Hand & Wrist
Hand and Wrist Anatomy
The hand in the human body is made up of the wrist, palm, and fingers. The most flexible part of the human skeleton, the hand enables us to perform many of our daily activities. When our hand and wrist are not functioning properly, daily activities such as driving a car, bathing, and cooking can become impossible.
The hand’s complex anatomy consists of 27 bones, 27 joints, 34 muscles, over 100 ligaments and tendons, numerous blood vessels, nerves, and soft tissue.
It is important to understand the normal anatomy of the hand in order to learn about diseases and conditions that can affect our hands.
The wrist is comprised of 8 bones called carpal bones. These wrist bones connect to 5 metacarpal bones that form the palm of the hand. Each metacarpal bone connects to one finger or a thumb at a joint called the metacarpophalangeal joint, or MCP joint. This joint is commonly referred to as the knuckle joint.
The bones in our fingers and thumb are called phalanges. Each finger has 3 phalanges separated by two joints. The first joint, closest to the knuckle joint, is the proximal interphalangeal joint or PIP joint. The second joint nearer the end of the finger is called the distal interphalangeal joint, or DIP joint. The thumb in the human body only has 2 phalanges and one interphalangeal joint.
Soft Tissue Anatomy
Our hand and wrist bones are held in place and supported by various soft tissues. These include
- Cartilage: Shiny and smooth, cartilage allows smooth movement where two bones come in contact with each other.
- Tendons: Tendons are soft tissue that connects muscles to bones to provide support. Extensor tendons enable each finger to straighten.
- Ligaments: Ligaments are strong rope like tissue that connects bones to other bones and help hold tendons in place providing stability to the joints. The volar plate is the strongest ligament in the hand and prevents hyperextension of the PIP joint.
- Muscles: Muscles are the fibrous tissues capable of contracting to cause body movement.
Interestingly, the fingers contain no muscles. Small muscles originating from the carpal bones of the wrist are connected to the finger bones with tendons. These muscles are responsible for movement of the thumb and little finger enabling the hand to hold and grip items by allowing the thumb to move across the palm, a movement referred to as thumb opposition. The smallest muscles of the wrist and hand are responsible for fine motor movement of the fingers.
- Nerves: Nerves are responsible for carrying signals back and forth from the brain to muscles in our body, enabling movement and sensation such as touch, pain, and hot or cold. The three main nerves responsible for hand and wrist movement all originate at the shoulder area and include the following
Radial: The radial nerve runs down the thumb side of the forearm and provides sensation to the back of the hand from the thumb to the third finger.
Median: The median nerve travels through the wrist tunnel, also called carpal tunnel, providing sensation to the thumb, index finger, long finger, and part of the ring finger.
Ulnar: The ulnar nerve travels through a tunnel in the wrist called Guyon’s tunnel formed by two carpal bones and the ligament that connects them together. The ulnar nerve supplies feeling to the little finger and half of the ring finger.
- Blood Vessels: The two main vessels of the hand and wrist are:
Radial Artery: The radial artery is the largest artery supplying the hand and wrist area. Traveling across the front of the wrist, nearest the thumb, it is this artery that is palpated when a pulse is counted at the wrist.
Ulnar Artery: The ulnar artery travels next to the ulnar nerve through Guyon’s canal in the wrist. It supplies blood flow to the front of the hand, fingers and thumb.
- Bursae: Bursae are small fluid filled sacs that decrease friction between tendons and bone or skin. Bursae contain special cells called synovial cells that secrete a lubricating fluid. When this fluid becomes infected, a common painful condition known as bursitis can develop.
Biomechanics is a term to describe movement of the body. The fingers of the hand permit the following movements at the metacarpophalangeal joint (MCP) or knuckle joint.
Flexion: Moving the base of the finger towards the palm.
Extension: Moving the base of the fingers away from the palm.
Adduction: Moving the fingers toward the middle finger.
