THE BONY FRAMEWORK 29 



Counting from the neck, the first seven pairs are called 

 the true ribs. They are all joined directly to the breastbone. 



The five lower pairs, known as the false ribs, are not joined 

 to the breastbone at all. Cartilages connect the first three 

 of them with each other, and with the last of the true ribs. 



The lowest two pairs of ribs are often known as the float- 

 ing ribs, because they are not even joined by cartilages, but 

 are quite free in front. 



45. The Hips and the Pelvis. The lower part of the 

 trunk is formed by two large, irregular bones, very firm 

 and strong, called the hip, or haunch bones. They are 

 joined to the sacrum behind, and to each other in front. 



The two hip bones, with the sacrum and coccyx, form a 

 kind of bony basin called the pelvis, which contains and 

 protects several important organs. 



Each hip bone has a cup-shaped cavity on its side, into 

 which the rounded head of the thigh bone fits. It is called 

 the acetabulum, meaning vinegar cup, because it has the 

 shape of the vinegar caps used by the Romans. 



THE BONES OF THE UPPER LIMBS 



46. The Bones of the Upper Limbs. Each of the upper 

 limbs consists of the shoulder, arm, forearm, and hand. 



The thirty-two bones of each upper limb are usually 



classified as follows. 



f Scapula, or shoulder blade 

 Shoulder | clavicle> or collar bone 



Arm Humerus, or arm bone 



{ Ulna 

 Forearm | Radius 



8 Carpal, or wrist bones 

 Hand \ 5 Metacarpal bones 



14 Phalanges, or finger bones 



