Sacrum: part of both appendicular and axial skeleton - Narrow caudal portion is sacral apex, broad superior surface base - Sacral promontory: prominent bulge at anterior tip of base - superior articular processes form synovial with last lumbar , only on S1 - Sacral canal begins between those processes. Spinal nerve roots continue into sacrum through this canal. extends length of sacrum ending at sacral hiatus - Median sacral crest: series of elevations formed by fused sacral vertebra - Sacral Cornu: laminae of 5th sacral vertebra don’t contact each other at midline - Sacral foramina: on either side of median sacral crest - Ala: fused transverse processes “wing” - Auricular surface: articulates with auricular surface of innominate bone - Sacral tuberosity: attach here

Coccyx: -formed by 3-5(often 4) coccygeal vertebrae fusing together by 26 -Coccygeal cornu: prominent laminae of first coccygeal vertebrae, curves to meet cornua of sacrum. Males point anteriorly, females inferiorly

Thoracic Cage: -Made up of thoracic vertebrae, , and sternum -Protects heart, lungs, thymus, and other structures within thoracic cavity -Site of attachment for muscles involving respiration, position of the , and movements of the pectoral girdle and upper limbs

Ribs:(12 pairs) -originate on or between thoracic vertebrae, end in wall of thoracic cavity -First 7 pairs called true ribs(vertebrosternal ribs). At anterior body wall true ribs connect to sternum by separate cartilages called costal cartilages. 7th attaches to junction between body of sternum and xiphoid process -Beginning with first rib, ribs gradually increase in length and radius of curvature -Ribs 8-12 called false ribs (vertebrochondral ribs)don’t attach directly to sternum. Costal cartilages of ribs 8-12 fuse together before reaching sternum -Ribs 11 and 12 called floating ribs because they don’t connect with sternum -Head(capitulum) of rib articulates with body of a thoracic vertebra or between adjacent vertebral bodies. After short neck, tubercle projects dorsally which articulates with transverse process of vertebra. -Angle of rib indicates where body (shaft) begins curving towards sternum. Costal groove along internal inferior border marks path of blood vessels/nerves -Radiate -Costotransverse ligament -Lateral costotransverse ligament

Sternum: -Manubrium: articulates with clavicles, costal cartilages of 1st pair of ribs -Body: costal cartilages from ribs 2-7, as well as the costal margin -Xiphoid process: smallest part of sternum, attachment for muscles -Jugular notch(sternal notch): shallow indentation on superior surface of manubrium between clavicular articulations -Clavicular notch: clavicles sitting in clavicular notch deepens jugular notch -costal cartilages of ribs 2-7 attach directly to sternum -costal cartilages of ribs 8-12 form costal margin -Sternal angle: between manubrium and body. 2nd rib attaches here -Xiphisternal junction: Joint between body and xiphoid. 7th rib attaches here