You have just received your flu vaccine in your deltoid muscle. Explain all of the layers and structures the needle passed through, from impact to muscle.

The layers and structures the needle passed through are - epidermis, dermis, subcutaneous layer or hypodermis, connective tissue layer and muscle.

The epidermis is the outermost layer of the three layers that make up the skin, the inner layers being the dermis and hypodermis. The connective tissues connects, binds and separates other tissues or organs. Muscles are soft tissues found in the body. They function to produce force and motion.