed down into ten major muscle groups, named according to their location, shape, action, number of divisions, bony attachments and size relationships. In a strength training routine, all ten should be worked in a balanced fashion. Here they are, starting at the top and working your way down the human body
Delts
The deltoids, also known as the shoulders, consist of three superficial muscles, the anterior, middle and posterior deltoids. Deeper layers consist of the rotator cuff muscle group, otherwise known as the supraspinatus, infraspinatus, teres minor and sub-scapularis. This is the most mobile joint in the body.
Back
The back is comprised of many muscles, the largest of which is the latissimus dorsi. Also included are the upper, middle and lower trapezius and the major and minor rhomboids, as well as deeper muscles such as the erector spinae muscles. These muscles are used in shoulder movements and core stabilization.
Pecs
The pecs, otherwise known as the chest muscles, contain the outer pectoralis major, used for shoulder motion, and the inner pectoralis minor, which has a big effect on posture. If they are shortened, they pull the shoulders forward leading to an aging, hunched posture.
Biceps
The biceps are located on the front upper part of the arms and consist of two muscles, the biceps brachii, and the brachialis. Their job is to flex the elbow.
Triceps
The triceps are located on the back upper part of the arm and consist of one muscle with three heads, the triceps brachii, medial head, lateral head and long head. These muscles extend the elbow.
Abs
The abdominals consist of three layers of muscle walls that run in different directions giving support to the core. The outer layer consists of rectus abdominis, a narrow flat muscle which is cross by three fibrous tendons creating the six-pack effect. The transverse abdominis is a thin muscle located in the deepest layer, encircling the abdominal cavity. The obliques, both external and internal are responsible for trunk rotation.
Glutes
The glutes are located posteriorly, the back uppermost part of the leg, above the hamstrings, and consist of three powerful muscles, the gluteus maximus, which is the largest and most superficial, the gluteus medius and the gluteus minimus. They mobilize the hip joint as well as extend and rotate the thighs.
Quads
The quadriceps muscles, also known as the thighs, are located in the front, upper part of the leg and their primary function is to extend the knee. They consist of four muscles, the rectus femoris, vastus medialis, vastus intermedius and vastus laterlis.
Hamstrings
The hamstrings are located on the back, upper part of the leg, and are responsible for flexion of the knee. They consist of three muscles, the biceps femoris, semitendinosus and semimembranosus.
Calves
The calf muscles are located on the back, lower part of the leg. The calves consist of two large superficial muscles, the ball of the calf or the gastrocnemius, and the outer part of the calf or the soleus, with additional deeper muscles located underneath. Their function is to move the ankle and the toes.
References
- American Council on Exercies, Personal Trainer Manual, 1997
- Making the Cut, Jillian Michaels, 2007
- Program Design for Personal Trainers, Douglas S. Brooks, 1998
