- One of the more complex structures, the hand has a high concentration of nerves and vessels. There are also many small intrinsic muscles which allow fine motor function.
- Tendons, blood vessels and nerves originating in the arm cross the wrist to enter the hand; the intrinsic muscles are solely within the hand.
- The structures crossing the double row of wrist bones are held in place by the flexor retinaculum on the volar (palmar) side (“carpal tunnel”), and by the extensor retinaculum on the dorsal side. The flexor retinaculum can sometimes thicken or scar, causing compression of the median nerve, or carpal tunnel syndrome.
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- The bones of the foot follow basically the same pattern of the hand bones. There is a double layer of sesamoid-like bones forming the ankle, which articulate with the long bones making up the central foot (metatarsals), which are in turn attached to the phalanges, or toes.
- The tendons and the many ligaments of the foot attach to the tough, thin tissue covering the bones, the periosteum. The ligaments attach the bones to each other, and the tendons connect the muscles to the bones.
- As in the hand, there are intrinsic muscles in the feet.
- The bones of the foot form a longitudinal arch and a transverse arch. Most of the body’s weight is borne on the metatarsal heads, particularly the first and fifth.
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- The carpal tunnel is a passageway on the palmar side of the wrist that houses the median nerve and finger flexor tendons. Anteriorly, the carpal tunnel is bordered by the transverse carpal ligament, a heavy band of fibers that forms the fibrous sheath containing the carpal tunnel; posteriorly, the carpal tunnel is bordered by carpal bones.
- Guyon’s canal contains the ulnar nerve and artery; this anatomy does not pass through the tunnel, but lies superficial to it.
- Carpal tunnel syndrome occurs when the median nerve, which controls sensations to the palm side of the thumb, first, second, and half of the third finger, becomes compressed at the wrist, within the carpal tunnel. This results in pain, weakness, or numbness in the hand and wrist, radiating up to the arm.
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- If conservative treatment is not effective, surgical intervention may be chosen. Surgery can be done as an open procedure or endoscopically.
- In endoscopic surgery, a small incision is made in the wrist and a dilator tube is inserted. An arthroscope with a camera is inserted in order to view the anatomy, then a cutting tool is used to sever the transverse carpal ligament in order to reduce pressure on the median nerve.
- This type of surgery is less invasive and allows for faster recovery and less postoperative pain.
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- The 7 vertebrae of the cervical spine help support the skull and protect the spinal cord as it exits the cranium to pass downward through the spinal canal.
- The transverse processes each have a small hole through which the vertebral arteries pass to join to form the basilar artery supplying the posterior and deep portions of the brain and brainstem.
- The cervical nerve roots form the brachial plexus which supplies sensation and movement to the upper extremities.
- Degenerative joint disease and disc disease are very common in the cervical spine, leading to arm and hand pain and dysfunction requiring decompression and sometimes fusion.
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- Degenerative joint disease is a result of normal activity and is found in most people as they get older; it develops more rapidly and more severely in the case of joint trauma.
- Articular surfaces are covered with glassy-smooth cartilage. As the cartilage disintegrates over time (chondromalacia), it flakes off until the bone is eventually exposed.
- If bone starts to rub against bone, it reacts by forming more bone in the form of osteophytes. This is a very painful condition and when severe enough, requires joint replacement.
- Degenerative joint disease is frequently called osteoarthritis; rheumatoid arthritis is an autoimmune disease with very different causes and a slightly different set of symptoms.
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- The largest joint in the body, the hip is composed of the large, round head of the femur which lies within the acetabulum or cup of the pelvis. Cartilage covers the articular surfaces, as in every other joint. There is a joint capsule and a number of muscles which cross and protect the joint and allow movement in a number of planes.
- The blood supply to the hip is relatively meager and easily disrupted with trauma.
- Since the entire weight of the body goes through this joint with every step, it is vulnerable to damage from use and is a common site for degenerative joint disease.
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- The lumbar spine is composed of large, strong bones which must support the entire weight of the spine and head.
- The vertebral bodies are separated by fibrous discs which serve as shock absorbers. The discs have a fibrous ring (annulus fibrosis) and a gel-like center (nucleus pulposus).
- The spinal canal is formed by the pedicles, laminae, and the vertebral bodies and discs; the canal protects the distal portion of the axial nervous system, the cauda equina.
- The large transverse and spinous processes serve as support for the many paraspinous muscles which allow for the fine movement of the spine.
- The sacrum is the large, wedge-shaped bone forming the posterior part of the pelvic bowl, and is composed of fused vertebrae.
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- One of the major joints in the body, the knee is required to support huge and repeated pressures over the course of a lifetime. The articular surfaces of the joint are covered with glassy-smooth articular cartilage, and the menisci act as shock absorbers with each step.
- The patella is a large sesamoid bone which lies within the quadriceps tendon. It articulates with the condyles of the femur.
- The anterior and posterior cruciate ligaments are located at the center of the joint and allow some rotatory motion. The lateral and medial collateral ligaments are attached on either side of the joint to maintain stability.
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- The tendons of the deep shoulder muscles (infraspinatus, supraspinatus, and teres minor) conjoin with the shoulder joint capsule to form the rotator cuff.
- Rotator cuff injuries are common and may be difficult to treat.
- The head of the humerus rests in the glenoid fossa, a relatively shallow depression in the scapula. The rotator cuff holds the head in the fossa during movement.
- The shoulder joint is prone to dislocation due to the shallowness of the glenoid fossa.
- The acromioclavicular joint lies over the shoulder and sometimes develops fibrosis, making movement painful or stiff.
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- A common condition, particularly among elderly women, osteoporosis is the reduction of bone density.
- Osteoporosis affects both the dense cortical portion on the outside of a bone and the spongy bone inside.
- Causes include age, low body mass, family history, smoking, malnutrition, alcoholism, insufficient physical activity and certain medications and toxins. It is also associated with a number of chronic diseases.
- The primary risk is that of fracture, particularly of the hip, a potentially devastating event in the elderly. In severely osteoporotic patients, healing may be slow and insufficient.
- Treatment depends on the cause but includes medication, dietary changes, and exercise.
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- One of the more common surgical procedures, diseased bone and articular surfaces (usually from either trauma and/or degenerative joint disease) are surgically removed.
- Most knee prostheses are made of a strong metal with a durable plastic overlay to serve as a joint surface.
- As with any bony prosthesis, these can be either cemented into place or have a roughened surface which allows bone to grow into the surface.
- All three units (femoral, tibial and patellar) can be inserted together or individually, depending upon the specific needs of the patient.
