Anatomy and Physiology
Organization of the body
Cells form tissues, tissues form organs, organs form systems, and systems form the organism. Estheticians need working knowledge of the integumentary, skeletal, muscular, nervous, circulatory, lymphatic, and endocrine systems because each affects how skin looks and how treatments are given.
The face and neck
Know the muscles you touch: frontalis raises the brows and wrinkles the forehead; orbicularis oculi closes the eye; orbicularis oris purses the mouth; zygomaticus lifts the corners of the mouth in a smile; masseter and temporalis are muscles of mastication; platysma tenses the neck. Nerves: the facial nerve (cranial nerve VII) is primarily motor to the muscles of facial expression, while the trigeminal nerve (cranial nerve V) carries sensation from the face. Arteries deliver oxygen and nutrients; veins drain; lymph vessels return fluid to lymph nodes in the submental, submandibular, and cervical chains.
Why it matters in the treatment room
Massage is performed in the direction of lymph flow, toward the nodes, with light pressure. Do not massage over swollen, tender, or enlarged nodes - that is a referral, not a treatment. Bones and bony prominences guide where pressure is safe. Endocrine changes (puberty, pregnancy, menopause, stress) show up as oiliness, pigment changes, and dryness.
Trap to watch: questions that call the epidermis a blood-rich layer (it is avascular) or that confuse the sensory and motor cranial nerves.