Dictionary

joint hypermobility syndrome See hypermobility syndrome.

joint aspiration See arthrocentesis.

joint, atlas and axis See atlantoaxial joint.

joint, acromioclavicular See acromioclavicular joint.

joint, acetabular The hip joint. The acetabulum is the cup-shaped socket of the hip joint, and it is a key feature of the pelvic anatomy. The upper end of the femur (thighbone) fits right into the acetabulum, articulates with it, and thereby forms the largest ball-and-socket joint in the human body.

joint, AC Acromioclavicular joint.

joint The area where two bones are attached for the purpose of permitting body parts to move. A joint is usually formed of fibrous connective tissue and cartilage. Joints are grouped according to their type of motion: ball-and-socket joint; hinge joint; condyloid joint, which permits all forms of angular movement except axial rotation; pivot joint;…

jogger’s nails Very common, small, semicircular white spots on the toenails. These spots result from injury to the base (matrix) of the nail, a structure under the visible nail where the cells that make up the visible nail are produced. The injury responsible for these white spots on the nails can be due to athletic…

jock itch A common fungal infection sometimes referred to as ringworm, involving the skin of the inner thighs, buttocks, and genitals. Also known as tinea cruris. It occurs most frequently in people who are overweight and/or who sweat profusely, such as athletes. Symptoms include an itchy, red, sometimes ring-shaped rash. Treatment involves topical or oral…

jet lag A temporary disorder that features fatigue and insomnia and that is caused when the body’s natural rhythms are interrupted by rapid travel across time zones. Other symptoms of jet lag include anxiety, constipation, diarrhea, confusion, dehydration, headache, irritability, nausea, sweating, coordination problems, and even memory loss. See also circadian clock.

jellyfish sting The injection into the skin of venom from the stinging unit (nematocyst) of the jellyfish. The jellyfish tentacles can extend for several feet and are lined with venom-filled cells (nematocysts). One tentacle may fire thousands of nematocysts into the skin on contact. The pain can be severe, particularly in the first hours after…

jejunum The middle portion of the small intestine. The jejunum is about 2.4 meters (8 feet) in length and located halfway between the duodenum and the ileum. The jejunum is responsible for much of the absorption of the fluids and calcium that we ingest. See also intestine; intestine, small.