Ch. 7 The Skeletal System Introduction Bones are ALIVE They have many functions There are a total of 206 bones in the human body Functions of Skeletal System Provide a surface for muscles to attach Protect and support softer tissues and organs Produce blood (hematopoeisis) Store salts Contains passageways for blood vessels and nerves 5 Tissues found in Bone Bone (osseous) tissue Cartilage Dense connective tissue Blood Nervous tissue 2 Bone (Osseous) Tissues 1. Compact Bone wall of the bone (along diaphysis); solid and strong 2. Spongy Bone softer, porous bone; found in ends of bones (epiphyses) Bone Structure 1.EPIPHYSIS - ends of bone; forms a joint with another bone. 2. DIAPHYSIS - shaft of the bone 3. ARTICULAR CARTILAGE - hyaline cartilage covering ends of bones 4. PERIOSTEUM - tough membrane-like covering over entire bone 5. MEDULLARY CAVITY - hollow chamber within the diaphysis, contains bone marrow - Red Marrow - mainly in spongy bone in adults, produces blood cells - Yellow Marrow - fat storage Microscopic Structure - MATRIX where all of the bone cells live - OSTEOCYTES - mature bone cells are enclosed in tiny chambers called LACUNAE -OSTEOCYTES form concentric rings called LAMELLA which surround HAVERSIAN CANALS that houses blood vessels -Volkmanns Canals run horizontally connecting the vessels between OSTEONS Bone Development Bones first form as hyaline cartilage, then gradually changes into bone tissue - a process called OSSIFICATION. OSTEOBLASTS produce bone cells called OSTEOCYTES OSTEOCLASTS - dissolve bone tissue to release minerals - a process called RESORPTION Bone Structures Long bones (Humerus, Femur) Longer than they are wide Short bones (Carpals, Tarsals) Approximately as wide as they are long Flat bones (Scapula, Cranium) Irregular bones (Mandible, Vertebra) The skeleton is divided into two portions: 1. AXIAL SKELETON 2. APPENDICULAR SKELETON Axial skeleton Supports and protects organs of the head, neck, and trunk Skull Hyoid supports tongue for speaking and swallowing Vertebral column Thoracic cage (sternum and ribs) Appendicular skeleton Upper and lower limbs AND bones that hold those limbs to the axial skeleton Upper limbs (arms) Humerus, radius, ulna, carpals, metacarpals, phalanges Pectoral girdle - scapula, clavicle Lower limbs (legs) Femur, fibula, tibia, patella, tarsals, metatarsals, phalanges Pelvic girdle (hip bones) 2 coxa Vertebral column 1)Cervical (7) neck curvature 2)Thoracic (12) attached to rib cage 3)Lumbar (5) lower back curvature 4) Sacrum and Coccyx (fused) **The ATLAS vertebrae is the 1 st vertebrae (C1) ** The AXIS vertebrae is the 2nd (C2) Abnormal spine curvature 1.Lordosis Swayback; the spine curves significantly inward at the lower back Abnormal Spine Curvature 2. Kyphosis - Humpback; abnormally rounded upper back Abnormal Spine Curvature 3. Scoliosis sideways or S- shaped curve to the spine Types of Fractures 1. Simple/Closed bone breaks, but does not damage surrounding tissue 2. Compound/Open bone breaks and breaks through the skin 3. Greenstick incomplete break and the bone bends 4. Comminuted fragmented and shattered break 5. Stress/hairline small crack caused by repeated impact Joints Unions between two or more bones A.k.a. articulations 3 Types of Joints 1. Fibrous joint found between bones that closely contact one another; connected with dense, fibrous tissue Ex: sutures between bones in the skull Least movable joint 3 Types of Joints 2. Cartilagenous joint connected by hyaline cartilage Ex: vertebral column and pubic symphysis Limited movement 3 Types of Joints 3. Synovial Joint Complex joints that allow free movement 6 Synovial Joints 1. Ball-and-socketex: shoulder 2. Condyloidex: metacarpals and phalanges 3. Glidingex: carpals 4. Hingeex: elbow 5. Pivotex: atlas and axis vertebra (head movement) 6. Saddleex: thumb