The skeletal system carries for about 20% of the body weight. Besides forming and gives shape to the body, the skeletal system perform other functions such as supporting soft organs of the body and produces movement of bones and muscles.
The most common ways of determining the sex of a skeleton is by looking at the size of the bones where males usually tend to have larger bones than females. One of the most considerable bones are the pelvis because the characteristics for both sex have large differences and easier to detect to especially the pubic arch where females has at least 90° or more wider while the males has less than 90°. Also, the pelvic cavity in the female is broad, oval and shallow while in the male, it is narrow, deep and funnel shape. The acetabulum, socket for articulation with head of femur[2], is normally smaller and farther apart in the female than male. Another helpful bone for sex determination is the skull. The males typically have squarer chin, and the frontal tends to be slanted back and in female it is likely to be more rounded[3].
The differences in male - female pelvis and skull
Research has shown that humans are born with 300 bones but the bones fuse together as human growing up[4] and an adults skeleton system consists of 206 bones. The process of bone formation is called ossicification. Three types of cells that are responsible for bone growth are the osteoblasts, osteocytes and osteoclasts. Osteoblast slowly change the shape to permanent bone and periosteum. Bone production begins first in the center of the bone and then in the ends. The final body fusion of all separate parts occurs sometime between puberty and the 25th year, ending the growth process[5]. The bone destruction is performed by osteoclasts.
Bone is made up from both living tissue and non-living materials. The two non-living materials are collagen fibers and crystalline salts. The crystalline salts composed of calcium and phosphate. Specifically, the collagen fibers have great tensile strength while the calcium salts have great compressional strength in which the combination of these two properties helps in strengthening the bones [6].
Broken bone or fractures usually may occur when a force exerted to the bone is stronger that the force the bone can resist. There are several factors that influence severity of bone fractures which is the degree and direction of the force, the particular bone involved, age and general health. Some of the bone fractures identified to be greenstick fracture, transverse fracture and oblique fracture. Greenstick, transverse and oblique fractures are fracture with small cracks normally often occurs in children, fracture in a straight line across the bone and fracture in which the break slopes, respectively.
Another bone problems that can occur is deformity that is typically a malalignment of the segment of a bone or joint. These malalignment refers to varus and valgus. Valgus deformity is the term used to describe the outward angulation of the segment of a bone or joint while varus deformity is the opposite (inward angulation). Taking knee for an example, varus deformity is considered to be quite destructive than valgus deformity because more stress and force is applied on the medial compartment of the knee[7] and there are possibilities of getting knee osteoarthritis.
REFERENCES
[1] Applegate, Edith. (2006). Skeletal System. In The Anatomy and Physiology Learning System Third Edition. Philadelphia : Elsevier Inc. pp. 101-106.
[2] Applegate, Edith. (2006). Skeletal System. In The Anatomy and Physiology Learning System Third Edition. Philadelphia : Elsevier Inc. pp. 105.
[3] Strachan, Dr. Richard A.. (Apr. 29, 2009). Sex Determination. Minnesota State University Mankato. January 10, 2010 <http://www.mnsu.edu/emuseum/biology/forensics/sex_determ.html>
[4] N.A. (2000). Skeletal System. Discovery Corporations Inc. January 10, 2010 <http://yucky.discovery.com/noflash/body/pg000124.html>
[5] Miller, Larry. (Dec. 9, 2007). We’re born with 270 bones. As Adults We Have 206. Groundreport.com. January 10, 2010 <http://www.groundreport.com/Health_and_Science/We-re-Born-With-270-Bones-As-Adults-We-Have-206/2846769>
[6] Morey-Holton, Emily. (2000). Bone Development and Structure. National Space Biomedical Research Institute. January 10, 2010.
[7] Eustice, Carold & Richard. (Oct. 2, 2008). What is varus and valgus knee deformity. About.com. January 10, 2010 <http://osteoarthritis.about.com/od/kneeosteoarthritis/a/varus_valgus.htm>
[8] Musculino, Dr. Joseph E. (2006). Kinesiology : The Skeletal System and Muscle Function. USA : MOSBY.
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