that fits into the acetabulum. Two processes called the greater and lesser trochanters are at the proximal end for the attachment of muscles. The neck of the femur, located between the head and the trochanters, is the site on the femur most frequently fractured. At the distal end are two bony prominences, called the lateral and medial condyles, which articulate with the tibia and the patella. Patella.—The patella is a small oval-shaped bone overlying  the  knee  joint.  It  is  enclosed  within  the tendon of the quadriceps muscle of the thigh. Bones like the patella that develop within a tendon are known as sesamoid bones. Tibia.—The tibia, or shin bone, is the larger of the two leg bones and lies at the medial side. The proximal end articulates with the femur and the fibula. Its distal end articulates with the talus (one of the foot bones) and the fibula (fig. 1-25). A prominence easily felt on the  inner  aspect  of  the  ankle  is  called  the   medial malleolus. Fibula.—The  fibula,  the  smaller  of  the  two  leg bones, is located on the lateral side of the leg, parallel to the tibia. The prominence at the distal end forms the outer ankle and is known as the lateral malleolus. Tarsus.—The tarsus, or ankle, is formed by seven tarsal   bones:   medial   cuneiform,   intermediate cuneiform,  lateral  cuneiform,  cuboid,  navicular, talus, and calcaneus. The strongest of these is the heel bone, or calcaneus. Metatarsus.—The  sole  and  instep  of  the  foot  is called   the   metatarsus   and   is   made   up   of   five metatarsal   bones  (fig.  1-25).  They  are  similar  in arrangement to the metacarpals of the hand. Phalanges.—The phalanges are the bones of the toes   and   are   similar   in   number,   structure,   and arrangement to the bones of the fingers. JOINTS LEARNING OBJECTIVE:   Recognize joint classifications and identify joint movements for the key joints in the body. Wherever  two  or  more  bones  meet,  a  joint  is formed.  A  joint  binds  various  parts  of  the  skeletal system  together  and  enables  body  parts  to  move  in response to skeletal muscle contractions. JOINT CLASSIFICATIONS Joints  are  classified  according  to  the  amount  of movement they permit (fig. 1-26). Joint classifications are as follows: ·  Immovable. Bones of the skull are an example of   an   immovable   joint.   Immovable   joints   are characterized by the bones being in close contact with each other and little or no movement occurring between the bones. ·  Slightly  movable.    In  slightly  movable  joints, the bones are held together by broad flattened disks of cartilage and ligaments (e.g., vertebrae and symphysis pubis). 1-15 HM3f0125 METATARSUS TARSUS PHALANGES METATARSALS MEDIAL CUNEIFORM NAVICULAR TALUS TIBIA FIBULA CALCANEUS TALUS NAVICULAR CUBOID LATERAL CUNEIFORM INTERMEDIATE CUNEIFORM MEDIAL CUNEIFORM PROXIMAL PHALANX MIDDLE PHALANX DISTAL PHALANX TARSALS METATARSALS PHALANGES Figure 1-25.—The foot: A. Lateral view of foot; B. Right foot viewed from above.