The human spine is a complex structure that supports the body, enables movement, and protects the delicate spinal cord. It is organized into distinct regions: the cervical spine in the neck, the thoracic spine in the mid-back, the lumbar spine in the lower back, and the fused bones of the sacrum and coccyx. This arrangement allows for flexibility and stability.
Anatomy and Location of T11
T11 refers to the eleventh thoracic vertebra, located in the lower part of the thoracic spine. This region spans the chest level, between the cervical and lumbar areas. Thoracic vertebrae, numbered T1 to T12, gradually increase in size from top to bottom, with T11 and T12 being larger and heavier to support increasing weight. T11 is classified as an irregular bone, sharing features with both typical thoracic vertebrae and the lumbar vertebrae below it.
The T11 vertebra has a robust vertebral body, its main weight-bearing structure. Pedicles and laminae extend from the vertebral body, forming the vertebral arch that encloses the spinal canal and houses the spinal cord. The spinous process of T11, a bony projection at the back, is relatively short and tends to be more horizontal compared to the longer, downward-sloping processes of upper thoracic vertebrae.
The transverse processes of T11 are shorter than those of upper thoracic vertebrae and lack articular facets for rib tubercles, unlike T1 through T10. T11 articulates with the eleventh pair of ribs, which are considered “floating ribs” because they do not connect directly to the sternum. The articular facets on T11 for the heads of the ribs are large and located primarily on the pedicles, a feature shared with T12. This distinguishes them from other thoracic vertebrae where facets are typically on the vertebral bodies. The eleventh thoracic spinal nerve exits from beneath the T11 vertebra, between T11 and T12.
Significance and Common Issues of T11
The T11 vertebra is located within the thoracolumbar junction, a transitional area of the spine from T11 to L2. This region experiences mechanical stress. It marks the shift from the rigid, outwardly curved (kyphotic) thoracic spine, stabilized by the rib cage, to the more mobile, inwardly curved (lordotic) lumbar spine. This change in spinal curvature and load-bearing dynamics makes the thoracolumbar junction a common site for spinal injuries.
The T11 spinal nerve is a mixed nerve, containing both motor and sensory fibers. The anterior (ventral) ramus of the T11 spinal nerve becomes the eleventh intercostal nerve, providing motor and sensory innervation to the abdominal wall. The posterior (dorsal) ramus innervates the deep muscles of the back and provides sensation to the overlying skin. These nerve roots contribute to sensation and movement in the lower back and upper abdomen.
Common issues affecting the T11 vertebra include vertebral fractures, disc herniations, and spinal stenosis. Compression fractures, often occurring at T11 and T12, happen when the vertebral body collapses due to excessive pressure, typically from osteoporosis or trauma. Symptoms of a compression fracture can include sudden back pain, which may worsen with movement and improve with rest, limited mobility, and sometimes numbness or tingling if nerves are affected.
Disc herniations in the thoracic spine are less common than in the cervical or lumbar regions, but about 75% occur between T8 and T12, with T11-T12 being a frequently affected area. A herniated disc at T11 can cause pain in the mid-back that may wrap around the chest, or radiate to the abdomen or legs. This can also lead to numbness, tingling, or weakness in the lower extremities due to pressure on the spinal cord or nerve roots. Spinal stenosis, a narrowing of the spinal canal, can also occur at T11, though it is less common in the thoracic region. Symptoms of thoracic spinal stenosis can include progressive weakness in the legs, difficulty walking, numbness in the legs or feet, and occasionally bowel or bladder dysfunction.