Spine Flashcards
5th Lumbar vertebrae
The fifth lumbar vertebra is the largest of the lumbar vertebrae. It is an atypical lumbar vertebra.
5th Lumbar vertebrae: Gross anatomy
Location: most inferior lumbar vertebrae
Anterior components:
- Body: large and wide
Posterior components:
- Pedicles – project backward
- Transverse processes – short, massive and pyramidal, project from the pedicles
- Lamina: broad, thick and minimally overlapping
- Facets: oblique in orientation
- Articular processes – superior and inferior
- Spinous process – single, short, thick and roughly horizontal
5th lumbar vertebrae: articulations
- Superior articular facet with the inferior articular facet of L4
- Inferior articular facet with the superior articular facet of the sacrum
- Intervertebral discs both superior and inferior
5th Lumbar vertebrae: relations
- Anterior: Anterior longitudinal ligament, union of the common iliac veins
- Posterior: Supraspinous ligament, erector spinae muscles, External vertebral venous plexus
- Lateral: iliolumbar ligaments, quadratus lumborum muscles, intertransverse ligaments
- Superior: L4
- Inferior: S1
- Central: cauda equina, basivertebrasl veins, internal vertebral venous plexus
5th Lumbar vertebrae: ligaments
- Anterior longitudinal ligament
- Posterior longitudinal ligament
- Ligamentum flavum
- Supraspinous ligament
- Interspinous ligament
- Intertransverse ligaments
- Iliolumbar ligaments
5th Lumbar vertebra: variants
- Sacralisation of L5/Lumboralisation of S1
- Incomplete posterior arch
- Limbus vertebrae
- Block vertebrae
- Hemivertebrae
- Butterfly vertebrae
- Posterior element fusion
7th cervical vertebra: Description
The seventh cervical vertebra is the most inferior of the cervical vertebra, also known as the vertebra prominens (due to it’s long palpable spinous process). It has some features distinct from the other cervical vertebrae making it one of the atypical vertebrae.
7th cervical vertebra: Gross anatomy
Anterior components:
- Body ovoid in shape with uncinated process from the lateral aspects of the superior end plates
- Pedicles that are direct posterolateral attaching the body midway such that the superior and inferior notches are the similar in depth
- Bilateral transverse process with anterior and posterior tubercles
- Small transverse foramina as they do not transmit the vertebral arteries
- intertubercular lamella of the transverse process
Posterior components:
- Superior and inferior articular process superior facing backward and upward, inferior facing anterior and inferior
- Lamina forming a wide vertebral arch with large vertebral foramen
- Long spinous process ending in a tubercle (not bifid as in typical cervical vertebrae)
7th cervical vertebra: articulations
- Superior and inferior articular facets with the facets above and below
- Intervertebral discs both superior and inferior
- Uncovertebral joint with C6
7th cervical vertebra: Vasculature
Arterial supply:
Branches from the ascending cervical and vertebral arteries
Venous drainage:
Basivertebral veins, internal and external vertebral venous plexi
7th cervical vertebra: variants
- C7 may possess a cervical rib
- C7 foramen may transmit the posterior vertebral vein (if doubled), and may transmit the grey ramus from the inferior cervical ganglion to the anterior ramus of C7
- vertebral artery may enter at this level (usually it enters the cervical transverse foramen at C6)
- serves as the attachment for scalenus pleuralis (variant)
Atlas: Description
The atlas (C1) is an atypical cervical vertrebrae.
Location: The most superior vertebrae of the spinal column
Function: support and movement of the head, protection of the spinal cord, passage of vessels
Atlas: Gross anatomy
Anterior components:
Anterior arch with articular facet for the dens
lateral masses with foramina bilaterally from the vertebral arteries
Posterior elements:
Posterior arch without a spinous process
Atlas: Relations
- Superior: basiocciput
- Inferior: C2 vertebrae
- Lateral: vertebral arteries, sternocleidomastoid
- Medial: spinal cord
- Anterior fossa of rossenmulla, nasopharynx
- Posterior: ligamentum nuchae
Atlas: Articulations
- Antlanto-occipital joints – hyaline covered synovial joint between the occipital condyles and concave articular facet of the lateral masses
- Medial atlanto-axial joint – hyaline covered synovial joint between the dens of the axis and the posterior aspect of the anterior arch of the atlas
- Lateral atlanto-axial joint – hyaline covered synovial joint between the inferior articular facet of the atlas and the superior articular facet of the axis
Atlas: Ligaments
- Anterior longitudinal ligament
- Posterior longitudinal ligament
- Intertransverse ligament
- Apical ligaments – tip of dens to foramen magnum
- Alar ligaments – Lateral of the tip of the dens to the foramen magnum
- Cruciform ligament – longitudinal band and transverse band
- Ligamentum flavum
- Accessory ligament – C2 body to the lateral masses of C1
- Tectorial membrane
Atlas: Neurovasculature
Arterial supply:
- Branches of the vertebral artery
Venous drainage: venous plexi of the spine
Innervation: C1
Atlas: Variants
- Os ondontoidium
- Os terminale
- Incomplete anterior arch
- Incomplete posterior arch
- Osscile of the ligamentum nuchae
- Fusion to occiput
- Block vertebra to the C2
- Limbus vertebrae
- Proatlantal artery
Axis: Description
The axis (C2) is the second cervical vertebra. It is an atypical cervical vertebra.
