Biomedical Engineering Reference
In-Depth Information
1.2.2
Structure of the Body
The bones of vertebrates compose the internal skeleton of these organisms. Bones
are divisible into four classes: long, short, flat, and irregular. The number of bones
in the organism is variable and depends on the age.
There are 206 bones in the adult human body and about 270 in an infant. A
human adult skeleton consists of the following distinct bones: skull (22): cranium
(8), face (14); spine and vertebral column (26), hyoid bone, sternum and ribs (26),
upper extremities (64), lower extremities (62), and auditory ossicles (6). The patellae
are included in this enumeration, but the smaller sesamoid bones are not taken
into account, cf. [66, 71-73, 77].
In particular, the metatarsal bones are a group of five long bones in the foot that
are located between the tarsal bones of the hind- and mid-foot and the phalanges
of the toes, see Figure 1.8. The metatarsal bones are numbered from the medial
side (side of the big toe): the first, second, third, fourth, and fifth metatarsal.
The metatarsals are analogous to the metacarpal bones of the hand. In human
anatomy, the metacarpus is the intermediate part of the hand skeleton that is
located between the phalanges (bones of the fingers) distally and the carpus, which
forms the connection to the forearm.
The bone fulfills three essential roles in the organism:
•
Mechanical (constructional) - being a scaffold of the body and being responsible
together with skeletal muscles for the movement and locomotion of the organism;
•
protective - shielding internal organs against external hurts;
•
metabolic - hematopoietic processes of blood production by red and yellow
marrow, within the medullary cavity of long bones and interstices of cancellous
bone, storage of fat as yellow bone marrow, storage of minerals such as calcium
and phosphorus, assuring acid-base balance by absorbing or releasing alkaline
salts, necessary for holding the ionic homeostasis in the organism.
Second
cun
Talus
Third
cunelf
Cuboid
Calcaneus
Figure 1.8
Skeleton of human foot with metatarsus, in lateral aspect. After [63].
