Vertebral Column Osteology Flashcards
Where does the Vertebral Column start and finish?
Extends from skull to apex of coccyx
What is the total length of the vertebral column in males?
~70cm
What is the total length of the vertebral column in females?
~60cm
How many bones are there in the vertebral column?
33 Vertebrae: 7 cervical + 12 thoracic + 5 lumbar +
5 sacral (fused to form sacrum) +
4 coccygeal (fused to form coccyx)
What are the general functions of the vertebral column?
Protects spinal cord and spinal nerves
Supports the weight of body
Important in maintaining posture and for locomotion
Why is the spine curved?
The advantages of a curve spine is that it acts like a series of springs
It enables the spine to act like a natural shock absorber since has flexibility in a sagittal plane when vertically loaded
The intervertebral discs absorb shock and allow a lighter more flexible structure
Since the discs are partially off-set, then the mass of the above vertebra is not solely placed directly on the disc, but spread between the disc and the facet joints
What is the definition of Kyphosis?
convex curvature of the spine e.g. thoracic region
What is the definition of Lordosis?
concave curvature of the spine e.g. lumbar region
What is the definition of Scoliosis?
sidewards curve of the spine in sagittal view
What are the primary curvatures of the vertebral column?
Thoracic and Sacral
Concave anteriorly (kyphotic)
Formed during foetal period
Caused by differences in height between anterior and posterior parts of vertebral body
What are the secondary curvatures of the vertebral column?
Cervical and Lumbar
Convex anteriorly (lordotic)
Only become obvious in infancy
Caused by differences in thickness between anterior and posterior parts of intervertebral discs
What do typical vertebrae consist of?
Body
Vertebral (Neural) Arch
Transverse AND spinous processes
Articular processes
Opposed surfaces of adjacent bodies are bound together by intervertebral discs
Vertebral foramina form vertebral canal for spinal cord
Between adjoining vertebral arches are intervertebral foramina for spinal nerves
True or false? Vertebrae vary in size and characteristics from one region to another and within regions
True
What does the vertebral body look like?
Viewed from above, most bodies are convex anteriorly and concave posteriorly where they complete the vertebral foramen
When viewed laterally, they are box shaped, with a concave surface anteriorly and a flat surface posteriorly
Superior and inferior surfaces are smooth with tiny perforations and a rim running around the perimeter of smoother raised bone called the ring apophysis
Nutrient foramina on posterior surface
What is the function of the vertebral body?
Weight bearing
(esp. longitudinal forces)
Due to their shape, they cannot resist sliding or twisting movements
Not a solid structure (lighter & more suitable to dynamic load bearing)
Solid structures fracture more easily
Weight bearing ability is enhanced by internal structure:
Shell of solid cortical bone
Cancellous cavity created from numerous trabeculae (vertical and transverse struts of bone)
Weight is first borne by vertical trabeculae as they start to bow under pressure, they are supported by transverse trabeculae
What does the vertebral arch consist of?
Pedicle
Lamina
Projecting from their junctions:
Transverse processes (paired)
Articular processes (paired, superior and inferior)
Spinous process (single, dorsally placed in median plane)
What are the vertebral pedicles?
Two short, stout, rounded processes
Projects posteriorly from superior part of vertebral body at junction of its posterior and lateral surfaces
Superior vertebral notch (above the pedicle) is shallower than inferior vertebral notch (below the pedicle)
Adjacent vertebral notches intervertebral foramen
Help to transmit tension and bending forces
What is pars interarticularis?
part of vertebra between inferior and superior articular process of facet joint
What is the lamina?
Directly continuous from each pedicle towards the midline
Meet and fuse in the midline
Flattened in vertical plane
What is a spinous process?
Projects dorsally and often caudally from junction of laminae
Act as attachments and levers for muscles which control posture and active movements of vertebral column
What are articular processes?
