The PELVIS is the basin-shaped cavity which forms the lowest portion of the trunk; and contains the bladder, the internal organs of generation, part of the intestines, and several great blood-vessels and nerves. The pelvis is composed of four bones—_2 Innominate or haunch-bones._ _1 Sacrum or rump-bone._ _1 Coccyx._ The INNOMINATE or haunch-bones, with the lower portion of spine (sacrum and coccyx), form the lowest portion of the trunk. The innominate bones on their outer surfaces have cup-like depressions for the reception of the heads of the thigh-bones. The SHOULDER is formed by the _clavicle_ or _collar-bone_ and _scapula_ or _blade-bone_. The CLAVICLE, or collar-bone, has a double curve; it marks the line dividing the neck and chest. The SCAPULA, or blade-bone, lies on the back of the chest, is of a triangular shape, and forms the socket for the humerus or arm-bone. The UPPER LIMB comprises—1 _Humerus_, arm-bone. 2 _Radius and Ulna_, fore-arm. 8 _Carpus_, wrist. _Metacarpus_, palm. _Phalanges_, finger-bones. The HUMERUS, or bone of upper arm, extends from the shoulder to the elbow; above, it is joined to the scapula, and below to the bones of fore-arm. The ULNA is the larger bone of the fore-arm, lies on the inside, and extends from elbow to wrist. The RADIUS lies on the outside of the fore-arm. The CARPUS is a double row of small bones which help to form the wrist-joint. The METACARPUS consists of five bones, and forms the body of the hand. The PHALANGES are the fourteen finger-bones. The LOWER LIMB is composed as follows:—1 _Femur_, thigh-bone. 1 _Patella_, knee-cap. 2 _Tibia and Fibula_, leg-bones. 7 _Tarsus_, ankle-bones. 5 _Metatarsus_, instep-bones. 14 _Phalanges_, toe-bones. The HIP joint is a ball-socket joint, and is somewhat similar to the joint at the shoulder. The FEMUR, or thigh-bone, extends from hip to knee joint, both of which joins it helps to form. The PATELLA (_knee-cap_) is the small oval bone which forms the prominent point of knee. The KNEE JOINT is formed by the lower end of femur, the patella, and the upper end of the tibia. The TIBIA is the main bone of the leg, and extends from knee to ankle, on the inside of the limb. The FIBULA is the small bone on the outside of the limb: the lower ends of the tibia and fibula form prominent projections at the sides of the ankle. The TARSUS, ankle-bones, are seven irregular shaped bones, firmly united together; above they are attached to the tibia and fibula, and in front to the metatarsus. The METATARSUS forms the instep, and together with the tarsus the arch of the foot. The PHALANGES, bones of the toes, are fourteen in number, two for the great toe, and three for each of the others. These bones are liable to be broken, dislocated, or fractured by violence. Fractures or broken bones, they are usually divided into four classes, which are termed— 1.—Simple fracture, a simple break.