Vertebral Column & Spinal Cord Flashcards
The Back includes:
The back includes:
Skin and fascial layers Muscles - extrinsic and intrinsic Ribs (in the thoracic region) Vertebral column Spinal cord and meninges Various segmental nerves and vessels
Axial skeleton
Curvatures of the spine: 1 primary, 2 secondary
- Cervical (2)
- Thoracic (1)
- Lumbar (2)
- Sacral (1)
Curvatures of the vertebral column:
Four curvatures:
Primary: thoracic and sacral
Secondary: cervical and lumbar
Lumbosacral angle and sacral curvature - differs between male and female.
LA greater and SC less in female. Results in greater pelvic outlet for female.
Shock absorbing resilience.
Abnormal curvatures of the vertebral column
- Scoliosis (lateral curvature)
- Thoracic kyphosis (humpback)
Dowager’s hump in women with osteoporosis
- Lumbar lordosis (swayback)
Thoracic kyphosis (humpback)
Dowager’s hump in women with osteoporosis
Osteoporosis
Causes bones to become weak and brittle.
The reduction of estrogen levels in women at menopause is one of the strongest risk factors for developing osteoporosis
Atlas and axis
Damage to the alar and cruciate ligaments (transverse and longitudinal) can cause displacement of axis, causing damage to the spinal cord
Upper Cervical Injuries
Hyperflexion:
Tearing of the transverse ligament of the atlas - dens into spinal cord; or fracture of the dens
Fracture of Dens:
Type I – Fracture of tip
Type II – Fracture of base
Type III – Fracture extends into body of axis
Upper Cervical Injuries - continued…
Hyperextension:
“Hangman’s fracture”
–> Ahangman’s fracture is described as bilateral fracture traversing the pars interarticularis of C2.
–> Judicial or suicidal hanging
Unlike the subaxial cervical spine, the C1 to C2 complex does not contain an intervertebral disc; there are unique ligaments allowing for support of the cranium as well as providing the majority of cervical rotation.
Pars interarticularis
A small bony arch between the facet joints
Joints of the vertebral bodies supported by:
Intervertebral discs and ligament
Anterior and posterior longitudinal ligaments
Joints of the vertebral arches:
Zygapophysial joints (synovial)
Accessory ligaments of the intervertebral joints:
Nuchal ligament (already seen in previous lecture) Supraspinous ligament Interspinous ligaments Ligamentum flavum Intertransverse ligaments
Craniovertebral joints supported by:
Atlanto-occipital joints - posterior membranes (tectorial membrane).
Atlanto-axial joints – alar and cruciate ligaments (transverse and longitudinal).
Theanterior atlantooccipital membrane(anterior atlantooccipital ligament) is broad and composed of densely woven fibers, which pass between?
Between the anterior margin of theforamen magnumabove, and the upper border of theanterior arch of theatlasbelow.
A: Anterior atlantooccipital membrane:
Laterally, it is continuous with thearticular capsules.
In front, it is strengthened in the middle line by a strong, rounded cord, which connects the basilar part of theoccipital boneto the tubercle on the anterior arch of the atlas.
This membrane is in relation in front with therectus capitis anterior muscles, behind with thealar ligaments.
Joints between vertebrae:
- Intervertebral Disc
- Zygaphophysical joints
- Intervertebral disc
Intervertebral disc:
Symphyses - secondary cartilaginous joints)
zygapophysical Joints (synovial joints):
Posterior rami of spinal nerves.
Each posterior ramus supplies two adjacent zygapophysical joints.
Intervertebral disc:
are made up of nucleus pulposus and anulus fibrosus.
Nucleus pulposus can herniate and compress spinal nerves (called as slip disc).
Ligaments to go through for anesthesia punctures:
- Supraspinous ligament
5. Interspinous ligament
Ligaments effected by neck flexion and extension
Anterior longitudinal ligament
Posterior longitudinal ligament
Fractures and dislocations of the vertebrae:
- Spondylosis
2. Sondylolisthesis
Spondylolysis:
Separation of the pars interarticularis
Spondylolisthesis:
Anterior slippage of one vertebra over another (in the front of the spine).
Contents of the Vertebral canal
Spinal cord.
Spinal nerve roots.
Spinal meninges and cerebrospinal fluid.
Vasculature of the spinal cord and spinal nerve roots.
3 coverings:
Pia, Arachnoid and Dura mater
3 spaces:
Subarachnoid – Between Pia and arachnoid – contains CSF
Subdural – Between Arachnoid and Dura
Epidural (extradural) –Between Dura and periosteum of vertebrae.