Location: between the atlas and C3
Function:
Support the head, axis for rotation of the head, transmits the spinal cord and vertebral arteries
Axis: Gross anatomy
- Irregular bone
- Anterior components:
- Dens
- Body
- Lateral masses
- Transverse processes with formina transversarium
- Superior articular facets
- Inferior articular facets
- Posterior elements:
- Pedicles
- Lamina
- Spinous process – typically bifid
Axis: Articulations
- Superior articular facet with the inferior articular facet of the atlas
- Dens articulates with the posterior aspect of the anterior arch of C1
- Inferior articular facet with the superior articular facet of C3
- Uncovertebral articulation with C3
- Intervertebral joint with C3 via the C2/C3 intervertebral disc
Axis: Relations
- Anterior: Anterior longitudinal ligament
- Posterior: ligamentum nuchae
- Lateral: vertebral arteries and veins
- Superior-posterior: sub-occipital triangle
- Centrally: spinal cord and basivertebral veins
Axis: Ligaments
- Cruciform ligament
- Apical ligament
- Alar ligaments
- Accessory ligaments
- Tectorial membrane
- Ligamentum flavum
- Anterior and posterior longitudinal ligaments
- Intertransverse ligaments (minor in the c-spine)
- Interspinous ligaments
- Supraspinous ligaments
Axis: Variants
- Os ondontoidium
- Persistent os terminale
- Bifid or non-bifid spinous process
- Aplasia/hypoplasia
Typical thoracic vertebra: Description
T2 to T8 are considered typical thoracic vertebrae.
Typical Thoracic vertebra: Gross anatomy
Relative to cervical and lumbar vertebrae, thoracic vertebrae have:
- medium-sized, heart shaped vertebral bodies
- medium-sized vertebral canal
- prominent transverse processes with costal facets
- long spinous processes angulating downwards
Typical thoracic vertebra: Features
Anterior components of thoracic vertebrae:
- body
- pedicle
- superior and inferior costal demifacets
Posterior components of typical thoracic vertebrae:
- downward angled spinous processes
- transverse processes with transverse costal facets
- Superior and inferior articular facets
- lamina
- intervertebral foramen
Typical thoracic vertebra: Articulations
Ribs
Each vertebra contains three points of articulation with ribs.
- The superior demifacet of a thoracic vertebra articulates with the corresponding rib (costovertebral joint).
- This rib articulates again with the costal facet on the transverse process (costotransverse joint).
- The inferior demifacet articulates with the rib below.
Intervertebral:
Facet (zygapophyseal) Joints
- The superior articular process arises from the upper border of pedicle. An oval facet faces posterolaterally.
- The inferior articular process arises from the lower border of the pedicle. The facets face anteromedially.
Intervertebral discs
- Similar to other vertebrae, discs are interposed between hyaline cartilage on the centrum of the vertebral bodies. The disc height is slightly less than cervical vertebrae.
Atlantoaxial joint:Description
The atlanto-axial articulation is a complex of three synovial joints between the C1 and C2 vertebrae.
Function: The atlanto-axial joint allows 10-15 degrees of flexion/extension, 30 degrees of axial rotation and only minimal lateral flexion.
Atlantoaxial joint: Articulation
- Paired lateral atlanto-axial joints: planar-type between the lateral masses of C1 and C2
- Medial atlanto-axial joint: pivot joint with articulation of the anterior aspect of the dens with the posterior aspect of the anterior arch of C1 and transverse ligament
Atlantoaxial joint: Ligament
- Anterior longitudinal ligament – inferior border of the anterior arch of C1 to the anterior axial body
- Posterior atlanto-occipital membrane (continuation of the ligamenta flava) – attaches from the lower border of the posterior atlantal arch to the lamina of C2
- Cruciform ligaments: Superior (to clivus), transverse and inferior (to C2) bands posterior to the dens
- Accessory ligaments: From the posterior body of C2 to lateral mass of C1
- Tectorial membrane: thin continuation of the posterior longitudinal ligament to the clivus
- Paired alar ligaments: Lateral margins of the dens to the lateral margins of the foramen magnum
- Apical ligament: From the tip of the dens to the anterior margin of the foramen magnum
Atlantoaxial joint: Variant
- Split atlas
Abnormalities of the axis tend to affect the odontoid process and include:
- persistent ossiculum terminale
- odontoid aplasia
- os odontoideum
Atlanto-occipital joint: Gross anatomy
- Concave surface on the lateral mass articulates with the convex surface of the occipital condyle.
