Hand Anatomy: Understanding the Structure of Your Hand

Why is it important to understand the anatomy of your hand?

Understanding the anatomy of your hand helps you better recognize your symptoms, understand your injuries, and take an active role in your treatment. As physical therapists who treat hand and wrist conditions, we find that this knowledge helps you put into words what you’re feeling and participate in decisions about your treatment.

What are the main structures of the hand?

The hand consists of bones, joints, ligaments, tendons, muscles, and nerves. Its 27 bones are divided into 8 carpal bones in the wrist, 5 metacarpal bones in the palm, and 14 phalanges in the fingers. An anatomical study confirms the presence of the eight carpal bones in the wrist¹. The hand also consists of several joints, stabilizing ligaments, flexor and extensor tendons, as well as about twenty small muscles located in the hand and about fifteen muscles in the forearm, whose tendons move the wrist or fingers.

The 27 Bones of the Hand

The hand skeleton is divided into three distinct groups:

The Carpus (8 wrist bones):

• First row: scaphoid, lunate, triquetrum, pisiform
  
• Second row: trapezium, trapezoid, capitate, hamate

These small bones articulate with one another to provide the wrist with its complex range of motion. The scaphoid is particularly important because it is frequently fractured when a person falls on their hand.²

A normal initial X-ray does not rule out a scaphoid fracture. After a fall, pain in the wrist on the thumb side warrants prompt medical attention if a fracture is possible. If the examination raises suspicion of a scaphoid fracture despite a normal X-ray, follow the immobilization instructions you have been given. A splint or cast can protect the wrist while the medical team arranges for a reevaluation or further imaging. ²

A scaphoid fracture that is detected too late may not heal properly. A delayed diagnosis complicates treatment, and documented complications include delayed union—when the bone fragments do not fuse properly—or failure to heal. The alignment of the wrist bones may also become distorted, and osteoarthritis may develop. Grip strength—that is, the ability to grasp and hold an object—may decrease. Mobility may also be reduced. ^{2, 3}

The Metacarpus (5 palm bones):
Each metacarpal bone corresponds to a finger. They form the structure of your palm and connect with the carpal bones on one side and the phalanges on the other.

The Phalanges (14 finger bones):

• The fingers (index, middle, ring, and little fingers): 3 phalanges each—the proximal phalanx near the palm, the middle phalanx in the middle, and the distal phalanx at the tip
  
• The thumb: 2 phalanges only (proximal and distal)

The Joints

The hand contains many joints that allow for its exceptional mobility:

• Radiocarpal Joint: Between the forearm (radius) and the first row of carpal bones, it allows for wrist movements
• Carpometacarpal Joints: Connect the carpus to the metacarpus
• Metacarpophalangeal Joints (MCP): The "knuckles" visible when you make a fist
• Interphalangeal Joints (IP): Between the finger phalanges

Ligaments, Tendons, and Muscles

Ligaments stabilize the carpal bones:

• Extrinsic ligaments: connect the radius and ulna to the carpus
  
• Intrinsic ligaments: connect the carpal bones to each other (scapholunate, triquetrolunate)

Tendons transmit muscle force to the bones:

• Flexor tendons: located on the palm, allow you to close your hand
  
• Extensor tendons: located on the back of the hand, allow you to open your fingers

The muscles that move the fingers are located in the palm or the forearm. Their tendons extend into the fingers.

Muscles:

• About 20 intrinsic muscles: located in the hand, they enable fine motor movements
  
• About 15 extrinsic muscles: located in the forearm, they move the wrist or fingers via their tendons

Several muscles form the raised area at the base of the thumb, known as the thenar eminence. These muscles contribute to thumb movement and the pincer grasp.

How does the hand work?

The hand grasps objects firmly and handles small objects with precision.⁴ The thumb performs opposition—the movement that brings it closer to the other fingers to form a pincer grip—while the intrinsic muscles contribute to fine coordination. Sensory receptors and nerves transmit tactile information.

The Two Types of Grip

Power Grip:
You use your entire palm and fingers to grasp heavy or bulky objects. This grip mainly involves the extrinsic muscles of the forearm, which generate significant force.

Precision Grip:
You use your fingertips to manipulate small objects or perform delicate tasks. This grip relies on the intrinsic muscles of the hand, which allow for fine control.

Thumb Opposition: A Unique Movement

The thumb has a unique ability among the fingers: opposition. This movement allows the thumb to touch the tip of each of the other fingers, creating the essential pincer grasp (thumb-to-index finger) needed for so many daily tasks.