Articular Processes
Superior and inferior articular processes arise at junction of lamina and pedicle
Superior articular processes extend superiorly, articular facets facing posteriorly
Inferior articular processes extend inferiorly, articular facets facing anteriorly
Accessory processes near attachment of transverse processes to pedicles
Receive forces acting on vertebra, including some weight bearing
Restricts certain movements
Prevents vertebrae from slipping anteriorly
Protects vertebral canal
What are transverse processes?
Projects posterolaterally from junction of pedicles and laminae on each side
Act as levers for muscles and ligaments
Particularly concerned with rotation and lateral flexion
What is the vertebral foramen formed by?
Vertebral body (posterior aspect)
Pedicles
Laminae
Spinous process (base)
What is contained within the vertebral foramen?
Spinal cord
Nerve roots
Meninges
Spinal Vasculature
What is the intervertebral foramen?
Principle route to and from vertebral canal
What is the intervertebral foramen formed of?
Vertebral notches
(superior & inferior)
Vertebral bodies
(adjacent posterolateral parts)
Intervertebral disc
(posterior aspect)
Articular processes
Capsule of zygapophyseal (facet) synovial joint
What is contained within the intervertebral foramen?
Spinal nerves
Smaller recurrent nerves
Blood and lymphatic vessels
What does the cervical body look like?
Viewed Anteriorly:
Superior surface is concave and inferior surface is convex
Superior borders of vertebral bodies are raised posteriorly, referred to as uncinate processes
Viewed Superiorly:
Convex anterior surface and flat/minimally concave posterior surface
A-P distance is half its side to side distance (width)
Viewed Laterally
Not wedge shaped
What does the thoracic body look like?
Larger than cervical, smaller than lumbar
Impression on left side by descending thoracic aorta
Viewed Laterally:
Slightly wedge shaped (deeper posteriorly)
Waisted cylinder
Viewed Superiorly:
Transverse and AP dimensions almost equal
Heart shaped
Circular vertebral foramina
What does the lumbar body look like?
Costal Facets:
Upper 6 vertebrae: Concave & face anterolaterally
Lower 6 vertebrae: Flatter & face superolaterally & slightly forwards
Larger superior facets:
Upper border of body, anterior to pedicles
Smaller inferior facets:
Lower border of body anterior to vertebral notches
Large, sturdy and kidney shaped
Wider transversely
What are the movements of the spine - the head in relation to c7?
flexion: approximately 85º (of which 10º in the atlanto-occipital joint and 30º in the atlanto-axial joint)
extension: approximately 55º (of which 20º in the atlanto-occipital joint)
lateroflexion: approximately 35°
rotation: approximately 85º (of which 35º in the atlanto-axial joint)
What are the movements of the spine - T1 in relation to T12?
T1 in relation to T12:
flexion/extension: very limited
lateroflexion: approximately 35°
rotation: approximately 55°
What are the movements of the spine - L1 in relation to S1?
flexion: approximately 25°
extension: approximately 55°
lateroflexion: approximately 35°
rotation: approximately 15°
What do cervical pedicles look like?
Project posterolaterally
Midway between posterior surface of vertebral body, so that superior and inferior vertebral notches are a similar depth
What do thoracic pedicles look like?
Do not diverge as in cervical vertebra
What do lumbar pedicles look like?
Short stout cylinders
What do cervical laminae look like?
Project posteromedially
Longer than pedicles
Thin and slightly curved
Thin superior and slightly thicker inferior border
What do thoracic laminae look like?
Short, thick and broad
Overlap from above downwards
What do lumbar laminae look like?
Sturdy
What do Cervical Vertebral Foramen look like?
Large
Triangular
Accommodates the cervical enlargement of the spinal cord
What do Thoracic Vertebral Foramen look like?
Is small and circular as the spinal cord is smaller and more circular
What do Lumbar Vertebral Foramen look like?
Varies in shape from oval to triangular
What the Cervical Intervertebral Foramina look like?
Large and triangular
Face anterolaterally 45 degrees
Superior and inferior vertebral notches of almost equal depth
Which way do the Thoracic Intervertebral Foramina face?
