You have just received your flu vaccine in your deltoid muscle. explain all of the layers and structures the needle passed through

The layers include the; epidermis, dermis, subcutaneous layer, a connective tissue layer, muscle.

The epidermis is the outermost layer and is made of flat squamous cells that have a lot of keratin.

The dermis is the layer below the epidermis and is much thicker than the epidermis and mainly composed of fibroblasts. It is also filled with blood and lymph vessels, glands and sensory receptors.

The subcutaneous is composed mainly of fat cells, called adipocytes, that act as an insulator layer. The connective tissue layer below has elastin and collagen fibres that connect the skin with the muscle tissue below.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave