THE HUMAN ORGANISM 293 



Supporting organs Motor system 



Skeleton Striped muscles of skeleton 



Bones Striped muscles of heart 



Ligaments Unstriped muscles 



Cartilage 

 Connective tissue 

 4. The vertebrate skeleton 



Comparison with invertebrate skeletons 

 Internal 



Consists of living tissue (capable of growth and repair) 

 Functions 



General framework 

 Protection for delicate organs 

 Brain box 

 Eye sockets 

 Thoracic cage 

 Pelvic basket 

 Levers for muscle action (nearly all bones) 

 Composition 

 Bones 

 Ligaments 

 Cartilage 

 Connections of bones 



Fusions (sacral vertebrae ; pelvic bones ; pelvis and sacrum) 

 Articulated (all movable joints) 



Unjointed attachments (pads between vertebrae ; cartilages of 

 ribs) 

 Arrangement of parts 

 Main axis 

 Vertebrae 

 Cervical 

 Thoracic 

 Lumbar 

 Sacral 



Coccygeal ("tail") 

 Ribs 



(In thoracic region among higher vertebrates) 

 (Indefinite in number among lower vertebrates) 

 (Absent in frog) 

 Sternum 