Face laterally
What do the Lumbar Intervertebral Foramina look like?
Oval to triangular
Face laterally
Lie between two principle lines of vertebral attachment of psoas major muscle
What do Cervical Transverse Processes look like?
Transverse foramina
Anterior and posterior tubercles
Shorter than thoracic and lumbar transverse processes
Face approximately 45 anterolaterally
What do Thoracic Transverse Processes look like?
Directed posterolaterally
Near tip is anterior oval facet (tubercle of corresponding rib)
Longer than cervical transverse processes
Shorten in caudal succession
What do Lumbar Transverse Processes look like?
Thin and long
Project laterally
Small accessory process marks posteroinferior aspect of root
What are Cervical Articular Processes?
Superior Articular Processes: Facets are flat & ovoid and face superoposteriorly
Inferior Articular Processes: Inferior facets are flat and ovoid and face inferoanteriorly
What are Thoracic Articular Processes?
Superior Articular Processes: Thin and almost flat and face posteriorly and slightly superolaterally
Inferior Articular Processes: Project inferiorly from laminae and
What are Lumbar Articular Processes?
Superior Articular Processes: Vertical concave articular facets that face posteromedially
On posterior surface of each is a rough rounded mamillary process (attachment for multifidus and medial intertransverse muscles)
Inferior Articular Processes: Vertical convex articular facets that face anterolaterally
What do Cervical Spinous Processes look like?
Short and usually bifid
C6 process is longer and often is not bifid
Project posteroinferiorly
Thinner than lumbar, shorter than thoracic
What do Thoracic Spinous Processes look like?
Long and slender
Slant posteroinferiorly
Overlap
What do Lumbar Spinous Processes look like?
Broad, flat and thickened along posterior and inferior borders
Project horizontally posteriorly
What is the C1 Atlas?
First cervical vertebra and supports skull
Ring shaped bone
What is the C1: Body, Pedicles, Laminae and Spinous Process?
No body, pedicles, laminae or spinous process
What is the C1: Anterior Arch?
Convex anteriorly
Shorter than posterior arch
Small anterior midline tubercle (anterior longitudinal ligament)
On posterior surface is concave almost circular facet for articulation with dens of C2
Transverse ligament holds dens against anterior arch
What is the C1: Posterior Arch?
Convex posteriorly
Longer than anterior arch
Small posterior midline tubercle (ligamentum nuchae)
Superior surface has groove for vertebral artery
What are the C1: Lateral Masses?
Ovoid
Their long axes converge anteriorly
Medially the masses have a tubercle for the attachment of transverse ligament of atlas
Superior articular facet (articulates with occipital condyle of skull) are kidney shaped and concave
Inferior articular facets (articulate with C2) are circular and flat/slightly concave
Inferior facet faces posteromedially
What is the C2 (Axis)?
Second and strongest cervical vertebra
What is the C2: Body?
Consists of less compact bone than dens
On anterior surface is deep depression on each side (attachment of vertical part of longus colli muscle)
Anterior border projects downward (attachment for anterior longitudinal ligament)
What are the C2: Pedicles?
Stout
Projects laterally and downward
Anterolateral surface grooved by vertebral artery
Inferior intervertebral notch
What does the C2: Laminae look like?
Thick
What does the C2: Transverse Processes look like?
Project inferiorly and laterally
Rounded tip
Transverse foramen directed laterally
What are the C2: Articular processes?
Superior Articular Processes:
Large, flat and circular (atlas)
Inferior Articular Processes:
Face anteroinferiorly (C3)
What does the C2: Spinous Processes look like?
Large
Bifid tip with a broad base
Concave anteriorly and inferiorly
What is the C2: Dens?
