The Skeletal System Chapter 4
FUNCTIONS OF THE SKELETAL SYSTEM Support o Provides shape Protection o Internal organs Movement o Provides structure for muscle to act upon Storage o Minerals & fat Blood cell formation o hematopoiesis
ORGANIZATION OF BONE 2 different types of tissue o Cortical - dense o Trabecular spongy Outer layer always composed of cortical
CLASSIFICATION OF SHAPE
CLASSIFICATION OF BONES Long bones o Long round shaft made of cortical bone o Bulbous knobs of trabecular bone at ends o Major bones of arm and leg
GROSS ANATOMY OF LONG BONE
CLASSIFICATION OF BONES Short bones o Shaped like a cube o Mainly trabecular bone o Bones of wrists and ankles
CLASSIFICATION OF BONES Flat Bones o Thin o Large surface area o Curved to some extent Structurally: o 2 thing layers of cortical bone with a layer of trabecular in between
CLASSIFICATION OF BONES Irregular bones o Do not fit in other categories o Individualized shapes
MICROSCOPIC ANATOMY OF BONE Osteon (Haversian System) o Unit of bone Central (Haversian) Canal o Opening in center of osteon o Carries blood vessels & nerves Perforating (Volkmann s) Canal o Canals that run perpendicular to the central canal
MICROSCOPIC ANATOMY OF BONE Lacunae o Cavities containing bone cells (osteocytes) o Arranged in concentric rings Lamellae o Rings around the central canal o Sites of lucunae Canaliculi o Tiny sideways canals
TYPES OF BONE CELLS Osteocytes o Mature bone cells Osteoblasts o Bone building cells Osteoclasts o Bone destroying cells o Break down bone for remodeling and calcium release Bone remodeling is a process by both osteoblasts & osteoclasts
BONE FORMATION In embryos the skeleton is primarily hyaline cartilage During development cartilage is replaced by bone Cartilage remains in: o Bridge of nose o Parts of ribs o Joints
BONE GROWTH Ossification o Process of bone formation Two phases o Bone matrix cell covers the hyaline cartilage through osteoblast activity o Osteoclasts resorb the hyaline cartilage creating a medullary cavity
BONE GROWTH Longitudinal growth o At epiphyseal plates o Through adolescence Circumference growth o Throughout most of life
ADULT BONE When we age o Loss of collagen (elasticity) o Increase in bone brittleness Bone mineral peaks o Women: 25-28 o Men: 30-35 Women have smaller bones, therefore more problematic
BONE GROWTH Hypertrophy o Subject to larger (stronger forces) o Increase in density and growth at the site of force o Physically active: denser and stronger o Bone accounts for 15% of body weight Atrophy o Subject to reduced forces o Loss of bone mineral and density o Bedridden people o Swimmers o Astronauts
THE AXIAL SKELETON Designed to provide stability to the core of the body o Skull o Vertebral (spinal) column o Thoracic cage
THE SKULL 22 bones divided into 2 groups: o Cranial 8 bones o Facial 14 bones
THE CRANIUM Parietal bone
FACIAL BONES 2 nasal 2 maxillary 2 zygomatic 2 lacrimal 2 palantines 2 inferior nasal conchae Mandible Vomer
THE SPINE 33 stacked individual vertebrae Differ in size and shape 5 different regions
REGIONS OF THE SPINE
VERTEBRAE
THE THORACIC CAGE (BONY THORACIC) Ribs Sternum Thoracic vertebrae Work together to form a protective bony cage Surround the heart and lungs in thoracic cavity
THE THORACIC CAGE (BONY THORACIC)
THE APPENDICULAR SKELETON Body s appendages Upper extremity Lower extremity 126 bones Built for motion
THE SHOULDER COMPLEX Shoulder girdle Left & right clavicles Left and right scapula o Coracoid process o Acromiolclavicular joint o Sternoclavicular joint o Glenohumeral joint
THE ARM - HUMERUS
THE FOREARM RADIUS & ULNA
WRIST & HAND 54 bones (R & L) Carpal (8) Metacarpal (5) Phalanges (14) o Proximal o Medial o Distal
WRIST & HAND
THE PELVIC GIRDLE Shelters the reproductive organs, bladder, and large intestines
THE PELVIC GIRDLE
UPPER LEG - FEMUR Longest and strongest Fits snugly into acetabulum Neck of femur o Most vulnerable o Hip fractures
LOWER LEG TIBIA & FIBULA Tibia o Shinbone o Bears most weight Fibula o Serves as site for muscle attachments
THE ANKLE & FOOT Foot acts like a spring that stores and releases energy Two largest talus (ankle) and calcaneus o Bear most the weight
JOINTS Determine the direction of movement of the bones Classified in different ways o Complexity o Number of axes o Joint structure o Joint function Three main categories (with regard to function) o Immovable o Slightly moveable o Freely moveable
IMMOVEABLE JOINTS Synarthroses o syn means together o arthron means joint Absorb shock but permit little to no movement Two types o Sutures Sutures of the skull o Syndesmoses held by bands Tibiofibular joint
SLIGHTLY MOVEABLE JOINTS Amphiarthroses amphi - on both sides Cartilaginous joints allow more motion Two types o Synchondroses Sternocoastal joints, epiphyseal plates o Symphyses Pubic symphysis, vertebral joints
FREELY MOVEABLE JOINTS Diarthroses Also referred to as synovial joints Six different types o Gliding o Hinge o Pivot o Condyloid o Saddle o Ball & socket
SYNOVIAL JOINTS
SYNOVIAL JOINTS
BONE INJURIES Common fractures Simple bone ends remain in the surrounding tissue Compound one or both ends protrude from the skin Greenstick incomplete break (more common in children since their bones are more flexible due to higher collagen) Comminuted when the bone is splintered Impacted broken ends are forced into each other (breaking a fall with arms
BONE INJURIES
OSTEOPOROSIS
SPRAINS
ARTHRITIS
LONG BONE IMMOBILIZATION Long Bone Immobilization Video https://www.youtube.com/watch?v=z5k-6q36hlk
Male vs. Female Skull
Male vs. Female Pelvis