Vertebral Column Flashcards
Functions of vertebral column
• Protects spinal cord and spinal nerves.
• Supports weight of body above pelvis.
• Provides a partly rigid and flexible axis for body.
• Plays important role in posture and locomotion.
Source of haematopoetic, gives blood to body
Number of vertebral columns
N= 33 Cervical=7 Thoracic= 12 Lumbar= 5 Sacrum= 5 Coccyx= 4
Composition of vertebrae
• Vertebral body consists of vascular, trabecular (spongy, cancellous) bone enclosed by thin compact bone layer.
Curvatures of the spine
Cervical curvature (lordosis): acquired secondarily when infant can support weight of it’s own head. Thoracic curvature (kyphosis): primary curvature present in fetus. Lumbar curvature (lordosis): acquired secondarily when infant can stand upright and support its own weight. Sacral curvature: primary curvature present in feature.
Typical vertebra features
• Seven processes arise from the vertebral arch of a typical vertebra Spinous process (1), transverse process (2), articular processes (4)
Cervical vertebrae
Greatest range of movement because of relatively thick IV discs, nearly horizontal orientation of articular facets and less mass of body surrounding cervical vertebrae.
Atlas (C1)
- No vertebral body or spinous process
- Paired lateral masses (bears weight)
- Widest cervical vertebra (most lateral transverse processes)
- Superior articulation with occipital condyles (atlanto-occipital joints)
- Inferior articulation with “Axis” C2
Axis (C2)
- Strongest
- Odontoid process (“Dens”)
- Small transverse processes
- Large bifid spinous process
- Superior articulation with “Atlas” C1
- Inferior articulation with C3
Function of transverse foramina
Vertebral artery branches from the SUBCLAVIAN ARTERY.
Ascends through C6-C1 to enter foramen magnum.
Instability caused by:
• Ligamentous laxity;
• Shallow and angled facet joints;
• Under-developed spinous processes;
• Incomplete ossification of odontoid process;
• Relatively large head;
• Fulcrum of motion at C2-C3 (adults C5-C6);
• Weak neck muscles.
• Younger children more susceptible to upper cervical spine injury (occiput -> C3).
• 8-10-years-old cervical spine reaches adult proportions.
Pediatric cervical spine
Structure that traverse the vertebral foramen
Spinal cord
Structure that traverse the intervertebral foramen
Spinal nerves
Structure that traverse the transverse foramen (only in cervical vertebra)
Vertebral artery
Intervertebral discs
Function: shock absorbers; give mobility Anulus fibrous = fibrocartilage Nucleus pulposus = gelatinous remnant (collagen, hydrated proteoglycans) of embryonic notochord •IV discs thickest in lumbar region; •Secured by anterior and posterior longitudinal ligaments. Pain insensitive inner 2/3 Pain sensitive outer 1/3
Hunchback
Kyphosis: Accentuated flexion of thoracic spine.
Aetiology: poor posture, osteoporosis.
Swayback
lordosis: Accentuated extension of lumbar spine.
Aetiology: weakened trunk muscles, late pregnancy, obesity.
Scoliosis
Accentuated lateral and rotational curve of the thoracic or lumbar spine.
Aetiology: genetic, trauma, idiopathic; occurs in adolescent girls more than boys
Most unstable lumbar vertebra
L4 - L5
Lumbar vertebrae
•Large kidney-shaped body for weight-bearing;
•Mid-sized triangular vertebral foramen;
•Facets are face medial or lateral direction permitting good flexion
and extension;
•Spinous processes are short.
Atypical lumbar
Extra ribs on L1
Coccyx
no vertebral arches or vertebral canal (dural sac of spinal cord ends at S2)
Anterior longitudinal ligament
Strong and prevents hyperextension of spine (only ligament that limits extension!)
Attached to vertebral bodies AND I.V. discs. Foramen magnum-sacrum
Posterior longitudinal ligament
Weaker and prevents hyperflexion of spine. Attached mainly to I.V. discs and less to vertebral bodies.
Supraspinous ligaments
connect spinous tips (C7 to sacrum) and are stronger and limit flexion.
Ligamentum nuchae
Connects spinous tips of cervical vertebrae to external occipital protuberance (i.e. superior continuation of supraspinous ligament!)
Intertransverse ligaments
Connect transverse processes and are weak
Ligamenta flava
Connects adjacent laminae of vertebrae.
Limits flexion and are more elastic than other ligaments.
