The first vertebra in the thoracic spine, otherwise known as the T1 vertebra, is the smallest vertebra in the thoracic spine and is also the first vertebra that connects to the rib cage. The T1 vertebra, like the rest of the 12 thoracic vertebrae, is characterized by its stability and strength. It is also this lack of flexibility that makes spinal deterioration less common in the thoracic spine than at other vertebral levels, such as the cervical (neck) and lumbar (lower back) segments.
The spine is made up of more than two dozen vertebrae, which are separated by soft, spongy intervertebral discs. There are five segments of the spine:
- Cervical spine in the neck
- Thoracic spine in the middle back
- Lumbar spine in the lower back
- Sacral spine in the buttocks
- Coccyx in the tailbone
Vertebrae provide flexion, extension and pivoting ability, and support much of the body’s weight. However, spinal vertebrae have differing roles. For example, the cervical spine supports the weight of the skull and gives the neck mobility. The vertebrae in the lumbar spine in the lower back are the largest and experience the most stress. The thoracic spine is much more stable and tasked with supporting the rib cage. Much of this stability is a result of the increase in the size of the thoracic vertebrae from the top of the thoracic spine to the bottom, with the T1 vertebra being the smallest and T12 being the largest.
The thoracic vertebrae—designated T1 through T12—are fused to the rib cage (with the exception of T11 and T12, known as “floating” vertebrae) via facets where the ribs meet the vertebrae. Existing between the last vertebra of the cervical spine (C7) and the T1 vertebra is the ulnar nerve root – a nerve root that extends from the spinal cord to the little finger and is unprotected near the elbow (the infamous “funny bone”). Compression of a nerve root at the T1 level can lead to a variety of painful symptoms, including local pain, muscle weakness and numbness in the arm.