Abduction: Moving the fingers away from the middle finger.
Flexion: Moving the last two segments of the finger towards the base of the fingers.
Extension: Moving the last two segments of the finger away from the base of the fingers.
Biomechanics of the wrist include the following:
Flexion: Moving the palm of the hand towards the front of the forearm.
Extension: Moving the back of the hand towards the back of the forearm.
Adduction: Moving the pinky side of the hand toward the outer aspect of the forearm.
Abduction: Moving the thumb side of the hand toward the inner aspect of the forearm.
The thumb performs different movements at three separate joints. The carpometacarpal joint is where the wrist bones, carpals, meet the metacarpals, the bones in the palm of the hand. At this articulation, the following movements can be performed.
Abduction: Moving the bone below the thumb towards the palm of the hand.
Extension: Moving the bone below the thumb away from the hand.
Adduction: Moving the bone below the thumb towards the back of the wrist.
Abduction: Moving the bone below the thumb towards the front of the wrist.
Opposition: Moving the thumb across the palm of the hand touching the other fingers.
The following movements occur at the metacarpophalangeal joint or MCP joint at the base of the thumb.
Flexion: Moving the joint at the base of the thumb towards the heel of the hand.
Extension: Moving the joint at the base of the thumb away from the heel of the hand.
Adduction: Movement of the thumb base towards the back of the hand.
Abduction: Movement of the thumb base away from the back of the hand.
At the interphalangeal joint of the thumb or IP joint, the following movements can be performed:
Flexion: Bending the top of the thumb towards the base of the thumb.
Extension hyperextension: Moving the top of the thumb away from the base of the thumb.
De Quervain's Tenosynovitis
The muscles and bones of the hand are connected by thick flexible tissue called tendons. Tendons are covered by a thin soft sheath of tissue known as synovium. Extensor pollicis brevis and abductor pollicis longus are two tendons located on the thumb side of the wrist. Inflammation and swelling of the tendon sheaths puts pressure on the adjacent nerves and leads to pain and numbness in the thumb side of the wrist.
Strain on these tendons can cause swelling and irritation and lead to a condition called De Quervain's tenosynovitis, which is characterized by inflammation. The condition is also referred to as De Quervain’s tendinitis, De Quervain’s tendinosis, De Quervain syndrome, or De Quervain’s disease.
The exact cause of De Quervain’s tenosynovitis is unknown, but is usually seen in individuals with repetitive hand or wrist movements, injury to the wrist or tendon, and inflammatory conditions such as rheumatoid arthritis and inflammatory arthritis. De Quervain’s tenosynovitis is most common in pregnant and middle age women.
Signs and Symptoms
The symptoms of De Quervain's tenosynovitis include pain and tenderness on the side of the wrist at the base of the thumb. You may also have a little swelling and redness in the area. Your symptoms may get worse while making a fist, grasping or gripping things, or turning the wrist. You may experience a "catching" or "snapping" sensation while moving your thumb.
Your physician diagnoses De Quervain’s tenosynovitis by observing your symptoms, medical history, and performing a physical examination of the wrist. De Quervain’s tenosynovitis can be confirmed through the Finkelstein test. For this test your doctor will ask you to make a fist with your fingers covering the thumb and bend the wrist towards the little finger. Pain during this movement will confirm the condition.
Treatment of De Quervain’s syndrome consists of both non-surgical and surgical therapy.
Non-surgical therapy includes avoiding activities that increase pain and swelling, applying ice, using a splint to support and immobilize the hand, and physical therapy. Anti-inflammatory drugs are helpful in relieving pain and swelling. Your physician may also recommend a corticosteroid injection to reduce the swelling of the tendon sheath.
Surgical therapy: Your physician will recommend surgery based on the severity of your pain symptoms and response to non-surgical treatment methods. The outpatient surgical procedure involves opening or cutting the inflamed part of the tendon sheath to relieve the pressure on the tendon and allow free movement of the wrist. After the surgical procedure, a wrist splint with your thumb and fingers free and mobile is applied for a month. Your surgeon will also instruct you on exercises to strengthen your wrist.
