Dalley, 10th Edition

Chapter 2 ■ Back

76

Dens of C2

(C1)

Atlas (C1) Axis (C2)

Vertebrae:

C1 C2 C3 C4 C5 C6 C7

(C2)

7 Cervical (C)

T1 T2 T3 T4 T5 T6 T7 T8 T9

12 Thoracic (T)

Spinous process overlapping inferior vertebra

Vertebral canal

Intervertebral foramina

T10 T11 T12

L1 L2 L3 L4 L5

Intervertebral (IV) discs

Parts of vertebral arches

Spinous process Lamina Pedicle

5 Lumbar (L)

Hip bone

S1 S2

Lumbosacral angle

Sacrum (S) (5 segments)

S3

S4

S5 Co1 Co2 Co3 Co4

Coccyx (Co) (4 segments)

(A) Anterior view

(B) Right lateral view

(C) Posterior view with vertebral ends of ribs

(D) Medial view of bisected column from left with ribs, cranium (skull), and pelvis

FIGURE 2.2. Vertebral column and its ve regions. A and B. Anterior and lateral aspects of vertebral column with isolated vertebra typical of each of three mobile regions. The continuous, weight-bearing column of vertebral bodies and IV discs increases in size as the column descends. Zygapophysial (facet) joints representative of each region are circled. C. Posterior view with vertebral ends of ribs. This represents more fully the skeleton of the back. D. Bisected vertebral column in context of axial skeleton and pelvis, demonstrating vertebral canal. The intervertebral (IV) foramina (also seen in B ) are openings in the lateral wall of the vertebral canal through which spinal nerves exit.

VERTEBRAE

fact that successive vertebrae bear increasing amounts of the body’s weight as the column descends. The vertebrae reach maximum size immediately superior to the sacrum, which transfers the weight to the pelvic girdle at the sac roiliac joints. The vertebral column is exible because it consists of many relatively small bones, called vertebrae (singular = vertebra ), that are separated by resilient IV discs (Fig. 2.2D). The 25 cer vical, thoracic, lumbar, and rst sacral vertebrae also articulate at synovial zygapophysial ( facet ) joints (see Fig. 2.5C), which facilitate and control the vertebral column’s exibility. Although the movement between two adjacent vertebrae is small, in ag gregate, the vertebrae and IV discs uniting them form a re markably exible yet rigid column that protects the spinal cord it surrounds.

The vertebral column in an adult typically consists of 33 vertebrae arranged in ve regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal (Fig. 2.2A–D). Signi - cant motion occurs only between the 25 superior verte brae. Of the 9 inferior vertebrae, the 5 sacral vertebrae are fused in adults to form the sacrum , and after approxi mately age 30, the 4 coccygeal vertebrae fuse to form the coccyx . The lumbosacral angle occurs at the junction of the long axes of the lumbar region of the vertebral col umn and sacrum (Fig. 2.2D). The vertebrae gradually be come larger as the column descends to the sacrum and then become progressively smaller toward the apex of the coccyx (Fig. 2.2A–D). The change in size is related to the

Copyright © 2027 Wolters Kluwer. Unauthorized reproduction of the article is prohibited.