Lecture 4 - Lumbar Spine Flashcards
Vertebral column
5 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 sacral vertebrae 4 coccygeal vertebrae
Single separate vertebrae capable of individual movement
C1-C7
T1-T12
L1-L5
Thoracic vertebrae
Less mobile as joined by by the ribs to the sternum
Fused vertebrae
Sacrum
Coccyx
Kyphotic curvature
Thoracic and sacral
Anteriorly concave
Develop during foetal period
Lordotic curvature
Cervical and lumbar
Anteriorly concave
Develop during childhood - lifting the head and sitting
Why do vertebral bodies increase in size inferiority
Compression forces increase
Sacral vertebrae
Fused
Widened
Anteriorly concave
Transmits the weight of the body through the pelvis to the legs
Functions of the vertebral column
- Supports the weight of the skull, pelvis, upper limbs and thoracic cage
- Protects the spinal cord and the cauda equina
- Posture
- Locomotion
- Haematopoiesis - bone marrow
Components of a vertebrae
1 spinal process 2 transverse processes 2 superior articular processes (facets) 2 inferior articular processes (facets) 1 vertebral body 1 Vertebral foramen 2 Lamina 1 vertebral notch 1 vertebral arch 2 pedicels
Vertebral foramen
Contains
Conus medullaris
Cauda equina
Meninges
Vertebral body
10% cortical bone
90% cancellous bone - reduces weight
Permits haematopoiesis
Major load bearing structure of the spinal column
Vertebral end plates
Superior and inferior articular surfaces
Covered in hyaline cartilage
Intervertebral discs
Link adjacent vertebral bodies
Posterior elements
All structures posterior to vertebral body
1/3 of the upright posture load is carried
Vertebral arch
Protective gunnel in which the spinal cord runs
Made up of 2 pedicles and 2 laminae
Lamina
Connect the transverse processes to the spinous processes
Pedicles
Connect the transverse processes to the ventral body
Which structures provide attachment points for muscles and ligaments
Spinous
Transverse
Inferior articular facets
Project caudally (down)
Superior articular facets
Project cephalically (up)
Inferior and superior articular facets
Articulate with adjacent vertebrae - provides a mobile facet joint (synovial) - zygapophyseal joint
Concave - produce vertebral notch
Vertebral notch can form intervertebral foramen
Intervertebral foramen
Allows passage of of the spinal nerves from the spinal canal to the periphery
Flexion and rotation in cervical vertebra
45 degrees to the axial in the coronal plane
Flexion - nodding
Extension
Lateral flexion
Rotation
Thoracic vertebrae flexion and rotation
60 degrees to axial plane
20 degrees to coronal plane
Lumbar flexion and rotation
90 degrees to axial
45 degrees to coronal
Intervertebral discs
25% of the length of the vertebral column
70% water
20% collagen
10% proteoglycans
Strong in axial compression
Less strong under tangential loading
Therefore important to keep spine straight while lifting heavy loads
2 regions of the intervertebral discs
Nucleus pulposus (central)
Annulus fibrosus (peripheral)
The nucleus pulposus is surrounded entirely by the annulus fibrosus
Annulus fibrosus
Shock absorber of the spine - resilient to axial compression (top to bottom)
Stronger than vertebral body
Avascular
Anueral
Comprises:
- lamellae of annular bands of collagen in varying orientations
- outer lamellae - type 1 collagen (fibrous)
- inner lamellae- fibrocartilaginous
Nucleus pulposus
Remnants of the embryonic notochord
Gelatinous
Type 2 collagen
High oncotic pressure
Decreases in height:
- during the day as water is squeezed out due to mechanical pressure
- with age
Becomes more posteriorly located in adults
How much weight is transmitted through the vertebral body and facet joints when young?
80% of the body weight - vertebral body
20% - facet joints
What proportion of a persons body weight is transmitted through the vertebral body and facet joints as we age?
Vertebral bodies - 65%
Facet joints - 35%
Increased load on facet joints causes osteoarthritis changes