Interspinous ligaments
Connect spines and are weak
Tranverse costal facets
On the transverse processes for articulation with tubercle of ribs
Superior and inferior costal facets
(mostly small demifacets) on posterolateral margins of vertebral body for articulation with head of rib
Sacroiliac joints
Thickest ligament very strong
Transverse ligament of Atlas
•Holds odontoid process (dens) in place
•Allows rotation
Extends between the medial aspect of the tubercles on the lateral masses of C1.
Alar ligaments
• Attachment: Dens to occipital condyles.
• Limit rotation at the atlanto-axial joint.
Extends from the sides of the dens to the lateral margins of the foramen magnum.
ATLANTO-OCCIPITAL joint
The articulations between the occipital condyles and the superior articular facets of C1 vertebra.Biaxial condyloid synovial joints. Allows flexion and extension (i.e. nodding head up and down) and lateral flexion (i.e. sideways tilting). Movement of joint limited by the anterior and posterior atlanto-occipital membranes.
ATLANTOAXIAL joints.
The articulations between the inferior articular facets of C1 vertebrae and the superior facets of C2 vertebrae plus the articulation between anterior articular facet of dens and the anterior arch of C1. 2x lateral atlanto-axial joint = gliding synovial
joint. 1x median atlanto-axial joint = pivot joint. Permits lateral rotation of head (i.e. shaking head saying “no”).
ZYGAPOPHYSEAL joint
The articulation between the inferior articular facet and superior articular facet of adjacent vertebrae
• Synovial plane joints.
• Allow for some gliding/sliding movement.
• C5-C6 is most mobile joint.
• L4-L5 permits most flexion.
• Sensory nerve fibres derived from dorsal rami of spinal nerves supply the synovial linings of the capsules surrounding these
facet joints => 15 % of back pain caused by changes in these joints.
UNCOVERTEBRAL joints
The articulations between the uncinated processes of C3-C7 vertebrae and the vertebral bodies immediately superior
INTERVERTEBRAL joints
The articulations between the intervertebral discs and the articular surfaces of vertebral bodies from C2-S1
• Weight-bearing joints.
• Shock-absorbers due to IV discs.
• Stabilised by anterior (strongest) and posterior longitudinal ligaments.
Movements of the cervical region
Plane of joint:horizontal (transverse)
Movements permitted:lateral rotation, lateral flexion, flexion and extension of head at atlanto-occipital joints
Movements of the thoracic region
Plane of joint: coronal plane
Movements permitted: lateral flexion; gliding during breathing
Movements of the lumbar region
Plane of joint: sagittal
Movements permitted: flexion and extension only
Posterior herniation of the intervertebral discs will compress what structure?
Spinal cord
Posterolateral herniation of the intervertebral discs or formation of osteophytes (bony spurs) on the posterolateral aspect of vertebral bodies will compress what structure?
Spinal nerve
Osteoarthritis
Progressive erosion of cartilage in joints of spine, fingers, knee and hip (most commonly).
In spine => can lead to spinal nerve impingement.
Osteophytes = bony outgrowth
Osteophytic encroachment compresses spinal
nerves.
Spondylolysis
Affects 3-6% population.
Defect where vertebral arch becomes separated from it’s body.
85-95% cases at L5; 5-15% at L4.
Spondylolithesis
Anterior or posterior displacement of vertebrae in relation to vertebrae below.
IV disc herniation
Peripheral tears (mostly posterolateral) of anulus fibrous allows for extrusion and herniation of nucleus pulposus which may impinge spinal nerves. Lumbar disc herniations are common and result in pain over SI joint, hip, posterior thigh and leg.
Mammillary processes
Posterior surface of the articular processes I’m the lumbar region.
Give attachment for multifidus and intertransversarii.
Weight bearers
L5 is the largest vertebrae that bears weight of entire body -> transfers to base of sacrum and the across SI joints.
Lower sacrum and coccyx do not bear weight so they at small.
Cruciform ligaments
Consist of transverse ligament of the atlas (strong) and the superior and inferior longitudinal bands (weak)
Vertebral venous plexuses
- 3 anterior spinal veins
- 3 posterior spinal veins
- Longitudinal
- Internal vertebral venous plexus communicates with dural sinuses and vertebral veins in cranium AND external vertebral venous plexuses on external surface of vertebrae.
What is another name for the zygapophyseal joint
Facet joints between inferior articular facet and superior articular facet of two vertebra
What is the distinguishing feature of C2?
Odontoid process (dens)
Which ligament limits extension of the spine?
Anterior longitudinal ligament
What type of movement occurs at the atlanto-axial joint
Lateral rotation of the head
Is the cervical curvature of the spine acquired in utero or after birth?
After birth once baby support own head weight
