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The Skeletal System Chapter 5 Long-Bone Structure • Compact bone • Spongy bone • Central cavity contains yellow marrow Compact-Bone Structure • Mature compact bone consists of many cylindrical Haversian systems Long-Bone Development • Cartilage “model” provides a template • Growth occurs at the bone ends (epiphyses) • Epiphysis is separated from the bone shaft by a plate of cartilage • Plates are replaced by bone when growth ends Bone Remodeling • In adults, bone building and bone breakdown continue constantly • Osteoblasts deposit bone • Osteoclasts secrete enzymes that degrade it • Remodeling adjusts bone strength and helps maintain blood calcium levels Bone Density • Exercise can increase bone density • Osteoporosis is a decrease in bone density – May occur when the action of osteoclasts outpaces that of osteoblasts – May also occur as a result of inability to absorb calcium Functions of Bone • Interacts with muscle to enable movement • Supports and anchors muscles • Encloses and protects internal organs • Stores calcium and phosphorus • Produces blood cells The Skeleton Appendicular Axial • Pectoral girdle • Skull • Arm, hand bones • 12 pairs of ribs • Pelvic girdle • 26 vertebrae • Leg, foot bones • Intervertebral disks • Sternum Human Skeleton clavicle scapula humerus radius sternum rib vertebral column ulna s pelvic girdle femur patella tibia fibula Skull and Facial Bones parietal bone frontal bone sphenoid bone ethmoid bone temporal bone lacrimal bone zygomatic bone maxilla occipital bone external auditory meatus mandible Sinuses frontal sinus ethmoid sinus sphenoid sinus maxillary sinus Vertebral Column cervical vertebrae (7) thoracic vertebrae (12) lumbar vertebrae (5) sacrum (5 fused) coccyx (4 fused) intervertebral disks Bone Marrow • Yellow marrow – Fills the cavities of adult long bones – Is largely fat • Red marrow – Occurs in spongy bone of some bones – Produces blood cells Ribs and Sternum • 12 pairs of ribs • Attach to vertebral column and sternum • Function as a scaffold for the body cavity of the upper torso Pectoral Girdle & Upper Limbs • Shoulder blade (scapula • Collarbone (clavicle) • Humerus fits into scapula and connects with radius and ulna of lower arm • 8 carpal bones in wrist • 5 metacarpals end at knuckles • Phalanges are bones of fingers Pelvic Girdle • Coxal bones attach to the lower spine (sacrum) in back, meet at pubic arch in front • Combined structure is the pelvis • Pelvis is broader in females than males Lower Limbs • Femur, or thighbone, is largest bone in body • Lower leg - thick tibia and slender fibula • Patella protects knee joint • Tarsal bones make up ankle and heel • Metatarsals are long bones of feet • Toes contain phalanges Joints • Areas of contact or near contact between bones • Fibrous joints – Short connecting fibers join bones • Synovial joints – Move freely; ligaments connect bones • Cartilaginous joints – Straps of cartilage enable slight movement Movement at Joints • Flexion and extension • Circumduction and rotation • Abduction and adduction • Supination and pronation Diseases and Disorders • Arthritis • Tendonitis • Carpal tunnel syndrome • Strains, sprains, dislocations • Fractures – Simple, complete, compound
