Question

the structural units of mature compact bone are called:

lacunae.
osteons.
osteocytes.
canaliculi.

question 61

which key feature distinguishes a synovial joint from other joint types?

presence of cartilage
presence of a joint cavity
presence of collagen fibers
presence of connective tissue

Explanation:

Identify structural units of compact bone

Using the Bone Histology knowledge point

• Compact bone is composed of repeating, cylindrical structural units.
• These microscopic structural units are called osteons (or Haversian systems).
• Lacunae are the small spaces housing osteocytes, and canaliculi are the tiny channels connecting them, which are sub-components rather than the overall structural units.
• Therefore, the correct choice is osteons.

Identify distinguishing feature of synovial joints

• Joints are classified structurally as fibrous, cartilaginous, or synovial.
• While cartilaginous joints contain cartilage and fibrous joints contain collagen fibers/connective tissue, only synovial joints possess a fluid-filled joint cavity (synovial cavity).
• This joint cavity allows for free movement between the articulating bones.
• Therefore, the presence of a joint cavity is the key distinguishing feature.

Answer:

Question 1

• lacunae.
• osteons. (Correct answer)
• osteocytes.
• canaliculi.

Question 2

• presence of cartilage
• presence of a joint cavity (Correct answer)
• presence of collagen fibers
• presence of connective tissue