Spinal column

Anatomical structure of the vertebral column

The spinal column, also known as the vertebral column or backbone, is a complex structure that provides support and flexibility to the human body. It is a central feature of the axial skeleton and plays a crucial role in protecting the spinal cord, supporting the head, and serving as an attachment point for ribs and muscles.

Anatomy of the Spinal Column

The spinal column is composed of 33 vertebrae, which are divided into five distinct regions:

Cervical Spine

Cervical vertebrae

The cervical spine consists of seven vertebrae (C1-C7) located in the neck. The first two vertebrae, the atlas (C1) and axis (C2), are specialized to allow for a wide range of head movements. The cervical spine supports the skull and enables nodding and rotation of the head.

Thoracic Spine

Thoracic vertebrae

The thoracic spine is made up of twelve vertebrae (T1-T12) and is located in the upper and mid-back. Each thoracic vertebra articulates with a pair of ribs, forming the rib cage that protects vital organs such as the heart and lungs. The thoracic spine is less mobile than the cervical spine due to the rib attachments.

Lumbar Spine

The lumbar spine consists of five vertebrae (L1-L5) in the lower back. These vertebrae are larger and stronger than those in the cervical and thoracic regions, as they bear the weight of the upper body and provide stability and flexibility for movements such as bending and twisting.

Sacrum

The sacrum is a triangular bone formed by the fusion of five sacral vertebrae (S1-S5). It connects the spine to the pelvis and forms the posterior part of the pelvic girdle. The sacrum is a key structure in transferring weight from the upper body to the lower limbs.

Coccyx

The coccyx, or tailbone, is composed of three to five fused vertebrae. It is the remnant of a vestigial tail and serves as an attachment point for ligaments and muscles of the pelvic floor.

Function of the Spinal Column

The spinal column serves several vital functions:

• Protection: It encases and protects the spinal cord, a critical component of the central nervous system.
• Support: It provides structural support for the body, allowing humans to stand upright and maintain balance.
• Movement: It enables a wide range of movements, including bending, twisting, and rotating.
• Shock Absorption: Intervertebral discs act as shock absorbers, cushioning the vertebrae during activities such as walking, running, and jumping.

Intervertebral Discs

Intervertebral disc

Intervertebral discs are fibrocartilaginous cushions located between adjacent vertebrae. Each disc consists of a tough outer layer called the annulus fibrosus and a gel-like center known as the nucleus pulposus. These discs allow for flexibility and act as shock absorbers, distributing loads across the spine.

Common Disorders of the Spinal Column

Several conditions can affect the spinal column, including:

• Herniated disc: Occurs when the nucleus pulposus protrudes through a tear in the annulus fibrosus, potentially compressing nearby nerves.
• Scoliosis: A lateral curvature of the spine that can lead to discomfort and reduced mobility.
• Osteoporosis: A condition characterized by weakened bones, increasing the risk of fractures in the vertebrae.
• Spinal stenosis: Narrowing of the spinal canal, which can compress the spinal cord and nerves, causing pain and neurological symptoms.

Related Pages

• Spinal cord
• Intervertebral disc
• Scoliosis
• Osteoporosis