Vertebral Column Flashcards

Flexible structure forming the longitudinal axis of the skeleton.
Made up of $26$ vertebrae in the typical adult:
- $7\;C$ (cervical) vertebrae
- $12$ thoracic vertebrae
- $5$ lumbar vertebrae
- Sacrum (fusion of $5$ bones)
- Coccyx (tailbone)
Intervertebral discs separate adjacent vertebrae; these are fibrocartilaginous cushions providing flexibility.

Primary Curves (1º): Thoracic and Sacral curves.
- Concave when viewed ventrally (anteriorly).
- Present during fetal life (hence 'primary').
- Functionally known as kyphosis (posterior concavity).
Secondary Curves (2º): Cervical and Lumbar curves.
- Convex when viewed ventrally (anteriorly).
- Develop after birth:
- Cervical curve develops as the child begins to hold up their head.
- Lumbar curve develops as the child begins to walk.
- Functionally known as lordosis (anterior concavity).
In the adult, there are four total curves:
- Cervical (secondary, lordosis)
- Thoracic (primary, kyphosis)
- Lumbar (secondary, lordosis)
- Sacral (primary, kyphosis)
Pelvic curve is concave on the ventral view and is a primary curve, extending from the sacrovertebral articulation to the coccyx.

Curves aid in weight bearing, shock absorption, and flexibility.
Intervertebral discs and curves together distribute loads during movement and posture.
Abnormal curvatures can affect balance, nerve roots, and load distribution.

Neural/Vertebral Arch: A circle of bone around the vertebral canal that houses the spinal cord.
$7$ Processes:
- Spinous process ( $1$ )
- Transverse processes ( $2$ )
- Superior articular processes ( $2$ )
- Inferior articular processes ( $2$ )
Centrum (Body): The anterior, weight-bearing portion.
Vertebral Foramen: Opening for the spinal cord between the neural arch and the body.
Pedicle: Connects the body to the arch anteriorly.
Lamina: Connects the pedicles to the spinous process posteriorly.
Intervertebral Foramen: Formed between adjacent vertebrae, through which spinal nerves exit.

Cervical Vertebrae (C1–C7)

Cervical curve: A secondary ( $2º$ ) curve; extends from the dens of the axis to the middle of the second thoracic vertebra; the least marked of all curves.
Characteristic cervical features:
- Relatively small vertebral body.
- Transverse foramina within each transverse process (for vertebral arteries).
- Short, bifid spinous process (except C1 and C7).
**Atlas (C1): Atypical Vertebra
- No vertebral body.
- Superior articular surfaces articulate with the occipital condyles to support and permit head movement (atlanto-occipital joint).
- Anterior arch with anterior tubercle; posterior arch with posterior tubercle.
- Lateral masses connected by anterior and posterior arches; contains superior articular facets.
- Articulates with the dens of the axis via the anterior arch (facet for dens).
**Axis (C2): Key Pivot Vertebra
- Odontoid process (dens) projects superiorly from the body and articulates with the atlas.
- Allows rotation of the atlas and skull around the dens (permitting left-right head turning).
- Includes superior articular facets and facet for dens articulation with atlas.
C7 Vertebra Prominens:
- Distinctive for a long, prominent spinous process.
- Generally not bifid but large; marks the transition to thoracic vertebrae.

Thoracic Vertebrae (T1–T12)

Features include broad, thick laminae, long spinous processes, and strong articular facets.
Each vertebra has attachments for ribs (costal facets):
- Superior costal facet
- Inferior costal facet
- Transverse costal facet (on the transverse process).

Lumbar Vertebrae (L1–L5)

Five large, robust vertebrae extending from the last thoracic vertebra (T12) to the sacrum.
Bodies are large; vertebral foramen is relatively small.
Spinous processes are thick and broad, designed for heavy load bearing.
Prominent anatomical features include mammillary processes and accessory processes on the posterior aspect.
Facets oriented to maximize bending resistance.
Intervertebral discs sit between adjacent lumbar vertebral bodies.

Sacrum

Large, triangular bone formed by the fusion of five sacral vertebrae (S1–S5).
Articulates with L5 above and coccyx below; forms the posterior part of the pelvis.
Key features include sacral ala, promontory, base, vertebral canal, sacral foramina (posterior and anterior), auricular surface, lateral, intermediate, and median sacral crests, sacral cornu, and sacral tuberosity.
In females, the sacrum is typically shorter and wider to accommodate childbirth.

Coccyx

At the base of the vertebral column; articulates with the sacrum via fibrocartilaginous discs.
Coccyx bones fuse with the sacrum over time; relatively mobile during pregnancy which aids passage of the fetus.

Fibrocartilaginous cushions located between adjacent vertebral bodies.
Components:
- Annulus Fibrosus: Outer ring.
- Nucleus Pulposus: Central gel-like core.
Provide flexibility and shock absorption to the spinal column.

Proper posture maintains the four natural curves; deviations can increase stress on discs and neural foramina.
Intervertebral discs may herniate or degenerate with age, injury, or repetitive strain; this can compress spinal nerves and cause pain (e.g., a herniated lumbar disc producing radicular pain down the leg).
The atlas and axis form the pivotal mechanism for head rotation; injuries here can profoundly affect head and neck mobility and neural pathways.
The cervical vertebrae's unique features (bifid spinous processes, transverse foramina) protect critical arteries (vertebral arteries) and nerves.
Pelvic curvature (sacral and coccygeal curves) has implications for childbirth and load transfer to the lower limbs; pregnancy-related mobility of the coccyx can alter pelvic tilt and influence labor mechanics.
Understanding vertebral anatomy is essential for diagnosing back pain, planning surgical approaches, and interpreting imaging (X-ray, MRI).
Knowledge of vertebral curves helps in evaluating posture, ergonomics, and mechanical load distribution in the spine.
Anatomical details inform physical therapy strategies for spine stabilization and rehabilitation.

Total vertebrae in adults: $26$ ( $7$ cervical, $12$ thoracic, $5$ lumbar, fused sacrum ( $5$ ), fused coccyx).
Primary curves: Thoracic and sacral (present in fetal life, kyphotic).
Secondary curves: Cervical and lumbar (develop after birth, lordotic).
Major distinguishing features by region:
- Cervical: Transverse foramina; bifid spinous processes (C3-C6); small bodies.
- Thoracic: Rib articulations (costal facets); long, downward-sloping spinous processes.
- Lumbar: Large bodies; mammillary and accessory processes; broad spinous processes.