Spine Flashcards
How many cervical vertebrae does the spine consist of?
7
How many thoracic vertebrae does the spine consist of?
12
How many lumbar vertebrae does the spine consist of?
5
How many sacral vertebrae does the spine consist of, are they discrete?
5, fused vertebrae
How many coccygeal vertebrae does the spine consist of?
3-5
What lies inbetween adjacent vertebrae?
Intervertebral discs
What occupies the vertebral canal from C1 to L1
Spinal cord
What occupies the vertebral canal from L1 down?
Corda equina
What does the spinal cord give rise to?
Nerve roots
Where do nerve roots emerge relative to the spinal cord?
Via the intervertebral foramen, below the pedicle of each vertebrae
How many nerve roots are there in the cervical region?
8
Why is there 8 nerve roots but only 7 vertebrae in the cervical region?
Root 1 emerges above C1.
What do nerve roots exit the spinal cord through?
Intervertebral foramen
Describe the curvature of the spine?
Cervical Lordosis
Thoracic Kyphosis
Lumbar Lordosis
What is a lordosis and a kyphosis?
Lordosis - posterior concavity
Kyphosis - posterior convexity
What can cause lateral scoliosis?
Ventral and medial somite cells surrounding the notochord and neural tube fail to migrate (to meet in the middle), on one side
What are the primary spinal curvatures? When do they develop?
Thoracic kyphosis and sacral curvature
During foetal development
What are the secondary spinal curvatures? When do they develop?
Cervical and lumbar lordosis
After birth
What forms first, lumbar or cervical lordosis?
Cervical
What signals somites to differentiate into sclerotome and dermomyotome?
Shh induces the most medial of somite cells to form sclerotome
What releases Shh that patterns the spine?
Notochord
What does the sclerotome form?
Vertebrae
Where does the sclerotome lie relative to the myotome?
Medial (towards notochord)
When sclerotome cells move medially what happens to it?
Cells meet the other sclerotome cells from the other side to form the vertebral body
How does sclerotome on fuse in a craniocaudal axis to form vertebrae?
The lower half of one sclerotome (from one somite) fuses with the upper half of the adjacent one to form each vertebral body.
Where do the spinal nerves emerge through a sclerotome?
Through fissure in one NOT through adjacent ones
What genes determine appropriate shapes of vertebrae along the spine?
Hox
What type of bone is a vertebrae?
Irregular bone
What type of ossification do vertebrae undergo?
Endochonral ossification
Describe the basic configuration of a vertebra
Vertebral body
Posterior part of a vertebra joins the vertebral body via two pedicles
Vertebral foramen created by body, pedicles and posterior
Laminae join together the central spinous process with the transverse processes.
What joins up the spinous and transverse processes?
Laminae
What joins the body with the posterior vertebrae?
Pedicles
What forms the intervertebral foramen (bone)?
Above and below the pedicles are vertebral notches (superior and inferior).
When the vertebrae articulate the notches align with those on adjacent vertebrae and these form the openings of the intervertebral foramina.
Which articular process is lined with hyaline cartilage?
Superior
What is characteristic about the body of cervical vertebrae?
Small
What is characteristic about the vertebral foramen of cervical vertebrae?
Large
What foramen is unique to cervical vertebra?
Transverse (vertebroarterial)
Where are transverse foramina (cervical spine)?
Lateral to body
What is the role of the transverse foramina (cervical spine)?
Passage of vertebral arteries
What is unique about the spinous process of the cervical vertebrae?
Bifid spine on spinous process - two prominences.
What is the vertebra prominens?
C7
What movements does the cervical spine C3-C7 allow?
Articulation facets allow flexion and extension but no rotation.
What allows the flexion and extension of the cervical spine?
Articulation facets
What are the names of C1/C2?
C1 - Atlas
C2 - Axis
What is the specialised function of C1/C2?
Allow a greater range of motion than normal vertebrae such as axial rotation.
What is specific about Atlas?
Extra facet for dens of the axis to insert.
No body
What is specific about Axis?
Very small/no body that projects the dens.
The dens (odontoid) process acts as a pivot
What holds the dens in place in the atlas facet?
Transverse ligaments
What movement does the dens allow?
Pivot that allows the atlas and attached head to rotate on the axis
What is the C1/C2 joint called?
Atlantoaxial joint
Does the atlantoaxial joint have an intervertebral disc?
