Chapter 7, Part 2 Axial Skeleton Spine and Ribcage

Posterior Anterior Posterior arch 7 cervical of atlas (C1) vertebrae Fig. 7.28 Posterior Anterior Posterior arch of atlas (C1) 7 cervical vertebrae (C1–C7) C1 2 3 4 Cervical curvature Vertebra prominens (C7) 5 6 7 T1 2 3 Transverse process 4 5 12 thoracic vertebrae (T1–T12) 6 7 8 Body Thoracic curvature 9 10 11 12

(4 fused coccygeal vertebrae) Fig. 7.28 L1 5 lumbar vertebrae (L1–L5) 2 3 Lumbar curvature 4 5 Sacrum (5 fused sacral vertebrae) (S1–S5) S1 2 Sacral curvature 3 4 5 Coccyx (4 fused coccygeal vertebrae) (Co1–Co4)

(4 fused coccygeal vertebrae) Fig. 7.28 Primary curves form during fetal development: thoracic sacral Secondary curves appear after birth: cervical curve—3-4 mos. (baby can hold head up) lumbar—1 year (learning to stand and walk) Posterior Anterior Posterior arch of atlas (C1) C1 2 3 4 Cervical curvature 5 Vertebra prominens (C7) 6 7 T1 2 3 Transverse process 4 5 6 7 8 Body Thoracic curvature 9 10 11 Intervertebral foramen 12 L1 Spinous process 2 3 Lumbar curvature 4 5 S1 2 Sacral curvature 3 4 5 Coccyx (4 fused coccygeal vertebrae) (Co1–Co4) (a) Anterior view (b) Right lateral view

Kyphosis (“hunchback”) Lordosis (“swayback”) Scoliosis Often results from osteoporosis, or vertebral compression fractures Lordosis (“swayback”) May be caused by osteoporosis, vertebral compression fractures, or added abdominal weight Scoliosis Most common curvature deformity; caused by abnormal formation of vertebral arch and/or body on one side

Fig. 7.29 – Basic vertebral anatomy Spinous process Transverse process Superior articular facet Lamina Vertebral arch Superior articular process Pedicle Vertebral foramen Spinal cord location Body (a) Superior view

Fig. 7.29 – Basic vertebral anatomy Body Transverse process Superior articular facet Intervertebral disc L3 Inferior articular process of L3 Superior articular process of L4 L4 Lamina Inferior articular process of L4 Spinous process (b) Posterior view

Fig. 7.29 – Basic vertebral anatomy Superior articular process of L1 Body Pedicle L1 Intervertebral foramen Intervertebral disc Transverse process L2 Spinous process Spinal nerve location L3 Inferior articular process of L3 Inferior articular facet (c) Lateral view

Discs together make ~1/4 of column Shock absorbers Anulus fibrosus fibrocartilage Nucleus pulposus gelatinous (high water content) Discs together make ~1/4 of column Shock absorbers Compressed while standing/walking Stretch back while sleeping (or doing yoga or Pilates) Anulus fibrosus Nucleus pulposus Herniated disc Pinched left nerve roots Normal right nerve roots Superior view of a herniated disc.

Table 7.5a-5 Cervical Vertebrae

Enables you to nod your head Fig. 7.30 Anterior arch Atlas (C1) Anterior tubercle Named for Atlas, titan condemned by Zeus to hold the heavens on his shoulders Enables you to nod your head Superior articular facet Transverse process Transverse foramen Posterior tubercle Posterior arch

Enables you to turn your head side to side Fig. 7.30 Anterior Axis (C2) Dens Superior articular facet Transverse foramen Body Transverse process Pedicle Lamina Enables you to turn your head side to side Spinous process (bifid) Posterior

Atlas and axis Axis of rotation Atlas (C1 vertebra) Fig. 7.30 Atlas and axis Axis of rotation Atlas (C1 vertebra) Articular facet for dens Dens Transverse ligament Axis (C2 vertebra)

Axis (C2) "C2 from top animation small" by Anatomography "Cervical vertebra 2 close-up top animation" by Anatomography

X-ray of Axis with dens visible "Dens axis" by Hellerhoff - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Dens_axis.jpg#/media/File:Dens_axis.jpg

Table 7.5a-1, Cervical Vertebrae Superior articular facet Transverse process Body Transverse foramen Transverse foramen Superior articular facet Spinal cord location Body Bifid spinous process Bifid spinous process Inferior articular facet

Cervical Vertebra Body shaped like kidney bean No costal articulation for ribs Spinous process is bifurcated (bifid) Small transverse processes Transverse foramen present – provide passage for arteries and veins to head C7, vertebra prominens, can be felt at base of neck

