Questions: A long bone is covered externally with a sheath called the whereas the marrow cavity is lined with the Multiple Choice epiphysis, diaphysis diaphysis, epiphysis compact bone; spongy bone periosteum; endosteum endosteum; periosteum

The answer is the fourth one: periosteum; endosteum.

Explanation for each option:

1. Epiphysis, diaphysis: These terms refer to parts of the bone itself. The epiphysis is the end part of a long bone, while the diaphysis is the shaft or central part of a long bone. They do not refer to coverings or linings.

2. Diaphysis, epiphysis: This is simply the reverse of the first option and still refers to parts of the bone, not the coverings or linings.

3. Compact bone; spongy bone: These terms describe types of bone tissue. Compact bone is dense and forms the outer layer of the bone, while spongy bone is lighter and found inside bones. They are not the coverings or linings of the bone.

4. Periosteum; endosteum: The periosteum is a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints. The endosteum is a thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity of long bones. This option correctly identifies the external covering and the lining of the marrow cavity.

5. Endosteum; periosteum: This option reverses the correct order. The endosteum lines the marrow cavity, and the periosteum covers the external surface of the bone.

In summary, the correct answer is that a long bone is covered externally with a sheath called the periosteum, whereas the marrow cavity is lined with the endosteum.