-
Describe and name the Long Bones.
- Long, longitudinal axis & expanded ends
- Arm: humerus, ulna (medial), radius (lateral), metacarpals (5), phalanges
- Leg: femur, tibia (medial), fibula (lateral), metatarsals, phalanges
-
Describe and name the Short Bones.
Equal in length, width & thickness; shaped irregularly
- Carpal Hand Bones (8) Tarsal Foot Bones (7)
- 1. Scaphoid 1. Calcaneus
- 2. Trapezium 2. Talus
- 3. Trapezoid 3. Cuboid
- 4. Triquetral 4. Navicular
- 5. Pisiform 5. Lateral (3) Cuneiform
- 6. Hamate 6. Inter. (2) Cuneiform
- 7. Capitate 7. Medial (1) Cuneiform
- 8. Lunate
-
Describe and name the Flat Bones.
- More thin and curved rather than "flat"
- Bones of the Cranium (skull):
- Frontal
- Parietal (2)
- Temporal (2)
- Occipital
- Other Flat Bones:
- Ribs Scapulae (shoulder blades)
- Clavicle Sternum (breast bone)
- Oz Coxae ("hip bones")
- ischium
- ileum
- pubis
-
Describe and name Irregular Bones.
- These bones don't fit neatly in any other category.
- 1. Vertebrae, sacrum, coccyx
- 2. Hyoid
- 3. Two of the cranial bones:
- Sphenoid
- Ethmoid
- 4. Facial Bones:
- Zygomatic (2)
- Palatine (2)
- Lacrimal (2)
- Vomer
- Inferior nasal concha (2)
- Maxilla (2)
- Mandible
- 5. Ear ossicles:
- Malleus, Incus, Stapes
-
Describe and name the Sesamoid Bones.
- Small bones embedded within tendons, usually where tendons pass over the joint of a long bone.
- Help overcome compression forces, increasing mechanical efficiency of joints--# varies among people
- 1. Knee: patella
- Within tendon of quadriceps femoris (thigh muscle)
- 2. Wrist: pisiform carpel bone
- Within tendons of flexor carpi ulnaris
-
Name and describe the Accessory Bones.
- Commonly found in feet
- Occur where developing bones don't fuse properly
- Look like extra/broken bones in x-rays
- *Sometimes small clusters between flat skull bones. ("Sutural" or "Wormian" bones.)
-
Describe: Epiphysis
- Expanded end portion
- Articulates (forms a joint)
-
Describe: Articular Cartilage
A layer of hyaline cartilage
-
Describe: Diaphysis
Shaft of the bone
-
Describe: Periosteum
- Tough, vascular covering of the fibrous tissue
- Surrounds bone
- Fibers are continuous with ligaments and tendons
- Functions in bone repair
-
Describe: Medullary Cavity
- Hollow bone portion of diaphysis of long bone
- Continuous with spaces of spongy bone
-
Describe: Endosteum
- Squamous epithelial lining of the medullary cavity and spaces in spongy bone
- Surrounds marrow
-
Describe: Compact bone
- Solid, strong, resistant to bending
- In diaphysis
-
Describe: Spongy Bone
- "Cancellous Bone"
- Numerous branching bony plates-"Trabeculae"
- Interconnecting spaces reduce weight
- Both types usually present in any bone
- Mostly spongy bones: short, flat, irregular
-
Describe: Marrow
- Soft, net-like connective tissue
- Irregular spaces of spongy bone (red)
- Medullary cavity of long bones (yellow)
-
Describe: Red Marrow
- Forms erythrocytes (RBCs)
- Forms leukocytes (WBCs)
- Forms thrombocytes (Platelets)
- Red color due to hemoglobin
- Found in:
- skull
- rib
- sternum
- clavicles
- vertebrae
- pelvis
-
Describe: Yellow Marrow
- Fat storage--adipose tissue
- Found in medullary cavities of long bones
-
Name the Bone cells
- Osteoblast
- Osteocyte
- Osteoclast
-
Describe: Osteoblast
- Bone cell capable of synthesizing new bone matrix
- Usually found in the growing portion of bone
-
Describe: Osteocyte
- Main cell of mature bone tissue
- Regulates the concentration of calcium in body fluids by helping release calcium from bone tissue into blood
-
Describe: Osteoclast
- Multinuclear bone-destroying cell
- Usually found where bone is resorbed during normal growth
-
Describe the general process for Osteogenesis.
