There are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae. They are distinguished by the presence of facets on the sides of the bodies for articulation with the heads of the ribs, as well as facets on the transverse processes of all, except the eleventh and twelfth, for articulation with the tubercles of the ribs. By convention, the human thoracic vertebrae are numbered T1–T12, with the first one (T1) located closest to the skull and the others going down the spine toward the lumbar region.
Each thoracic disc is comprised of the following:
- Outer layer (annulus fibrosus). This durable exterior of the disc is comprised of tough collagen fibers to help distribute major loads placed on the spine and protect the disc’s soft interior.
- Inner core (nucleus pulposus). This jelly-like interior is a loose network of fibers floating in a mucoprotein gel. The disc’s inner core provides more cushioning and movement between adjacent vertebrae than the outer layer.
Intervertebral discs are the largest structures in the human body that do not have blood vessels. A super-thin structure between the disc and vertebra, called a vertebral end plate, provides diffusion so that nutrients can get into the disc.
Common conditions of thoracic disc include:
- thoracic degenerative disc disease
- thoracic disc herniation
- thoracic disc prolapse
- thoracic disc injury.
The thoracic spine is strengthened by the presence of numerous ligaments.
Present Throughout Vertebral Column
- Anterior and posterior longitudinal ligaments: Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.
- Ligamentum flavum: Connects the laminae of adjacent vertebrae.
- Interspinous ligament: Connects the spinous processes of adjacent vertebrae.
- Supraspinous ligament: Connects the tips of adjacent spinous processes.
Unique to Thoracic Spine
A number of small ligaments also support the costovertebral joints:
- Radiate ligament of head of rib – Fans outwards from the head of the rib to the bodies of the two vertebrae and intervertebral disc.
- Costotransverse ligament – Connects the neck of the rib and the transverse process.
- Lateral costotransverse ligament – Extends from the transverse process to the tubercle of the rib.
- Superior costotransverse ligament – Passes from the upper border of the neck of the rib to the transverse process of the vertebra superior to it.
The muscles of the thorax consist of the intercostals and diaphragm. The intercostal muscles are arranged as three layers (external layer, internal layer and an incomplete innermost layer) between the ribs. The diaphragm closes the thoracic outlet and separates the thoracic cavity from the abdominal cavity. The three layers of the intercostal muscles are:
- external layer — external intercostal
- internal layer — internal intercostal
- innermost layer — transversus thoracic (anterior), innermost (lateral) and subcostal (posterior)
The diaphragm is the most important muscle of the thoracic wall. During normal respiration, this muscle is the primary component.
The innermost layer is split into three differently named muscle groups. The transversus thoracis, innermost intercostal and subcostal muscles make up the deepest layer of muscles from anterior to posterior, respectively.
Common conditions of thoracic muscles and ligaments include:
- Thoracic Intervertebral Joint Sprain
- Thoracic Muscle Rupture
- Costovertebral Joint Disorders.
Thoracic Bones and Joints
The thoracic vertebrae are a group of twelve small bones that form the vertebral spine in the upper trunk. Thoracic vertebrae are unique among the bones of the spine in that they are the only vertebrae that support ribs and have overlapping spinous processes.
The cartilaginous joints in your thoracic cage allow you to breathe. The 1st ribs don’t move at all, but the act of breathing requires the other ribs to move up and down a bit, so the joints formed between the rest of the ribs and thoracic vertebrae allow for some movement.
The joints of the thoracic spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the thoracic spine.
Present throughout Vertebral Column
There are two types of joints present throughout the vertebral column:
- Between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage. This is a type of cartilaginous joint, known as a symphysis.
- Between vertebral arches – formed by the articulation of superior and inferior articular processes from adjacent vertebrae. It is a synovial type joint.
Unique to Thoracic Spine
The articulations between the vertebrae and the ribs are unique to the thoracic spine. For each rib, there are two separate articulations – costovertebral and costotransverse.
Each costovertebral joint consists of the head of the rib articulating with:
- Superior costal facet of the corresponding vertebra
- Inferior costal facet of the superior vertebra
- Intervertebral disc separating the two vertebrae
Within this joint, the intra-articular ligament of head of rib attaches the rib head to the intervertebral disc. Only slight gliding movements can occur at these joints, due to the close articulation of their components.
The costotransverse joints are formed by the articulation of transverse processes of a thoracic vertebra and the tubercle of the adjacent rib. They are present in all vertebrae except T11 and T12.
Common conditions of thoracic joints include:
- Thoracic Osteoarthritis
- Facet Joint Disorders
The thoracic nerves refer to the cluster of nerve fibers found in the upper body, particularly within the chest region. These nerve fibers are considered spinal nerves, which carry and transmit information between the spinal cord and parts of the body.
The nerves stem from portions of the vertebrae. Eleven of the 12 nerves are situated in spaces located between two ribs. These are known as the intercostal nerves. The last thoracic nerve, known as subcostal, is found just below the final rib. Collectively, these nerves communicate with various parts of the chest and abdomen.
The fibers of the first two thoracic nerves extend to the shoulder and arms, and the next four nerves direct signals to the chest. The lower five thoracic nerves are found in the chest and abdomen. The last thoracic nerve supplies the abdominal wall and the buttocks, specifically the skin.
Each of the thoracic nerves is divided into anterior and posterior branches known as the dorsal ramus and ventral ramus. These fiber extensions direct signals to various parts of the upper body, including muscles, deep tissues, skin, and blood vessels.
Common conditions of thoracic nerves include:
- Thoracic Nerve Injuries
- Thoracic Spinal Stenosis
- Thoracic Radiculopathy.
For approximately the first 72 hours following an injury, the RICE regime should be followed to ensure control of inflammation and pain relief.
R – Rest
I – Ice
C - Compression
E - Elevation
Rest from aggravating activity.
Ice should be applied in the first 72 hours or when inflammation persists. Ice should be applied for 15 to 20 minutes at a time. Ice should not be applied directly to the skin, but through a wet towel or cloth.