Carpal Tunnel Syndrome
Carpal tunnel syndrome is a common, painful, progressive condition that is caused by compression of the median nerve at the wrist area.
Common symptoms of carpal tunnel syndrome include numbness and tingling sensation in all the fingers except little finger; pain and burning sensation in hand and wrist that may radiate up the arm and elbow; and weakness in hand with diminished grip strength.
Exact causes of the condition are not known. However certain factors increase the risk of developing carpal tunnel syndrome and they include congenital abnormalities, repetitive motion of hand and wrists, fractures and sprains, hormonal imbalance, and other medical conditions such as hypothyroidism, rheumatoid arthritis, diabetes, obesity, gout, overactive pituitary gland, or the presence of a cyst or tumor in the canal.
Conservative Treatment Options
Carpal tunnel syndrome may be treated using conservative approaches or surgery. The conservative treatments include:
- Treating underlying medical conditions
- Immobilization of the hand and wrist with a splint or wrist brace for 4-6 weeks
- Rest the hand for 2 weeks or more
- Ice packs to avoid swelling
- Avoid activities that tend to worsen the symptoms
- Medications such as non-steroidal anti-inflammatory drugs and steroid injections
- Strengthening and stretching exercises once symptoms diminish
If conservative treatment options fail to resolve the condition your surgeon may recommend surgical procedure.
Carpal Tunnel Release Surgery
Carpal tunnel syndrome can be treated with carpal tunnel release Surgery Traditional surgery involves up to a 2- inch incision in the palm and wrist area, whereas endoscopic surgery involves one or two half-an-inch incisions and the use of an endoscope. During the surgery, the transverse carpal ligament will be dissected to release the pressure on the median nerve and enlarge the carpal tunnel. Your surgeon will decide which options are best for you based on your general and medical conditions.
Your surgeon may suggest you practice certain post-operative procedures for better recovery and to avoid further complications.
- Elevate the hand above heart level to reduce swelling.
- A splint may be worn
- Ice packs to the surgical area to reduce swelling.
- Keep the surgical incision clean and dry. Cover the area with plastic wrap when bathing or showering.
- Physical therapy may be ordered to restore wrist strength.
- Eating a healthy diet and not smoking will promote healing
Risks and Complications
The majority of patients suffer no complications following carpal tunnel release surgery. However, some patients may suffer from pain, infections, scarring, and nerve damage causing weakness, paralysis, or loss of sensation and stiffness in the hand and wrist area.
The wrist is comprised of two bones in the forearm, the radius and ulna, and eight tiny carpal bones in the palm. The bones meet to form multiple large and small joints. A wrist fracture refers to a break in one or more of these bones.
Types of wrist fracture include:
- Simple wrist fractures in which the fractured pieces of bone are well aligned and stable.
- Unstable fractures are those in which fragments of the broken bone are misaligned and displaced.
- Open (compound) wrist fractures are severe fractures in which the broken bones cut through the skin. This type of fracture is more prone to infection and requires immediate medical attention.
Wrist fractures may be caused due to fall on an outstretched arm, vehicular accidents or workplace injuries. Certain sports such as football, snowboarding, or soccer may also be a cause of wrist fractures. Wrist fractures are more common in people with osteoporosis, a condition marked by brittleness of the bones.
Signs and Symptoms
Common symptoms of a wrist fracture include severe pain, swelling, and limited movement of the hand and wrist. Other symptoms include:
- Deformed or crooked wrist
Your doctor performs a preliminary physical examination followed by imaging tests such as an X-ray of the wrist to diagnose a fracture and check alignment of the bones. Sometimes a CT scan may be ordered to gather more detail of the fracture, such as soft tissue, nerves or blood vessel injury. MRI may be performed to identify tiny fractures and ligament injuries.
