Understanding the Parts of Your Spine

The spine is one of the most essential structures of the body, allowing us to stand, walk and keep ourselves upright. First and foremost, the spine provides your body with proper support. The support of the spine is essential to various bodily movements and functions, such as standing and walking.Additionally, your spine allows for flexible movements, such as bending and twisting. Another function of the spine is that it protects the delicate spinal cord from potential damage. The spinal cord is a collection of nerves that connect the brain to the rest of the body, allowing for various movements and processes. The spinal cord helps the body and internal organs function properly. A healthy spine is a key aspect of leading a healthy lifestyle.

Parts of the Spine and Their Function

The various parts of the spine provide support and enable unique functions and mobilities. With time, the various parts of the back may wear down or degenerate. The degradation of healthy joints and aspects of the spine can lead to limited mobility, inflexibility and even acute or chronic back pain. In addition to chronic back pain, some of the most common spinal conditions include degenerative disc disease, herniated discs, facet joint syndrome, disc tears and more.

• 1. Vertebrae

  The vertebrae are important spinal bones that consist of a cylindrical body in the front and a bony ring in the back. The main body of the vertebra is a stacking agent that helps to create the entire spinal column. The vertebrae help provide basic weight support to the spine. The delicate spinal cord also runs through the tunnel formed by the stacked vertebrae. The vertebral anatomy includes:

  • Pedicles: Each vertebra features two cylinder-shaped projections of bone known as pedicles. These pedicles of hard bone protrude outwards from the back part of the vertebral body and help protect the sides of the spinal nerves and spinal cord. The pedicles of the spine also act as a bridge that joins the back and front parts of the vertebra.
  • Laminae: The vertebral laminae are bony sheets or ridges that help connect various morphological landmarks of the vertebrae, including zygapophyses and diapophyses. The laminae typically feature some variation throughout the spinal column.
  • Transverse processes: A transverse process is a small bony projection off the left and right sides of each vertebra. There are two transverse processes of each vertebra that serve as the attachment site for ligaments and muscles of the spine and are the point of articulation of the ribs.
  • Spinous processes: A spinous process is a bony projection that is on the back of each vertebra. The spinous process begins to protrude from where the laminae of the vertebral arch join and acts as a point of attachment for various spinal ligaments and muscles.
  • Endplates: The endplates of the vertebral body are anatomically discreet structures that form the interface between the intervertebral discs and vertebral bodies. The endplates are constituted peripherally by the epiphyseal bone ring and centrally by a layer of cartilage.
  • Intervertebral foramina: The intervertebral foramina are often referred to as the neural foramina and are located between two spinal vertebrae. The lumbar, thoracic and cervical spine all have intervertebral foramina. Numerous structures pass through the foramina.
• 2. Facet Joints

  The facet joints of the spinal column are situated behind the vertebral body and help the spine twist, bend and extend in various directions. While the facet joints enable movement, they also help restrict excessive motion that may result in hyperflexion or hyperextension. Each vertebra of the spinal column has two facet joints. The superior articular facet joint faces upwards and works similar to a hinge with the inferior articular facet joint.

  The facet joints are similar to other joints in the body as they are surrounded by connective tissue, which provides synovial fluid for the joint's nourishment and lubrication. The surfaces of the facet joints are coated in cartilage which protects the joints and allows for smooth movement. Because the facet joints feature interconnected characteristics, they play an essential role in keeping the spinal column stable during movement.

• 3. Intervertebral Discs

  In between each vertebra, there is a cushion known as the intervertebral disc. The intervertebral disc helps absorb the shock and stress the body may experience during movement while preventing the vertebrae from grinding against one another. The intervertebral discs are also the largest bodily structures that do not have a vascular supply. Each intervertebral disc can also absorb necessary nutrients through the process of osmosis. Each intervertebral disc is comprised of two parts, including the nucleus pulposus and annulus fibrosis.

  • Nucleus pulposus: The nucleus pulposus works in unison with the annulus fibrosis to transmit weight and stress from vertebra to vertebra. The nucleus pulposus consists of proteoglycans, collagen and water. When compared to the annulus fibrosis, the nucleus pulposus contains more water. One of the main functions of the nucleus pulposus is that it helps the vertebral disc withstand torsion and compression.
  • Annulus fibrosus: The annulus fibrosis is a sturdy and almost tire-like structure that encases the nucleus pulposus. The annulus helps enhance the spine's ability to rotate and helps to resist compressive stress. The annulus fibrosus consists of sturdy elastic collagen fibers and water. The fibers are oriented at various angles horizontally. The collagen gains strength from strong bundles of protein that are linked together.
• 4. Ligaments

  The tendons and ligaments of the spine are bands of fibrous connecting tissue that adhere to the bones. A ligament is designed to connect multiple bones together while stabilizing joints. Ligaments and tendons are relatively elastic and also vary in size. The ligament system in the vertebral column works in conjunction with the muscles and tendons to provide a brace and protect the spine. Ligaments also help to stabilize the joints during movement and rest. The three major ligaments of the spine include:

  • Ligamentum flavum: Meaning "yellow ligament," ligamentum flavum has a yellow coloring due to an abundance of elastin. The elastin pulls the ligament out of the canal when the spine is extended. With age, it is normal for the ligament to lose elastin, which may cause the ligament to encroach on the canal. During lumbar decompression surgery, ligamentum flavum may be removed, as it is often a leading contributor to spinal stenosis.
  • Anterior longitudinal ligament: The anterior longitudinal ligament is a strong band that varies in width and thickness and covers the anterior regions of the vertebral bodies and intervertebral discs through the length of the vertebral column. The deepest fibers are known as the short intersegmental fibers, with the intermediate fibers spanning two or three vertebrae and the superficial fibers spanning three or four vertebrae.
  • Posterior longitudinal ligament: The posterior longitudinal ligament is a strong ligament that forms the anterior wall of the vertebral canal and spans the body from C2 to the sacrum's posterior surface. It features deep intersegmental fibers and more superficial fibers that can span up to four vertebrae.
• 5. Tendons and Muscles

  Tendons function similarly to ligaments, as these fibrous tissues help secure muscle to bone and are made of collagen fibers. Whether in groups or individually, muscles are supported by fascia, a sturdy, sheath-like connective tissue. The tendon that helps attach the muscle to the bone is part of the fascia.

  The spine's muscular system is complex and has several muscles that play essential roles. The muscles located in the vertebral column help support the spine, provide stability and rotate, flex or extend the spine. Different muscles and muscle groups help to provide mobility to various parts of the body. The sternocleidomastoid muscle in the neck area assists with the mobility of the head. Additionally, the psoas major is a muscle in the lower back area that helps with thigh flexion.