3.5 Human Anatomy & Physiology: Cells, Tissues, Body Systems & Facial Structures
Key Takeaways
The NIC outlines list four tissue types (epithelial, connective, nerve, and muscular), and the skin is the body's largest organ.
The trigeminal nerve (cranial nerve V) carries sensation from the face, while the facial nerve (cranial nerve VII) controls the muscles of facial expression.
A muscle's origin is its fixed attachment and its insertion is the movable attachment; microcurrent lifting and lengthening techniques are described by moving between them.
The orbicularis oculi closes the eyelid, the corrugator draws the brows down and together, and the platysma depresses the lower jaw and lip.
The common carotid artery divides into the internal and external carotid arteries, and the external carotid's facial and superficial temporal branches supply the face.
Why Anatomy Appears on the Exam
The NIC Esthetics Combined Practice outline asks candidates to "demonstrate a basic understanding of human physiology and anatomy related to" cells, tissues, organs, and body systems. Advanced Practice questions use the same knowledge indirectly: lymphatic drainage follows neck anatomy, microcurrent moves along muscles, and contraindications depend on the heart, nerves, and hormones.
Cells
The cell is the basic unit of all living things. Each cell has:
- a cell membrane that controls what enters and leaves;
- cytoplasm, the watery fluid where cell work takes place;
- a nucleus that holds the genetic material (DNA) and controls cell activity; and
- organelles such as mitochondria, which produce the cell's energy (ATP).
Cells grow and reproduce by mitosis, in which one cell divides into two identical daughter cells. Metabolism is the sum of a cell's chemical processes: anabolism builds larger molecules and stores energy, and catabolism breaks molecules down and releases energy. In the skin, mitosis takes place in the basal layer (section 3.1).
The Four Tissue Types
| Tissue | Function | Skin and esthetics examples |
|---|---|---|
| Epithelial | Covers and lines surfaces and forms glands | Epidermis, lining of sweat and sebaceous glands |
| Connective | Supports, binds, and protects | Dermis (collagen and elastin), adipose tissue, blood, bone |
| Muscular | Contracts to produce movement | Facial expression muscles, arrector pili, heart |
| Nerve | Carries messages to and from the brain | Sensory nerve endings in the dermis |
Organs and Body Systems
An organ is a structure made of two or more tissue types that performs a specific job, such as the skin, heart, lungs, brain, liver, kidneys, and stomach. The skin is the largest organ of the body. Organs work together in body systems:
| System | Main organs | Why it matters to an esthetician |
|---|---|---|
| Integumentary | Skin, hair, nails, glands | The organ you treat |
| Skeletal | Bones, joints | Bony landmarks guide massage and device placement |
| Muscular | Muscles | Massage, microcurrent, and facial expression lines |
| Nervous | Brain, spinal cord, nerves | Sensation, pain, and seizure-related contraindications |
| Circulatory (cardiovascular) | Heart, arteries, veins, capillaries | Erythema, heat, and pacemaker-related contraindications |
| Lymphatic and immune | Lymph vessels, nodes, spleen | Lymphatic drainage, healing, and infection defense |
| Endocrine | Glands that secrete hormones | Acne, melasma, healing, and sensitivity changes |
| Digestive | Stomach, intestines, liver | Nutrition for skin repair |
| Excretory | Kidneys, bladder, skin, lungs, large intestine | The skin excretes water and salts in sweat |
| Respiratory | Lungs, airways | Oxygen supply; sensitivity to aerosols and fragrance |
| Reproductive | Ovaries, testes | Hormonal effects on sebum and pigmentation |
Bones of the Head and Neck
The cranium protects the brain: frontal (forehead), two parietal, two temporal, occipital (back of the skull), sphenoid, and ethmoid. The facial skeleton includes two nasal bones, two lacrimal bones near the inner eye, two zygomatic (cheek) bones, two maxillae (upper jaw), and the mandible (lower jaw, the only movable skull bone). The hyoid bone sits in the front of the neck, and seven cervical vertebrae form the neck's spine.
