THE SKELETAL SYSTEM

The Skeletal System  The skeleton is a framework of bones held together by _________ to form movable _________. There are 206 bones in the adult skeleton.

Functions  The skeletal system has 5 main functions Framework – the skeleton gives our body its shape Framework – the skeleton gives our body its shape Movement – the bones are leavers upon which muscles pull Movement – the bones are leavers upon which muscles pull Protection – the skeleton protects vital organs Protection – the skeleton protects vital organs Blood cell formation – the long bones contains bone marrow which produces all red blood cells and some white blood cells Blood cell formation – the long bones contains bone marrow which produces all red blood cells and some white blood cells Storage – the skeleton stores mineral salts, especially calcium Storage – the skeleton stores mineral salts, especially calcium

SKELETAL DIVISIONS APPENDICULAR – 126 BONES APPENDICULAR – 126 BONES EXTREMETIES,SHOULDER GIRDLE, PELVIS AXIAL – 74 ( SKULL, VERTEBRAE, RIBS) - 6 ( AUDITORY OSSICLES)

COMPACT VS. SPONGY 2 MAIN TYPES OF BONE COMPACT: Regions of high stress SPONGY : Light weight, ‘ mesh’, bone marrow, low stress ( skull)

BONE STRUCTURE 3 MAIN CELLS Osteocytes: Osteocytes: mature bone cells Osteoblasts: Osteoblasts: build and repair bone Osteoclasts: Osteoclasts: help reshape in response to stress.

BONE GROWTH INTRAMEMBRANOUS OSSIFICATION - - Osteoblasts secrete bone matrix and trap osteocytes - - Appearance is spongy bone, compact bone develops ENDOCHONDRAL OSSIFICATION - - Cartilage models form and replaced by bone tissue. - - Formation begins in the middle of the diaphysis( shaft) and continues to the epiphyseal regions ( end of bones)

CATEGORIES OF BONE ( BASED ON SHAPE p. 35)

Diet: Vitamin A: important for bone growth: Vitamin A: important for bone growth: Milk fat, egg yolks, dark green / yellow vegetables;Milk fat, egg yolks, dark green / yellow vegetables; Vitamin C: important for collagen giving bones strength: Vitamin C: important for collagen giving bones strength: Citrus fruits;Citrus fruits; Vitamin D: Promotes calcium absorption: Vitamin D: Promotes calcium absorption: Milk, Fish-liver oils;Milk, Fish-liver oils; Calcium: Creates bone rigidity: Calcium: Creates bone rigidity: Dairy products.Dairy products.

BONE DISEASE INFLAMMATORY AND DEGENERATIVE CONDITIONS  Osteoporosis-bone mass loss  Bursitis- inflammation of bursa  Tendonitis-overuse and repetition  Sprain-stretched or torn ligament  Cartilage-Tears in cartilage  Arthritis- degenerative disease  Dislocation- bones displace

AXIAL :The spine/vertebral column 33 individual Vertebrea 33 individual Vertebrea Made up of five groups: Cervical spine (7); Cervical spine (7); Thoracic spine (12); Ribs and Muscles Thoracic spine (12); Ribs and Muscles Lumbar spine (5); Weight of body Lumbar spine (5); Weight of body Sacrum (5 fused); Muscle attachment Sacrum (5 fused); Muscle attachment Coccyx (4 fused); Muscle attachement Coccyx (4 fused); Muscle attachement  Top two vertebrae are the atlas and axis; Rotation  Vertebrae are stacked on top of each other to create a canal in which the spinal cord runs down;  Vertebrae are separated by discs that absorb shock.

APPENDICULAR PECTORAL GIRDLE Clavicle (collar bone) Scapula ( shoulder blade) UPPER LIMBS Upper Arm: Humerus Forearm : Ulna (pinky, medial) Radius (thumb, lateral) Hand: Carpals ( 8) Metacarpals ( 5) Phalanges ( 14)

APPENDICULAR PELVIC GIRDLE COXAL BONES= illium, ischium, LOWER LIMB = femur, patella, fibula (pinkie toe side), tibia (big toe side) tarsals (7), metatarsals (5), phalanges(14)

Structures of the Skeletal System  JOINTS – joints (articulations) occur when two or more bones meet  There are 3 types: Immovable – bones are fused together and no movement is possible Immovable – bones are fused together and no movement is possible Slightly movable – joined by cartilage and small amounts of movement are possible Slightly movable – joined by cartilage and small amounts of movement are possible Freely movable – synovial joints where there is movement in at least one direction Freely movable – synovial joints where there is movement in at least one direction

Joints - examples

Structures cont’d  CARTILAGE A glassy, smooth, slightly elastic tissue A glassy, smooth, slightly elastic tissue Reduces friction between bones Reduces friction between bones The ends of bones in synovial joints are coated with hyaline cartilage The ends of bones in synovial joints are coated with hyaline cartilage The vertebrae of the spine are separated by discs of cartilage. The vertebrae of the spine are separated by discs of cartilage. The hard part of the ear and tip of the nose are also cartilage The hard part of the ear and tip of the nose are also cartilage

Cartilage

Structures cont’d  LIGAMENTS Slightly elastic tissue that joins bones together Slightly elastic tissue that joins bones together Their function is to provide stability to the joint, preventing dislocation Their function is to provide stability to the joint, preventing dislocation When ligaments are torn they need to be repaired surgically When ligaments are torn they need to be repaired surgically Frequent dislocation of the same joint results in overstretched ligaments that are no longer able to do their “stability” job correctly Frequent dislocation of the same joint results in overstretched ligaments that are no longer able to do their “stability” job correctly

Ligaments

Structures cont’d  TENDONS Tendons join muscle to bone Tendons join muscle to bone They are elastic and very strong They are elastic and very strong They allow movement to take place, as they help pull across the joints on the bone They allow movement to take place, as they help pull across the joints on the bone

Tendons