Support and Movement

• The branch of Science which deals with the study of human bone is called Osteology.
• 300 bones at birth and 206 in adults
• The major proportion of the bone is formed by Collagen fibers.
• Collagen is the Fibrous Protein.
• The terminal region of bone is called Epiphysis, Middle region is called Diphysis and in between middle and terminal region is the Metaphysis at both ends.
• The epiphysis is Cancellous or Spongy part of the bone.
• Epiphysis has small weight bearing cross linked regions called Trabeculae.
• Epiphysis is filled with Red bone marrow.
• The external part of Diphysis is called Cortical Bone.
• Cortical Bone forms 80% of the skeletal structure.
• Diphysis consist of many small cylinders known as Osteons.
• Each osteon is made up of many Lamellae.
• Lamellae are the concentric layers made of an Organic Part Collagen and the inorganic part called Hydroxyapatite.
• Hydroxyapatite is mostly Calcium phosphate.
• In the center of every Osteon is a Harversian Canal.
• Harversian Canal contains the blood supply and innervation of the bone cells.
• In the centre of the bone is the Medullary Canal, a hollow space lined by a honeycomb like structure.
• The overall outer covering of bone is called Periosteum.
• The inner layer of bone is Endosteum.
• Endosteum have Progenitor Stem cells.
• Progenitor stem cells develops into Osteoblast.
• Osteoblast secrets the Bone Matrix and the Chondroblast secrets Cartilage.
• Osteoblast is isolated by the surrounded matrix in the spaces called lacunae.
• Osteocytes are the mature cells that form bones.
• Osteocytes phagocytize the bony matrix.
• The outer layer of of cartilage is called Perichondrium.
• Cartilage get Nutrition by Diffusion.
• Between the ribs and sternum Hyaline Cartliage is present.
• Fibrocartliage is the hardest among all, present at intervertebral disc, Knee joint and Pectoral girdle.
• Elastic cartlage is the most flexible&strong located in the pinna of the ear, external and internal auditory tubes, epiglottis and larynx.
• Axial skeleton— 80 bones.
• Cranial bones—8.
• FOES— Single bones.
• Temporal and Parietal— In pairs.
• Auditory Ossicles ( Malleus, Incus) are the smallest bone present in the body.
• Non-articulated— Hyoid bone("U" shaped)—lies b/w skull and Postcranial skeleton.
• 34. 7-Cervical > 7Cer > Neck 12-Thoracic > 12Tho > Chest 5-Lumber > 5Lum > Abdominal region 1-Sacrum > 1Sac > form by 5 vertebrae 1-Coccyx > 1Coc > form by 4 vertebrae
• The first seven pairs of bones in the rib cage are called True Ribs 1-7.
• The remaining five pairs of bones in the rib cage are called False Ribs 8-12.
• The last two pairs of bones in the rib cage are called Floating ribs 11-12.