Which of the following bones has no medullary cavity -
Ans 'b' i.e., Clavicle CLASSIFICATION OF BONESA ACCORDING TO SH APEI. Long bones : Each long bone has a shaft (diaphysis) and 2 expanded ends (epiphysis) wich are smooth and articular. The shaft has a nutrient foramen directed away from the growing end.Typical long bones : Humerus, femurMiniature long bones : Metacarpals, phalangesModified long bones : Have no medullary cavity. Eg. Clavicle and body of vertebraII Short bones : Carpals and tarsalsIII Flat bones : cranial bones, ribs, sternum, scapulaIV Irregular bones : Vertebrae, hip bone, bones in the base of the skullV. Pneumatic bones : maxilla, sphenoid, ethmoidVI Sesamoid bones : Found embedded in tendons and capsules. They have no periosteum and ossify- after birth. Eg. Patella, pisiform, fabellaB. DEVELOPMENTAL CLASSIFICATIONI Membrane bones (Intramembranous or mesenchymal ossification)o Bones of the skull vault and facial boneso A defect in membranous ossification causes a syndrome called cleidocranial dysostosis, characterized by :Varying degrees of aplasia of claviclesIncrease in transverse diameter of craniumRetardation in fontanelle ossificationII Cartilaginous bones (Enchondral ossification)o They are derived from preformes cartilaginous models,o Bones of limbs, vertebral column, thoracic cage,o A defect in enchondral ossification causes achondroplasia.III. Membrano - cartilaginous boneso They ossify- partly in membrane and partly in cartilage,o Clavicle, mandible, sphenoidC. STRUCTURAL CLASSIFICATIONI. Compact boneo Dense but extremely porouso Best developed in the cortex of the long boneso It is an adaption to bending and twisting forcesII Cancellous/trabecular boneo Made up of a meshwork of trabeculaeo It is an adaption to compressive forcesD. MICROSCOPIC CLASSIFICATIONI Lamellar bone : most of the human bonesII Fibrous bones : young fetal bonesIII DentineIV Cement : occurs in teeth
Ulna
Clavicle
Fibula
Humerus
Cartilage and Bone