This exceptional mobility comes from:

• The carpometacarpal joint of the thumb (saddle-shaped)
  
• The muscles at the base of the thumb, known as the thenar muscles
  
• The orientation of the thumb, relative to that of the other fingers

Fine Coordination and Sensitivity

The intrinsic muscles allow for:

• Independent movement of each finger
  
• Coordination between fingers
  
• Precise adjustments to grip strength

The hand also contains countless nerve endings that provide:

• Tactile sensitivity (texture, temperature)
  
• Proprioception (awareness of finger position in space)
  
• Protection (detecting what could damage tissues)

What are Common Hand Injuries?

Common hand problems include carpal tunnel syndrome, De Quervain’s tenosynovitis, finger sprains, and osteoarthritis. These problems affect the nerves, tendons, ligaments, or joints. The following sections explain each of these conditions.

Carpal Tunnel Syndrome

Carpal tunnel syndrome is one of the most common problems affecting the hand and wrist. It occurs when the median nerve is compressed within the carpal tunnel at the wrist.⁵

Typical Symptoms:

• Numbness in the thumb, index, and middle fingers
  
• Nighttime tingling
  
• Weakness in the thumb-index finger pinch
  
• Pain radiating to the forearm

De Quervain's Tenosynovitis

De Quervain's tenosynovitis affects the tendons of the long abductor and short extensor muscles of the thumb at the wrist. These muscles are responsible for abducting and extending the thumb, respectively. The condition causes friction between the tendons and the tunnel through which they glide.⁶

Topics to discuss during the evaluation:

• Repetitive movements, such as texting or using a mouse: describe the ones that trigger your pain
  
• Twisting movements that trigger or worsen your pain
  
• Pregnancy and the months following childbirth are associated with De Quervain’s disease. In a survey of 121 caregivers, the authors suggest that infant care activities may play a role. Another study of postpartum women found associations with a first pregnancy and a prolonged pregnancy. The precise role of hormones remains unclear.^{7, 8}

Symptoms:

• Pain on the thumb side of the wrist
  
• Visible swelling
  
• Difficulty pinching or gripping

Studies on repetitive work and telephone use report associations with De Quervain's disease. However, they are not sufficient to attribute the condition to a specific movement in an individual.^{9, 10, 11}

Finger Sprains

Sprains occur when the ligaments in the interphalangeal joints are stretched or torn, often during sports or falls.

Among the finger joints, the middle one—the proximal interphalangeal joint—is most commonly affected by dislocation, which occurs when the joint surfaces shift out of alignment. ¹²

Signs of a Sprain:

• Localized pain in the joint
  
• Swelling
  
• Limited movement
  
• Sometimes joint instability

After an injury, go to the emergency room if a finger is misshapen, turns blue, or remains numb, or if a wound exposes bone. These signs may indicate a fracture, a dislocation, or a circulation problem.¹³

Hand Osteoarthritis

Osteoarthritis involves changes in the joints that often come with age, much like gray hair or wrinkles. It particularly affects:

• The joint at the base of the thumb (rhizarthrosis)
  
• The distal interphalangeal joints, near the fingertips
  
• The proximal interphalangeal joints, in the middle of the fingers

Osteoarthritis can be present with or without pain. When it causes pain, it often manifests as stiffness, pain during use, and sometimes visible changes in the shape of the fingers. Physical therapy does not cure osteoarthritis. When osteoarthritis of the hand is painful, exercises and certain orthoses—devices that stabilize a joint—can help reduce pain and make daily activities easier. Orthoses are particularly recommended for osteoarthritis at the base of the thumb. Results vary from person to person.¹⁴

Trigger Finger

Trigger finger—a condition in which a finger gets stuck in a bent position before suddenly snapping back into place—cannot be treated with surgery alone. Experts agree on several treatment options: wearing a splint, cortisone injections, or surgery. ¹⁵

How does physical therapy help with hand problems?

Physical therapy helps treat hand problems through exercises, mobilization techniques, and advice tailored to the patient's symptoms and limited activities.

Physical therapy for wrist and hand pain begins with an assessment of symptoms, range of motion, and the structures that may be affected: bones, ligaments, tendons, and nerves. The treatment plan may include strength, flexibility, and coordination exercises, as well as mobilization and manual techniques tailored to the specific problem.

