1 Structure and Function

Question 1

The musculoskeletal system is derived from what embryonic layer?

Answer 1

Mesoderm

Question 2

Embryonal cells that form the teeth and some facial bones, cartilage, and connective tissue of the anterior skull

Answer 2

Cells from the dorsal margins of the embryonic neural crest

Question 3

Embryonal cells that form the axial skeleton

Answer 3

Paraxial mesodermal cells (somites)

Question 4

Embryonal cells that form the appendicular skeleton

Answer 4

Lateral plate mesodermal cells

Question 5

Ossification of the fibrous membranes and hyaline cartilage that constitute the primordial skeletal scaffold begins at

Answer 5

7th week AOG

Question 6

Organic vs Inorganic: Hardness of bone

Answer 6

Organic

Question 7

Organic vs Inorganic: Tensile strength of bone

Answer 7

Organic

Question 8

Organic vs Inorganic: Hydroxylapatite

Answer 8

Inorganic

Question 9

Organic vs Inorganic: Collagen

Answer 9

Organic

Question 10

Organic vs Inorganic: Proteoglycans

Answer 10

Organic

Question 11

Organic vs Inorganic: Calcium and phosphate salts

Answer 11

Inorganic

Question 12

Organic vs Inorganic: Matrix proteins

Answer 12

Organic

Question 13

Organic vs Inorganic: Flexibility of bone

Answer 13

Organic

Question 14

Organic vs Inorganic: Compressive strength

Answer 14

Inorganic

Question 15

Bone classification: Withstand and adapt to fluctuating stresses of weight-bearing

Answer 15

Long

Question 16

Bone classification: Allow for rotation and leverage

Answer 16

Long

Question 17

Bone classification: Support and facilitate movement

Answer 17

Short, cuboid-shaped bones

Question 18

Bone classification: Attachment sites for musculature and shield vital organs

Answer 18

Broad flat bones

Question 19

Bone classification: Protect the face and spinal cord

Answer 19

Irregular

Question 20

Bone classification: Smooth, round ossifications to counteract compressive forces within tendons

Answer 20

Sesamoid

Question 21

The only sesamoid bones consistently present in humans

Answer 21

Patellae

Question 22

Sesamoid bones inconsistently but usually present in humans

Answer 22

(1) Hallux sesamoid bone of the foot (2) Pisiform of the wrist

Question 23

Bone classification based on ossification process

Answer 23

(1) Endochondral (2) Intramembranous

Question 24

Bone classification: Intramembranous

Answer 24

Facial, cranial, and clavicular bones

Question 25

Bone classification: Endochondral

Answer 25

Most appendicular and axial skeleton bones

Question 26

Process of intramembranous ossification

Answer 26

(1) Mesenchymal cells within the unossified skeleton coalesce and then differentiate into either capillaries or osteoblasts (2) Osteoblasts secrete unmineralized osteoid matrix into which mineral salts (calcium and phosphorus) are deposited (3) When ossified, osteoid produced around capillaries becomes honeycomb-like trabecular bone (cancellous or spongy bone) that encroaches on the vasculature, compacting it into red marrow

Question 27

Endochondral vs intramembranous: Progressive replacement of the primordial cartilaginous scaffold with bone

Answer 27

Endochondral

Question 28

Process of endochondral ossification

Answer 28

(1) Mesenchymal stem cells differentiate into cartilage-producing chondrocytes (2) Proliferating chondrocytes synthesize the extracellular matrix comprising predominantly type II collagen, some type IX and XI collagens, and proteoglycans (3) Mature, hypertrophied chondrocytes secrete a matrix rich in type X collagen, which provides the supporting framework (cartilaginous framework) for endochondral ossification (4) When ossified, blood flow to the chondrocytes is impeded, the cells die, and adjacent cartilage breaks down, leaving a medullary cavity into which new vessels invade to deliver bone-producing osteoblasts

Question 29

Site of primary ossification center

Answer 29

Diaphysis

Question 30

Site of secondary ossification center

Answer 30

Epiphysis

Question 31

Site of the cartilaginous growth plate (physis)

Answer 31

Between the epiphysis and diaphysis (metaphysis in adult long bone)

Question 32

Sites of new bone formation but do not contribute to bone length; instead, they generate new bone in response to tendinous or ligamentous traction

Answer 32

Apophyses

Question 33

Apophyses

Answer 33

Tibial tuberosity, posterior calcaneus, greater and lesser trochanters, and iliac crests

Question 34

Fundamental physiological unit of most mammalian compact bone

Answer 34

Osteon

Question 35

Bone contains these 4 cell types

Answer 35

Mesenchymal stem cells Osteoblasts Osteocytes Osteoclasts

Question 36

Location of bone mesenchymal cells

Answer 36

1) Adjacent to vascular channels 2) Periosteum

Question 37

Substances that osteoblasts produce

Answer 37

Organic constituents of bone, mainly collagen Osteocalcin Osteopontin

Question 38

A hormone that acts on pancreatic beta cells to promote insulin production in response to leptin and can activate bone-based adipocytes to regulate insulin responsiveness

Answer 38

Osteocalcin

Question 39

Participates in bone remodeling by securing osteoclasts to the inorganic (mineral) matrix of bone.

Answer 39

Osteopontin

Question 40

Mechanosensory cells of the bone

Answer 40

Osteocytes

Question 41

Mineralizes hydroxylapatite, the bone’s organic matrix

Answer 41

Osteocytes

Question 42

Most abundant bone cells

Answer 42

Osteocytes

Question 43

Cells of the bone that maintain the physiological balance between bone formation and bone resorption, thus preserving bone integrity

Answer 43

Osteocytes

Question 44

Bone cells that mediate bone remodeling in response to mechanical stresses

Answer 44

Osteocytes

Question 45

After birth, longitudinal bone growth occurs from the ___

Answer 45

Epiphyseal plate

Question 46

4 zones of the epiphyseal plate from the top (outermost) to bottom (closest to the diaphysis)

Answer 46

1) Reserve (resting) zone 2) Proliferative zone (young proliferating cartilage) 3) Hypertrophic zone (maturing cartilage with hypertrophic chondrocytes) 4) Calcified zone

Question 47

Diaphyseal vs epiphyseal side of epiphyseal plate: Retained as articular cartilage

Answer 47

Epiphyseal side

Question 48

Diaphyseal vs epiphyseal side of epiphyseal plate: Epiphysis ossifies to increase bone length

Answer 48

Diaphyseal side

Question 49

Conventional methods for assessing skeletal maturation

Answer 49

Tanner-Whitehouse and Greulich-Pyle protocols

Question 50

Radiographs of these sites are used for bone aging using the Tanner-Whitehouse and Greulich-Pyle protocols

Answer 50

Left hand and wrist