General Osteology PDF

General Osteology By Dr. Osama Abdel Mohsen Osteology: It is the science dealing with the study of bones The skeleton is applied to the framework of hard structures which supports and protects the soft tissues of animal....

General Osteology By Dr. Osama Abdel Mohsen Osteology: It is the science dealing with the study of bones The skeleton is applied to the framework of hard structures which supports and protects the soft tissues of animal. it is usually restricted to the bones and cartilages + may be ligaments. The skeleton  The skeleton Skeleton Endoskeleton Exoskeleton  is embedded in the soft  Situated externally as the scales of fishes, the shell tissues. of turtles, feathers, hair  It is derived chiefly and hoofs of the higher from the mesoderm vertebrates.  It is derived from the ectoderm  The skeleton Endoskeleton Axial Appendicular Splanchnic  comprises the  includes  consists of certain vertebral the bones bones developed in column, ribs, of the the viscera or soft sternum, and limbs organs, skull  the os penis of the dog  the os cordis of ox  os diaphragmaticus in camel The skeleton  Classes of the bones The bones are commonly divided into four classes according to their shape and function into:- 1. Long bones. 2. Short bones 3. Flat bones 4. Irregular bones.  1) Long bones It is elongated cylindrical form with enlarged 2 extremities (proximal and distal). The body is tubular and contain the medullary cavity, which contains the medulla or marrow They occur in the limbs, where they act as supporting columns and as levers. e.g. Humerus and femur.  2) Short bones It has similar dimensions in length, breadth, and thickness. Their chief function appears to be that of diffusing concussion. e.g. carpus and tarsus. Sesamoid bones Are developed in the capsules of some joints or in tendons, may be included in this group. They diminish friction or change the direction of tendon. e.g. Patella, Fabellae, Navicular (Horse) Equine left Equine left Palmar sesmoids Thoracic limb Pelvic limb Lateral view Palmar view Equine left metatarsus Cross-section, Dorsal view  3) Flat bones are expanded in two directions. They furnish sufficient area for the attachment of muscles and afford protection to the organs which they cover as brain, lung, heart. e.g. scapula, ribs and bones of the skull.  4) Irregular bones It is irregular in shape, they are median and unpaired. Their functions are various and not so clearly specialized as those of the preceding classes. e.g. vertebrae and the bones of the cranial base  Classes of the bones Specialized bones Develop in soft organs Examples: os penis (dog and cat) and ossa cordis in the heart of ruminants Lateral view Canine os penis Dorsal view  Classes of the bones Specialized bones Pneumatic Bones  Bones which are excavated to provide air spaces  Examples: paranasal sinus of mammals, bird skeleton  Pneumatic Bones Frontal Sinus Structure of the bones  the bone consists of an external shell of dense compact substance, within which is the more loosely arranged spongy substance.  In long bone, the shaft is hollowed to form the medullary cavity. 1) The compact substance differs greatly in thickness in various situations, in conformity with the stresses and strains to which the bone is subjected. In the long bones it is thickest in the middle part of the shaft and thins out toward the extremities. Structure of the bones 2) The spongy substance ( Cancellous bone ), consists of delicate bony plates and spicules which run in various directions and intercross. These plates are definitely arranged with regard to mechanical requirements.  The intervals (marrow spaces) between the plates are occupied by marrow.  It forms the bulk of short bones and of the extremities of long bones ; in the latter it is not confined to the ends, but extends a variable distance along the shaft also Structure of the bones  In certain situations the two compact layers of flat bones are not separated by spongy bone, but fuse with each other. Or may be a variable amount of spongy bone, here termed diploe.  Structure of the bones 3) The periosteum is the membrane which invests the outer surface of bone, except where it is covered with cartilage. It consists of : 1. outer protective fibrous layer, It varies much in thickness, being in general thickest in exposed situations. 2. inner cellular osteogenic layer. During active growth the osteogenic layer is well developed, but later it becomes much reduced. It rich by osteoblasts in growth phase that share in mineralization of organic matrix. The adhesion of the periosteum to the bone also differs greatly in various places; it is usually very thin and easily detached where it is thickly covered with muscular tissue which has little or no attachment. The degree of vascularity conforms to the activity of the periosteum.  Structure of the bones Function of the periostium:- 1. increase the diameter of the bone. 2. healing the fracture. 3. Route for nerves and vessels.  Structure of the bones 4) The Endosteum is the lining membrane to the bone surface that face the medullary cavity and also the trabeculae of the spongy bone. 5) The marrow:- It is the site of blood cells production.  occupies the interstices of the spongy bone and the medullary cavity of the long bones. There are two varieties;  in the adult, red and yellow types.  In the young subject there is only red marrow, but later this is replaced in the medullary cavity by yellow marrow.  The red marrow contains several types of characteristic cells and is a blood-forming substance, while the yellow is practically ordinary adipose tissue. Longtudinal section through a mature equine tibia Medullary cavity  Spongy Bone Hyaline Cartilage  Equine Right Tibiae, Caudal View Epiphysis Metaphysis Long bones – 3 primary ossification centers (1 diaphysis and 2 epiphyses) – has 2 extremities ( Diaphysis proximal and distal) and body in between. – Example: Humerus, Femur Metaphysis Epiphysis Nutrient Foramen  Blood supply to bones  5% to 10% of the cardiac output  Large nutrient arteries enter through nutrient foramina then branch into numerous smaller blood vessels which follow complex paths through the bone.  There are two sets of arteries, the periosteal and the medullary (nutrient artery). 1. The periosteal arteries :  ramify in the periosteum and give off in numerable small branches which enter minute openings (Volkmann's canals) on the surface and reach the Haversian canals of the compact substance. Other branches enter the extremities of the long bones and supply the spongy bone and marrow in them. 2. Medullary (nutrient arteries).  enters at the so-called nutrient foramen, passes in a nutrient canal through the compact substance, and ramifies in the marrow; its branches anastomose with the central branches of the periosteal set. 3- Epiphyseal arteries: enter the bone at the epiphysis. 4- Metaphyseal arteries: enter the bone at the metaphysis. 5- larger veins of the spongy bone do not, as a rule, accompany the arteries, but emerge chiefly near the articular surfaces. 6- The lymph-vessels form perivascular channels in the periosteum and the Haversian canals of the compact substance. Lymph-spaces exist at the periphery of the marrow. B) The nerves appear to be distributed chiefly to the blood-vessels. Special nerve-endings in the periosteum are to be regarded as Sensory.  Structure of the bones CHEMICAL COMPOSITION OF BONE  Bone consists of 25% water, 45% minerals(37% Ca and 18.5% phosphorus) and 30% organic matters  Dried bone consists of organic and inorganic matter in the ratio of 1 : 2  Organic matter is responsible for elasticity while inorganic matter is responsible for hardness.  The bone is composed of gelatin, lime phosphate, lime carbonate, magnesium phosphate, sodium carbonate, sodium chloride. Structure of the bones Physical characters of bones 1) Colour: - yellowish white in fresh dead bone. - white when boiled and bleached. 2) Specific gravity of fresh compact bone 1.9 3) The bone is very hard and resistant to pressure.  Terminology of the bones Terms of the bones Articular Non-articular Projections Depressions Projections Depressions Head Glenoid cavity process fossa Condyle Cotyloid cavity eminence fovea Trochlea Facet epicondyle sulcus trochonter sinus tuberosity fissure tubecle canal ridge  Shoulder (Scapula) Shoulder joint Bones of the Arm (Humerus) forelimb Elbow joint Fore arm (Radius & ulna) Carpal joint Manus (Carpus, metacarpus, digits) Thank You