First cervical vertebra
atlas
- A
from above
- B
from below
- A
- 1
Anterior arch and tubercle
- 2
Facet for dens of axis
- 3
Groove for vertebral artery
- 4
Lateral mass with inferior articular facet
- 5
Lateral mass with superior articular facet
- 6
Posterior arch
- 7
Posterior tubercle
- 8
Transverse process and foramen
The superior articular facets (5) are concave and kidney-shaped.
The inferior articular facets (4) are circular and almost flat.
The anterior arch (1) is straighter and shorter than the posterior arch (6) and contains on its posterior surface the facet for the dens of the axis (2).
The atlas is the only vertebra that has no body.
Second cervical vertebra
axis
- C
from above
- D
from the front
- E
from below
- F
articulated with the atlas, from above
- C
- 1
Anterior arch of atlas
- 2
Bifid spinous process
- 3
Body
- 4
Dens (odontoid peg)
- 5
Impression for alar ligament
- 6
Inferior articular facet
- 7
Lamina
- 8
Pedicle
- 9
Superior articular surface
- 10
Transverse process and foramen
- 11
Vertebral foramen
The axis is unique in having the dens (4) which projects upwards from the body, representing the body of the atlas.
Fifth cervical vertebra
- 1
Anterior tubercle of transverse process
- 2
Bifid spinous process
- 3
Body
- 4
Foramen of transverse process
- 5
Inferior articular process
- 6
Intertubercular lamella of transverse process
- 7
Lamina
- 8
Pedicle
- 9
Posterior tubercle of transverse process
- 10
Posterolateral lip (uncus)
- 11
Superior articular process
- 12
Vertebral foramen
Seventh cervical vertebra
vertebra prominens
- D
from above
- D
- 1
Anterior tubercle of transverse process
- 2
Body
- 3
Foramen of transverse process
- 4
Intertubercular lamella of transverse process
- 5
Lamina
- 6
Pedicle
- 7
Posterior tubercle of transverse process
- 8
Posterolateral lip (uncus)
- 9
Spinous process with tubercle
- 10
Superior articular process
- 11
Vertebral foramen
All cervical vertebrae (first to seventh) have a foramen in each transverse process (as A4).
Typical cervical vertebrae (third to sixth) have superior articular processes that face backwards and upwards (A11, C11), posterolateral lips on the upper surface of the body (A10), a triangular vertebral foramen (A12) and a bifid spinous process (A2).
The anterior tubercle of the transverse process of the sixth cervical vertebra is large and known as the carotid tubercle.
The seventh cervical vertebra (vertebra prominens) has a spinous process that ends in a single tubercle (D9).
The rib element of a cervical vertebra is represented by the anterior root of the transverse process, the anterior tubercle, the intertubercular lamella (with its groove for the ventral ramus of a spinal nerve) and the anterior part of the posterior tubercle (as at D1, 4 and 7).
Seventh thoracic vertebra
typical
- E
from above
- F
from the left
- G
from behind
- E
- 1
Body
- 2
Costal facet of transverse process
- 3
Inferior articular process
- 4
Inferior costal facet
- 5
Inferior vertebral notch
- 6
Lamina
- 7
Pedicle
- 8
Spinous process
- 9
Superior articular process
- 10
Superior costal facet
- 11
Superior vertebral notch
- 12
Transverse process
- 13
Vertebral foramen
Typical thoracic vertebrae (second to ninth) are characterised by costal facets on the bodies (F10, 4), costal facets on the transverse processes (F2), a round vertebral foramen (E13), a spinous process that points downwards as well as backwards (F8, G8) and superior articular processes that are vertical, flat and face backwards and laterally (E9, F9, G9).
First thoracic vertebra
- A
from above
- B
from the front and the left
- 1
Body
- 2
Inferior articular process
- 3
Inferior costal facet
- 4
Lamina
- 5
Pedicle
- 6
Posterolateral lip (uncus)
- 7
Spinous process
- 8
Superior articular process
- 9
Superior costal facet
- 10
Transverse process with costal facet
- 11
Vertebral foramen
Twelfth thoracic vertebra
- E
from the left
- F
from above
- G
from behind
- 1
Body
- 2
Costal facet
- 3
Inferior articular process
- 4
Inferior tubercle
- 5
Lateral tubercle
- 6
Pedicle
- 7
Spinous process
- 8
Superior articular process
- 9
Superior tubercle
The atypical thoracic vertebrae are the first, tenth, eleventh and twelfth.
The first thoracic vertebra has a posterolateral lip (A6, B6) on each side of the upper surface of the body and a triangular vertebral foramen (features like typical cervical vertebrae), and complete (round) superior costal facets (B9) on the sides of the body.
The tenth, eleventh and twelfth thoracic vertebrae are characterised by a single complete costal facet on each side of the body that in successive vertebrae comes to lie increasingly far from the upper surface of the body and encroaches increasingly onto the pedicle (C2, D2 and E2). There is also no articular facet on the transverse process.
