Microscopic Anatomy of Long/Compact Bone

Question 1

What is the Haversian system or osteon?

Answer 1

• Repeating structural unit of compact bone.
• Elongated cylinder parallel to the long axis of the bone

Question 2

What is the Lamella?

Answer 2

The lamella is each matrix tube in an osteon
* Weight-bearing, column-like matrix tubes composed mostly of collagen
* Looks similar to the rings inside of a tree trunk

Question 3

Circumferential

Answer 3

• Just deep to the periosteum & just superficial to the endosteum.
• Extend around the entire circumference of the diaphysis
• Resists twisting of the long bone

Question 4

Central/Haversian Canal

Answer 4

• Runs through the core of each osteon/Haversian canal
• Contains blood vessels and nerves

Question 5

Volkmann’s Canal

Answer 5

• Lie at right angles to the long axis of the bone.
• Connect the blood & nerve supply of the periosteum to these in the the central canals of the medullary cavity.
• Lined with endosteum.

Question 6

Sharpey’s Fibers

Answer 6

• What the periosteum is secured by
• Tuffs of collagen fibers that extend from fibrous layer into bone matrix.

Question 7

Osteocytes

Answer 7

Mature bone cell

Question 8

Lacunae

Answer 8

• Small cavities in bone that contain osteocytes
• Lacunae in bone are occupied by cells

Question 9

Canaliculi

Answer 9

Hair-like canals connect lacunae to each other and central canal.

Question 10

Which way does the canaliculi run?

Answer 10

It runs parallel to the long axis of the bone.

Question 11

What does the canaliculi connect to?

Answer 11

The canaliculi connect to each other (other lacuna) and other canals

Question 12

Why does the canaliculi connect?

Answer 12

The canaliculi connect cause they need blood and nutrients.

Question 13

What makes up the periosteum?

Answer 13

Dense irregular tissue

Question 14

What does the periosteum do?

Answer 14

The periosteum helps connect tendons to bone.

Question 15

What do the Sharpey’s fibers do?

Answer 15

The Sharpey’s fibers secure the periosteum to the bone.

Question 16

Proximal Epiphysis

Answer 16

Top/Head of the long bone

Question 17

Endosteum

Answer 17

Delicate membrane covering internal surface of bone

Question 18

Diaphysis

Answer 18

• Tubular shaft that forms the axis of a long bone.
• Composed of compact bone that surrounds the medullary cavity

Question 19

Articular Cartilage

Answer 19

• Covers the ends of long bones
• Hyaline cartilage
• Allows smooth movement with little friction

Question 20

Distal Epiphysis

Answer 20

Bottom of a long bone

Question 21

Epiphyseal Plate/Line

Answer 21

Separates the diaphysis from the proximal and distal epiphysis

Question 22

Medullary Cavity

Answer 22

• Contains blood vessels, nervous tissue, and yellow marrow.
• Made of primarily compact bone, but has some spongy bone