1.2. Vertebrae

What are the components of a vertebral arch?

Spinous process, lamina, and pedicle

How many vertebrae make up the vertebral column?

33

What are the 5 regions of the vertebral column and how many vertebrae are in each?

Cervical (7, C1-C7), Thoracic (12, T1-T12), Lumbar (5, L1-L5), Sacral (5, S1-S5), Coccygeal (4, Co1-Co4)

What is the curvature of the cervical spine?

Convex (lordosis)

What is the curvature of the thoracic spine?

Concave (kyphosis)

What is the curvature of the lumbar spine?

Convex (lordosis)

What is the curvature of the sacrum?

Concave (kyphosis)

What curvatures are kyphotic?

Thoracic and sacral

What curvatures are lordotic?

Cervical and lumbar

What type of curvature is present at birth?

Primary kyphosis

What movements does the cervical spine allow?

Rotation, flexion/extension, and side flexion

What movement does the thoracic spine primarily allow?

Rotation

What movements does the lumbar spine allow?

Flexion/extension and lateral flexion

What is exaggerated thoracic curvature called?

Kyphosis (Dowager's hump)

What is exaggerated lumbar curvature called?

Lordosis

What is exaggerated lateral curvature called?

Scoliosis

Why do vertebrae gradually increase in size descending to the sacrum?

Due to increasing amounts of body weight they must support

How does the sacrum transfer weight?

Via the sacroiliac joints to the pelvic girdle

What separates individual vertebrae?

Intervertebral (IV) discs

What joints do cervical, thoracic and lumbar vertebrae also articulate at?

Zygapophysial (facet) joints

What does a typical vertebra consist of?

A vertebral body, arch, and 7 processes

What is the function of the vertebral body?

It is the massive cylindrical anterior part that gives strength to the column and supports body weight

What are the 7 processes of a typical vertebra?

1 median spinous process (projects posteriorly), 2 transverse processes (project posterolaterally), 4 articular processes (2 superior, 2 inferior)

Which vertebrae do not share the typical vertebral morphology?

Sacral and coccygeal vertebrae

What are the distinguishing features of cervical vertebrae?

Bifid spinous processes, nearly horizontal articular processes, and a transverse foramen

What is unique about C1 (Atlas)?

It has no body and is formed of 2 lateral masses; its facets form the atlanto-occipital joint with the occipital condyles

What movements does the atlanto-occipital joint allow?

Flexion, extension, and lateral flexion — but no rotation

What is unique about C2 (Axis)?

It has a large upright odontoid process (dens) that acts as a pivot for the atlanto-axial joint

What movement does the atlanto-axial joint allow?

Rotational movement

What is the dens?

A large upright process on C2 (Axis) that acts as a pivot for rotation

What are the distinguishing features of thoracic vertebrae?

Two costal demi-facets for rib articulation, long downward-hooking spinous processes, and bilateral costal facets

Why is flexion and extension limited in the thoracic spine?

Due to overlapping spinous processes

What are the distinguishing features of lumbar vertebrae?

Short hatchet-shaped spinous processes; they are the most sturdy of all vertebrae

How is the sacrum formed?

By fusion of 5 vertebrae

What does the sacrum articulate with superiorly and inferiorly?

Superiorly with L5, inferiorly with the coccyx

What are the ala of the sacrum?

Wing-like projections that articulate laterally with the hip bones, forming the sacroiliac joints

How is the coccyx formed?

By fusion of 4 tiny irregularly shaped vertebrae

What is a laminectomy?

Surgical excision of spinous processes and vertebral laminae/pedicles to gain access to the vertebral canal and spinal cord

What conditions may require a laminectomy?

Tumour, herniated disc, or bone hypertrophy causing pressure on the spinal cord

What is vertebral body osteoporosis?

A common metabolic bone disease caused by net demineralisation of bone due to disrupted calcium deposition and resorption balance

What areas are most affected by osteoporosis?

Neck of femur, bodies of vertebrae, metacarpals, and the radius

What characterises early osteoporosis on imaging?

Vertical striations in vertebral bodies

What characterises moderate osteoporosis on imaging?

Radiolucency

What characterises late-stage osteoporosis?

Thoracic kyphosis due to collapse of vertebral bodies

What are the two components of an intervertebral disc?

Annulus fibrosus (peripherally) and nucleus pulposus (centrally)

What is the annulus fibrosus made of?

Concentric lamellae of fibrocartilage

What is the nucleus pulposus?

A hydrophilic, gelatinous structure made of glycosaminoglycans (GAGs)

What percentage of vertebral column length do IVDs contribute?

Approximately 20-25%

What are the functions of intervertebral discs?

They aid movement and act as shock absorbers

What ligaments are associated with the vertebral column?

Ligamentum flavum, supraspinous ligament, interspinous ligament, anterior longitudinal ligament, posterior longitudinal ligament

What is the function of the anterior longitudinal ligament?

It prevents hyperextension of the vertebral column — it is the only ligament that limits extension

What is the function of the posterior longitudinal ligament?

It weakly resists hyperflexion and helps prevent posterior herniation of IV discs

What is herniation of the nucleus pulposus?

Protrusion of the nucleus pulposus through the annulus fibrosus, a frequent cause of back pain

Why does disc herniation most often occur posterolaterally?

Because the annulus fibrosus is thinnest there and receives no support from either longitudinal ligament