Your doctor will order a bone scan to identify stress fractures due to repeated trauma. The radioactive substance injected into the blood gets collected in areas where the bone is healing and is detected with a scanner.
Your doctor may prescribe analgesics and anti-inflammatory medications to relieve pain and inflammation.
Fractures that are not displaced are treated with either a splint or a cast to hold the wrist in place.
If the wrist bones are displaced, your surgeon may perform fracture reduction to align the bones. This is performed under local anesthesia. A splint or a cast is then placed to support the wrist and allow healing.
Surgery is recommended to treat severely displaced wrist fractures and is carried out under the effect of general anesthesia.
External fixation, such as pins may be used to treat the fracture from the outside. These pins are fixed above and below the fracture site and are held in place by an external frame outside the wrist.
Internal fixation may be recommended to maintain the bones in proper position while they heal. Devices such as rods, plates and screws may be implanted at the fracture site.
Crushed or missing bone may be treated by using bone grafts taken from another part of your body, bone bank or using a bone graft substitute.
During the healing period, you may be asked to perform some motion exercises to keep your wrist flexible. Your doctor may recommend hand rehabilitation therapy or physical therapy to improve function, strength and reduce stiffness.
Risks and Complications
As with any procedure, wrist fracture surgery involves certain risks and complications. They include:
- Residual joint stiffness
Metacarpal fracture is a condition characterized by the breakage or dislocation of the long hand bones called metacarpals that form the skeleton of the palm. Metacarpal fractures can damage associated soft tissues such as cartilage, ligament, tendons, joint capsule, as well as adjoining nerves.
The hand is composed of 3 types of bones – carpals or wrist bones, metacarpals or long hand bones, and phalanges or finger bones. Metacarpals consist of five long bones that connect the carpals with the phalanges. Structurally, metacarpal bones can be divided into four parts- base, shaft, neck, and head.
Metacarpal fractures need immediate treatment that include proper alignment and casting of the bones to ensure proper healing. In severe cases surgery may be recommended.
The common causes involved in metacarpal fractures include:
- Directly falling on the hand
- Trauma or direct impact to the hand
- Punching on a hard object
The main symptoms that arise from metacarpal fractures are pain and swelling along with bruising in the inner or outer palm area; Misalignment or deformity may be visible. Pain may be intense with movement of the hand. Metacarpal fracture can even affect the movement of the fingers.
The diagnosis of metacarpal fracture includes physical examination and X-ray of the hand to confirm the exact location of the fracture. In cases of complex fractures, other imaging techniques such as CT scan and MRI scan may also be necessary.
Metacarpal fracture or dislocation can be treated non-surgically by aligning the fractured bones and checking the movement of fingers, under local anesthesia. The fractured hand is wrapped with forearm-based splints or a cast to immobilize the bone to promote natural healing. A follow-up X-ray can be taken to confirm the alignment and healing process. Physical therapy is recommended to regain the strength and movement of hand. Complete healing may take 3-4 weeks.
In severe cases, surgery may be recommended and is performed under local or general anesthesia. Surgery includes making an incision over the fracture, followed by alignment and fixation of the fractured bone using plates and screws. After surgery, the incision is sutured and covered with a splint. Healing of the bone may take 6 weeks whereas complete recovery needs a few months.
Common post-operative instructions to be followed after metacarpal fracture surgery include:
- Get adequate rest and keep your hand above heart level to reduce swelling
- Avoid heavy lifting of objects till the hand is completely healed
- In case of pain and swelling, take the prescribed medications
- Physical therapy is recommended to strengthen and restore hand movements
- Follow the specific instructions given by your doctor
Risks and complications
The possible risks and complications associated with metacarpal fracture surgery include:
- Nonunion (bone fails to unite)
- Malunion (Deformed union of the fractured bone)
- Damage of the surrounding nerves or blood vessels