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 Pectoral girdle Arm, hand bones Pelvic girdle Leg, foot bones Axial Skull 12 pairs of ribs Sternum 26 vertebrae Intervertebral disks

Human Skeleton s sternum rib vertebral column humerus scapula clavicle ulna radius patella femur tibia fibula pelvic girdle

Skull and Facial Bones parietal bone frontal bone temporal bone occipital bone sphenoid bone external auditory meatus ethmoid bone lacrimal bone zygomatic bone maxilla mandible

Sinuses frontal sinus sphenoid sinus ethmoid sinus maxillary sinus

Vertebral Column intervertebral disks cervical vertebrae (7) thoracic vertebrae (12) lumbar vertebrae (5) sacrum (5 fused) coccyx (4 fused)

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