The Surface Anatomy of the Vertebrae and Back Muscles

By David Terfera, Shereen Jegtvig

Examining the surface anatomy of the back includes inspecting the skin, noting the symmetry (or asymmetry) of the back and its muscles, and assessing the curvatures of the spine. Knowing what landmarks to look for can help you locate potential problem areas for patients with back pain.

When you examine a patient from behind, the spine should be in a straight vertical line. Scoliosis is an abnormal lateral curvature and rotation of the spine. It can be mild and not cause any symptoms at all, or it can be quite severe and painful.

When you look at a standing person from the side, you should see four curves:

  • The neck (cervical region) and low back (lumbar region) should have curves that are concave posteriorly; in other words, they curve in toward the front of your body.

  • The mid back (thoracic region) and sacral portion of the spine should have curves that are convex posteriorly; in other words, they curve outward, away from the front of your body.

These curves help to provide flexibility and strength to the spine.

You may see a couple of conditions related to excessive curvature:

  • Scoliosis is an abnormal lateral curvature and rotation of the spine.

  • Kyphosis (dowager’s hump, or hunchback) is due to an excessively curved thoracic region of the vertebral column. Osteoporosis, especially in elderly women, can result in kyphosis.

  • Lordosis is an excessive curve in the lumbar region. It may be caused by disease of the vertebral column or by an increase in weight in the abdominal region. It is common during the later stages of pregnancy.

Scoliosis is usually diagnosed in the tween or early teen years and is more common in girls than in boys. Treatment for scoliosis starts with observation as long as the curve remains below 25–30 degrees. If the curve gets worse, a brace may be used, depending on the age of the person. Severe scoliosis, with a 45 degree curve or higher, may require surgery.

A bony bump called the occipital protuberance is at the midline of the base of the skull, just above the neck. Running directly below the occipital protuberance and down the middle of the neck is the nuchal groove that you can feel with your fingers. The nuchal ligament covers the palpable spinous processes of the cervical vertebrae in the neck.

The most prominent bump in the midline of the back, near the base of the neck, is usually the spinous process of the 7th cervical vertebra, although for some people it may be the 1st thoracic vertebra. Some, and possibly all, of the spinous processes of the thoracic and lumbar vertebrae are visible when a patient bends forward. The transverse processes aren’t visible, but they can be palpated on either side of the spinous processes.

The iliac crests of the hip bones should be level while the patient is standing and can be used as landmarks to draw an imaginary horizontal line to locate the level of the 4th lumbar vertebra. Inferior to that line, you may also see two dimples on either side of the sacrum, just over the sacroiliac joints.

The median sacral crest is a vertical bony ridge in the midline of the sacrum. You can palpate the sacral hiatus and the tip of the coccyx at the superior part of the intergluteal cleft.

In the midline of the back you can see the posterior median furrow, which lies over the spinous processes of the vertebral column. The erector spinae muscles run on either side of the furrow. You may be able to see (or at least palpate) them as two bulges on either side of the furrow.

Some of the extrinsic back muscles are visible in the lateral thoracic portions of the back, including the trapezius, rhomboid, and latissimus dorsi muscles that help to attach the upper extremities to the axial skeleton. The trapezius muscles form a diamond-like shape over the upper back, and the latissimus dorsi give the back its V-shape. The positions of the scapulae are also visible.