- The joint is reinforced by fibrous capsules which support each joint.
Atlanto-occipital joint: Attachments
- anterior atlanto-occipital membrane – continuation of the anterior longitudinal ligament, between the anterior arch and the anterior foramen magnum.
- posterior atlanto-occipital membrane – continuation of the posterior atlantoaxial membrane, connects the posterior aspect of the posterior edge of the foramen magnum.
Atlanto-occipital joint: Neurovasculature
Arterial supply:
Vertebral arteries
Venous drainage:
Internal and external, posterior and anterior vertebral plexi
Innervation:
The joint capsule is innervated by the C1 nerve.
Atlanto-occipital joint: Variant anatomy
- Variable degree of communication between the atlanto-occipital joint and the cavity between the dens (odontoid peg) and transverse ligament
- Third occipital condyle (condylus tertius) which may articulate with the anterior arch of the atlas, or the dens
- Paracondylar process
- Occipital condyle hypoplasia
- Division of the superior articular facet of the atlas
Atlanto-occipital joint
The atlanto-occipital articulation is comprised of a pair of condyloid synovial joints that connect the occiput to the first cervical vertebra (atlas/C1).
L4/5 intervertebral disc: Description
Intervertebral discs are located between the vertebral bodies of C2/3 to L5/S1, totalling 23 in the conventional spine. Together they account for approximately 25% of the total height of the vertebral column. This decreases with age as disc height is lost.
The upper thoracic discs are the thinnest and in general thoracic discs are the same width anteriorly as they are posteriorly. This is not the case in the cervical and lumbar spine, where greater thickness anteriorly contributes to the normal cervical and lumbar lordosis.
L4/5 intervertebral disc: Gross anatomy
Each intervertebral disc is comprised of:
- peripheral annulus fibrosus – consisting of multiple laminations of fibrous cartilage
- central nucleus pulposus – mucoprotein gel
- hyaline cartilage covers the endplates of the vertebral bodies
Above and below the intervertebral disc are the vertebral body endplates.
L4/5 Intervertebral disc: Arterial supply
The inner layers of the annulus fibrosus and nucleus pulposus have neither innervation nor blood supply; they receive nutrition via diffusion across the vertebral body endplates. The outer fibres of the annulus fibrosus are innervated by sinuvertebral nerves arising from the dorsal root ganglia.
Erector spinae muscles: Description
The erector spinae group and a longitudinal group of muscle in the midline back.
They consist of three sub groups ordered lateral to medial.
- Iliocostalis
- Longissimus
- Spinalis
Iliocostalis
Divided into:
- Cervicis
- Thoracis
- Lumborum
Longissimus
- Capitis
- Cervicis
- Thoracis
Spinalis
- Capitis
- Cervicis
- Thoracis
Erector spinae: Neurovasculature
Arterial supply:
- Dorsal branches of the posterior intercostal and lumbar arteries
Innervation:
- Dorsal rami of the cervical to lumbar nerve
Erector spinae: Relations
- Deep to the thoracolumbar fascia caudally
- Between layers of the thoracolumbar fascia in the lumbar regions
Arterial supply of the spinal cord:Description
- Deep to the thoracolumbar fascia caudally
- Between layers of the thoracolumbar fascia in the lumbar regions
Arterial supply of the spinal cord
- The spinal cord is supplied by three longitudinal arteries:
- Single anterior spinal artery – supplies the anterior 2/3 of the spinal cord
- Paired posterior spinal arteries – supplies the posterior 1/3 of the spinal cord
- Anastomosis between the spinal arteries is the Arterial vasocorona through the spinal cord and pial plexuses encasing the cord
Anterior spinal artery: Gross anatomy
Origin: vertebral artery in the regional of the medulla, two limbs anastomoses in the midline
Course: Descending down the anterior surface of the spinal cord in the anterior median fissure covered by pia mater.
Anterior spinal artery: Branches
- Anterior segmental medullary arteries
- Ascending cervical artery
- Posterior intercostal
- Artery of Ademkiewicz (usually between T9-T12)
- Cone artery (branch of the iliolumbar arteries)
Posterior spinal arteries
Origin: From the posterior inferior cerebellar arteries or the vertebral arteries (may be intra or extra dural)
Course: Descending down the posteriolateral surface of the spinal cord
Branches: Re-enforced by the same branches as the anterior spinal artery
Arterial supply of the spinal cord :variants
Duplication of the anterior spinal artery
Single origin of the anterior spinal artery
Venous drainage of the vertebrae and spinal cord
- The venous drainage is via three anterior and three posterior longitudinal spinal veins .
