bones and joints

How many bones are in the human skeleton

206

What three structures make up the skeletal system?

Bones, cartilage, and ligaments

What are the four major functions of bones?

Movement, protection, mineral homeostasis, and hematopoiesis

Why are bones considered organs?

They contain multiple tissue types

What are bone's main matrix components?

35% organic components

65% inorganic components (hydroxyapatites)

What are the two divisions of the skeleton?

Axial

Appendicular

What structures form the axial skeleton?

Skull

Vertebral column

Bony thorax

What structures form the appendicular skeleton?

Upper limbs and shoulder girdle

Lower limbs and pelvic girdle

What are the three types of skeletal cartilage?

Hyaline

Elastic

Fibrocartilage

What are the five bone shape classifications?

Flat

Irregular

Short

Long

Sesamoid

What is the primary function of long bones?

Leverage

What determines the surface features of bones?

Function

Location

Ligament/tendon attachment

Blood vessels

Nerves

What is the primary function of the cranium?

Surrounds and protects the brain

What are the major anatomical parts of a long bone?

Epiphyses

Diaphysis

Metaphysis

Articular cartilage

Compact/spongy bone

Marrow

Periosteum

Epiphyseal lines

Where do blood vessels and nerves enter bone?

Nutrient foramen

What structures are in the anatomy of a long bone?

Spongy/compact bone

Cartilage

Connective-tissue covering

Marrow

Vessels

What is the difference between periosteum and endosteum?

Periosteum: covers outer bone surface

Endosteum: lines medullary cavity

How is flat bone structurally arranged?

Spongy bone is between layers of compact bone

What structures compose spongy bone?

Trabeculae

Osteocytes

Red marrow (some bones)

What are the four primary bone cell types?

Osteogenic cells

Osteoblasts

Osteocytes

Osteoclasts

What do osteogenic cells develop into?

Osteoblasts

How does an osteoblast become an osteocyte?

Trapped within the calcified bone matrix

What bone tissue is organized into osteons?

Compact bone

What is the basic structural unit of compact bone?

Osteon

What does compact-bone histology examine?

Microscopic structure and organization of compact bone

What does the central or haversian canal contain?

Artery

Vein

Nerve

How do lamellae strengthen bone?

Arrangement inhibits the propagation of cracks

What is the basic microscopic organization of compact bone?

Osteons

How are the layers of an osteon arranged?

Concentric lamellae around a central canal

What structural arrangement helps compact bone withstand stress?

Layered lamellae

What gives an osteon its layered appearance?

Concentric lamellae

What material within lamellae contributes flexibility and tensile strength?

Collagen fiber

How do collagen fibers in lamellae resist torsion?

Orientation alternates between concentric lamellae

What are the two types of ossification?

Intramembranous

Endochondral

What type of bones are produced by intramembranous ossification?

Flat bones

What are the major events of intramembranous ossification?

Embryonic tissue differentiates

Ossification center forms

Osteoid mineralizes

Trabeculae/periosteum form

What type of bones are produced by endochondral ossification?

Long bones

What tissue serves as the template for endochondral ossification?

Hyaline cartilage

What structure is responsible for longitudinal bone growth?

Epiphyseal plate

What are the five zones of the growth plate?

Reserve cartilage

Cell proliferation

Hypertrophy

Calcification

Bone deposition

What structure allows a growing bone to increase in length?

Epiphyseal or growth plate

What remain after the epiphyseal plate closes?

Epiphyseal line

Why is bone both strong and flexible?

Collagen fibers provide strength and flexibility

Mineral crystals provide hardness and stiffness

Which cells perform mineral deposition during bone remodeling?

Osteoblasts

How do osteoclasts dissolve calcium crytals?

Secrete HCl, producing an acidic environment

How do osteoclasts resorb collagen from bone matrix?

Secrete enzymes such as acid phosphatase

What are the major functions of bone remodeling?

Reshaping/repair bone

Maintaining blood calcium levels

How does mechanical stress stimulate bone remodeling?

