Vertebral Column Anatomy

• The human body has 33 vertebrae

Anatomy of Vertebral Column

• It forms the central axis of the skeleton
• Located in the mid-sagittal plane, in posterior trunk
• Cerebral spinal fluid is found alongside the spinal cord
• Imaging of spinal cord and spinal area is done by meylography.
• The vertebral column encloses and protects the spinal cord
• The vertebral column supports the trunk and skull
• It provides for attachment to the deep muscles of the back and the ribs laterally
• Sacroiliac joint Articulates with each hip bone at SI joints.
• This articulation supports the vertebral column and transmits the weight of trunk to the lower limbs
• The vertebral Column is composed of small segments of bone called vertebrae
• Disks of fibrocartilage sits between vertebrae and act as cushions.
• The vertebral column is held together by ligaments and is jointed and curved, providing considerable flexibility and resilience
• The vertebral column has curvatures for strength and flexibility
• There are 33 vertebrae in early life
• Vertebrae are divided into five groups named according to region they occupy
• The five groups are Cervical, Thoracic, Lumbar, Sacral, Coccygeal
• The True vertebrae is also known as moveable vertebrae
• There are Upper 24 vertebrae in the first 3 regions
• True vertebrae remain distinct throughout life
• The false vertebrae are also called fixed vertebrae because of change they undergo in adults
• False Vertebrae are found in the lower 2 regions
• Sacral and Coccygeal segments fuse into one bone.

Vertebral Curvature

• The vertebral column has 4 curves that arch anteriorly and posteriorly from the mid-coronal plane
• Lordotic curves are convex anteriorly
• Kyphotic curves are concave anteriorly
• Cervical curve is lordotic
• Thoracic is kyphotic
• Lumbar is lordotic
• Pelvic is kyphotic
• Cervical and thoracic curves merge smoothly
• Lumbar and pelvic curves join at an obtuse angle termed the lumbosacral angle.
• An obtuse angle is an angle > 90deg
• Thoracic and pelvic curves are called primary curves because they are present at birth
• Cervical and lumbar curves are called secondary or compensatory curves because they develop after birth
• Cervical curve is the least pronounced of the curves
• Cervical curve develops when an infant begins to hold the head up at about 3 or 4 months of age and sits alone at about 8 or 9 months of age
• Lumbar curve develops when the child begins to walk at about 1 to 1 1/2 years of age

Spinal Pathologies

• Scoliosis: Abnormal lateral curvature of the spine
• Kyphosis: Abnormal increase in anterior concavity of T-spine
• Lordosis: Abnormal increase in the anterior convexity of C or L-spine
• Width of the spine gradually increases from C2 to the superior part of the sacrum and then decreases sharply
• A slight lateral curvature is sometimes present in the upper thoracic region
• The curve is to the right in right-handed persons and to the left in left-handed persons
• The vertebral column develops a second or compensatory curve in the opposite direction to keep the head centered over the feet

Typical Vertebra

• It is composed of 2 main parts
• These are the Body and the Arch
• Body = anterior mass of bone
• Arch = posterior ringlike portion
• The 2 parts enclose a space -the vertebral foramen
• The articulation of vertebral foramina = vertebral canal
• The body is cylindric in shape
• It is largely composed of cancellous bony tissue covered by a layer of compact tissue
• From its superior aspect, posterior vertebral surface is flattened
• From its lateral aspect, the vertebral's anterior and lateral surfaces are concave
• Superior and inferior surfaces of the vertebral bodies are flattened and are covered by a thin plate of articular cartilage
• Intervertebral disks = intervertebral joints separate each vertebral body
• Intervertebral Disks are approx 1/4 of length of the vertebral column
• Has a central mass of soft, pulpy, semigelatinous material called the nucleus pulposus, surrounded by outer fibrocartilaginous disk called annulus fibrosus
• Herniated nucleus pulposus (HNP) (slipped disk) = Rupture or protrusion of pulpy nucleus into the vertebral canal, impinging on a spinal nerve
• HNP Most often occurs in L-spine due to improper body mechanics and also in C-spine as a result of trauma or degeneration
• Arch is formed by 2 pedicles and 2 laminae
• 2 Laminae which support four articular processes
• 2 transverse processes
• 1 spinous process
• Pedicles are Short and thick processes
• One is on each side, from posterior surface of the vertebral body
• The bottom of each pedicle is concave to form vertebral notches
• Articulation of vertebral notches form intervertebral foramina for the transmission of spinal nerves and blood vessels
• Laminae are located at back of pedicles
• They are are Broad & flat
• Laminae are Directed posteriorly and medially from pedicles
• Transverse processes project laterally and posteriorly from the junction of the pedicles and laminae
• Spinous process projects posteriorly and inferiorly from the junction of the laminae in the posterior midline
• Spina bifida =A congenital defect of vertebral column in which the laminae fail to unite posteriorly at the midline
• There are 4 articular processes: 2 superior and 2 inferior
• They Arise from junction of pedicles and laminae to articulate with the vertebrae above and below
• Articulating surfaces of the 4 articular processes = facets
• Articulations between articular processes of the vertebral arches form zygapophyseal joints (interarticular facet joints)
• Movable vertebrae, except C1 and C2, are similar in general structure

