jaundice - a yellow discoloration of the skin and whites of the eyes due to abnormally high levels of bilirubin (bile pigmentation) in the bloodstream.

jejunum - middle section of the small intestine between the duodenum and ileum.

joint - where the ends of two or more bones meet.

joint locking - extremely painful condition usually caused by entrapment of a loose body within the joint, between the joint surfaces.

Jordan frame - specialized stretcher developed for transport of patients with a suspected spinal injury.   

jugular veins - veins that carry blood from the head back to the heart.

Jumper's knee - associated with a small area of degeneration of the tendon attachment at the lower pole of the patella (knee-cap), characterized by pain and extreme local tenderness. 

juvenile rheumatoid arthritis (JRA) - a form of arthritis in children ages 16 or younger that causes inflammation and stiffness of joints for more than six weeks. Unlike adult rheumatoid arthritis, which is chronic and lasts a lifetime, children often outgrow juvenile rheumatoid arthritis. However, the disease can affect bone development in the growing child.