Comprehensive assessment

Our physical therapists assess your symptoms, your movements, and the structures that may be contributing to the problem:

• Joint tests to assess wrist and finger mobility
  
• Muscle tests to measure grip strength
  
• Sensitivity and strength tests to assess nerve function
  
• Examination of Tendons and Ligaments by Palpation

This assessment helps guide the selection of treatments and exercises tailored to your situation.

Physiotherapy Treatments

Joint Mobilization:
Gentle manual techniques to restore normal movement to the wrist and finger joints.

Neural Mobilization:
Coordinated movements of the arm, wrist, and fingers to improve tolerance for movement when the nerves are sensitive. The median, ulnar, and radial nerves supply different regions of the hand. Your physical therapist selects the movements and adjusts them based on your symptoms.

Therapeutic Exercises:

• Grip strengthening
  
• Flexor and extensor stretches
  
• Fine motor coordination exercises
  
• Proprioception exercises to help you better sense and control the position of your fingers

Soft Tissue Work:
Manual therapy techniques use movements and pressure levels tailored to your tolerance. They can be part of a program designed to relieve pain. In a study of 120 women with carpal tunnel syndrome, a manual therapy program improved pain and function. The results were comparable to those of surgery at 6 and 12 months.¹⁶ This result pertains to a comprehensive program for this condition; it does not prove the isolated effect of a single technique. Progressive exercises remain an important part of your treatment plan, depending on your needs.

Education and Advice:

• Workplace Ergonomics
  
• Modifying repetitive movements
  
• Joint protection strategies
  
• Home exercise program

Physical therapy for wrist and hand pain combines these approaches to help you resume your activities. Your physical therapist monitors your progress and adapts the program to address any lingering issues.

What are some common questions about the anatomy of the hand?

Frequently asked questions about the hand concern its 27 bones, as well as the nerves, muscles, and tendons that enable its movement. The thumb forms a pincer grip with the fingers. The median nerve passes through the carpal tunnel at the wrist. The following answers provide more details about these anatomical landmarks and possible injuries.

How many bones are in the hand?

An adult's hand contains 27 bones divided into three groups: 8 carpal bones (wrist), 5 metacarpal bones (palm), and 14 phalanges (fingers). By way of comparison, both hands together contain 54 bones, which is slightly more than a quarter of all the bones in the human body.

Which nerve passes through the carpal tunnel?

The median nerve passes through the carpal tunnel. Compression of this nerve causes carpal tunnel syndrome. The median nerve primarily transmits sensations from the palmar surface of the thumb, index finger, middle finger, and the half of the ring finger closest to the thumb. It also controls several muscles at the base of the thumb.

Why is the thumb so important?

Thanks to its opposition movement—that is, its ability to touch the other fingers—the thumb plays a unique role in the function of the hand. It enables the thumb-index finger pinch, which is essential for grasping and manipulating objects.

What is the difference between intrinsic and extrinsic muscles?

The intrinsic muscles are located entirely within the hand (about 20 in total). They control fine, precise movements. The extrinsic muscles are located in the forearm, about 15 in total. Their tendons transmit their force to the wrist or fingers. Depending on the muscle, they flex or extend the wrist, or close or open the fingers.

How do hand tendons work?

Tendons act like cords connecting the muscles of the forearm to the bones of the fingers. The flexor tendons (on the palm) allow the fingers to close, while the extensor tendons (on the back of the hand) allow them to open. The fingers are moved by the tendons of muscles located in the palm or forearm.

What is a finger sprain?

A finger sprain occurs when the ligaments that stabilize the joints between the phalanges are stretched or torn. It can cause pain, swelling, and a feeling that the joint is less stable. A fall or a forced movement during sports can injure these ligaments. In a study of school sports injuries among children and adolescents, finger sprains were common in volleyball. Basketball also caused many finger injuries of various types.¹⁷

How to prevent hand injuries?

To prevent injuries:

• Take regular breaks during repetitive tasks
  
• Vary your positions and movements
  
• Maintain good ergonomics at work
  
• Strengthen your grip muscles
  
• Regularly stretch your forearms
  
• Protect your hands during risky activities

If you experience persistent pain, see a physical therapist as soon as possible to identify the problem and adjust your activities accordingly.

References

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3. Almigdad A, Al-Zoubi A, Mustafa A, Al-Qasaimeh M, Azzam E, Mestarihi S, et al. A review of scaphoid fractures, treatment outcomes, and consequences. Int Orthop. 2024;48(2):529-536. ↩ Back to text
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Our physical therapists defined the research strategy, plan, and clinical content of this article. An AI tool assisted with the literature review and text editing to ensure consistency in content and writing style.