Vertebral Column Flashcards
The Mobile Segment
Smallest functional unit of the spine
Consists of any two adjacent vertebrae, the intervening intervertebral disc, and all the soft tissues that secure them together
Vertebral Column Composed of:
33 vertebrae
23 intervertebral discs (IVDs)
5 regions
All vertebrae have commonalities in structural design but do show regional variations
What are the 5 regions of the vertebral column and how many?
Cervical: 7
Thoracic: 12
Lumbar: 5
Sacral: 5 (fused)
Coccygeal: 4 (fused)
Vertebral movements are named for ___________ and ____________ of the vertebral body are doing
the cranial vertebrae; the anterior aspect
Vertebral arthrology
2 Major Parts
Anterior: Cylindrically shaped vertebral body
Posterior: Irregularly shaped neural arch
Vertebral Body
Weightbearing surface
Restrict compression
Its structure dictates its function
Block of tubercular bone covered by a layer of cortical bone
Neural Arch
Pedicles
Posterior element
Pedicles
Short, stout pillars with thick walls that connect the vertebral body to the posterior elements
Transmit bending forces from posterior elements to vertebral body
Posterior elements
Laminae
Pas Interarticularis
Articular Processes: from the articular pillar
-2 Superior facets
-2 Inferior facet
Spinous process
Transverse Processes
Laminae
Thin, vertical plate that constitutes the central portion of the arch posterior to the pedicles
Pars interarticularis transfers force from the articular, transverse, and spinous processes to the pedicles
Transverse processes
Lateral projections of bone that originate from the laminae
Serve as muscle attachments and provide mechanical lever
Spinous process
A posterior projection of bone that originates from the central portion of the laminae
Serves as muscle attachment and provides mechanical lever; may also serve as a bony block to motion
Vertebral foramen
Opening bordered by the posterior vertebral body and the neural arch
Combined with all segments, forms a passage and protection for the spinal cord
Intervertebral Disc (IVD)
2 Principal Functions
- To separate two vertebral bodies, thereby increasing available motion
- To transmit load from one vertebral body to the next
Size of the IVD
Amount of motion
Magnitude of the loads
Thickness of the IVD varies per region
3mm (cervical)
9mm (lumbar)
Ratio of disc thickness with vertebral body height determines the available motion
What region has the greatest ratio, and what does that mean?
Cervical has the greater ratio, which means there is greater intersegmental mobility available.
Lumbar is 2nd
Thoracic has the smallest
Common structure: IVD
All are composed of 3 parts:
1. Nucleus pulposus
2. Annulus fibrosus
3. Vertebral endplate
Nucleus pulposus
Gelatinous mass found in the center
80% water
Type I and II (more; resist compressive loads) collagen 15%
Proteoglycans 65%
Annulus Fibrosus
Fibrous outer ring
60 % water
20% proteoglycans
50% collagen Type I (more; resist tensile forces) and II
Attached to the endplates
Vertebral endplate
Cartilaginous layer covering the superior and inferior surfaces of the disc, separating it from the cancellous bone of the vertebral bodies above and below
Proteoglycans, collagen, and water,
What type of cartilage does the vertebral endplates consist of?
Both hyaline cartilage and fibrocartilage.
Hyaline cartilage is present closest to the vertebral body and is found mainly in young discs. Fibrocartilage is present closest to the nucleus pulposus
Innervation and Nutrition of the IVD
Do not receive blood supply from any major arterial branches.
Endplates receive supplied from metaphyseal arteries
Annulus fibrosus supplied from small branches of the metaphyseal arteries
The rest via diffusion
Common Joint Articulations
Interbody Joints: Cartilaginous, symphysis-type
Zygapophyseal (facets) Joints: Synovial, planar joint
Interbody joints
The joints between the vertebral bodies; 6 DOF
Available Movements:
Sliding/translation-anterior to posterior, medial to lateral, and as axial rotation (torsion)
Distraction-combination
Compression-combination b
Tilting-anterior to posterior and in lateral directions
Zygapophyseal (apophyseal or facet) joints
Orientation of the facets vary based on region
Motion is referred to as sliding/gliding:
Anterior/posterior
Superior/inferior
Anterior longitudinal ligament
Limits extension and reinforces anterolateral portion of annulus fibrosus and anterior aspect of intervertebral joints
Posterior longitudinal ligament
Limits forward flexion and reinforces posterior portion of the annulus fibrosus
Ligamentum flavum
Limits forward flexion, particularly in the lumbar area, where it resists separation of the laminae
Interspinous ligament
Resist flexion, end-range extension, posterior shear of superior vertebra on the vertebra below
Supraspinous ligament
Limit forward flexion
Intertransverse ligament
Limit forward flexion, and contralateral lateral flexion
