A look at structure of the hand and wrist

The human hand contains little-sized bones, called the phalanges, metacarpals and the carpals; whereas, the wrist encompasses the ending of the larger bones of the ulnar and radius from the lower arm. A total of 27 bones comprise the hand and wrist. Muscles of the hand can be divided into just three groups depending upon location or depth. Thenar muscles control the thumb; while, hypothenar muscles regulate the little finger. The three middle fingers fall under control of three other sets of muscles. These muscles control fine motor skills used for such skills as grasping objects, writing or brushing teeth. Overall, 30 different muscles in the hand and forearm work together and supply an array of intricate movements that set humans apart from other creatures. Tendons for the lower arm muscles and the palm attach to the bones of the three middle and little fingers on both hands. The tendon’s role is to be the intermediary structure between bone and muscle. Ligaments consist of the fibrous tissue that connects bone to bone in the fingers, palm area and wrist. The small size of the bones in the palm and their ligament connections endow our hands and wrists with incredible strength and flexibility. Cartilage, present as a cushion at the end of each bone in the hand and wrist, acts as a spongy pad containing a thick fluid to protect the bones hard sharp edges. Bones repair easily due to the excellent blood supply; while, cartilage contains almost no blood vessels so it cannot mend very well. Three nerves, the radial, the median and the ulnar nerves, supply the hand with movement and feeling. Factors affecting the function of the nerves to the hand include: recurring motion, force, position and vibratory stimuli.

Injuries and Traumas of the Hand

Fractures of the hand represent the most common fracture in the human body. These everyday injuries include fractures of the fingertips and the thumb, and broken knuckles. Fractures to the hand transpire due to improper use of tools, blunt trauma to the hand (punching or hitting objects), crush injuries, falls or sports injuries. The symptoms are usually obvious due to antecedent events along with signs of swelling, bruising, pain, distortion, inability to grasp or reduced range of motion of the fingers. Almost all injuries of the hand require an x-ray to detect broken bones. First aid to the hand occurs first with control of bleeding, removal of jewelry and application of an ice pack wrapped in a towel. If the hand appears deformed, place it on a pillow to transport to an emergency room. If open wounds are evident at the site, the person can expect irrigation of the wound and placement on antibiotics. A hand specialist will be called depending on the need for surgery. Dislocation of the digits (fingers) or hand continue to be another routine hand injury, but, generally, the dislocation can be reduced to its proper location by an emergency room physician, and a hand surgeon can give follow-up care. X-rays show the degree of dislocation or complexity. Treatment consists of pain medication and rest for simple dislocation. The more complicated dislocations require consultation with a hand surgeon who decides on surgical or non-surgical treatment. Sprains refer to ligament injuries or partial tears to the ligaments. The treatment for wrist sprains usually involves rest with placement of a wrist support brace. Tendon injuries (cut, torn, frayed or pulled apart) universally occur on the fingers, because the flexor tendon lies on the palmar side of the finger or the side that grasps objects. These injuries arise from a knife, sharp tool, broken glass or workers using cutting tools. Puncture wounds or lacerations over the tendon can result in partial or complete cuts (transection). Tendon lacerations require surgical intervention to reconnect the open area on the tendon. Microsurgery may be necessary if blood vessels or nerve injury occurs, concomitantly.

Chronic Conditions of the Hand and Wrist

Carpal Tunnel Syndrome refers to a condition arising from compression on the median nerve that runs under a band of fibrous tissue in the wrist. Repetitive movement of the hand or wrist from such activities as typing, lifting items or throwing balls remains one of the main causes; though, illness from diabetes, hypothyroidism, pregnancy and rheumatoid arthritis can also cause swelling of the carpal tunnel resulting in the usual symptoms of tingling, numbness, weakness or pain in the thumb and three middle fingers. Conservative care at home treats mild symptoms. Treatment consists of stopping repetitive activity or instilling rest periods, ice packs on the wrists, using nonsteroidal anti-inflammatory drugs (like ibuprofen or celebrix) and wearing a wrist splint at night. Surgery is considered only if symptoms remain after weeks or months of treatment or cause protracted time off of work.

Arthritis and deformities

Osteoarthritis or rheumatoid arthritis, though not disease per se of the hand, causes significant alterations in the joints of the hand and wrist due to inflammation. The multiple small joints work together to generate movement to carry out such activities as threading a needle or tying a bow. Overtime, the arthritis worsens, pain develops, the joints lose their natural shape and activities with the hands become more difficult. In osteoarthritis, the most common form of arthritis, the cartilage in the small joints wears away; whereas, in rheumatoid arthritis, the fluid in the joint lining swells leading to pain and stiffness. X-rays, MRIs or bone scans help to diagnosis arthritis. Your doctor advises you on treatment options that can include medication, splinting, injections, or surgery.