The longissimus muscle is the longest of the sacrospinalis subdivision. It is located laterally to the semispinalis, and extends forward into the back side of the cervical vertebrae. The longissimus thoracis is the longest continuation of the sacrospinalis and lies intermediate to it. It blends with the iliocostalis lumbornum in the lumbar area, where a part of its fibers connect with the entire length of the back side of the lumbar vertebrae and the front surface of the lumbodorsal fascia. The longissimus cervicis originates along the slender tendons from the top of the upper thoracic vertebrae. It is located around the median of the longissimus dorsi. The longissimus capitis is located towards the median of the cervicis, between the semispinalis capitis and the cervicis. The longissimus muscle originates along the articular processes of the cervical vertebrae and the transverse processes of the thoracic vertebrae. It inserts into the back side of the mastoid process, below the splenius capitus. This muscle is usually intersected by a tendinous branch close to its insertion.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Longissimus