There are more than 600 muscles in the human body. Some are described as superficial, located just under your skin, while others are described as deep, located beneath the superficial muscles. While every muscle is vital in controlling movement, some muscles play a bigger roll than others. Your back, buttocks and legs contain a number of important superficial muscles.
Back Muscles
Your back contains a large array of muscles. Running up either side of your spine is a series of eight muscles collectively called your erector spinae. These muscles work together to extend your spine, hold it upright and allow you to bend sideways. Located between, above and below your shoulder blades, your trapezius elevates, depresses and retracts your shoulder-girdle. Your latissimus dorsi, literally your side back muscles, are essential in activities such as climbing and control many of the movements of your shoulder joint, including adduction and extension. Positioned between your shoulder blades and working alongside your trapezius, your rhomboids work to keep your shoulder blades pulled together. This is important for maintaining good posture.
Buttocks
The buttocks or butt contains three major muscles: gluteus maximus, gluteus medius and gluteus minimus. These muscles work together to extend your thigh backward and also rotate your hip. Gluteus maximus is the biggest muscle in the human body and also the strongest. Ironically, it also has relatively few sensory nerves, which is why your doctor often will choose it as a suitable site for intramuscular injections. Well-conditioned glutes are essential in activities such as running, jumping and lifting objects off the floor.
Anterior Leg
The major muscles in the anterior or front of your leg are the quadriceps, which actually are four separate muscles that share a common attachment point just below your knee. The quadriceps are responsible for extending your knee and flexing your hip. The four quadriceps muscles are rectus femoris, vastas lateralis, vastas intermedialis and vastas medialis. The main muscle on the front of your lower leg is the tibialis anterior, which is responsible for pulling your toes up toward your shin, a movement called dorsiflexion.
Posterior Leg
The most prominent muscle in the posterior or rear aspect of your leg are the hamstrings. Consisting of three muscles, the hamstrings flex your knee and extend your hip to the rear. The three hamstring muscles are semimembranosus, semitendonosus and biceps femoris. The main lower posterior leg muscles that collectively make up your calves are gastrocnemius and soleus. These muscles work together to extend your ankle, a movement called plantarflexion. Gastrocnemius also works with the hamstrings in flexing your knee.
Inner and Outer Thighs
There are muscles on the inside and outside of your thighs that commonly are referred to as your adductors and abductors, respectively. The muscles on the inside of your thighs draw your thigh into the midline of your body and are adductor longus, adductor brevis and adductor mugnus. The main muscles on the outside of your thigh are gracilis, tensor fascia lata and illiotibial band. While these last two are not strictly muscles, they are essential for abduction or drawing your thigh out and away from the midline of your body.
References
- "Atlas of Skeletal Muscles by Robert J. Stone and Judith A. Stone"; 2008
- "Anatomy and Physiology for Dummies"; Donna Rae Siegfried; 2002
- "Principles of Anatomy and Physiology"; Gerard J. Tortora and Bryan H. Derrickson; 2008
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