axial vs appendicular skeleton. what is part of each? what is their functions?
Axial Skeleton
- skull, vertebral column, ribs, sternum
- support and protect vital organs
primary function:
- protection of CNS and thoracic organs (vital organs)
- structural support for posture such as head, neck and trunk
Appendicular skeleton
- limbs and girdles
- movement and locomotion
Primary Function:
- movement and manipulation
- leverage for skeletal muscles
adapted for mobility and force transmission
what are the 6 functions of the skeletal system
Functions of the Skeletal System
1. Structural support
Provides a framework for the entire body
- protection
protects the skull/brain, the vertebrae/spinal cord, and the ribs/heart and lungs - leverage and movement
Bones act as levers and joints act as fulcrums
muscles apply force and movement occurs - mineral storage & homeostasis
bone stores 99% of the body’s calcium
calcium and phosphate are released or stored to maintain blood homeostasis
links directly to endocrine control - hematopoiesis (blood cell production)
occurs in red bone marrow and produces:
red blood cells
white blood cells
platelets - lipid storage
yellow marrow contains adipocytes which act as an energy reserve
Can revert red marrow in extreme demand
what are the six categories of bones based on their shapes
Flat bones (protection and hematopoiesis)
Sutural bones (skull flexibility during development
Long bones (leverage and movement)
Irregular bones (protection and support)
Sesamoid bones (reduce tendon friction)
Short bones (stability with limited motion)
why are bone markings important?
theyre important for 3 main reasons. they are:
1. The site of the muscle, tendon, and ligament attachment,
2. surfaces where bones articulate/form joints,
3. passageways for nerves and blood vessels.
what are the Openings And Spaces (passageways/cavities) (6 of them)
These allow vessels, nerves, or air to pass through or occupy bone
Canal → passageway through bone. Its function is to transmit blood vessels or nerves. Think of it as a tunnel through the bone.
Foramen → small rounded opening through which blood vessels or nerves penetrate bone
Fissure → elongated cleft or narrow gap. Can be part of the eye skeleton
Sulcus → deep narrow groove. Its function allows vessels or nerves to lie along the bone surface
Sinus → chamber within bone that is normally filled with air. An example is the frontal sinus in the skull
Fossa → shallow depression or recess in bone surface. Often receives another bone in a joint
what are the projectons for muscle/ligament attachment? 8 of them
Projections for Muscle/Ligament Attachment
These are roughened or elevated areas
Process → any bump or projection.
Tubercle → small rounded projection
Tuberosity → large rough projection that may occupy a broad area. So tubercle is small, and tuberosity is larger and rougher
Trochanter → very large rough projection (found only on femur)
Crest → prominent ridge
Line → low ridge, more delicate than crest
Spine → pointed narrow process (like a sharp projection)
Ramus → thick extension that makes an angle with main body of bone
what are the projections that form joints + long bone structural thing
These are smooth and covered with articular cartilage
Head → expanded proximal end of bone that forms part of a joint. Usually rounded and connected to shaft by neck
Neck → narrow connection between head and diaphysis
Condyle → smooth rounded articular process and forms joint with another bone
Trochlea → smooth articular process shaped like a pulley
Facet (face) → small, flat articular surface
Long Bone Structural Terms
diaphysis → shaft of a long bone/the elongated body portion
describe the structure of a long bone and what each of its compartments do
Structure of a Long Bone
diaphysis
This is the shaft of a bone
Hollow tube of compact bone
Medullary cavity
Hollow interior of the diaphysis
Contains bone marrow (connective tissue)
Types of marrow:
Red marrow → RBC production
Yellow marrow → adipose tissue for energy storage
Epiphyses
Ends of bone
Made mostly of spongy bone
Contains red marrow
Articular cartilage
Covers epiphyses
Reduces friction
Shock absorption/cushioning
Periosteum
Strong OUTER membrane
Covers bone EXCEPT at joint surfaces
Important in growth, repair and blood supply
Endosteum
Lines medullary cavity (internal hollow interior of the compact bone/diaphysis)
whats the difference between bone marrow in children and adults? what happens to bone marrow after chemo?
Bone Marrow
In children → mostly red marrow
In adults → mostly red marrow in the skull, sternum, ribs, clavicles, hip bones and vertebrae.
Bone marrow transplants can be used after chemotherapy because it gets destroyed during it.
what is dipole?
Diploë:
Spongy bone layer
Sandwiched between two compact bone layers (cancellous bone)
what are the two main vessels for blood supply of the bone
Growth and maintenance requires extensive blood supply.
Main vessels:
1. Nutrient artery + nutrient vein: is usually one of each per bone
- Metaphyseal arteries and veins: carry blood to and from metaphysis and connect epiphyseal vessels
Bone is HIGHLY vascular
what is hematopoiesis
Hematopoiesis = process by which immature precursor cells develop into mature blood cells. This occurs in red bone marrow (blood cell production)
what are osteogenic (osteoprogenitor) cells function and location
Osteogenic (osteoprogenitor) cells = make osteoblasts
- stem cells
- derived from mesenchyme
- differentiate into osteoblasts
Locations:
- inner periosteum
- endosteum
- passageways containing blood vessels
- important in fracture repair
Think OG = original generator
what are osteoblasts functon and steps and what are they for
Osteoblasts = building new bones. BLASTS BUILD!
Function:
- produce new bone matrix
- process = osteogenesis (ossification)
Steps:
1. Produce osteoid (unmineralized matrix)
2. Deposit calcium salts to convert osteoid to bone
3. Become osteocytes when surrounded by bony matrix
what are osteocytes and their function and location
Osteocytes = maintain the existing bones
- Mature bone cells
- Cant divide
- Maintain mineral and protein content of matrix
- Located in lacunae
- Surrounded by lamellae
- Connected through canaliculi
- Cyt = cell caretaker
what are osteoclasts function
Osteoclasts = breaking down and remodel
Function:
- Remove bone matrix
- Remodel bone
- release acids + proteolytic enzymes to dissolve matrix and release stored minerals
- process called osteolysis (loosening) / bone resorption
- releases stored minerals into blood
- think clast = clash/crush and remodel
what is the bone matrix composition and what two things make it up
Bone Matrix Composition
1. Organic portion (roughly ⅓ weight)
- collagen fibers
- provide flexibility and resist bending and twisting
- cannot resist compression alone (can tolerate bending and twisting but not compression)
- Inorganic portion (roughly ⅔ the weight)
- calcium phosphate Ca₃(PO₄)₂
- interacts with calcium hydroxide Ca(OH)₂
- forms hydroxyapatite crystals Ca₁₀(PO₄)₆(OH)₂
- also contains calcium carbonate, (CaCO3) sodium (Na+), magnesium (Mg2+), and fluoride (F-)
- provides hardness, strength and resistance to compression
why is bone so strong compared to steel/reinforcd concrete?
Why Bone is So Strong
The hydroxyapatite crystals are hard, brittle and resist compression.
The collagen fibers are flexible, and resist bending and twisting
Together, they have the protein-crystal composite, which is highly resistant to shattering, and stronger than steel reinforced concrete!