Contains fat and veins
Nerves of Vertebral Column:
Recurrent (meningeal) branches of spinal nerves
Periosteum
Ligamentum flavum
Annulus fibrosis
Anterior and posterior longitudinal ligaments
Spinal dura mater
Blood vessels within the vertebral canal
Spinal Cord:
Part of CNS located within vertebral canal
Begins at foramen magnum,
It is continuous with medulla oblongata
Ends inferiorly at L1/L2 intervertebral disc ( –> )
Cylindrical in shape
2 Enlargements
- cervical enlargement: C5 to T1 spinal cord segments (not vertebral) –> gives rise to brachial plexus
- Lumbosacral (lumbar) enlargement: L1 to S3 spinal cord segments (not vertebral) –> gives rise to lumbar and sacral plexuses
inferior to lumbosacral enlargement spinal cord tapers off into conus medullaris
Herniation of intervertebral disc between C5- C6 will press on what nerve?
C6 nerve
C8 nerve emerges between?
C7 and T1 vertebrae
Cauda Equina
In adults, spinal cord ends at upper border of L2
Lower end of cord is cone shaped known as conus medullaris
Piamater continues from apex of conus medullaris as internal filum terminale.
External filum terminale is made of duramater.
Posterior and anterior roots of lumbar, sacral and coccygeal nerves form a cluster of roots by side of filum terminale known as cauda equina.
Spinal Nerve Roots
The length of the nerve roots increases progressively, as vertebral column grows longer than spinal cord.
Lumbar spinal stenosis - lumbar region has the largest spinal nerves but narrowest foramina which increases the chance for compression if nucleus pulposus herniation occurs.
Spinal nerve roots
Spinal cord ends at upper border of L2.
Arachnoid ends at S2
So the subarchnoid space between L2 and S2 has no spinal cord. The subarachnoid space from L2 to S2 has internal filum terminale and cauda equina.
Dura continues beyond S2 as external filum terminale. The space between external filum terminale and periosteum of vertebrae is the epidural space.
Disc Anatomy and Herniation
Intervertebral foramina (lower thoracic and lumbar region)
Upper half for spinal nerve
Lower half for intervertebral disc
Disc when herniates projects posteriorly or posterolaterally.
For example:
Intervertebral foramina between L4 and L5 vertebra will have L4 nerve in upper part and L4-5 disc in the lower part.
When L4-5 disc herniates it will project backwards and not upwards. It will NOT press on L4 nerve. It will press on L5 nerve. Because L5 is passing obliquely to intervertebral formina between L5 and S1
Disc Anatomy and Herniation: nucleus pulpus
The general rule is that when intervertebral disc (IV) protrudes posterior or posterolateral in the lumbar and lower thoracic regions it usually compresses the nerve root numbered one inferior to the herniated disc;
For example, the L5 nerve is compressed by L4-L5 disc herniation.
Disc between vertebrae:
C5- C6 C6- C7 L3- L4 L4-L5 L5-S1
Spinal nerve compressed
C6 C7 L4 L5 S1
Spinal Meninges and Cerebrospinal Fluid
- Spinal dura matter
- Spinal arachnoid mater
- Spinal pia mater
Spinal dura mater:
Epidural space - internal vertebral venous plexus and Epidural fat., space ends at S2.
Dura form external filum terminale confirm from gray
Spinal arachnoid mater:
Subdural space (Dura-arachnoid interface - potential space).
Subarachnoid space contains CSF, becomes large to enclose cauda equina known as lumbar cistern.
Spinal pia mater:
Denticulate ligaments
Forms internal filum terminale
Function of the meninges and of the CSF is to protect the?
Central nervous system
Lumbar puncture:
When lumbar puncture is performed, the needle enters the subarachnoid space to extract cerebrospinal fluid (CSF) or to inject anesthetic
Remember, the spinal cord may end as low as?
L2 in adults and does end at L3 in children
The dural sac extends caudally to?
To level of S2
The needle is usually inserted between?
L3/L4 or L4/L5
Level of horizontal line through upper points of iliac crests
Vasculature of the spinal cord
Spinal blood supply:
Vertebral and ascending cervical arteries in the neck.
The major segmental arteries of the trunk:
- Posterior intercostal arteries in the thoracic region.
- Subcostal and lumbar arteries in the abdomen.
- Iliolumbar and lateral and medial sacral arteries in the pelvis.
- They supply two posterior spinal arteries one anterior spinal artery
Spinal Veins:
internal and external vertebral venous plexus
intervertebral veins.
Vasculature of the spinal cord
Veins in the vertebral venous plexuses have no valves.
Allow blood to flow superiorly or inferiorly
Plexuses can serve a routes for cancer spread from the pelvis to the vertebrae, vertebral canal, and cranial cavity.
