Some assaults occur in confined spaces such as an elevator, small room, on public transit, to name a few possibilities. These settings can have a significant impact on how you protect yourself. Here are some potential factors.
Limited space. Due to a small space or a crowd, you will have little opportunity to move and create or sustain space between you and the assailant. Likely you will be forced to fight in close quarters using appropriate tools such as elbows, knees, hooks, uppercuts, pinching biting.. whatever it takes.
Your Immediate Surroundings. Walls, side of a car, tables, chairs, other people (e.g. a crowded subway). You need to be aware of your space. Being pushed into a wall, for instance, presents danger from the pushing assailant and the wall itself. Tables and chairs might prevent an immediate escape or compromise your footing. Alternatively, you might use a table as a barrier or a chair to shield yourself.
Common Objects. Is there something you can use to protect yourself? We already mentioned a chair. In an office setting, there are various items on most desks. You might be carrying a backpack or a water bottle. Use them.
Other people. Are you by yourself or with friends, family or co-workers? You might be in a situation where you are trying to protect a family member. Also, in a crowd there are strangers. Some might be vulnerable (e.g. a subway assault where there are children close by). Some of these strangers might also be working with the primary assailant(s). Be aware.
Escape Routes. There might not be one immediately available (e.g. an elevator or moving subway). Perhaps there is an escape route but it is being blocked by the assailant. How do you get to it?
If you are involved in self-defense training ask your instructor(s) to devote training time to defending in confined spaced and explore numerous scenarios.