The Skeletal System

The Skeletal System

The Skeletal System• Newborn Baby= 350

bones• Fusion of bones

• Mature Adult= 206 bones

Purposes of the bones of the Skeletal System:• Provide a framework for the

body• Protect vital organs (brain,

spinal cord)• Serve as levers, when muscles

are attached, to help us lift and move

• Store calcium, which may be reabsorbed into the blood if there is not enough calcium in the diet

• Produce blood cells in the red bone marrow

Bones• Five most common

categories:• Long• Short• Flat• Irregular• Sesamoid

Long bones• Form legs and arms (humerus,

femur)• Parts of long bones:

• Shaft (diaphysis): longest portion

• Compact bone: solid, outer layer

• Epiphysis: end of the bone that is shaped to connect to other bones (using ligaments and muscles)

• Spongy bone: layer inside the compact bone that covers the space in which marrow is stored

Short bones• Small, cube-shaped

bones of the wrists, ankles and toes

• Outer layer of compact bone

• Inner layer of cellous bone-bone with a latticework structure

Flat bones• Large, flat surfaces

• Cover organs

• Provide a surface for large areas of muscle

• Shoulder blades, pelvis, skull

Irregular bones• Specialized bones with

specific shapes

• Ears, vertebrae, face

Sesamoid bones• Formed in a tendon near

joints

• Patella (kneecap)

• Also found in hands and feet

Extensions and depressions

• Serve as sites for attaching muscles and tendons

• Ex: greater trochanter-bony extension near upper end of femur

Bone marrow• Soft connective tissue • Production of blood cells• Red Bone Marrow: infant

bones and flat bones of adults; where red blood cells (RBC’s) start to develop

• Yellow Bone Marrow: in most other adult bones; made of connective tissue filled with fat

Bones of the Head

• Sutures: points where skull or cranial bones join

Bones of the Spinal Column

• Five segments of vertebrae

• Each separated by a cartilaginous disc

• Space between vertebral body and back= spinal cord

Cervical: 7

Thoracic: 12

Lumbar: 5

Sacrum: 5 at birth, fuse in adulthood

Coccyx: 4 fused bones

Bones of the Chest• Clavicle• Scapula• Sternum• Xyphoid Process• Ribs:

• True Ribs (7)• False Ribs (3)• Floating Ribs (2)

Bones of the Pelvis• Pubic Symphysis

• Pelvic Girdle• Ilium• Ischium• Pubis

Bones of the Extremeties• Arm:

• Humerus• Radius• Ulna• Carpals• Metacarpals• Phalanges

Bones of the Extremeties• Leg:

• Femur• Tibia• Fibula• Tarsals• Calcaneus• Metatarsals• Phalanges

Joints:• Points where bones

connect• Bones connect to other

bones using ligaments• Ligaments: bands of

fibrous tissue• Movement of joint

depends on the body’s need

Diarthroses:

joints that move freely

Amphiarthroses:Cartilaginous Joints that move slightly

Synarthroses:Joints that do not move; Join bones firmly

Synovial Joints: (another name for diarthroses)

Joints covered with a membrane that secretes a fluid lubricant to help the joint move easily

Fractures• Breaks or cracks in bones• Types:

• Closed: break with no open wound

• Simple (hairline): fracture, does not move any part of the bone out of place

• Open (compound fracture): break with an open wound

Fractures, cot’d• Types:

• Greenstick (incomplete): incomplete bone break

• Comminuted: break in which the bone is fragmented or shattered

• Colles’: break of the lower end of the radius

• Complicated: fracture with extensive soft tissue injury

Fractures, cot’d• Types:

• Impacted: fragment from one part of a fracture is driven into the tissue of another part

• Compression: break in one or more vertebrae caused by a compressing or squeezing between the vertebrae

• Spiral: occurs when a bone is twisted apart

Diseases of the Skeletal System

• Osteoporosis: softening of the bones due to lack of calcium• Occurs most often in post-menopausal women

• Loss of bone density and easily broken bones

• Osteomyelitis: bacteria in the bone tissue•Severe pain at the end of the bone

•Bone damage

Diseases of the Skeletal System

• Arthritis: inflammation of the joints• Pain, stiffness, aching• Limited range of motion

•Range of motion: measurement of the degree to which a joint is capable of moving

• Osteo- and rheumatoid arthritis

Diseases of the Skeletal System

• Sprain: injury or trauma to the joints that tears ligaments• Pain, swelling, tenderness, inability to move the area

• Usually heal within two weeks

Diseases of the Skeletal System

• Herniated Disc: one or more of the spinal discs balloon out from inside the bony parts of the vertebrae• Can cause unbearable pain if pressing on a nerve

Diseases of the Skeletal System

Posture/Spinal Conditions

• Kyphosis: humpback, rounding forward of the thoracic vertebrae

• Lordosis: swayback; abnormal inward curvature of the lumbar vertebrae

• Scoliosis: side-to-side curvature of the spine