Spinae (a.k.a. sacrospinalis and erector spinae) - a group of muscles and tendons that stretch vertically from the posterior of the ilium (largest bone in the pelvis) to the base of the skull - parallel to the vertebral column.
Moving up, the muscles start at the ilium, sacrum and lumbar vertebrae (crossing the lumbar region without attachment to lumbar vertebrae), branches into 3 (iliocostalis, longissimus and spinalis), which insert into ribs and vertebrae and are joined by other muscle strips as they approach the neck. The muscles are covered by the thoracolumbar fascia. Fascia is a connective tissue system that extends throughout the body, providing support, structural integrity and protection.
Spinae is involved in maintaining curvature of the spine, posture, spine extension, and lateral (side to side) bending.
Spinae also is the name for bacterial appendages (close to pili or fimbriae). These spinae are long tube-like structures made of the protein spinin. No function has been completely proven. But they may be involved in attachement or in long distance cell-cell connection.
Unrelated, "Spinae" is the Roman name for a town in Berkshire, England now called "Speen." I only mention the Roman reference because, while doing different searches on 'spinae', I found that in Roman chariot races, the two tracks where separated by a raised median called a 'spina.' Anyway, you can see the structural similarities between the spinae and the spina. Not to mention the etymological similarities between the words spina, spinae and spine.
Spinae or erector spinae is a group of muscles in humans and some other animals. Its function is to keep the back straight and to turn it from one side to other.
In humans this muscles runs in a pair almost vertically along the entire length of the back, Starting from the level of pelvis, and extend throughout the cervical, lumber and thoracic region. When it reaches the level of small back it divides in three columns. It lies in the grooves to the side of vertebral column.