- There veins are valveless forming an anastomotic network along the surface of the spinal cord
- The drain into the anterior and posterior, internal and external vertebral plexi.
- Anterior and posterior radicular veins also freely communicate between the spinal veins and plexi.
- The internal vertebral plexus drains into the dural venous sinuses and the external vertebral plexus.
- The external plexi drain into the systemic segmental veins
Spinal cord: Description
The spinal cord is a component of the central nerves system located in the spinal canal
Function: Transmission of the nerves to and from the brain to the peripheral nervous system
Spinal cord: Gross anatomy
- Extension of the medulla at level C1 to the conus medullaris at the level T12/L1 in adults
- 42-45cm in length
Components:
Divided into the following segments:
- Cervical
- Thoracic
- Lumbar
Spinal cord: Nerve roots
31 pairs in total:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Spinal cord structure
Meninges: dura mater, pia and arachnoid
Internal structure:
- White matter externally, grey matter (butterfly shape internally), central canal in the centre
- Posterior sulcus and anterior fissure divide the cord to two halves
Spinal cord arterial supply
- Anterior spinal artery (supplies the anterior 2/3)
- Paired posterior spinal arteries
- Anastomosis between the anterior and posterior arteries is the arterial vasocorona
- These arteries are reinforced by multiple radicular arteries from:
- Ascending cervical arteries
- Deep cervical arteries
- Posterior intercostal arteries
- Lumbar arteries
- Lateral sacral arteries
Radicular arteries branch to anterior and posterior divisions once they enter the neuronal foramina
Spinal cord venous drainage
Anterior and paired posterior spinal veins
Radicular veins with anterior and posterior divisions
Multiple communications with the plexi: Internal and external verterbral venous plexi
Spinal cord: Relations
- Superior: medulla oblongata
- Inferior: cord equina
- Lateral: pedicles
- Anterior: Vertebral bodies
- Posterior: laminal process
Spinal cord:Variants
- Termination level may vary
- Syrinx
Cauda equina: Description
Known as the ‘horses tail’ it is the continuation of the lumbar/sacral/coccygeal nerve roots hanging inferior from the conus. Responsible for the innervation of the pelvic, perineal and lower limbs.
Function:
To transmit the spinal nerve roots through the vertebral canal
Location:
Sits inferior to the Conus Medullaris which is at the L1/2 level in Adult due to elongation of the vertebral canal; , L3 in neonate
Cauda equina: Gross anatomy
- Within the lumbar cistern/ subarachnoid space thecal sac surrounded by CSF enclosed in dural sac
- Origin arises from conus
- Terminates as the Filum terminale
- The corresponding nerve root will exit the intervertebral foramen bilaterally, Sacral Foramina S1-4 or Sacral hiatus S5
Cauda equina: Relations
- Superior: Conus
- Inferior: Filum Terminale, Coccyx
- Lateral: Vertebral canal and intervertebral foramina, nerve roots, Ganglia, radicular arteries
- Anterior: posterior longitudinal ligaments, intervertebral disc, vertebral body
- Posterior : Interspinous ligament and Flaval ligament
Cauda equina: Vasculature
Arterial Supply:
Radicular arteries through intervertebral foramen
Venous:
Internal venous plexus to external plexus then Azygos V
Cauda equina variants
Conus Medullaris – Changes vertebral level with age
Ventricularis Terminalis (cystic structure at transition of conus – Filum)
Dorsal rami of the lumbar spinal nerves
- Formed from the dorsal aspect of the spinal nerve as it emerges from the neuronal foramen.
- After the dorsal and ventral roots have merged
- After they form they travel backwards
- Dorsal rami divide into medial, intermediate, and lateral branches.
- The lateral branch supplies innervation to the iliocostalis muscle, as well as the skin lateral to the muscle on the back.
- The Intermediate branch supplies innervation to the spinalis muscle and the longissimus muscle. The medial branch supplies innervation to the rest of the epaxial derived muscles on the back (including the transversospinales, intertransversarii muscles, interspinalis muscles, suboccipital muscles, and splenius), and the zygapophyseal joints.
Spinal meninges and associated spaces: Description
The space between the spinal dura mater and the vertebral column.
Location: extends from the foramen magnum to the mid sacral canal
Spindal meninges: Gross anatomy
The spinal epidural space is distinctly separate from and not continuous with the cranial epidural space.
Spinal meninges: boundaries
Inner: spinal dura mater
Outer: Posterior longitudinal ligament, neural arches, intervertebral foramen, ligamentum flavum
Spinal meninges: Contents
- Loose connective tissue
- Fat
- Internal vertebral venous plexus
- Lympathics
- Arteries
- Spinal nerve roots