Cervical vertebra looks like a fish face

Table 7.5a-6

Table 7.5a-2: Thoracic vertebrae Superior articular facet Body Costal facet Costal facet Costal facet Superior articular facet Body Transverse process Spinous process Inferior articular facet Costal demifacet Spinous process

Table 7.5a-2: Thoracic vertebrae Body shaped like heart Costal facets for ribs present articulate with head or tubercle of rib T11 and T12 lack costal facets on transverse processes Costal demifacet articulate with edge of head of rib No transverse foramen Long, slender spinous process

Thoracic vertebra looks like a giraffe head

Table 7.5b-3 Lumbar Vertebrae

Table 7.5b-1 Lumbar Vertebra Transverse process Body Body Spinous process Superior articular facet Transverse process Inferior articular facet Spinous process

Table 7.5b-1 Lumbar Vertebra Body shaped like oval or circle No costal facets for ribs present No transverse foramen Large, blunt transverse process Short, blunt spinous process

Lumbar vertebra looks like a moose head OsteoMenagerie images from BoneBrokeBlog.wordpress.com

Fig. 7.31 Sacrum and coccyx Base anterior view Superior articular process Ala Promontory S1 S2 Anterior sacral foramina S3 Transverse ridges S4 Apex S5 Co1 Co2 Co3 Co4

Fig. 7.31 Sacrum and coccyx posterior view Sacral canal Superior articular facet Median sacral crest Auricular surface Posterior sacral foramina Sacral hiatus Sacral cornu Coccygeal cornu Coccyx

Sacrum Apex is narrow, pointed portion (inferior) Superior end called base 5 vertebrae fused transverse ridges at horizontal lines of fusion superior articular processes at base articulate with L5 vertebral canal continues through sacral canal terminates in sacral hiatus anterior and posterior sacral foramina for nerves to pelvic organs sacral hiatus

Coccyx 4 fused vertebrae In males, coccyx tilts anteriorly begin to fuse by age 25 In males, coccyx tilts anteriorly In females, coccyx tilts inferiorly In old age coccyx may fuse with sacrum

Manubrium Suprasternal notch 1 Clavicular notch Costal notch 2 Fig. 7.32 Thoracic Cage Manubrium Suprasternal notch 1 Clavicular notch Costal notch 2 Sternal angle True ribs (1–7) 3 Body Sternum 4 Costal notch 5 6 Xiphoid process 7 8 T12 Costal cartilages False ribs (8–12) 9 12 L1 10 Floating ribs (11–12) 11

Sternum 3 parts Clavicular notches are articulations with clavicles Manubrium 3 parts Clavicular notches are articulations with clavicles Suprasternal notch is between clavicular notches Costal notches are articulations with ribs Rib 1 articulates with manubrium Rib 2 articulates at sternal angle Ribs 3-7 articulate with body of sternum Xiphoid process may not ossify until age 40 Sternal angle Body Costal notches Sternal foramen Xiphoid process

Fig. 7.33 Ribs Head Neck Crest Tubercle Superior Angle Articular facets for vertebral bodies Inferior Articular facet for transverse process Junction with costal cartilage Costal groove Shaft (a) Rib

T6 Ribs originate on or between thoracic vertebrae Fig. 7.33 Ribs originate on or between thoracic vertebrae Vertebral end of rib articulates with head of rib Head has superior and inferior articular facets articulate with costal facets on vertebrae Tubercle of rib articulates with costal facet on transverse process of rib Costal facet for rib 6 Costal facet Rib 6 Tubercle Neck Costal demifacet for rib 6 Head T6 (b) Superior view

Fig. 7.32 Thoracic Cage 1 Ribs 1-7 are true ribs: articulate individually with sternum by separate costal cartilages Ribs 8-12 are false ribs: costal cartilages don’t attach to sternum Ribs 8-10: costal cartilages fuse with costal cartilage of Rib 7 Ribs 11-12: no connection with sternum, so called floating ribs 2 True ribs (1–7) 3 4 5 6 7 8 T12 False ribs (8–12) 9 12 L1 10 Floating ribs (11–12) 11

Fig. 7.34 Parietal bones Frontal bones Occipital bone Zygomatic bone Copyright © McGraw-Hill Education. Permission required for reproduction or display. Parietal bones Frontal bones Occipital bone Zygomatic bone Temporal bone Maxilla Vertebrae Nasal bone Mandible Clavicle Sternum Scapula Carpal bones Humerus Metacarpal bones Ribs Phalanges Radius Ulna Femur Ilium Tibia Sacrum Fibula Coccyx Phalanges Tarsal bones Metatarsal bones Hyaline cartilage Endochondral ossification center Intramembranous ossification center

Fig. 7.35 Fetal development of sternum Copyright © McGraw-Hill Education. Permission required for reproduction or display. Sternal bars 8 weeks 9 weeks