The Lumbar Spine And Associated Disorders Flashcards
How many vertebrae are there?
33 7 cervical 12 thoracic 5 lumbar 5 sacral 4 coccygeal
Which regions of the vertebral column are mobile?
• Mobile – Cervical and Lumbar • Relatively Immobile – Thoracic • Fused Vertebrae • 9 vertebrae fused to give 2 innominate structures – Sacrum (fusion of 5 vertebrae) – Coccyx (fusion of 4 vertebrae)
What are the functions of the vertebral column?
- Central bony pillar of the body.
- Supports the skull, pelvis, upper limbs and the thoracic cage.
- Protection of the spinal cord and the cauda equina
- Movement - Highly flexible structure of bones, intervertebral discs and ligaments
- Haemopoiesis – red marrow
Describe teh structure of a lumbar vertebra
General characteristics:
• Kidney shaped vertebral body
•Vertebral arch posteriorly
•Vertebral foramen: contains conus, cauda equina and meninges
Vertebral arch: Gives rise to 7 processes •x1 Spinous Process •x2 Transverse Process •x2 Superior Articular Process •X2 Inferior Articular Process
What is a vertebral body?
- Largest part of the vertebra –
- 10% Cortical Bone
- 90% Cancellous Bone
- Usually the main weight bearing Greater Compressive forces distally part of the vertebra
- End Plates – Superior and Inferior Articular surfaces covered with hyaline cartilage
- Linked to adjacent vertebral bodies by intervertebral discs
- Size Vertebra increases from superior to inferior?
What are vertebral processes
- 1 spinous process,
- 2 transverse processes (left and right)
- 2 superior articular processes (facets) interlock with the vertebra above
- 2 inferior articular processes (not shown) interlock with the vertebra below.
What is the vertebral arch?
- Lamina connects transverse process to spinous process
- Pedicle connects transverse process to body
- Pedicles longer and larger bigger intervertebral foramen
- Lamina + pedicle = vertebral arch
What is a facet joint?
• Lined with hyaline cartilage
• Paired
• Spinal nerves emerge through intervertebral foramina
• Orientated in a sagittal plane
• Interlocking design
– Prevents anterior displacement of vertebrae
– Orientation determines amount of flexion and rotation permitted
What are the movements of the lumbar spine?
Flexion and extension
Lateral flexion
Rotation
What are the types of joints in the spine?
- Fibrous – (ligaments) non- mobile
- Cartilaginous – Partially mobile
- Synovial Joints
What are intervertebral discs?
• Account for 25% of the length of the vertebral column
• 70% Water, 20% Collagen, 10% Proteglycans (proteoglycans keep water in the disc)
• Lose height with age (proteoglycans lose ability to retain water)
• Slightly wedge-shaped posteriorly
• Consist of two regions:
– nucleus pulposus (central)
– annulus fibrosus (peripheral)
What is an annulus fibrosus?
- Highly complex design
- Made from lamellae of annular bands in varying orientations
- Type 1collagen
- Avascular and Aneural
- Surrounds nucleus pulposus
- Is the major ‘shock absorber’
- Highly resilient under compression - stronger than the vertebral body
What is the nucleus pulposus?
- Remnant of notochord
- Gelatinous, Type 2 Collgen
- High osmotic pressure
- Disc Height changes throughout day
- Disc Height changes with age
- Surrounded entirely by annulus fibrosus
- Centrally located in the infant
- Located more posteriorly in the adult
What is the function of the ligaments of the vertebral column
- Provide stability
- Major ligaments: anterior longitudinal and posterior longitudinal ligament (anterior and posterior to vertebral bodies)
- Anterior is stronger than posterior
What is the anterior longitudinal ligament?
- Anterior tubercle of atlas to sacrum
- Blends with periosteum of vertebral bodies
- Mobile over intervertebral discs
- Prevents hyperextension
Becomes taught when leaning back
Prevents extension
What is the posterior longitudinal ligament?
- Body of axis to sacral canal
- Continues superior to axis as ‘tectorial membrane’
- Weaker than ALL
- Prevents hyperflexion
- Reinforces annulus centrally leading to paracentral disc prolapses
Becomes taught when leaning forwards
What are the ligamentum flavum
• Yellow in colour: elastin elastic fibres
• Between laminae of adjacent vertebrae
• Stretched during flexion of the spine
See slide for position
What are interspinous ligaments?
- Relatively weak sheets of fibrous tissue
- Unite spinous processes along adjacent borders
- Well developed only in the lumbar region (stability in flexion)
- Fuse with supraspinous ligaments
See slide for positioning