The answer is upside-down. Mud cracks spread downward keen on soft sediment. When more sediment is eroded in, this second layer will seal the cracks underneath. Later, after the layers have toughened, the rock may be rotated upside-down and then the layers cracked. If you see edges in a mud-crack pattern, you are seeing at the side of the second layer that initially was down. You can tell that this shows edges, and not holes, through the shadow, the edges have a well-lit on one side and a shadow on the other, while holes have light and shadow on the similar side.
Antibiotics are usually derived from bacteria.
You are giving your hypothesis.
The nurse should assess the patient vital sign and notify the healthcare provider. For 2.5 hour after neck dissection, production of 40ml by the drainage is a bit excessive. There might be a bleeding in the site of operation that becomes the source of the drainage. Change dressing will not do anything. Applying pressure can be done if the site of bleeding is known.