Muscles Estheticians Use Most
A muscle's origin is the more fixed attachment; its insertion is the attachment that moves. Its belly is the middle portion. The microcurrent techniques in section 7.2 describe "lifting" as moving probes from the origin and insertion toward the belly, and "lengthening" as moving from the belly outward. The NIC practical microcurrent task lifts the orbicularis oculi, beginning at the corrugator.
| Muscle | Action |
|---|---|
| Frontalis | Raises the eyebrows and wrinkles the forehead |
| Corrugator | Draws the eyebrows down and together (vertical frown lines) |
| Procerus | Pulls the brows down and wrinkles the bridge of the nose |
| Orbicularis oculi | Rings the eye and closes the eyelid |
| Orbicularis oris | Rings the mouth; closes and puckers the lips |
| Zygomaticus major and minor | Pull the corners of the mouth up and out (smiling) |
| Risorius | Draws the corner of the mouth out and back |
| Buccinator | Compresses the cheeks (blowing, chewing) |
| Depressor anguli oris | Pulls the corners of the mouth down |
| Mentalis | Raises and wrinkles the chin |
| Masseter and temporalis | Chewing (muscles of mastication) |
| Platysma | Depresses the lower jaw and lip; neck bands |
| Sternocleidomastoid (SCM) | Turns and bends the head; a landmark for neck lymphatic work |
Nerves of the Face and Neck
- Trigeminal nerve (cranial nerve V): the chief sensory nerve of the face, with ophthalmic, maxillary, and mandibular branches. It also supplies the chewing muscles.
- Facial nerve (cranial nerve VII): the chief motor nerve of the face. It emerges near the lower part of the ear and branches (temporal, zygomatic, buccal, marginal mandibular, cervical) to the muscles of expression.
- Accessory nerve (cranial nerve XI): controls the sternocleidomastoid and trapezius.
Motor points are where a nerve enters a muscle. Light, sub-sensory microcurrent avoids twitching muscles, while galvanic current in milliamperes can stimulate nerves; section 7.2 explains the difference.
Blood Supply
Blood contains red blood cells (carry oxygen), white blood cells (fight infection), platelets (clotting), and plasma (the fluid portion). The common carotid arteries divide into the internal carotid (brain and eyes) and external carotid (face, scalp, neck). External carotid branches include the facial artery (lower face, mouth, nose), the superficial temporal artery (temples and scalp), and the occipital and posterior auricular arteries. Blood returns through the internal and external jugular veins.
Hormones That Change the Skin
- Androgens increase sebum and drive acne (section 3.3).
- Estrogen and progesterone affect pigmentation; pregnancy and hormonal contraceptives are classic melasma triggers.
- Insulin problems (diabetes) slow healing and raise infection risk.
- Thyroid hormones affect skin dryness, sweating, and hair growth.
Tip
Link each structure to a service: the SCM and thyroid cartilage to lymphatic drainage, the facial nerve to motor points, and the carotid branches to why heat makes the face flush.
Which list names the four tissue types in the NIC Combined Practice outline?
Skin, bone, blood, and lymph
Epidermal, dermal, subcutaneous, and fascial
Epithelial, connective, nerve, and muscular
Collagen, elastin, keratin, and melanin
A client cannot raise one side of the mouth after an injury near the ear. Which nerve most likely controls the affected muscles?
Facial nerve (cranial nerve VII)
Accessory nerve (cranial nerve XI)
Optic nerve (cranial nerve II)
Trigeminal nerve (cranial nerve V)
Which muscle closes the eyelid and is the target of the microcurrent lift section on the NIC Advanced Practice practical?
Orbicularis oris
Orbicularis oculi
Zygomaticus major
Depressor anguli oris
Sections you finish are checked off in the contents.