Conical structure projecting superiorly from body around which atlas rotates
Apex is pointed, from where apical ligament arises
Posterior surface has broad groove for transverse ligament of atlas
Held in place by transverse ligament (prevents horizontal displacement of C1)
Posterolateral surfaces (above groove for transverse ligament) are flattened, from where alar ligaments arise
Anterior surface has ovoid articular facet for anterior arch of atlas
What is the C7 (Vertebra Prominens)?
Characterized by long spinous process
Thick and prominent transverse processes are largest in cervical spine
Transverse foramen does not contain the vertebral artery, only vertebral veins (may be small or absent)
Anterior tubercle on transverse process is small, whereas posterior tubercle is prominent
What are Atypical Thoracic Vertebrae (T1-T4)?
Some features of cervical vertebrae
Bodies are smaller and narrower
Superior articular facets tend to face more superiorly
What does T1 look like?
Body typically cervical with a transverse diameter almost twice the anteroposterior
Long almost horizontal spinous process nearly as prominent as C7
What does T2 look like?
Body retains cervical shape but difference in AP to lateral diameters are less
What does T3 look like?
Body is smallest with a convex anterior aspect unlike T1 &T2, which are flattened
What does T4 look like?
Body is typically heart shaped
What do Atypical Thoracic Vertebrae (T9-T12) look like?
Some features of lumbar vertebrae
Larger broader bodies
Spinous processes more horizontal
What does T9 look like?
Often fails to articulate with 10th ribs
Inferior demifacets often absent
What does T10 look like?
Only articulates with 10th ribs and only superior costal facets appear on body
Transverse process may not bear a facet for 10th rib tubercle
What does T11 look like?
Only articulates with heads of 11th ribs
Costal facets are small, circular and close to upper border of body extending onto pedicles
No costal facets on small transverse processes
11th and 12th spinous processes are triangular with blunt apices
What does T12 look like?
Costal facets just below upper border of body & extend onto pedicles
Transverse process is small & irregular
What is Atypical Lumbar Vertebra - L5?
Body is wedge shaped, thicker anteriorly than posteriorly
Massive transverse process continuous with whole of pedicle and part of body
Inferior articular facet faces anteriorly preventing vertebra from sliding anteriorly on sloping superior surface of sacrum
Largest of movable vertebrae, and responsible for lumbosacral angle
Body weight is transferred from L5 to base of sacrum
What is the sacrum?
Composed of 5 fused sacral vertebrae
Articulates with L5 at 130-160º
Four pairs of smaller dorsal and larger pelvic foramina for exit of dorsal and ventral divisions of sacral nerves
Inferior smaller half is not weight bearing
Wider in proportion to length in females
Body of 1st sacral vertebra larger in males
Provides strength and stability to pelvis
Transmits body’s weight through sacroiliac joints to pelvic girdle
What is the sacrum comprised of?
Body: Large and wider transversely
Sacral promontory: Projecting anterior margin of body of S1 vertebra
Pedicles: Short & divergent posterolaterally
Laminae: Slant down posteromedially to meet at tubercle
Superior articular processes: Project cranially with concave articular facets directed posteromedially to articulate with inferior articular processes of L5 vertebra
Transverse processes: Extend laterally from body
Sacral/Vertebral foramen: Triangular
Sacral canal: Contains cauda equina, meninges, cerebrospinal fluid, internal venous plexus, spinal nerves & fat
Sacral hiatus: deficient posterior wall of the sacral canal inferiorly. Contains terminal filum, fatty connective tissue, S5 & coccygeal nerves
Sacral cornua: Project inferiorly on each side of hiatus
Auricular surface: Roughened area in upper part of lateral sacrum, where sacrum articulates with ilium
Sacral Base
Directed superiorly and slightly anteriorly
Formed by upper surface of S1
Sacral Apex
Inferior aspect of 5th sacral vertebral body bears an oval facet for articulation with coccyx
What is the coccyx?
Sacral Base
Directed superiorly and slightly anteriorly
Formed by upper surface of S1
Sacral Apex
Inferior aspect of 5th sacral vertebral body bears an oval facet for articulation with coccyx
