Skeletal System THE SKELETAL SYSTEM INTRODUCTION The organs

Skeletal System

THE SKELETAL SYSTEM INTRODUCTION • The organs of the skeletal system include the bones and the structures that connect bones to other structures, including ligaments, tendons, and cartilages. • The adult skeleton is composed of 206 separate bones.

Bones of Skeleton. • Bony framework of the body is known as skeleton. • The human skeleton consists of 206 bones. • Upper limb - 64 ; Lower limb - 62 ; Vertebrae 33 ; Skull - 29 ; Ribs - 24 ; Sternum - 1. • (Skull-Facial -14, Cranial -14, Hyoid-1)

Division of skeleton – Axial skeleton – Includes the bones of: – Skull, vertebral column, and rib cage. – These bones are involved in protection, support, and carrying other body parts.

AXIAL SKELETON VERTEBRAL COLUMN • Divided into 5 main regions 1. Cervical spine (7) 2. Thoracic spine (12) 3. Lumbar spine (5) 4. Sacrum (5) 5. Coccyx (4)

Axial Skeleton.

Division of skeleton Appendicular skeleton Bones of upper & lower limbs and the girdles (shoulder bones and hip bones) that attach them to the axial skeleton. Involved in locomotion and manipulation of the environment.

Upper Limb • Clavicle • Scapula • Humerus • Radius • Ulna • Carpals • Metacarpals • Phalanges.

Lower Limb • Hip bone (Innominate bone) • Femur • Tibia • Fibula • Tarsal • Meta tarsal • Phalanges.

Classification of bones. • According to position. (Axial & Appendicular) • According to Size & Shape. • According to Gross structure. (Compact, Spongy, Diploic) • According to Development. (Membranous, Cartilaginous)

According to Size & Shape. • Long bones. E. g. - Humerus, Femur etc. • Short long bones. E. g. - Metacarpals, Phalanges etc. • Short bones. E. g. - Carpals, Tarsals. • Flat bones. E. g. - Scapula, Sternum etc. • Irregular bones. E. g. - Vertebrae, Some skull bones. • Pneumatic bones. E. g. - Ethmoid, Maxilla etc. • Sesamoid bones. E. g. - Patella, Pisiform.

Bone Classification 4 types of bones: Long Bones – ● ● ● Much longer than they are wide. All bones of the limbs except for the patella (kneecap), and the bones of the wrist and ankle. Consists of a shaft plus 2 expanded ends. Short Bones – ● ● Roughly cube shaped. Bones of the wrist and the ankle. Carpal Bones Femur

Types of bones: Flat Bones – ● ● Thin, flattened, and usually a bit curved. Scapulae, sternum, (shoulder blades), ribs and most bones of the skull. Sternum Irregular Bones – ● ● Have weird shapes that fit none of the 3 previous classes. Vertebrae, hip bones, 2 skull bones ( sphenoid and the ethmoid bones). Sphenoid Bone

Parts of long bone Diaphysis: main shaft like structure, its hollow cylindrical shape, its functions of providing strong support bone. Epiphysis: both end of long bone, epiphysis have a bulbous shape that provide generous space near joint. Metaphysis: is epiphysial end of Diaphysis.

Parts of long bone Articular cartilage : thin layer of hyaline cartilage that covers joint surface. Periosteum: dense white fibrous membrane that cover bone except at joint surface and anchoring bone to muscles. Marrow cavity: a tubelike hollow space in the diaphysis of long bone. Endosteum: a thin epithelial membrane that line the medullry cavity.

Parts of long bone

Composition of bone matrix Inorganic salts: the hardness of bone result from the deposition of high specialized chemical crystal of calcium and phosphorous called hydroxyapatite, the process called calcification in addition to mg, Na, sulphate and fluoride. Organic substance: collagenous fiber and mixture protein and poly saccarids called ground substance, provide support and adhesion between cellular and fiberous. ● Chondroitin and glucosamine are required for repair and maintenance of bone and cartilage.

This bone: a. Has been demineralized b. Has had its organic component removed

Microscopic Structure of Compact Bone ● ● Canaliculi—ultrasmall canals radiating in all directions from the lacunae and connecting them to each other and to the Haversian canal—extends lengthwise through the center of each osteon and contains blood vessels and lymphatic vessels

Blood supply of long bone Nutrient artery Periosteal artery Epiphysial artery Metaphysial aretry

Bone Marrow ● ● ● Specialized type of soft, diffuse connective tissue; called myeloid tissue Site for the production of blood cells Found in medullary cavities of long bones and in the spaces of spongy bone

Bone Marrow ● Two types of marrow are present during a person’s lifetime: – Red marrow ● ● – Found in virtually all bones in an infant’s or child’s body Functions to produce red blood cells Yellow marrow ● ● As an individual ages, red marrow is replaced by yellow marrow Marrow cells become saturated with fat and are no longer active in blood cell production

Functions of Bone ● ● ● Support—bones form the framework of the body and contribute to the shape, alignment, and positioning of the body parts Protection—bony “boxes” protect the delicate structures they enclose Movement—bones with their joints constitute levers that move as muscles contract Mineral storage—bones are the major reservoir for calcium, phosphorus, and other minerals Hematopoiesis—blood cell formation is carried out by myeloid tissue

Fracture Types – Open (compound) bone ends penetrate the skin. – Closed (simple) bone ends don’t penetrate the skin. – Spiral ragged break caused by excessive twisting forces. Sports injury/Injury of abuse – Greenstick bone breaks incompletely. One side bent, one side broken. Common in children whose bone contains more collagen and are less mineralized

● Osteomalacia – Literally “soft bones. ” – Includes many disorders in which osteoid is produced but inadequately mineralized. ● ● ● Causes can include insufficient dietary calcium Insufficient vitamin D fortification or insufficient exposure to sun light. Rickets – Children's form of osteomalacia – More detrimental due to the fact that their bones are still growing. – Signs include bowed legs, and deformities of the pelvis, ribs, and skull.

● Osteomyelitis – Inflammation of bone and bone marrow caused by pus-forming bacteria that enter the body via a wound (e. g. , compound fracture) or migrate from a nearby infection. – Fatal before the advent of antibiotics.