The most important concept in this region is the
concept of segmentation. The vertebral column is divided into vertebrae and spinal nerves
exit the spinal cord at each level.
A consequence of this segmentation is the
formation of dermatomes and myotomes.
Remember that spinal nerves divide into dorsal and
ventral rami which define 'true back muscles' from the superficial back muscles.
True back muscles function in movement of the
vertebral column (support). Other back muscles are involved with respiration or movement
of the upper limb (scapula and humerus).
It is important to remember that with development
the vertebral column continues to lengthen after the spinal cord has reached its
adult length.
