6.2 Body Systems of the Arms, Hands, Legs & Feet
Key Takeaways
- The hand contains 27 bones — 8 carpals, 5 metacarpals and 14 phalanges — with the distal phalanx directly beneath each nail unit; the foot contains 26, including the calcaneus under the heel.
- Massage is directed from insertion toward origin, working the limb toward the heart, which supports venous return without amounting to lymphatic drainage — a service OAC 4713-1-07(G)(3) places outside the licence.
- The median nerve is compressed at the wrist in carpal tunnel syndrome, and sustained wrist flexion, repetitive gripping and e-file vibration are the technician's classic occupational exposures.
- Peripheral neuropathy destroys protective sensation, so water temperature is verified with a thermometer or the inner wrist rather than by asking the client whether it feels comfortable.
- Compromised peripheral circulation means impaired healing and immune delivery, which is the mechanism behind serious post-pedicure infections in clients with diabetes or peripheral arterial disease.
Body Systems of the Arms, Hands, Legs and Feet
Ohio State Board Exam Alert: "Body Systems / Physiology" is a named sub-topic of the 20 % Anatomy & Physiology domain, and Ohio's own 200-hour curriculum lists "general anatomy" under General Sciences. Expect items naming a bone, a muscle, a nerve or an artery of the limb a manicurist actually touches — and items that use those names to define the legal massage boundary.
A manicurist massages the hands and forearms to the elbow and the feet and lower legs to the knee. Knowing what lies under those surfaces is the difference between a competent massage and one that puts pressure where it does not belong.
1. The Eleven Body Systems in One Table
| System | Principal function | Contact point for a nail technician |
|---|---|---|
| Integumentary | Skin, hair, nails; protection and temperature regulation | The entire working surface |
| Skeletal | Framework, protection, mineral storage, blood cell production | Phalanges, metacarpals, carpals, radius, ulna, tarsals, metatarsals |
| Muscular | Movement and posture | Intrinsic hand and foot muscles; the technician's own overuse injuries |
| Nervous | Controls and coordinates all other systems | Dense sensory supply of fingertips and soles |
| Circulatory (cardiovascular) | Moves blood, oxygen and nutrients | Capillary bed of the nail bed; peripheral circulation in diabetic clients |
| Lymphatic / immune | Drains excess fluid, fights infection | Why lymphatic drainage is expressly out of scope under OAC 4713-1-07(G)(3) |
| Endocrine | Hormonal regulation | Thyroid and pregnancy effects on nail growth |
| Digestive | Breaks down food | Nutritional deficiency shows in nail quality |
| Excretory | Eliminates waste | Sweat glands; kidney disease shows in nail colour changes |
| Respiratory | Gas exchange | Chemical vapour and dust exposure is a respiratory hazard |
| Reproductive | Reproduction | Pregnancy is a chemical-exposure consideration |
2. Bones of the Arm and Hand
| Bone | Location | Count |
|---|---|---|
| Humerus | Upper arm | 1 |
| Ulna | Forearm, little-finger side | 1 |
| Radius | Forearm, thumb side | 1 |
| Carpals | Wrist, in two rows | 8 |
| Metacarpals | Palm | 5 |
| Phalanges (digits) | Fingers — three per finger, two in the thumb | 14 |
The hand contains twenty-seven bones in total (8 carpals + 5 metacarpals + 14 phalanges). The distal phalanx of each digit is the bone directly beneath the nail unit, which is why a heavy blow to a fingertip can produce both a subungual haematoma and a fracture — and why any dark, spreading, painful discolouration after trauma is a referral, not a cover-up with polish.
3. Bones of the Lower Leg and Foot
| Bone | Location | Count |
|---|---|---|
| Tibia | Larger inner bone of the lower leg | 1 |
| Fibula | Smaller outer bone of the lower leg | 1 |
| Talus (ankle) | Joins tibia and fibula to the foot | 1 |
| Tarsals | Ankle and rear foot, including the calcaneus (heel) | 7 |
| Metatarsals | Long bones of the mid-foot | 5 |
| Phalanges | Toes — three per toe, two in the great toe | 14 |
The foot has twenty-six bones. The calcaneus is the largest tarsal and the bone under the heel, which is where callus forms in response to load — and where a technician is most tempted to over-file.