- 1. Connective tissue is laid down.
- 2. Periosteum is formed from the connective tissue.
- 3. Blood vessels and undifferentiated connective tissue cells begin to fill the developing area.
- 4. The undifferentiated connective tissue differentiates into osteoblasts.
- 5. Osteoblasts deposit bone tissue.
-
Describe Intramembranous Ossification (Interstitial growth)
- Occurs in Flat bones
- 1. Layers of undiff. CT appear in the site of a future bone.
- 2. CT cells arrange around blood vessels within the layers.
- 3. CT differentiates into osteoblasts.
- 4. Osteoblasts form a spongy bone matrix around themselves which then forms trabeculae.
- 5. When the bony matrix (trabeculae) surround the osteoblasts, they become osteocytes.
- 6. As the matrix fills in, some spongy bone becomes compact bone.
- 7. Primitive tissue on the surface becomes the periosteum.
-
Describe Endochondral Ossification (Intracartilaginous Bone Formation)
- 1. Mesenchyme cells multiply and accumulate in the site of a future bone, forming a rough outline of future bone.
- 2. Mesenchyme cells differentiate into chondroblasts; form matrix.
- 2. Hyaline cartilage "bone model" is made.
- (Cells at edge become perichondrium, then differentiate into fibroblasts)
- 3. Cartilaginous bone model grows at ends--Interstitial growth bc matrix added internally.
- Midportion chondrocytes greatly enlarge
- Phosphatase enzymes are secreted.
- Calcification occurs
- 4. Cartilaginous bone model grows in width--Appositional growth.
- 5. Perichondrium invaded by capillaries.
- Some perichondrium (osteogenic cells) become osteoblasts & osteocytes.
- 6. Thin bone layer forms in mid-cartilaginous bone.
- CT around this bone becomes periosteum.
- Innermost periosteum can make chondrocytes in adulthood.
- 7. Calcified cartilage in mid-bone breaks down and blood vessels, osteocytes & osteoblasts fill region--forms ossification center.
- Osteoblasts make cancellous bone.
- 8. Ossification center expands in both directions of bone.
- Cartilage breaks down, replaced by cancellous bone = shaft/diaphysis of bone.
- Center is resorbed, becomes marrow cavity.
- 9. Appositional growth: Ca2+ resorbed from medullary cavity while it is deposited by periosteum.
-
-
-
Describe the growth of Endochondral Bone.
- 1. Cartilage in center of diaphysis (1* Ossification Center) is replaced.
- Osteoblasts deposit a thin layer of compact bone by interstitial ossification.
- Bone forms center--> end.
- 2. At epiphysis, 2* Oss. Ctr. appears, remains cartilaginous as it grows.
- Spongy bone forms in all directions.
- 3. Compact bone is deposited in diaphysis of 1* Oss. Ctr.
- 4. Spongy bone deposited in epiphysis of 2* Oss. Ctr.
- 5. Bone changes shape as it grows.
- Continuous and extensive bone remodeling
- Haversian systems replaced with new ones.
-
-
True or False: Can bones continue to grow even after the onset of sexual maturity?
True.
-
True or False: Intramembranous bones grow by way of the periosteum?
True.
-
True or False: Endochondral bones enlarge in size with excessive weight gain.
False.
-
True or False: The precise mechanism for bone remodeling is known.
False.
The precise mechanism is unknown.
-
True or False: Bone decalcifies in response to stress on the matrix.
False.
Bone CALCIFIES in response to stress on the matrix.
-
True or False: Bone decalcifies in zero gravity.
True.
-
True or False: Weak electric currents speed up bone repair.
True.
