Good posture is a combination of balanced strength and flexibility in the skeletal muscles, enabling people to walk, sit or stand in a graceful manner. Conscious activation of the postural muscles is important, especially when sitting or standing for long periods of time. The Cleveland Center, rated one of America's best hospitals, advocates training the body to move in such a way that the least strain is placed on supporting muscles during movement and weight-bearing activities. The postural muscles are primarily located in the torso.
Weighing between 10-12 pounds, the average adult head must be carried over the spine in balance to avoid pain and discomfort in the neck and spine. Enabling the head to be flexed when touching the chin to the chest are the scalenus, prevertebral, and sternomastoid muscles. The extensor muscles of the neck, used to point the nose towards the sky, are named splenius, semi-spinalis and capitis.
Anchoring the shoulder blades to the spine is a flat, triangular shaped muscle called the trapezius. This muscle covers the neck, shoulders and thorax. Effective posture necessitates that the trapezius muscle is strengthened equally in the front and back of the body. The most common imbalance of this muscle is overextended across the back, and too short or tight across the chest, enabling the shoulder blades to pop out like wings, which often causes pain and discomfort.
Beginning with the muscles on the back side of the body are those which run laterally to the spine, called the erector spinae muscles. Individually, they are the spinalis, longissimus and iliocostalis, all working together to extend the spine. The multifidus muscles, a smaller group deep in the back, connect the vertebra. From the front of the body, the abdominal muscles are probably the most widely known of the postural muscles. The rectus abdominis is a long vertical muscle running the entire length of the abodomen, while the oblique muscles stretch around the sides and front of the stomach like a corset.
Many multi-tasking muscles are located in this region of the torso, including some postural muscles. Transverse abdominis is a flat, horizontal muscle lying below the belly button. Working synergistically with the abdominal muscles are the iliacus and psoas muscles to support the lumbar back. According to Lawrence Gold, practitioner of The Dr. Ida P. Rolf method of Structural Integration, "A protruding belly may indicate tight psoas muscles, not weak abdominal muscles." The tail end of the posture support structures are the gluteus and hamstring muscles. Physical Therapist Rod Dunn, PhD, of the Sciatica Clinic in Great Britain, explains the postural role of the hamstrings, "During standing and walking they work indirectly to maintain an erect posture."