Microcracks trigger osteoblast and osteoclast activity

Which two hormones regulate bone deposition and resorption?

Calcitonin and parathyroid hormone

What vitamin is required for bone homeostasis?

Vitamin D

How are vitamin D, calcium, and bone health related?

Vitamin D supports calcium availability needed for bone homeostasis

What is osteoporosis?

Loss of bone mass

Why does bone become porous and fragile in osteoporosis?

Bone resorption occurs faster than bone deposition

At what age does bone density peak?

30 years old

What are the four major stages of bone-fracture repair?

Fracture hematoma

Callus formation

Replacement by trabecular bone

Remodeling

Name the types of fractures.

Closed

Open

Transverse

Spiral

Comminuted

Impacted

Greenstick

Oblique

How can a joint brace help after a bone fracture?

Reinforces the underlying bone structure while it heals

what are the minerals in bone reserve

calcium, phosphorus, and magnesium

what is hematopoiesis

blood cell formation

what does yellow bone marrow contain and do and where is it found

contains fat

provides storage

found in medullary cavity

what does red bone marrow do and where is it found

allows for hematopoiesis

found in spongy bone

what is the diaphysis

shaft of a long bone

what is the epiphysis

rounded ends of long bone

what is spongy bone composed of

composed of trabecular that contains osteocytes

which arrangement helps prevent the propagation of cracks the best

picture on the left

what makes bone hard and stiff but also strong and flexible

hard and stiff: mineral crystals

strong and flexible: collagen fibers

what do calcitonin do and where does it come from

controls bone deposition

comes from C cells in the thyroid gland

what does PTH do and where does it come from

controls bone resorption

comes from parathyroid gland

what vitamin d does the liver produce

25 dihydroxyvitamin D3

what vitamin d does the kidney produce

1,25-dihydroxyvitamin D3

which fracture is the most dangerous

open fracture

which fracture is found in children under the age of 13

greenstick fracture

what are the three joints based on degree of mobility

diarthrosis = freely movable

amphiarthorsis = slightly movable

synarthrosis = little to no movement

what are the 4 joint types by classification by anatomy

fibrous

cartilaginous

bony

synovial

examples of a synarthrosis joint

sutures

teeth in sockets

what is the movement and anatomy classification of intervertebral discs

amphiarthrosis (mobility)

made from fibrocartilage so they form a symphysis type of cartilaginous joint

what is a multiaxial joint

diarthrosis by mobility

allows for three types of movement

easily injured

what do fibrous joints do and what are some examples

form strong connections between bones

ex: sutures, syndesmosis between radius and ulna, gomphosis

what are examples of cartilaginous joints

hyaline cartilage forms synchondrosis

fibrocartilage forms a symphysis

what are synovial joints

two bones separated by a space filled with synovial fluid

most structurally complex

what is a tendon

attaches muscle to bone

what is a ligament

attaches bone to bone

what is a bursa

sac filled with synovial fluid

what are the types of synovial joints

pivot joints - rotation around axis - first and second vertebrae

hinge joint - like a door - elbow

saddle joint - between carpal and first metacarpal

plane joint - allows for gliding - between tarsal bones of the feet

condyloid joint - radio carpal joint of the wrist

ball and socket - hip and shoulder

what are the most common joint injuries

sprains - ligaments stretched or torn

dislocations - bones forces out of normal position

cartilage damage - tearing menisci

what is bursitis

inflammation of bursa due to direct injury or friction

what is tendonitis

inflammation of the tendon sheaths due to overuse

what is arthritis

pain and stiffness and swelling of joints

what is osteoarthritis

most common

one sided

over use injury

non systemic inflammation

what is rheumatoid arthritis

autoimmune disease

may effect all joints (symmertical)

chronic inflammation

what is gout

abnormal nucleic acid metabolism

crystals of uric acid ppt in joints

commonly starts with the big toe

avoid foods high in purines