3.2 Anatomy of the Hand, Arm, Foot & Lower Leg
Key Takeaways
- The human hand and wrist comprise 27 bones (8 carpals, 5 metacarpals, 14 phalanges), while the foot and ankle consist of 26 bones (7 tarsals, 5 metatarsals, 14 phalanges).
- The forearm contains two bones: the radius on the lateral (thumb) side and the ulna on the medial (little finger) side, which is larger at the elbow forming the olecranon process.
- Key muscle movements include flexors (bend joints inward), extensors (straighten joints), pronators (turn palm down), and supinators (turn palm up).
- Nerve control in the lower arm and hand relies on the radial, median, and ulnar nerves; compression of the median nerve in the wrist causes Carpal Tunnel Syndrome.
- Primary arterial blood supply to the hand is delivered by the radial and ulnar arteries, which form palmar arches supplying digital arteries to the matrix and fingertips.
Last updated: August 2026
Anatomy of the Hand, Arm, Foot & Lower Leg
Professional nail technicians in New York State perform extensive work on the hands, wrists, arms, feet, and lower legs. A comprehensive understanding of the skeletal (osteology), muscular (myology), nervous (neurology), and circulatory (angiology) systems of the extremities is vital for delivering safe massage treatments, avoiding nerve compression, maintaining ergonomic posture, and recognizing anatomical landmarks during manicures and pedicures.
Skeletal System: Bones of the Extremities
The human body contains 206 bones, over half of which are located in the hands and feet.
Bones of the Hand and Wrist (27 Total Bones)
The hand and wrist unit consists of 27 bones organized into three functional divisions:
- Carpus (Wrist): Composed of 8 carpal bones arranged in two transverse rows of four:
- Proximal Row (thumb to pinky): Scaphoid (boat-shaped, most frequently fractured wrist bone), Lunate (crescent-shaped), Triquetrum (three-cornered), and Pisiform (pea-shaped sesamoid bone resting on triquetrum).
- Distal Row (thumb to pinky): Trapezium (articulates with thumb metacarpal), Trapezoid (smallest distal bone), Capitate (largest carpal bone), and Hamate (hooked bone).
- Metacarpus (Palm): Composed of 5 metacarpal bones numbered I through V starting from the thumb (radial side) to the little finger (ulnar side).
- Phalanges (Digits/Fingers): Composed of 14 phalangeal bones:
- Each of the four fingers contains 3 phalanges: proximal, middle, and distal.
- The thumb (pollex) contains only 2 phalanges: proximal and distal.
Bones of the Forearm and Arm
- Radius: The lateral bone of the forearm on the thumb side; shorter than the ulna, rotates around the ulna to produce pronation and supination, smaller at the elbow and wider at the wrist.
- Ulna: The medial bone of the forearm on the little finger side; longer than the radius, larger at the elbow forming the prominent olecranon process (elbow point).
- Humerus: The single large long bone of the upper arm, articulating with the shoulder girdle and radius/ulna at the elbow joint.
Bones of the Foot and Ankle (26 Total Bones)
The foot and ankle unit consists of 26 bones structured to bear weight and propel the body:
- Tarsus (Ankle & Heel): Composed of 7 tarsal bones:
- Talus: Ankle bone that articulates superiorly with the tibia and fibula to form the ankle joint.
- Calcaneus: Heel bone; the largest and strongest tarsal bone in the foot.
- Navicular: Boat-shaped bone lying between the talus and cuneiforms.
- Cuboid: Cube-shaped bone located on the lateral side of the foot.
- Cuneiforms: Three wedge-shaped bones (Medial, Intermediate, and Lateral) situated between the navicular and metatarsals.
- Metatarsus (Instep/Midfoot): Composed of 5 metatarsal bones numbered I through V from the big toe to the little toe.
- Phalanges (Toes): Composed of 14 phalangeal bones:
- Four lesser toes each contain 3 phalanges: proximal, middle, and distal.
- The big toe (hallux) contains only 2 phalanges: proximal and distal.
Bones of the Lower Leg
- Tibia: Shin bone; the larger, medial, weight-bearing bone of the lower leg.
- Fibula: The smaller, lateral bone of the lower leg running parallel to the tibia; provides muscle attachment but does not bear body weight.
- Patella: Kneecap; a sesamoid bone protecting the knee joint.
Muscular System: Movement & Mechanics
Muscles contract to produce movement of joints. Nail technicians must understand muscle actions to perform relaxing massage strokes (effleurage, petrissage) along muscle fibers.
| Muscle Group | Primary Movement & Function | Location & Application in Nail Services |
|---|---|---|
| Flexors | Bend joints inward toward the body (e.g., flexing wrist/fingers). | Located on anterior forearm; targeted during lower arm massage to relieve palm tension. |
| Extensors | Straighten joints outward away from the body. | Located on posterior forearm; massage relieves dorsal wrist and finger tension. |
| Pronators | Turn the forearm and hand inward so the palm faces downward (pronation). | Pronator teres in forearm; active when client turns hand palm down for nail polish application. |
| Supinators | Turn the forearm and hand outward so the palm faces upward (supination). | Supinator muscle; active when turning hand palm up for palm massage. |
| Abductors | Draw fingers or toes apart, moving away from the hand/foot midline. | Interosseous muscles; flexed during finger spreading for manicure separation. |
| Adductors | Draw fingers or toes together, moving toward the hand/foot midline. | Interosseous muscles; relaxed when resting hand in natural anatomical position. |
| Tibialis Anterior | Dorsiflexes and inverts the foot (pulls toes upward toward shin). | Anterior lower leg muscle massaged during leg pedicures. |
| Gastrocnemius & Soleus | Plantar flexes foot (points toes downward); calf muscles. | Posterior lower leg; primary target for deep kneading massage during pedicures. |
Nervous & Circulatory Systems
Nerves of the Upper and Lower Extremities
- Radial Nerve: Supplies the thumb side of the arm and back of the hand.
- Median Nerve: Passes down the forearm through the carpal tunnel at the wrist, supplying sensory impulses to the thumb, index finger, middle finger, and half of the ring finger. Compression leads to Carpal Tunnel Syndrome.
- Ulnar Nerve: Runs along the little finger side of the arm, supplying the pinky finger and ulnar side of the ring finger.
- Digital Nerves: Sensory nerve endings branching into the fingers and toes.
- Tibial & Peroneal Nerves: The sciatic nerve divides in the thigh into the tibial nerve (supplies calf and sole of foot) and common peroneal/fibular nerve (supplies anterior leg and top of foot).
Blood Supply of the Hand and Foot
- Arterial Supply to Hand: The brachial artery splits at the elbow into the radial artery (thumb side) and ulnar artery (pinky side). These unite in the hand to form the superficial and deep palmar arches, which send digital arteries to nourish matrix beds and fingertips.
- Arterial Supply to Foot: The anterior tibial artery becomes the dorsalis pedis artery on top of the foot, while the posterior tibial artery supplies the sole via plantar arteries.
- Venous System: Deoxygenated blood is returned via deep veins and superficial veins, including the cephalic and basilic veins in the arm, and the great and small saphenous veins in the lower leg. Technicians must avoid heavy pressure over varicose saphenous veins during pedicure massage.
Test Your Knowledge
Which carpal bone is located on the thumb side of the proximal row of the wrist and is the most frequently fractured wrist bone?
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Test Your Knowledge
Which nerve passes through the carpal tunnel of the wrist and supplies sensory sensation to the thumb, index finger, middle finger, and half of the ring finger?
A
B
C
D
Test Your Knowledge
The foot and ankle structure consists of how many total bones?
A
B
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D