Trauma and orthopaedics (7): The vertebral column Flashcards
the vertebral column
A series of 33 bones (vertebrae) which are separated by intervertebral discs. The column can be divided into 5 different regions (all diff vertebral structure):
- Cervical (7)
- Thoracic (12)
- Lumbar (5)
- Sacral (5, fused)
- Coccyx (4, fused)
function
- Protect- spinal cord within the spinal canal
- Support- carries the weight of the body above the pelvis
- Axis- central axis of the body
- Movement – role in movement and posture
curves in the spine
2 kyphosis and 2 lordosis
Vertebral column in a foetus
- Flexed in single curvature
- C-shaped
- Concave anteriorly= Kyphosis
- Primary curvature
- Retained throughout life in the thoracic, sacral and coccygeal regions
- Concave anteriorly= Kyphosis
evolution of the spine by 18 month
(1)
- Primary curvature is remodelled to add two secondary curvatures
- Cervical spine develops the first posterior concavity (cervical lordosis)
- When young child begins to lift its head
- Muscle get stronger lordosis head life (why young babies cannot lift head up)
(2)
- The lumbar spine loses its primary kyphosis during crawling
- When the child begins to stand up and walk lumbar lordosis
- Lumbar lordosis is the secondary curvature
vertebral column in old age
- Start to lose secondary curvatures
- Loss of disc height and osteoporotic fractures
- Continuous primary curvature is re-established
common structure of vertebrae
All vertebrae consist of: a vertebral body and a posterior vertebral arch
Vertebral body
- Anterior part of each vertebrae
- Weight bearing component
- In the lower portion of the back the vertebra have larger bodies than those in the upper portion (to better support the increase weight)
- Superior and inferior aspects of the vertebral body are lined with hyaline cartilage
- Adjacent vertebral bodies are separated by a fibrocartilaginous intervertebral disc
vertebral arch
Forms the lateral and posterior aspect of each vertebrae. Along with the vertebral body, the vertebral arch line up to form the vertebral canal which encloses the spinal cord.
Several bony prominences which act as attachment sites for muscles and ligaments:
- Spinous processes – each vertebra has a single spinous process, centered posteriorly at the point of the arch.
- Transverse processes – each vertebra has two transverse processes, which extend laterally and posteriorly from the vertebral body. In the thoracic vertebrae, the transverse processes articulate with the ribs.
- Pedicles – connect the vertebral body to the transverse processes.
- Lamina – connect the transverse and spinous processes.
- Articular processes – form joints between one vertebrae and its superior and inferior counterparts. The articular processes are located at the intersection of the laminae and pedicles.
joints between vertebra (2)
(1) between vertebral bodies
(2) between articular facets (facet joints)
Between vertebral bodies
indirectly articulate via intervertebral discs
- Cartilaginous joints designed for weight-bearing
- Covered in hyaline
intervertebral discs
- Accounts for 25% of the length of the vertebral column
- Disc height changes throughout day/ age
-
70% water, 20% collagen, 10% proteoglycans
- Water content responsible for height- i.e. we are always shorter in the evening water loss from intervertebral discs due to dehydration of the discs caused by gravity
intervertebral discs structure
Annulus fibrosus- outer region which is very strong and a major shock absorber
- Made from lamellae (layers) of annular bands in varying orientations
- Type 1 collagen
- Avascular and aneural- blood supply derived from bone diffusion and osmosis
Nucleus pulposus- inner region
- Remnant of notochord- hyaline cartilage
- High oncotic pressure→ proteoglycans attracts water→ GAGs
Facet joints (between articular facets)
Allow movement
- Left and right superior articular facets articulate with the vertebra above
- Left and right inferior articular facets articulate with the vertebra below
ligaments which support the vertebral column
Ligaments around the vertebral body
-
Anterior and posterior longitudinal ligaments
- Run the full length of the vertebral column
- Strengthens the vertebral body joints
- Anterior longitudinal ligament: thick, preventing hyperextension of the vertebral column
- Posterior longitudinal ligament: weaker, prevents hyperflexion
Ligaments around the vertebral arch
- Ligamentum flavum- between lamina of adjacent vertebrae
-
Interspinous ligament- between the spinous process
- Well-developed only in the lumbar region
- Supraspinous ligament- run along the tips of the spinous process
- Intertransverse ligaments- between transverse processes.
what type of vertebra is rthis
Cervical spine
the C spine
There are 7 cervical vertebrae (C1-7). Positioned in the neck and is the most superior part of the spine.
- Mobile
- Nerve roots exit above their respective vertebra (e.g. C1 nerve root is above C1 vertebra)
- Until the C7/T1- C8 nerve root exits between these and then as you move inferiorly down the spine the nerve roots exit below their respective vertebrae
characteristic features of Cervical vertebra
- Small vertebral body (don’t need to carry much weight)
- Bifid spinous process (bar C1 and C7)
- Transverse foramina- an opening in each transverse process, through which vertebral arteries travel to the brain
- Triangular vertebral foramen (like lumbar)
C1
Atlas
- This is the first cervical vertebra.
- It articulates with the occiput of the skull superiorly (this joint is responsible for majority of flexion and extension in the neck), and axis inferiorly (this joint is responsible for majority of rotation in the neck).
-
Distinguishing features
- No vertebral body
- No spinous process
C2
Axis
- Axis is the second cervical vertebra, and is also atypical compared to the others.
- One of its features is the Odontoid process (or Dens) which, along with the transverse ligament, prevents displacement of Atlas- allows for mobility
C1 and C2 articulation
- Dens (odontoid) and transverse ligament prevent horizontal displacement of Atlas
- Pivot which allows rotation
X-ray of C spine
the thoracic spine
There are 12 thoracic vertebrae (T1-T12). Specialised function is to articulate with ribs, producing the bony thorax- relatively immobile.
Function
- Projection of internal viscera such as the heart and lungs
joints of the throacic spien
Each vertebra have two demi-facets which articulate with the heads of two different ribs
- T9-10 have whole facets
- On the transverse processes of the thoracic vertebrae- costal facets for articulation with the shaft of a spinal rib
- For example, the head of Rib 2 articulates with the inferior demi facet of thoracic vertebra 1 (T1) and the superior demi facet of T2, while the shaft of Rib 2 articulates with the costal facets of T2
cauda equina
The cauda equina is the terminal portion of the spinal cord (L1/2) and roots of the spinal nerves (central (motor) and dorsal (sensory) routes) beginning at L1.
Why does it form?
The vertebra continues growing after the spinal cord has finished during development
characteristic features of Lumbar vertebra
Characteristic features
- Large, kidney shaped vertebral bodies (L5 is the biggest- supports weight of upper body)
- Triangular vertebral foramen (like cervical)
- Shorter spinous processes than thoracic vertebrae and do not extend inferiorly below the level of the vertebral column
- Size and orientation allow for clinical access
- E.g. epidural anaesthesia
- E.g. lumbar puncture
They lack the characteristics of other vertebral bodies including: no transverse foramina, coastal facets or bifid spinous processes
sacrum
- Sacrum consists of 5 fused vertebrae (S1-S5)
- Articulates (borders) with L5 superiorly, ilium (hip) laterally and coccyx inferiorly
- On the lateral walls of the sacrum are facets for articulation with the pelvis at the Sacro-iliac joints
- The sacral fibres of the cauda equina runs through the central canal of the sacrum