-
True or False: Bone responds to stress imposed by body weight and muscle movement.
True.
-
The term for the adipose tissue that fills the hollow shaft of the diaphysis of a long bone.
Yellow marrow
-
When does the bony epiphysis fuse with the diaphysis?
When the organism reaches adulthood.
-
In mammals, what constitutes the core of the bony epiphysis?
Spongy bone and red marrow.
-
Prior to becoming an adult, what is the term for the structure that separates the epiphysis from the ossified diaphysis?
Epiphyseal plate
-
Describe the Endochondral Ossification of Long Bones.
- 1. Mesenchyme cells form a hyaline cartilagous template.
- The cartilaginous template is contained in a dense irreg. CT called a perichondrium.
- 2. Perichondrium differentiates into a periosteum.
- Periosteum deposits a thibn outer layer of intramembranous bone (around outer diaphysis, beneath periosteum)
- 3. Blood vessels enter cartilage template, & mesenchyme cells differentiate into osteoblasts.
- 4. Osteoblasts lay down an ossified bony matrix that replaces cartilage with replacement bone.
- 5. In the developing replacement bone, some mesenchyme diff. into osteoclasts.
- Osteoclasts resorb bony matrix, forming hollow medullary cavity.
- The cavity runs the length of the diaphysis and is surrounded by solid lamellae of bone.
- 6. Haversian systems develop around nerve/blood supply canals in developing matrix.
- Osseus tissue is deposited in concentric cylinders called osteons.
- Ossification can occur at one or more secondary center to replace cartilage.
-
True or False: Epiphyseal bone is mostly lamellar (spongy).
True.
-
What is the term for the marrow cavity that develops in the epiphysis?
Red Marrow
-
The growth and development of bones is best understood in what organisms?
Mammals
-
Besides growth in size, how else do bones grow?
Bone remodeling to maintain their shape
-
Where does diaphysis length increase?
Cartilaginous plates separating the diaphysis and epiphysis
-
What happens to the epiphyseal plates once a mammal reaches adulthood?
The epiphyseal plates calcify and become epiphyseal lines and growth in bone length stops
-
How do long bones grow in width (transverse diameter)?
Osteoblasts deposit bone at the outer surface in the periosteum while osteoclasts resorb bone in the medullary cavity of the endosteum.
-
Name the 4 Regions of the Epiphyseal Plate.
- 1. Zone of Resting or Reserve
- 2. Zone of Proliferation
- 3. Zone of Maturation
- 4. Zone of Calcification
-
Describe the Zone of Resting (Reserve, Cartilage).
- Consists of hyaline cartilage
- Chondrocytes are irregularly spaced next to the bone of epiphysis
- Purpose: Attach cartilaginous plate to epiphyseal bone
- Blood vessels carrying nutrients enter the epiphyseal plate from the epiphysis side, through this zone.
- Chondrocytes in the resting zone do not contribute to bone length.
-
Describe the Zone of Proliferation.
- Chondroblasts are stacked on eachother
- It is considered the Mitotic Zone due to new chondrocytes made here to replace the dead ones at the diaphyseal end of the epiphyseal plate.
- Partly responsible for expansion of length of the epi. plate.
-
Describe the Zone of Maturation.
- Chondrocytes are larger, stacked and have lacunae that are more visible.
- Chondrocyte hypertrophy also contributes to growth of length.
- Older cells are closer to the diaphysis.
- Chondrocytes in the Maturation zone dies when matrix calcifies.
-
Describe the Zone of Calcification.
- This zone functions as attachment to the diaphysis.
- Mature chondrocytes secrete phosphatase.
- Calcification of extra cellular matrix occurs, cutting off nutrient supply, causing chondrocytes to die.
- Capillaries, osteoblasts and osteoclasts travel to this zone.
- Osteoclasts remove dead, calcified cartilage.
- Osteoblasts lay new bone down on calcified spicules.
- Bone resorption occurs at the boundary of marrow cavity.
-
Describe Woven bone.
