Vertebrae Flashcards
State the number of vertebrae in each spinal region
In total = 33
- Cervical = 7
- Thoracic = 12
- Lumbar = 5
- Sacral = 5 - fuse into a single bony element = sacrum
- Coccyx = 3-4 - rudimentary in structure and often fuse into a single coccyx
Number and specific characteristics of the vertebrae vary depending on the body region with which they are associated
What does a typical vertebrae consist of
Vertebral body
Vertebral (neural) arch - pedicle and laminae
7 processes:
Articular processes (X4) - 2 superior and 2 inferior
Transverse processes (X2)
Spinous process (X1)
Intervertebral foramen
No vertebrae are the same - each spinal region has different characteristics
Vertebrae slowly morph characteristics as spine lowers, e.g. C3 looks less like a typical cervical and more thoracic than C2
What is the vertebral body and it’s function
Vertebral body is anterior
Function: is the major weightbearing component of the bone. It increases in size from C2 to L5 as amount of weight supported increases
Fibrocartilaginous intervertebral discs separate the vertebral bodies of adjacent vertebrae
At risk of wedge # - slanted body causing kyphosis as vertebrae stack on slanted bodies
What is the vertebral (neural) arch and its function
Vertebral (neural) arch = firmly anchored to the posterior surface of the vertebral body by two pedicles, which form the lateral pillars of the vertebral arch
Pedicle = bony pillars that attach the vertebral arch to the vertebral body
Lamina = flat sheets of bone that extend from each pedicle to meet in the midline and form the roof of the vertebral arch, also form the lateral and posterior walls of the vertebral foramen
Vertebral foramen of all the vertebrae together form the vertebral canal - extends from CI to S5 vertebrae
□ Encloses and protects the spinal canal - passageway for spinal cord
What are the articular processes and their function
Articular process x 4 - 2 superior and 2 inferior
Located On each side of the vertebral arch, from the region where a lamina meets a pedicle a superior articular process and an inferior articular process articulate with similar processes on adjacent vertebrae to form facet joints
Function:
□ transmit weight
□ enable movement
□ Limit movement i.e. controls direction of movement
□ CS: rotation due to horizontal facet orientation
□ LS: minimal rotation due to vertical ‘wrapped’ facet orientation
What are the Transverse processes (TP) and their function
Transverse process (TP) x2 - on each side of the vertebral arch, a TP extends laterally from the region where a lamina meets a pedicle
Function:
□ levers for muscles that side flex or rotate
□ Insertion for ligts that control movement at each vertebral segment
□ articulation with ribs in the thoracic region
What are spinous processes and their function
Spinous process (Sp) x1 - projects dorsally and often inferiorly from roof of vertebral arch (from the junction of the two laminae)
Vary in size, shape and direction
Function:
□ Levers for muscles which extend the spine
□ Insertion for ligts to control spinal movement
What is the intervertebral foramen and its function
Intervertebral foramen - formed from adjacent neural (vertebral) arches of adjacent vertebrae
Function - exit for spinal nerves from spinal cord between vertebrae; occurs at each level
Superior and inferior margins are formed by notches in adjacent pedicles.
Posterior margin is formed by the articular processes of the vertebral arches and the associated (facet) joint.