4. Muscles a Manicurist Works Over
| Muscle | Location | Action |
|---|---|---|
| Flexors | Anterior forearm | Bend the wrist and draw the hand toward the arm |
| Extensors | Posterior forearm | Straighten the wrist, hand and fingers |
| Pronator | Forearm | Turns the palm downward |
| Supinator | Forearm | Turns the palm upward |
| Abductors | Base of the thumb and between metacarpals | Separate the fingers |
| Adductors | Palm, between metacarpals | Draw the fingers together |
| Tibialis anterior | Front of the lower leg | Lifts the foot upward and inward (dorsiflexion) |
| Gastrocnemius / soleus | Calf | Point the foot downward (plantar flexion) |
| Extensor digitorum longus | Front of the lower leg | Straightens the toes |
Abductors and adductors are the small muscles between the metacarpals — the ones a technician separates and works during the finger portion of a hand massage.
Massage direction principle: massage is generally directed from the insertion toward the origin — that is, from the movable attachment toward the fixed attachment — which in practice means working the limb toward the heart, supporting venous and lymphatic return without ever claiming to perform lymphatic drainage, which Ohio places outside the licence.
5. Nerves of the Hand and Foot
| Nerve | Supplies |
|---|---|
| Ulnar nerve | Little-finger side of the arm and palm |
| Radial nerve | Thumb side of the arm and back of the hand |
| Median nerve | Forearm and hand; compressed at the wrist in carpal tunnel syndrome |
| Digital nerves | The fingers and toes themselves |
| Tibial nerve | Sole of the foot; compressed in tarsal tunnel syndrome |
| Common peroneal / superficial peroneal | Front and outer lower leg and top of the foot |
The median nerve is the one that matters to the technician personally: sustained wrist flexion, repetitive gripping and vibration from an electric file are the classic contributors to carpal tunnel syndrome, which is why neutral wrist posture is an occupational safety issue and not merely a comfort preference.
Sensory loss is the one that matters to the client. A client with peripheral neuropathy — most often from diabetes — may not feel water that is too hot, a file that is too aggressive, or a nick that draws blood. Loss of protective sensation is why the temperature of a pedicure bath is checked with a thermometer or the inner wrist and never by asking the client whether it feels comfortable.
6. Circulation to the Extremities
| Vessel | Role |
|---|---|
| Ulnar and radial arteries | Supply oxygenated blood to the forearm and hand |
| Digital arteries | Supply the fingers; branches feed the nail bed capillary network |
| Popliteal, anterior and posterior tibial arteries | Supply the lower leg and foot |
| Dorsalis pedis artery | Runs across the top of the foot; the pulse a clinician checks for peripheral circulation |
| Ulnar, radial, saphenous veins | Return deoxygenated blood toward the heart |
The pink colour of a healthy nail plate comes from the capillary bed of the nail bed showing through translucent keratin. That is why blanching under pressure and rapid return of colour indicates good perfusion, and why a persistently pale, dusky or blue nail bed is a circulatory sign that belongs with a physician.
Three service consequences follow directly:
- Massage supports venous return, which is a genuine physiological benefit and may be described as such — but a claim that it treats poor circulation, lymphoedema or vascular disease is a medical claim barred by OAC 4713-8-07(D).
- Compromised peripheral circulation raises the stakes on every break in the skin. Diminished blood flow means diminished healing and diminished immune delivery, which is the mechanism behind serious post-pedicure infections in clients with diabetes or peripheral arterial disease.
- Heat and pressure both need moderating where circulation or sensation is impaired: warm rather than hot water, light rather than deep massage, abrasives rather than blades.
How many bones are in the human hand, and which bone lies directly beneath the nail unit of each finger?
A pedicure client has diabetic peripheral neuropathy. Which physiological fact most directly changes how the service must be delivered?
Which nerve is compressed in carpal tunnel syndrome, and why does that matter to a working nail technician?