A bone is a rigid organ that constitutes part of the vertebrate skeleton. Bones support and protect the various organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility.
Types of bone
Flat bones are as they sound, strong, flat plates of bone with the main function of providing protection to the bodies vital organs and being a base for muscular attachment. The classic example of a flat bone is the Scapula (shoulder blade). The Sternum (breast bone), Cranium (skull), os coxae (hip bone) Pelvis and Ribs are also classified as flat bones. Anterior and posterior surfaces are formed of compact bone to provide strength for protection with the centre consisiting of cancellous (spongy) bone and varying amounts of bone marrow. In adults, the highest number of red blood cells are formed in flat bones. Flat bones are bones whose principal function is either extensive protection or the provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates, as in the cranium (skull), the ilium (pelvis), sternum and the rib cage
These bones typically have an elongated shaft and two expanded ends one on either side of the shaft. The shaft is known as diaphysis and the ends are called epiphyses. Normally the epiphyses are smooth and articular. Long bones are some of the longest bones in the body, such as the Femur, Humerus and Tibia but are also some of the smallest including the Metacarpals, Metatarsals and Phalanges. The classification of a long bone includes having a body which is longer than it is wide, with growth plates (epiphysis) at either end, having a hard outer surface of compact bone and a spongy inner known an callousness bone containing bone marrow. Both ends of the bone are covered in hyaline cartilage to help protect the bone and aid shock absorbtion.
Short bones are about as long as they are wide. Located in the wrist and ankle joints, short bones provide stability and some movement. The carpals in the wrist (scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium) and the tarsals in the ankles (calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, and medial cuneiform) are examples of short bones.
These bones are short in posture and can be of any shape. Most of them a
re named according to their shape. Examples of this class of bones include cuboid, cuneiform, scaphoid, trapezoid etc. In fact all the carpal and tarsal bones are included in this category.
The shape of these bones is completely irregular and they do not fit into any category of shape. Examples of this type of bones are vertebrae, hip bone and bones in the base of skull. Irregular bones vary in shape and structure and therefore do not fit into any other category (flat, short, long, or sesamoid). They often have a fairly complex shape, which helps protect internal organs. For example, the vertebrae, irregular bones of the vertebral column, protect the spinal cord. The irregular bones of the pelvis (pubis, ilium, and ischium) protect organs in the pelvic cavity.
In anatomy, a sesamoid bone (/ˈsɛsəmɔɪd/) is a boneembedded within a tendon or a muscle. It is derived from the Latin word “sesamum” (sesame seed), due to the small size of most sesamoids. Often, these bones form in response to strain. These are not like the other types of bones because they are in the form of nodules embedded in tendons and joint capsules. They do not possess any periosteum and their ossification also takes place after birth. Examples of this type of bones are patella, pisiform and fabella.
Basis development bone
A dermal bone or membrane bone is a bony structure derived from intramembranous ossification forming components of the vertebrate skeleton including much of the skull, jaws, gill covers, shoulder girdle and fin spines rays (lepidotrichia), and the shell (of tortoises and turtles). These are also known as dermal bones and the process by which they ossify is called intra-membranous ossification. These bones ossify from mesenchymal condensations in the intrauterine life. Examples are bones of the skull and facial bones.
These bones ossify from a cartilage model and this type of ossification is known as intra- cartilaginous ossification. These bones do not form from mesenchymal condensations but from preformed cartilage models. Examples of this type of bones include bones of limbs, vertebral column and thoracic cage. Cartilaginous joint. Cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline). Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint
These bones ossify partly from cartilage and partly from mesenchymal condensations. Examples of this class of bones include clavicle, mandible, occipital, temporal and sphenoid etc.