Anterior border is formed by the intervertebral disc between the vertebral bodies of the adjacent vertebrae
Describe the characteristics of typical cervical vertebrae
Small kidney shaped vertebral body - as only carrying weight of skull
Short pedicles projecting laterally
Long, narrow lamina projecting posteriorly posteriorly & medially
Large, triangular vertebral foramen - spinal cord is at its largest because at cervical region the fewest spinal nerves have exited
TPs - sl. anterior stout projection from side of body and pedicles w/ anterior and posterior tubercles; has foramen transversium between anterior and posterior tubercles of TPs; Vertebral artery passes through
Short, slender Bifid (C2-4)spinous process Uncovertebral joints (joints of von Lushka) - lipping of vertebral bodies
Articular processes horizontal and sloped antero-posteriorly - increasingly vertically sloped as vertebra descends; superior facet convex facing superiorly and posteriorly, inferior facet concave facing inferiorly and anteriorly
○ Allows for lot of rotation of the neck and facilitates flexion, extension with coupled side flexion/rotation
Describe characteristics and function of the atlas (C1)
CI (the atlas) articulates with the head/skull at the atlanto-occipital joint and articulates with C2 (axis) at the atlanto-axial joint
C1 lacks vertebral body giving ring shape - vertebral body of CI fuses onto the body of C2 (axis) during development to become the dens of C2 thus no intervertebral disc between C1 and C2
Lacks SP - small posterior tubercle
TPs of the atlas (C1) are large
Composed of two lateral masses interconnected by an anterior arch and a posterior arch
Each lateral mass articulates above with an occipital condyle of the skull and below with the superior articular process of C2 (the axis).
□ The superior articular surfaces are bean shaped and concave
□ The inferior articular surfaces are almost circular and concave
Describe characteristics and function of the axis (C2)
Axis (C2) is characterized by the large tooth-like dens, which extends superiorly from the vertebral body.
Dens acts as a pivot that allows the atlas (C1) and attached head to rotate on the axis, side to side
Anterior surface of the dens has an oval facet for articulation with the anterior arch of the atlas
2 lateral superior articular facets for articulation with atlas (C1) 2 TP and foramen transversarium C2 has a vertebral body 2 narrow lamina Bifid SP
Describe characteristics of the typical thoracic vertebrae
T2-8
Characterised by their articulation with ribs
Round vertebral body - heart shaped (viewed from superior) with costal demifacets for articulation for corresponding head of rib and rib below
Short pedicles projecting posteriorly
Overlapping laminae between vertebrae
Vertebral foramen - circular and small
Long, inferiorly slanted, overlapping spinous process, upper and lower Thx shorter
Long thick rounded TP with a costal facet for articulation with the tubercle of its own rib
Articular processes - flat project vertically but AP sloped; superior facet concave facing posteriorly, sl. superiorly & laterally, inferior facet convex facing anteriorly, sl. inferiorly & medially . Facet orientation allows some rotation but limits flexion/extension
Describe characteristics of typical lumbar vertebrae
L1-4
Large, kidney shaped vertebral body - to carry weight of head, shoulders and trunk
short, strong pedicles projecting posteriorly
Narrow laminae projecting posteriorly & medially
Vertebral foramen - triangular; larger than thoracic vertebrae but smaller than cervical; relatively small to large body as spinal cord seizes at L2, forming conus medularis
spinous process - broad thick posterior border projecting posteriorly
Thin short TP projecting laterally and posteriorly with small accessory process at root of TP
Articular process projects vertically with Mamillary Process (x2) on internal aspect of superior articular facets; attachment site for muscles
Vertical articular facets - wrapped orientation - inferior facets convex face outwards; superior facets concave face inwards; adjacent processes interlock in facet joints - this orientation limits rotation but allows flexion, extension
Describe characteristics of sacral vertebrae
5 fused vertebrae - sacrum; triangular in shape
Base articulates with L5
Sacral promontory and superior articular process
Apex - pointed inferiorly
Sacral canal - sacral nerve roots descend in sacral canal before exiting through sacral foramina
4 pairs of posterior sacral foramina and 4 pairs of anterior sacral foramina for the passage of the posterior and anterior rami, respectively, of sacral nerves
Concave anteriorly - kyphotic curvature
Spinous tubercle - palpable
Two large L -shaped facets - one on each lateral surface, for articulation with the pelvic bones
NB:
Can locate S1 vs L5 as movement occurs in L5 only as S1 is fused
Describe characteristics of coccyx
Small triangular
3-4 rudimentary vertebrae fused
Absence of vertebral arches and therefore a vertebral canal
Directed inferiorly and ventrally
Decrease in size
Commonly find intervertebral disc between S5 and 1st coccyx vertebra - small degree of movement
