Chapter 5 Skeletal System Axial Skeleton Vertebral Column

Functions Surrounds/Protects spinal cord Provides attachment sites for – Ribs – Muscles of neck and back Axial support of the trunk (skull to pelvis) Discs absorb shock and provide flexibility

© 2015 Pearson Education, Inc. Vertebral Column (Spine) 26 single vertebral bones – 7 cervical vertebrae are in the neck – 12 thoracic vertebrae are in the chest region – 5 lumbar vertebrae are associated with the lower back REMEMBER: 7, 12, 5, 1/1 intervertebral discs separate vertebrae

© 2015 Pearson Education, Inc. Sacrum and Coccyx 9 vertebrae fuse to form two composite bones Sacrum formed by the fusion of 5 vertebrae Coccyx (tailbone) formed by the fusion of 3 to 5 vertebrae (most common to have 4 fuse)

Figure 5.16 The vertebral column. 1st lumbar vertebra Intervertebral foramen Intervertebral disc Spinous process Transverse process 1st thoracic vertebra 1st cervical vertebra (atlas) 2nd cervical vertebra (axis) Anterior Posterior Cervical curvature (concave) 7 vertebrae, C 1 – C 7 Thoracic curvature (convex) 12 vertebrae, T 1 – T 12 Lumbar curvature (concave) 5 vertebrae, L 1 – L 5 Sacral curvature (convex) 5 fused vertebrae Coccyx 4 fused vertebrae

© 2015 Pearson Education, Inc. Curvatures of the Sine Primary curvatures (present at birth) – Spinal curvatures of the thoracic and sacral regions – Present from birth – Form a C-shaped curvature as in newborns Secondary curvatures (form after birth) – Spinal curvatures of the cervical and lumbar regions – Develop after birth – Form an S-shaped curvature as in adults

Figure 5.17 The C-shaped spine typical of a newborn. Primary Curvature: C- Shaped Curvature of the Spine

Figure 5.18 Abnormal spinal curvatures. (a) Scoliosis(b) Kyphosis (c) Lordosis

© 2015 Pearson Education, Inc. Anatomy of a Vertebra Body (centrum) Vertebral arch – Pedicle – Lamina Vertebral foramen Transverse processes Spinous process Superior and inferior articular processes

Figure 5.19 A typical vertebra, superior view. Lamina Posterior Vertebral arch Transverse process Spinous process Vertebral foramen Body Anterior Pedicle Superior articular process and facet

Atlas and Axis- the neck region Atlas (C1) – No body – Large depressions to accommodate occipital condyles of the occipital bone Allows head to nod Axis (C2) – Dens (large process) provides pivot point for atlas – Allow head rotation when articulating with atlas

Figure 5.20a Regional characteristics of vertebrae. Transverse process (a) ATLAS AND AXIS Posterior arch Superior view of axis (C 2 ) Anterior arch Superior view of atlas (C 1 ) Transverse process Spinous process Dens Body Facet on superior articular process

Figure 5.20b Regional characteristics of vertebrae. (b) TYPICAL CERVICAL VERTEBRAE Right lateral view Spinous process Facet on superior articular process Vertebral foramen Transverse process Superior view Body Facet on inferior articular process Transverse process Superior articular process Spinous process Transverse foramina of cervical vertebrae are ONLY characteristics of cervical vertebrae

Figure 5.20c Regional characteristics of vertebrae. (c) THORACIC VERTEBRAE Right lateral view Transverse process Body Spinous process Facet for rib Vertebral foramen Facet on transverse process Spinous process Costal facet for rib Superior view process Facet on superior articular process Only vertebrae to articulate w/ribs

Figure 5.20d Regional characteristics of vertebrae. (d) LUMBAR VERTEBRAE Right lateral view Transverse process Vertebral foramen Facet on superior articular process Body Superior articular process Spinous process Facet on inferior articular process Superior view Spinous process Signature short spinous processes

Figure 5.21 Sacrum and coccyx, posterior view. Ala Sacrum Coccyx Sacral hiatus Posterior sacral foramina Median sacral crest Body Auricular surface Superior articular process Sacral canal