Vertebral Column Anatomy

• Concept: Vertebral Column

Function of Vertebral Column

• Provides protection for the spinal cord, surrounding meninges, and spinal nerves.
• Supports the body's weight.
• Includes sites for muscle attachment.
• Controls and limits torso movements.

Components of Vertebral Column

• Composed of 33 vertebrae.
• Includes 7 cervical vertebrae.
• Includes 12 thoracic vertebrae.
• Includes 5 lumbar vertebrae.
• Includes 5 sacral vertebrae which are fused into the sacrum
• Includes 1-4 coccygeal vertebrae fused as the coccyx.
• Numbered from superior to inferior.
• Separated by intervertebral discs.

Curvatures of Vertebral Column

• Primary curvatures develop during the fetal period (3rd-9th month).
• Thoracic and Sacral/Pelvic curvatures are primary curvatures.
• Primary curvatures are concave anteriorly.
• Secondary curvatures complete development after birth
• Cervical and Lumbar curvatures are secondary curvatures.
• Secondary curvatures are concave posteriorly.
• Cervical curvature becomes prominent after a child holds their head up.
• Lumbar curvature becomes prominent after a child walks.

Vertebral Column - Angles

• Lumbosacral angle is at the junction between L5 and S1.
• The lumbosacral angle is generally smaller in females due to the sacrum projecting more posteriorly.
• Sacral angle refers to the concavity of the sacrum.
• The sacral angle is less acute in females, described as more vertical.

Typical Vertebra Features

• Transverse Process: projects laterally
• Superior Articular Process: projects superiorly to articulate with vertebrae above.
• Vertebral Foramen: passage for the spinal cord in a single vertebra.
• Vertebral Body: anterior
• Spinous Process: posterior
• Lamina & Pedicle form the Vertebral (Neural) Arch.

Vertebral Foramen vs. Vertebral Canal

• Vertebral foramen: opening in a vertebra through which the spinal cord passes.
• Vertebral foramen is formed by the vertebral arch and vertebral body.
• Vertebral canal: formed when two or more vertebral foramina are in line with each other.

Cervical Vertebra

• Transverse Foramen are passages for vertebral arteries.
• Transverse Foramen are present on all cervical vertebrae (C1-C7).
• Short, bifid spinous processes are present only on C2-C6.
• Cervical vertebrae are small and kidney-bean-shaped.

Atlas (C1)

• The Atlas (C1) vertebra has no body or spinous process, appearing ring-like.
• The superior articular surfaces of the atlas articulate with the occipital condyles of the skull.
• The atlas holds up the skull and swivels around the axis.
• The atlas creates the "yes" motion when C1 articulates with the occipital condyles of the skull.

Axis (C2)

• The Axis (C2) vertebra's body has a vertical projection called the dens.
• The dens is a structure that initially would have been the C1 body and embryologically migrated to become the dens.
• The Axis (C2) is the strongest of all cervical vertebrae.
• Ligaments support the mechanism of rotation for the cervical spine.
• The dens is the "axis" of rotation.
• The Atlas (C1) creates the “no” motion.

Thoracic Vertebra

• Every Thoracic Vertebra articulates with a rib.
• The angles of articulation facets are Anteromedial (Inferior) and Posterolateral (Superior)
• Medium-sized vertebrae, larger than cervical.
• The body has a heart shape.
• There are costal facets for ribs, where transverse foramina are absent.
• Long spinous process projects inferiorly.

Lumbar Vertebra

• The Lumbar vertebra is characterised as the largest.
• They have a large, round/oval body shape.
• There are no costal facets for ribs or transverse foramina.
• Includes short, thick, and blunt spinous process
• Angles of Articular Facets are Lateral (Inferior) and Medial (Superior).
• Transverse processes are Large, thick, and blunt

Sacrum & Coccyx

• Ala is the "wing" of the sacrum, representing fused remnants of transverse processes.
• Anterior Sacral Foramina transmit anterior rami of spinal nerves.
• Median Sacral Crest is composed of fused spinous processes of S1-S3.
• Auricular Surface articulates with the ilium to form the sacroiliac joint.
• Posterior Sacral Foramina transmit posterior rami of spinal nerves.
• Sacral Hiatus is the opening at the distal end of the vertebral/sacral canal resulting from the failure of S4/5 spinous processes to form.

Intervertebral Discs

• Intervertebral Discs are the fibrocartilage pads between the vertebrae.
• Intervertebral discs are composed of a nucleus pulposus and an annulus fibrosus.
• Nucleus pulposus: inner gelatinous material which gives the disc elasticity and compressibility.
• Annulus fibrosus: surrounds the nucleus pulposus with a collar composed of cartilage matrix with concentric rings of fibers, strengthening the disc.
• Intervertebral discs act as flexible shock absorbers due to their composite construction.

Vertebral Column Stabilizing Ligaments

• Posterior Longitudinal Ligament reinforces support of the vertebral column posterior to the body of the vertebrae.
• The Posterior Longitudinal Ligament resists hyperflexion of the vertebral column.
• "Herniation” of nucleus pulposus is typically posterolaterally, rarely directly posterior.
• Anterior Longitudinal Ligament reinforces support of the vertebral column anterior to the body of vertebrae.
• The Anterior Longitudinal Ligament resists hyperextension of the vertebral column.

Herniated Disc

• A herniated disc occurs when the annulus fibrosus weakens.
• Nucleus pulposus will herniate (protrude).
• Compression of the spinal nerves (or nerve roots) can exit the spine in this area.
• Typically occurs in the posterolateral direction, influenced by the posterior longitudinal ligament.
• The posterior longitudinal ligament supports the vertebral column posterior to the body of the vertebrae.

Abnormal Curvatures of Vertebral Column

• Include Scoliosis, Kyphosis, and Lordosis.

Scoliosis

• Scoliosis symptoms include a crooked or curved back
• Scoliosis includes the abnormal lateral curvature of the spine (especially in the thoracic region).
• Causes of Scoliosis include weakness in intrinsic back muscles (myopathic) and failure of half of the vertebra to develop causing hemivertebra
• Also be caused by a difference in Limb length
• Commonly found in pubertal girls aged 12-15 years.

Kyphosis

• Kyphosis = Hunchback.
• This is due to an excessive Thoracic Curvature.
• Causes include degeneration of the anterior body of the vertebra and fracture.
• Also be caused by congenital defects and osteoporosis.
• Can cause Dowager's hump in osteoporotic females.
• Commonly occurs in geriatric people of both sexes.

Lordosis

• Lordosis is also known as swayback.
• Main cause is an excessive Lumbar Curvature.
• This causes an anterior rotation of the pelvis and an abnormal extension deformity.
• Also be caused by a weakening of the anterolateral abdominal wall
• Is common during pregnancy.