Cervical Vertebrae

• C1 - C2 are atypical = structurally modified to join skull
• C7 is atypical = slightly modified to join T-spine
• C1 is also known as atlas
• Atlas is Ringlike with no body & a very short spinous process
• Atlas consists of Anterior arch, Posterior arch, 2 lateral masses,2 transverse processes
• The atlas' ring is divided into anterior and posterior portions by transverse atlantal ligament
• The dens works as the body for C1 since C1 has no body
• Anterior portion of the ring receives the dens (odontoid process) of C2 (axis) & posterior portion transmits the proximal spinal cord
• The Transverse process is longer than those of the other cervical vertebrae
• Atlantooccipital joints exist between the C1 & the occipital bone of skull
• The dens lies inside the C2
• Axis has a strong conical process arising from the upper surface of its body (dens / odontoid)
• At each side of the dens on the superior surface of the vertebral body are the superior articular processes, adapted to join with the inferior articular processes of the atlas
• The range of motion changes at the C1 -C2 Z-joints in position and direction from other cervical zygapophyseal joints
• Laminae of C2 vertebrae are broad and thick
• Spinal process of C2 vertebrae is horizontal in position
• The vertebral prominens has a long, prominent spinous process that projects almost horizontally to the posterior
• The thoracic and body portions of vertebrae are similar in anterior view
• Articular Pillar
• The Typical C-spine vertebrae are C3-C6
• They Have a small, oblong body with slightly elongated anteroinferior borders = AP overlapping of the bodies in the articulated column
• They are Short and wide in anteroposterior view
• These arise partly from sides of the body and partly from the vertebral arch and is Perforated by transverse foramina
• The transverse foramina provide transmission of the vertebral artery and vein and provides blood for posterior portion of the brain, as well as, present a deep concavity on their upper surfaces for passage of the spinal nerves
• All cervical vertebrae contain 3 foramina: right and left transverse foramina and the vertebral foramen.
• If the vertebral foramina are connected on top of each other that forms the veterbral canal
• The Vertebral arteries are vessels that receives the spinal cord
• Pedicles project laterally and posteriorly from the body, and their superior and inferior vertebral notches are nearly equal in depth
• Laminae are narrow and thin
• Spinous processes are short and have double-pointed (bifid) tips
• Pedicles on Typical cervicals project laterally and posteriorly from the body and the superior & inferior vertebral notches are nearly equal in depth. Superior & inferior articular processes are posterior to the transverse processes/ TP's at the pedicle-lamina junctions.
• The articular processes form short, thick columns of bone called articular pillars
• The Zygapophyseal facet joints lie at right angles to the MSP and can be clearly shown in a lateral projection
• IVF oblique view is needed because these joints located at a 45-degree angle
• To obtain an * IVF oblique view*, a 15-degree cephalic longitudinal gantry angulation and a 45 degree medial rotation of the patient

Thoracic Vertebrae

• They have 3 types of facets (2 on body & 1 on TP)
• Bodies withstand weight
• Increase in size from T1 - T12
• Superior thoracic bodies resemble cervical bodies
• Inferior thoracic bodies resemble lumbar bodies
• Bodies of typical (T3 - T9) are approx. triangular
• Posterolateral margins of each body have costal facets for articulation with the heads of the ribs
• With the exception of T11 - T12, each transverse process has on the anterior surface of its extremity a small concave facet for articulation with the tubercle of a rib
• The Laminae are broad and thick, and overlap the subjacent lamina
• Zygapophyseal joints (except the inferior articular processes of T12) angle anteriorly approx. 15 to 20° to form an angle of 70 to 75° to MSP.
• The Lumbar spine & the thoracic spine Z joints have a FLIPPED oblique view and lateral view, compared to the C spine.
• To show the Z- joints, pt's body must be rotated 70 to 75° from anatomic position or 15 to 20° from lateral position
• The IVFs are perpendicular to MSP. IVF is clearly shown in a true lateral position

Lumbar Vertebrae

• Transverse processes are long and slender

• These are bean-shaped bodies that increase in size from L1 - L5

• The mammillary process is a smoothly rounded projection on the back of each superior articular process. The accessory process is at the back of the root of the transverse process. The body of L5 is deeper in front than behind with a wedge shape that adapts it for articulation with the sacrum.

• They are deeper anteriorly than posteriorly -

• Their superior and inferior surfaces are flattened or slightly concave

• Transverse processes are smaller than those of thoracic vertebrae

• The average angle from the coronal plane increases from cephalad to caudad with L1–L2 being at 15°, L2–L3 at 30°, and L3–L4 and L5–S1 at 45°.

• Z-joints for lumbar lie almost in sagittal (the image must be rotated) from coronal plane

• Body position, showing the lumbar lumbar zygapophyseal joints , are most clinically at oblique 45 degrees

• The spinous processes are large, thick, and blunt

• They have an almost horizontal projection posteriorly

• The Superior pairs of transverse processes are directed almost exactly laterally, whereas the Inferior two pairs are inclined slightly superiorly.

• The Pedicles are strong and are directed posteriorly, and the laminae are thick.

Explore the anatomy of the vertebral column, the central axis of the human skeleton. Learn about its structure, including the 33 vertebrae, fibrocartilage disks, and ligaments, and its vital functions in protecting the spinal cord, supporting the trunk and skull. Also, discover how it articulates with the hip bones and provides flexibility and resilience.