A child is growing at a rate appropriate for their age. What cells are responsible for the secretion of bone matrix that eventually results in bone growth?

Choice A rationale

Bone densitometry is a non-invasive test that measures bone mineral density (BMD). It helps to identify the presence of osteoporosis and assess fracture risk by comparing the patient's bone density to that of a healthy young adult. Low BMD indicates higher fracture risk. This test is essential for monitoring osteoporosis progression and guiding treatment decisions.

Choice B rationale

Arthrography involves injecting contrast dye into a joint before imaging with X-ray or MRI. It evaluates joint structures, such as cartilage, ligaments, and capsules, but it is not specifically designed to measure bone density or assess fracture risk.

Choice C rationale

A bone scan involves injecting a small amount of radioactive material into the bloodstream, which accumulates in areas of high bone activity. It detects bone abnormalities, such as fractures, infections, or tumors. However, it is not used for assessing bone density or fracture risk.

Choice D rationale

Arthroscopy is a minimally invasive surgical procedure that allows direct visualization of joint structures using a small camera. It is primarily used for diagnosing and treating joint problems, such as torn ligaments or cartilage, but it does not assess bone density or fracture risk.

Choice A rationale

The oculomotor nerve (cranial nerve III) is responsible for innervating the muscles that move the eye and lift the eyelid, as well as controlling pupil constriction and lens shape for focusing.

Choice B rationale

The vestibulocochlear nerve (cranial nerve VIII) is involved in hearing and balance, not in the movement of eye muscles or eyelids.

Choice C rationale

The facial nerve (cranial nerve VII) controls muscles of facial expression, taste sensations from the anterior two-thirds of the tongue, and functions in tear and saliva production.

Choice D rationale

The trigeminal nerve (cranial nerve V) is responsible for sensation in the face and motor functions such as biting and chewing, not for eye movements.