First lumbar vertebra
- A
from above
- B
from the left
- C
from behind
- 1
Accessory process
- 2
Body
- 3
Inferior articular process
- 4
Inferior vertebral notch
- 5
Lamina
- 6
Mamillary process
- 7
Pedicle
- 8
Spinous process
- 9
Superior articular process
- 10
Superior vertebral notch
- 11
Transverse process
- 12
Vertebral foramen
Lumbar vertebrae are characterised by the large size of the bodies, the absence of costal facets on the bodies and the transverse processes, a triangular vertebral foramen (A12), a spinous process that points backwards and is quadrangular or hatchet-shaped (B8) and superior articular processes that are vertical, curved, face backwards and medially (A9) and possess a mamillary process at their posterior rim (A6).
The rib element of a lumbar vertebra is represented by the transverse process (A11).
The level at which facet joint orientation changes between the thoracic and lumbar regions is variable.
Posterior view
- D
second lumbar vertebra
- E
third lumbar vertebra
- F
fourth lumbar vertebra
- G
fifth lumbar vertebra
Viewed from behind, the four articular processes of the first and second lumbar vertebrae make a pattern (indicated by the interrupted line) of a vertical rectangle; those of the third or fourth vertebra make a square, and those of the fifth lumbar vertebra make a horizontal rectangle.
View from above
- H
fifth lumbar vertebra
- 1
Body
- 2
Lamina
- 3
Pedicle
- 4
Spinous process
- 5
Superior articular process
- 6
Transverse process fusing with pedicle and body
- 7
Vertebral foramen
The fifth lumbar vertebra is unique in that the transverse process (H6) unites directly with the side of the body (H1) as well as with the pedicle (H3).
Sacrum
- 1
Auricular surface
- 2
Pelvic surface
- 3
Promontory
In the female, the pelvic surface is relatively straight over the first three sacral vertebrae and becomes more curved below. In the male, the pelvic surface is more uniformly curved.
The capsule of the sacro-iliac joint is attached to the margin of the auricular (articular) surface (A1, B1).
Base of the sacrum
upper surface
- C
in the female
- D
in the male
- C
- 1
Body of first sacral vertebra
- 2
Lamina
- 3
Lateral part (ala)
- 4
Promontory
- 5
Sacral canal
- 6
Spinous tubercle of median sacral crest
- 7
Superior articular process
In the male, the body of the first sacral vertebra (judged by its transverse diameter) forms a greater part of the base of the sacrum than in the female (compare D1 with C1).
In C, there is some degree of spina bifida (non-fusion of the laminae, 2, in the vertebral arch of the first sacral vertebra). Compare with the complete arch in D.
Sacrum and coccyx
- A
pelvic surface
- B
dorsal surface
- 1
Coccygeal cornu
- 2
Facet for coccyx
- 3
First coccygeal vertebra
- 4
Fused second to fourth vertebrae
- 5
Intermediate sacral crest
- 6
Lateral part
- 7
Lateral sacral crest
- 8
Median sacral crest
- 9
Promontory
- 10
Sacral canal
- 11
Sacral cornu
- 12
Sacral hiatus
- 13
Second pelvic sacral foramen
- 14
Site of fusion of first and second sacral vertebrae
- 15
Superior articular process
- 16
Third dorsal sacral foramen
- 17
Transverse process
- 18
Upper surface of lateral part (ala)
The sacrum is formed by the fusion of the five sacral vertebrae. The median sacral crest (B8) represents the fused spinous processes, the intermediate crest (B5) the fused articular processes, and the lateral crest (B7) the fused transverse processes.
The sacral hiatus (B12) is the lower opening of the sacral canal (B10).
The coccyx is usually formed by the fusion of four rudimentary vertebrae but the number varies from three to five. In this specimen, the first piece of the coccyx (3) is not fused with the remainder (4).
Sacrum
with sacralisation of the fifth lumbar vertebra
- A
pelvic surface
- B
dorsal surface, and sacral muscle attachments
- A
- 1
Body of fifth lumbar vertebra
- 2
Coccygeus
- 3
Erector spinae
- 4
First coccygeal vertebra fused to apex of sacrum
- 5
First dorsal sacral foramen
- 6
First pelvic sacral foramen
- 7
Foramen for dorsal ramus of fifth lumbar nerve
- 8
Foramen for ventral ramus of fifth lumbar nerve
- 9
Fusion of transverse process and lateral part of sacrum
- 10
Gluteus maximus
- 11
Iliacus
- 12
Lamina
- 13
Piriformis
- 14
Sacral canal
- 15
Spinous process of fifth lumbar vertebra
- 16
Superior articular process of fifth lumbar vertebra
In sacralisation of the fifth lumbar vertebra, that vertebra (A1) is (usually incompletely) fused with the sacrum. In the more rare condition of lumbarization of the first sacral vertebra (not illustrated) the first piece of the sacrum is incompletely fused with the remainder.
In this specimen, as well as fusion of the fifth lumbar vertebra with the top of the sacrum, the body of the first coccygeal vertebra (4) is fused with the apex of the sacrum.
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