Which of the following are only found in spongy bone? a. canaliculi b. Volkmann's canals c. trabeculae d. calcium salts

First, let's define each option given: a. Canaliculi: Small channels within the bone that connect individual osteocytes (bone cells) and allow them to communicate and exchange nutrients. b. Volkmann's canals: Canals that run perpendicular to the long axis of the bone, connecting the blood vessels inside the bone with those in the periosteum (outer layer of the bone). c. Trabeculae: Lattice-like network of bony spicules found in spongy bone, providing structural support and reducing weight. d. Calcium salts: Inorganic minerals that make up a significant portion of bone tissue, providing rigidity and strength to the bone matrix.

Now, let's analyse which option(s) are unique to spongy bone as compared to compact bone: a. Canaliculi are found in both spongy and compact bone since they are necessary for osteocyte communication and nutrient exchange. b. Volkmann's canals are primarily found in compact bone, as they help to connect blood vessels between the Haversian systems (structural units of compact bone). c. Trabeculae are composed of spongy bone and are not found in compact bone. They are unique to spongy bone, providing structural support and reducing weight in regions where forces are applied from various directions. d. Calcium salts are present in both spongy and compact bone, contributing to the rigidity and strength of the bone matrix.

Based on our analysis, we can conclude that the correct answer is: c. Trabeculae, as they are only found in spongy bone and provide structural support and weight reduction in areas where forces are applied from various directions.