The longissimus dorsi is a muscle in your back, supporting the spine and enabling movement. It is one of the primary muscles in the erector spinae group, a powerful collection of muscles that run along the length of the vertebral column. This muscle stabilizes posture and facilitates spinal motion.
Anatomy of the Longissimus Dorsi
The longissimus dorsi is the longest and most centrally positioned muscle within the erector spinae group. It runs parallel to the spinal column, extending from the sacrum and iliac crest upwards towards the skull. It is divided into three sections, named for their primary region: the longissimus thoracis, which spans the thoracic or middle back region; the longissimus cervicis, located in the cervical or neck region; and the longissimus capitis, which extends to the mastoid process of the skull, behind the ear. These segments form a continuous pathway that supports the entire back.
Function in Daily Movement
The longissimus dorsi muscle performs actions fundamental to everyday movements and maintaining body stability. When both sides of this muscle contract simultaneously, their primary action is spinal extension. This movement involves straightening the back, such as when you stand up from a bent-over position or arch your back backward.
When only one side of the longissimus dorsi contracts, it facilitates lateral flexion of the vertebral column. This allows you to bend your torso sideways, for instance, reaching for an object on the floor beside you without twisting. The muscle also plays a role in maintaining upright posture, supporting the natural curves of the spine and preventing slouching.
Common Sources of Pain
Pain in the longissimus dorsi muscle often arises from various forms of strain and overuse. Acute strains can occur from improper lifting mechanics, such as bending at the waist instead of using the legs to lift heavy objects. This puts excessive stress on the lower back muscles, including the longissimus dorsi.
Chronic strain is frequently linked to poor posture, particularly prolonged periods of slouching while sitting or standing. This sustained incorrect alignment can overstretch or tighten the muscle fibers, leading to persistent discomfort. Additionally, overuse injuries are common in sports and activities that involve repetitive spinal extension or twisting motions. Athletes participating in golf, rowing, or tennis, for example, may experience strain due to the repeated engagement of these back muscles.