Anatomy: Skeletal System Test

functions of the endoskeleton

• support

  • provides a framework for the body’s soft tissues

• protection

  • shields vital organs, including the brain, heart, and reproductive organs

• movement

  • muscles pull on bones to produce movement

• mineral storage

  • stores calcium for bone growth and maintenance

• blood cell production

  • hematopoiesis: red blood cells are produced in red bone marrow

• energy storage

  • yellow bone marrow stores fat as an energy reserve

axial

• spine

• rib cage

• hyoid bone

• skull/face

appendicular

• upper and lower extremities

• bones that girdle them

fontanelles

soft spots on baby’ s skull allow compression of skull during birth fuse and form sutures / joints before baby is 1-2 years old

ribs

• 12 pairs

  • true ribs (1-7): attach directly to sternum

  • false ribs (8-10): don’t attach to sternum directly (share 7th ribs cartilage)

  • floating ribs(11-12): don’t attach to sternum at all

pelvic girdle

pectoral girdle and upper extremity

lower extremity

anatomy of a long bone

osteon/haversian system

structural unit of a compact bone

haversian canal

space where blood vessels and nerves pass

osteocyte

bone cells

lacunae

spaces that house osteocytes

canaliculi

canals that connect haversian canals to osteocytes

volkman’s canals

connect haversian canals to periosteum horizontally

synarthrosis joints

• no movement (immovable)

• bones are tightly joined by fibrous connective tissue

• provide strength and protection

• little to no movement

• ex: cranial sutures

coronal suture

• between frontal and parietal bones

sagittal suture

between parietal bones

lambdoidal suture

between parietal and occipital bones

amphiarthrosis joints

• slight movement (limited movement)

• bones are joined by cartilage (fibrocartilage or hyaline cartilage)

• provide strength and stability

• allow limited movement

• ex: pubic symphysis and intervertebral joints

pubic symphysis

• between the two pubic bones

intervertebral joints

between vertebrae

diarthrosis joints

• free movement (highly moveable)

• bones are held together by a synovial joint capsule with ligaments

• allow a wide range of movement

• provide stability while allowing mobility

• ex: ball and socket joint, hinge joint, pivot joint, saddle joint, gliding joint

ball and socket joint

• shoulder joint

• hip joint

hinge joint

• knee joint

• elbow joint

pivot joint

• atlantoaxial joint (neck)

saddle joint

• thumb joint

gliding joint

• wrist (between carpal bones)

• ankle (between tarsal bones)

meniscus

C-shaped pad of fibrocartilage that cushions the joint, absorbs shock, increases stability, and helps distribute weight across the joint surface

cartilage

• flexible, gel-like matrix (made of mostly collagen and water)

• large cells, spaced far apart within the matrix

• chondrocytes (living cartilage cells)

• no blood vessels (nutrients diffuse much slower into cells)

bone

• rigid, calcified matrix(made of collagen and mineral salts)

• smaller cells, tightly packed (within the matrix)

• osteocytes (living bone cells)

• has blood vessels (nutrients diffuse quickly into cells, allowing faster repair)

endochondral ossification

1. hyaline cartilage model (most long bones begin as a model of hyaline cartilage in the embryo)

2. cartilage calcifies and breaks down(cartilage in the center calcifies and chondrocytes die. blood vessels invade)

3. primary ossification center - diaphysis (bone tissue replaces the cartilage in the center)

4. secondary ossification centers - epiphyses (bone formation later occurs in the epiphysis. cartilage remains at the growth plate until growth stops)

5. mature bone (cartilage model is completely replaced by bone, except for articular cartilage and the growth plate until adulthood)

osteoclasts

bone cells that RESORB (break down) bone

osteoblasts

bone cells that BUILD bone

osteoid

new bone matrix

wolfe’s law

bone adapts to stress

importance of endochondral ossification

• allows bone to respond to stress/injury by changing size, shape and density

• stresses on bone INCREASE the rate bone is deposited

bone aging

• young adult: thick trabeculae (more bone mass)

• older male: thinner trabeculae (some bone less, more gaps)

• older female: much thinner trabeculae (more bone loss, larger gaps)

osteoarthritis

• joint paint (worse with activity)

• stiffness and decreased range of motion

• swelling

• loss of joint function

• treatment:

  • pain management

  • physical therapy and exercise

  • weight loss

  • joint injections

  • joint replacement in severe cases