Biomedical Engineering Reference
In-Depth Information
generally across its “waist.” In some fractures the blood supply
of the proximal fragment may be compromised, resulting in
aseptic necrosis. The lunate is broader on the anterior than the
posterior side. Anterior dislocation of the lunate is a fairly com-
mon injury of the wrist.
• The metacarpals (10) consist of five pairs of bones that articulate
with the distal carpal bones forming the palm of the hand. The
carpus is connected to the phalanges by five metacarpal bones,
referred to collectively as the metacarpus. They are numbered
from one to five, from the thumb to the little finger. The first is
the shortest and the second the longest. They contribute to the
palm, and their posterior aspects can be felt under cover of the
extensor tendons. Each metacarpal is technically a long bone,
consisting of a base proximally, a shaft, and a head distally. The
base articulates with the carpus and, except for that of the first,
with the adjacent metacarpal(s) also. The base of the first meta-
carpal has a saddle-shaped facet for the trapezium. The head of
each metacarpal articulates with a proximal phalanx and forms
a knuckle of the fist.
• The phalanges (28) consist of 14 pairs of finger bones. Four fingers
contain three phalanges while the pollex (thumb) has only two.
They are designated proximal, middle, and distal. Each phalanx
is technically a long bone, consisting of a base proximally, a shaft,
and a head distally. The base of a proximal phalanx articulates
with the head of a metacarpal, and the head of the phalanx pres-
ents two condyles for the base of a middle phalanx. Similarly, the
head of a middle phalanx presents two condyles for the base of
a distal phalanx. Each distal phalanx ends in a rough expansion
termed its tuberosity. Sesamoid bones are found related to the
anterior aspects of some of the metacarpophalangeal and inter-
phalangeal joints. Two located anterior to the head of the first
metacarpal are almost constant.
• The pelvic girdle (2) articulates with the femur. The bony pelvis is
formed by the hip bones in front and at the sides and by the sacrum
and coccyx behind. The hip bone (also, innominate bone or coxal
bone) is a large, flattened, irregularly shaped bone, constricted in
the center and expanded above and below. It has one of the few
ball-and-socket synovial joints in the body: the hip joint.
• Lower limbs. The skeleton of the lower limb may be divided into
five main regions: the upper leg (thigh), the lower leg, the ankle, the
arch of the foot, and the toes. The upper leg has a single long bone,
the femur, which is the longest bone in the body. The two  bones
of the lower leg are the tibia (shinbone) in front and the fibula
behind.  The  tibia is the larger of the two and extends from the
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