The thumb is a unique and complex part of the human hand, notable for its range of motion and ability to oppose the other fingers, a feature crucial for fine motor skills. Here's a brief overview of its anatomy:
1) Bones: The thumb consists of two major bones:
Metacarpal bone: This is the larger bone that forms the base of the thumb, connecting to the wrist.
Phalanges: There are two phalangeal bones in the thumb (as opposed to three in the other fingers). These are the proximal phalanx and the distal phalanx.
2) Joints: The thumb has two primary joints:
Carpometacarpal (CMC) joint: This joint is between the metacarpal bone and the carpal bones of the wrist. It's a saddle joint, allowing for the swiveling and pivoting motions that make the thumb so versatile.
Interphalangeal (IP) joints: These include the metacarpophalangeal (MCP) joint between the metacarpal bone and the proximal phalanx, and the interphalangeal joint between the two phalanges.
3) Muscles and Tendons: Several muscles and tendons control thumb movement:
The opponens pollicis allows the thumb to oppose the fingers.
The abductor pollicis brevis and abductor pollicis longus move the thumb away from the hand (abduction).
The flexor pollicis brevis and flexor pollicis longus bend the thumb (flexion).
The adductor pollicis moves the thumb towards the hand (adduction).
4) Nerves: The thumb is primarily innervated by the median nerve, which provides sensation and motor control.
5) Blood Supply: Blood is supplied to the thumb by branches of the radial and ulnar arteries.
The thumb's unique structure and the ability to oppose the other fingers (opposition) make it crucial for gripping and manipulating objects, setting humans apart in the animal kingdom for fine motor skills and tool use. This complexity also means that injuries to the thumb can be particularly debilitating, requiring careful medical attention.
Two conditions that seem to be occurring more often in our technology based society are painful thumb conditions such as DeQuervain’s tenosynovitis and CMC Osteoarthritis. Let’s explore these conditions.
DeQuervain's tenosynovitis (also called “Texting Thumb”) is a painful condition affecting the tendons on the thumb side of your wrist. It's sometimes known as DeQuervain's syndrome or DeQuervain's disease. Here are the key aspects of this condition:
1) Affected Area: DeQuervain's involves the two tendons that control thumb movement: the abductor pollicis longus and the extensor pollicis brevis. These tendons run side by side through a tunnel (sheath) near the wrist.
2) Symptoms: The primary symptoms of DeQuervain's tenosynovitis include:
Pain or tenderness at the base of the thumb.
Swelling near the base of the thumb.
Difficulty moving the thumb and wrist when doing activities that involve grasping or pinching.
A "sticking" or "stop-and-go" sensation in your thumb when moving it.
3) Causes: The exact cause of DeQuervain's tenosynovitis is not always clear, but it can be associated with:
Repetitive hand or wrist movements, particularly those involving twisting or gripping.
Chronic overuse of the wrist.
Inflammatory conditions, like rheumatoid arthritis.
Pregnancy and hormonal changes can also be contributing factors.
4) Risk Factors: Certain factors can increase the risk of developing DeQuervain's, including:
Gender: It's more common in women than men.
Age: People between the ages of 30 and 50 are at higher risk.
Certain activities: Jobs or hobbies that involve repetitive hand and wrist motions.
5) Diagnosis: Diagnosis is often based on symptoms and a physical examination. A common test is the Finkelstein test, where you bend your thumb across the palm of your hand and bend your fingers down over your thumb, then bend your wrist towards your little finger. If this causes pain on the thumb side of your wrist, it's indicative of DeQuervain's.
6) Treatment: Treatment options may include:
Resting the affected hand and wrist.
Splinting the thumb and wrist to restrict movement.
Anti-inflammatory medications to reduce pain and swelling.
Corticosteroid injections to reduce inflammation.
In severe cases, surgery may be necessary to release the pressure on the tendons.
7) Prevention: Preventive measures can include ergonomic adjustments to work and activity practices, stretches, and exercises to strengthen the wrist and improve flexibility.
Carpometacarpal (CMC) osteoarthritis is a condition that affects the joint located at the base of the thumb, where the thumb metacarpal meets the trapezium bone in the wrist. This particular form of osteoarthritis is also known as thumb arthritis or basal joint arthritis. Here are the key aspects of CMC osteoarthritis:
1) Anatomy Involved: The CMC joint of the thumb is a saddle joint, allowing for a wide range of thumb movements. However, this flexibility also makes it susceptible to wear and tear.
2) Symptoms: The symptoms of CMC osteoarthritis typically include:
Pain at the base of the thumb, especially during activities that involve gripping, pinching, or twisting motions.
Swelling, stiffness, and tenderness at the base of the thumb.
Decreased strength and range of motion in the thumb.
In advanced cases, a bony prominence or bump may develop at the base of the thumb.
3) Causes: The exact cause of CMC osteoarthritis is not always clear, but it is generally attributed to a combination of factors, including:
Age-related wear and tear of the joint.
Previous injuries to the thumb or wrist, such as fractures or sprains.
Repetitive stress on the joint over time.
Genetic predisposition to osteoarthritis.
4) Risk Factors: Certain factors can increase the risk of developing CMC osteoarthritis:
Gender: It's more common in women, especially after menopause.
Age: The risk increases with age.
Certain activities and occupations that place repetitive stress on the thumb joint.
5) Diagnosis: Diagnosis typically involves a physical examination of the thumb and hand, assessment of the symptoms, and imaging tests like X-rays to evaluate the extent of joint damage.
6) Treatment: Treatment for CMC osteoarthritis aims to relieve pain and restore function. It may include:
Nonsteroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation.
Thumb splints or braces to restrict movement and provide support.
Corticosteroid injections into the joint to reduce inflammation.
Physical or occupational therapy to strengthen surrounding muscles and improve joint function.
In severe cases, surgical options such as joint fusion, osteotomy, or joint replacement may be considered.
7) Prevention and Management: While it's difficult to completely prevent CMC osteoarthritis, managing risk factors, maintaining a healthy lifestyle, and protecting the thumb joint from excessive stress can help slow its progression.
One of the things we see in Physical Therapy is that long before arthritic changes have occurred in the carpometacarpal joint, people begin experiencing pain and tightness in the muscles around the base of the thumb.
Both of these conditions respond readily to Trigger point dry needling and ASTYM therapy in conjunction with a home stretching and strengthening program which addresses the chronic inflammation and allows the thumb to heal.
If you would like help treating your thumb condition, please schedule your consult with a Physical Therapist at Lanier Therapy in Motion today.
