Figure 3-20.Forearm and hand.
site of fractures; the shaft, which is the main part
of the humerus; and the distal end, which includes
the prominences called epicondyles and the sur-
faces that articulate with the bones of the forearm.
When the arm is in the anatomical position
with the palm turned forward, the RADIUS is on
the lateral, or thumb, side and the ULNA is on
the medial, or little finger, side of the forearm.
When the hand is pronated (palm turned
downward), the bones rotate on each other and
cross in the middle. This makes it possible to turn
the wrist and hand as in opening doors. The ulna
and the radius articulate at their proximal ends
with the humerus, at their distal ends with some
of the carpal bones, and with each other at both
There are eight CARPAL bones, arranged in
two rows, forming the wrist.
The METACARPAL bones are numbered
one to five corresponding with the five fingers,
or digits, with which they articulate. The fingers
are named as follows: 1st - thumb; 2nd - index;
3rd - middle; 4th - ring; and 5th - little.
The small bones of the fingers are called
PHALANGES, and each one of these bones is
called a PHALANX. Each finger has three
phalanges, except the thumb which has two. The
phalanges are named for their anatomical posi-
ion proximal phalanx is the bone closest to the
hand; the distal phalanx is the bone at the end
of the finger; and the middle phalanx, the bone
located between the proximal and distal
LOWER EXTREMITY. The lower extrem-
ity includes the bones of the hip, thigh, leg, ankle,