No
Where is the dens of the axis derived from?
Dens of the axis is derived from the vertebral body of the atlas (C1) (in development lower sclerotome joins upper sclerotome)
What does the atlas articulate with above?
Occipital condyles of bone
What is the joint between the occipital bone and the atlas called?
Atlanto-occipital joint
What type of joint is the atlanto-occipital joint?
Synovial
What movements does the atlanto-occipital joint allow?
Flexion and extension, which gives nodding of the head.
Sight lateral motion, lateroflexion, to one or other side
What is characteristic about the vertebral foramen of the thoracic vertebrae?
Small
What is characteristic about the spinous processes of the thoracic vertebrae?
Long
What unique facets to the thoracic vertebrae have?
Costal facet for rib articulation
What movements do the articulation facets allow in thoracic vertebrae?
Almost no flexion and extension but some rotation.
What is characteristic about the body of the lumbar vertebrae, why is this?
Large body - designed for weight bearing.
What movements do the articulation facets allow in lumbar vertebrae?
Flexion and extension but no rotation
What is unique about the sacral vertebrae?
Fused
What are the joints between vertebrae (below C2) called?
Intervertebral
What are the two types of joint that make up the intervertebral joint?
Synovial joints between the articular processes of neighboring vertebrae.
Secondary cartilaginous joints between the vertebral bodies (Intervertebral discs).
What joint type is between the vertebral bodies/discs?
Secondary cartilaginous
What is the function of the intervertebral discs?
Distribute hydraulic pressure in all directions within each intervertebral disc under compressive loads.
What does the notochord give rise to?
Nucleus palposus
What makes up a vertebral disc?
The nucleus pulposus and the fibers of the anulus fibrosus
What is the anulus fibrosus?
Fibrocartilage outer layer that gives strength
What is the nucleus palposus?
Central, gelatinous and compresses to withstand forces
What is the anulus fibrosus derived from?
Sclerotome
What is the role of ligaments in the spine?
Stabilise and maintain posture in the spine
What are the ligaments of the spine from anterior to posterior?
Anterior longitudinal ligaments
Posterior longitudinal ligaments
Ligamentum flavum
Intertransverse
Interspinous
Supraspinous
What do the anterior and posterior longitudinal ligaments do?
Hold together the vertebral bodies on both A and P side, encase the intervertebral discs.
What does the ligamentum flavum do?
Joins the ventral parts of the laminae of adjacent vertebrae.
What do the intertransverse ligaments do?
Joins between the transverse processes of adjacent vertebrae.
What do the interspinous ligaments do?
Joins between the spinous processes of adjacent vertebrae.
What do the supraspinous ligaments do?
Joins the most outer part of the spinous processes together.
Where does the spinal cord terminate in an adult vs a child?
Below L1 in adults (L3 in child).
How do roots exit the thoracic vertebrae (angle) in thoracic spine?
Almost parallel to the transverse processes
How do roots exit the thoracic vertebrae (angle) in lumbar spine downwards, what is an implication of this?
Emerge from lumbar vertebrae downwards
The root can often be mistaken to come from the vertebrae below.
What is a disc herniation?
Tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion to bulge out beyond the damaged outer rings,
What is the most common region of the spine to herniate and why?
L4-L5 and L5-S1 as greatest weight bearing.
Upper lumbar principle movement?
Extension
Osteoblasts that form the body of a vertebrae are derived from the…
Bone marrow
The lateral masses of the atlas articulate with the …
Occipital condyles
Which movements are possible between the atlas and axis vertebrae?
Flexion, extension and axial rotation
What about the pedicles of the vertebrae allows nerve passage?
Notching of them, to allow intervertebral foramina
Where are the costal articulating points on thoracic vertebrae?
Transverse process
How is rotation prevented in lumbar vertebrae?
Have large vertical facets to prevent rotation
The sacral nerves transmit which modalities?
motor, parasympathetic, sensory, sympathetic
At which level does the subarachnoid space terminate?
S2
The anterior sacral foramina transmit …
Both the anterior rami of the sacral nerves and the lateral sacral arteries
What innervates intrinsic back muscles?
Dorsal rami of spinal nerves
Intrinsic back muscles include?
Erector spinae, splenius, transversospinales
Extrinsic back muscles include?
Rhomboids, levator scapulae, trapezius and latissimus dorsi
