C6 7-11

Question 1

Gross anatomy of a long bone?

Answer 1

Diaphysis, medullary cavity, epiphyses, epiphyseal line or plate.
Has periosteum, endosteum

Question 2

Gross anatomy of a flat bone?

Answer 2

Thin layer of diploe covered by compact bone. Periosteum/endosteum. Contain marrow, but do not have a defined cavity.

Question 3

Diploe

Answer 3

Internal layer of SPONGY bone in flat, short and irregular bones

Question 4

Diaphysis

Answer 4

tubular shaft consisting of compact bone

Question 5

Epiphyses

Answer 5

expanded area at each end of the diaphysis in a long bone.
containing mostly spongy bone
Layer of articular cartilage

Question 6

Epiphyseal line and plate

Answer 6

Hyaline cartilage at the junction of the diaphysis and epiphysis that provides for growth at the end of a long bone. (Plate = young, line = adult)

Question 7

Periosteum

Answer 7

Double layered CT that covers and nourishes the bone (does not cover joint surfaces) (fibrous layer dense irreg, osteogenic layer of osteogenic stem cells)

Question 8

Endosteum

Answer 8

Covers internal bone surfaces. Contains osteogenic cells, osteoblasts, osteoclasts

Question 9

Medullary cavity

Answer 9

Central cavity of a long bone. Contains yellow or red marrow.

Question 10

Trabeculae

Answer 10

Strut or thin plate in SPONGY bone
(Align precisely along lines of stress and help bones resist stress)
Only a few cells thick, contain irregularly arranged lamellae, osteocytes and are connected by canaliculi

Question 11

Yellow marrow - location/function

Answer 11

LOC: medullary cavity, spongy bone FCTN: fat storage

Question 12

Red marrow - location/function

Answer 12

LOC: trabecular cavities in spongy bone in long bones, diploe of flat bones.
FCTN: hematopoiesis
(in adults red marrow is found in ends of pelvis/femur/humerus, vertebrae bodies, ribs, sternum.)

Question 13

Articular cartilage

Answer 13

Hyaline CT that covers the end of bones rather than periosteum

Question 14

Cells in bone?

Answer 14

Osteogenic, osteoblasts, Osteoclasts, osteocytes

Question 15

Osteogenic cell function?

Answer 15

Mesenchymal stem cells that divide to produce osteoblasts. Found in the inner layer of periosteum and the endosteum.

Question 16

Osteoblast cell function?

Answer 16

Produce new bone matrix (ossification). Release the proteins and other organic components of matrix. (matrix is called osteoid)

Question 17

Osteoclast cell function?

Answer 17

Break down bone (osteolysis/resorption) via proteases (protein digesting and acids). Important in Ca and phosphate homeostasis. Giant cells with 50 or more nuclei. Not related to osteoprogenitor cells or their descendents - derived from the samestem cells that produce monocytes and macrophages

Question 18

Osteocyte function?

Answer 18

Maintain present bone. Mature bone cells that make up most of cell population.

Question 19

Compact bone?

Answer 19

relatively solid, forms a sturdy protective layer that usually surrounds a medullary cavity with osteons. Contains: Osteons, lamellae, central haversian/volkmann’s canals, osteocytes, lacunae, canaliculi

Question 20

Spongy or cancellous bone?

Answer 20

consists of an open network of struts [trabeculae] and plates that resembles latticework with a thin covering Contains: trabeculae. Can contain either red or yellow marrow

Question 21

Osteon/Haversian system

Answer 21

basic functional unit of mature compact bone. Compressional strength comes from matrix - resilience comes from collagen fibers.

Question 22

Lamellae

Answer 22

• layers of matrix/matix tube in compact bone.
• Collagen fibers alternate direction in the lamella.
• withstand torsion

Question 23

Central (haversian) canals

Answer 23

Run thru core of Osteon, contain blood vessels and nerve fibers

Question 24

Volkmann’s canals

Answer 24

Lie at right angles to long axis of bone and connect blood and nerve supply to medullary cavity

Question 25

Canaliculi

Answer 25

Tiny canals that connect osteocytes in the lacunae with one another (communication) and allow for nutrients and wastes to be relayed.

Question 26

Chemical composition of bones - organic

Answer 26

Cells, osteoid (matrix - proteoglycans/glycoproteins/collagen)
Give bone tensile strength by resisting stretching and twisting and contribute to overall flexibility.

Question 27

Chemical composition of bones - inorganic

Answer 27

Calcium phosphate (primary) + calcium hydroxide forms crystals of hydroxyapatite. Include other salts and ions also. Crystals harden the matrix and account for the rigidity or relative inflexibility of bone that provide its compressioinal strength.

Question 28

Two types of bony skeleton formation?

Answer 28

Intramembranous ossification, edochondral ossification

Question 29

Intramembrous ossification steps

Answer 29

Almost always flat bone.

1. ossification centers appear in the fibrous ct membrane.
2. Osteoid is secreted by mesenchymal cells within the fibrous membrane and calcifies and trapped osteoblasts become osteocytes.
3. Woven bone and periosteum form.
4. lamellar bone replaces woven bone, just deep to the periosteum and red marrow appears

Question 30

Endochondral ossification steps

Answer 30

Almost all bone except flat bone. 1. bone collar forms around diaphysis of the hyaline cartilage model.

2. cartilage in the center of the diaphysis calcifies and then develops cavities.
3. The periosteal bud invades the internal cavities and spongy bone forms.
4. Diaphysis elongates, medullary cavity forms, ossification centers appear in epiphysis
5. Epiphysis ossify, hyaline remains only in epiphyseal plates and articular cartilage

Question 31

Lacunae

Answer 31

Small space/depression/cavity. Lacunae at the junctions of lamellae are occupied by osteocytes

Question 32

Osteoid

Answer 32

Unmineralized bone matrix

Question 33

Ossification/osteogenesis

Answer 33

Process of bone formation

Question 34

What does an osteon consist of?

Answer 34

Lamellae, central/haversian canals, volkmanns canals, osteocytes in lacunae, canaliculi

Question 35

Endochondral vs intramembranous

Answer 35

ORIGIN TISSUE: I = membranes of embryonic ct, E = preformed in hyaline cartilage
OSTEOBLAST ORIGIN: I = ct cells become osteoblasts, E = cartilage is calcified and osteoblasts derive from perichondrium
GROWTH: I = osteoblasts from the periosteum deposit compact bone over spongy, I = osteoblasts of periosteum form collar of compact bone that grows towards the end of each bone
WHERE: I = skull bones, E = most bones of the body