- It is the bone initially made during Intramembranous Ossification and Endochondral Ossification.
- Collagen fibers run in all directions (not parallel like lamellar bone).
- Not suitable for stress and strain.
- Provides framework for lamellar bone to be laid down for Bone Remodeling.
-
Describe Lamellar Bone.
- After woven bone is laid down, osteoclasts replace it with lamellar bone.
- Lamellar bone is strong and stable.
- It is deposited in concentric rings around a blood vessel.
- Osteoblasts in lacunae become osteocytes and are connected to the blood supply through the cannaliculi.
-
Describe Cortical Bone.
- Has very distinct and highly-ordered osteons in outer compact layers near external surface of bone.
- Is a thin shell-like layer.
-
Describe Cancellous (Spongy) Bone.
- This is the central portion of most bones.
- It is interspersed with blood-filled cavities called Cancellae.
- The blood in Cancellae nourishes osteocytes.
- (This arrangement takes the place of Haversian Systems in Compact (Cortical) bone).
-
Function of Vitamin A.
Bone Resorption.
-
Function of Vitamin C.
Synthesis of collagen in bone matrix.
-
Function of Vitamin D.
- Converts Vitamin D to 1,25 dihydroxycholecalciferol by a parathormone.
- Affects calcium absorption from gut.
-
Function of Pituitary Growth Hormone.
Stimulates cartilage production in epiphyseal disks.
-
Function of Testosterone.
- Steroidal growth from testes and adrenal cortex.
- Promotes size and strength of bone growth (esp. long bones)
- Stimulates protein synthesis, increasing bone matrix production.
-
Function of Estrogen.
Promotes closure of epiphyseal plates of long bones--terminates lengthening process.
-
Function of Parathyroid hormone.
- Helps osteoclasts absorb Ca2+ and PO42- from bone.
- Maintains a stable blood calcium level.
- Converts Vit. D to 1,25 dihydroxycholecalciferol.
- Affects calcium absorption from gut.
- Affects deposition and reabsorption of bone.
-
Function of Calcitonin.
Promotes osteoblastic activity and deposition of bone
-
Complete fracture
- Bone is broken through completely
- Occurs in adults (due to fully calcified bones)
-
Incomplete fracture
- Aka "green stick fracture"
- Bone is not broken completely through
- Occurs in children (due to the collagen content of bones)
-
Simple Fracture
Skin over the break is intact.
-
Compound fracture
Bone pierces the skin
-
Communited fracture
Splintered or fragmented bone
-
Pathologic Fracture
Occurs in an already diseased bone
-
What are the 3 stages of a Fracture Healing?
- 1. Procallus
- 2. Fibrocartilaginous Callus
- 3. Osseus Callus
-
How long does it take to heal a fracture?
6 weeks
-
What is the primary requirement for a fracture to heal correctly?
- The bones must make contact with one another.
- i.e., "the fracture must be reduced"
-
Describe the Procallus Stage of a healing fracture.
- This stage initially binds the fracture together.
- It takes 48 hours for a blood clot (hematoma) to be converted into soft tissue (procallus).
- Loose network of fibers is laid down.
- RBCs are destroyed, stimulating an inflammatory reaction (swelling, edema)
- Increased blood flow and white cells (by mast cells).
- - Macrophages phagocytize debris
- - Fibroblasts begin to repair by laying down CT
-
Describe the Fibrocartilaginus Callus Stage of a healing fracture.
- This occurs on the 3rd or 4th day.
- Fibroblasts lay down fibrous CT network.
- New chondrocytes form cartilanginous spicules throughout callus.
- After 1 week, early forms of newly formed bone and cartilage are found in the callus.
- Osteoblasts and chondroblasts are made from the periosteum and endosteum of the fracture site.
- Inflammatory response subsides over the next few days.
-
Describe the Osseus Callus Stage of a healing fracture.
- This occurs at the 2-3 week mark of the fracture.
- The healing fractured bone is wider in diameter than the original bone.
- In this stage remodeling begins and continues until it is healed and almost undetectable.
|
|