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Skeletal System Axial Skeleton Axial Skeleton Includes 80 bones of the skull, vertebral column and bony thorax Functions: – Supports head, neck & trunk – Protects brain, spinal cord and thoracic organs Skull Composed of flat bones Function: – Used for attachment of head muscles & protects the brain Sutures of the Skull Sutures: interlocking joints that unite skull bones – Coronal: where parietal bones meet frontal – Sagittal: where 2parietal bones meet superiorly – Squamos: where parietal and temporal bones meet on lateral aspects of skull – Lambdoidal: where parietal bones meet occipital bones meet posteriorly Vertebral Column aka the Spine Location: runs from the base of the skull to the coccyx (tailbone) Function: – Surrounds and protects the spinal cord – Provides attachment sites for ribs and back muscles Vertebral Column Characteristics – 26 interconnected irregular bones – Provides a flexible, curved structure – Serves as axial support of the trunk Vertebral Column Curvatures of the Spine: – – – – S-shaped to prevent shock to head in motion Allows for trunk flexibility Increases resiliency & flexibility of the spine Functions like a spring, not a rod Cervical & Lumbar Curves: concave posteriorly Thoracic & Sacral Curves: convex posteriorly Curvatures of the Spine Abnormal Curvatures of the Vertebral Column Lordosis: aka sway back – An accentuated lumbar curve Kyphosis: aka hunchback – An exaggerated thoracic curve Scoliosis: the twisted disease – An abnormal lateral curvature in the thoracic region – Typical in girls in late childhood Lordosis & Kyphosis Scoliosis Cervical Vertebrae 7 total extending from base of skull to ~ shoulder line Numbered C1-C7 Smallest & lightest vertebrae Unique vertebrae – Atlas or C1: no body; holds the occipital bone, allows nodding motion (“yes”) – Axis or C2: acts as a pivot for rotation; shake head (“no”) Thoracic Vertebrae 12 total; runs through mid-back Numbered T1-T12 Larger than cervical Longer, palpable spinous processes Ribs attach here posteriorly Lumbar Vertebrae 5 total Numbered L1-L5 Huge bodies and short spinous processes Holds most of body weight & stress; very sturdy Sacrum & Coccyx Sacrum – Formed from 5 fused vertebrae – Numbered S1-S5 – Makes up posterior wall of pelvis – Strengthens & stabilizes pelvis Coccyx – 4 fused vertebrae Ligaments of the Spine There are several; only 2 you need to know – Anterior Longitudinal Ligament: resists back hyperextension – Posterior Longitudinal Ligament: resists back flexion Intervertebral Discs Cushion-like pads between vertebrae Asts as shock absorbers during motion Makes up ~25% of length of column Flattens during the day Intervertebral Discs Ribs Flat bones 12 total pairs Attach posteriorly to thoracic spine Function: – Protect thoracic organs True Ribs: the superior 7 pairs – Attach directly to sternum by costal cartilage False Ribs: the inferior 5 – 8-10: join each other by cartilage and indirectly attach to sternum – 11& 12: the floating ribs, no anaterior attachment Rib Cage Pelvis Has 2 regions: true and false pelvises False pelvis superior to true pelvis True pelvis dimensions are a concern to child-bearing women Pelvic structure differs between men and women Gender Difference of Pelvis Men – Narrow outlet – Heavier & thicker bone structure – Ilia less flared, more vertical – Sacrum long and curved – Ischia close together – Less rounded pubic arch Women – Inlet circular & large – Pelvis shallow, lighter & thinner – Ilia flare laterally – Sacrum shorter & less curved – Ischia farther apart & shorter – Pubic arch is more rounded Female vs. Male Pelvis Female vs. Male Skulls FUNTION OF JOINTS They hold bones together. Allow the rigid skeleton mobility Joints are classified in 2 ways: 1. Functionally –amount of movement 2. Structurally – type of tissue Functionally- amount of movement 1. Synarthrosis- immovable Ex) sutures in skull 2. Amphiarthrosis- slightly movable Ex) intervertebral joints 3. diarthrosis-freely movable Ex) limbs Structurally- tissue type between bones 1) Fibrous- connected by fibrous tissue - sutures skull 2) Cartilaginous- connected by cartilage -pubic symphysis 3) Synovial- separated by a joint containing fluid -6 types based on articulating bone surface Types of Synovial Joints 1. Plane Joint-wrist 2. Hinge Joint- elbow 3. Pivot Joint- ulna & radius 4. Condyloid Joint- metacarpels 5. Saddle Joint- thumb 6. Ball & Socket- shoulder or hip Stress Fracture of the Tibia STAGES OF BONE REPAIR