troponin test A sensitive and specific blood test used to determine whether a heart attack or damage to the heart muscle has occurred. Troponin is a complex of proteins found in skeletal and cardiac muscle. Normally, very low levels of troponin are present in the bloodstream. Heart attack and other forms of damage to heart…
tropical typhus See typhus, scrub.
trophoblastic tumor, gestational A tumor of women, which develops in the tissues that are formed following conception by the joining of sperm and egg. Gestational trophoblastic tumors start inside the uterus, the hollow, muscular, pearshaped organ where a baby grows. This type of tumor occurs in women during the years when they are able to…
trochlear nerve The nerve that controls the superior oblique muscle of the eye, one of the muscles that move the eye (extraocular muscles). Paralysis of the trochlear nerve results in rotation of the eyeball upward and outward (and, therefore, in double vision). The trochlear nerve is the fourth cranial nerve, and it is the only…
The lesser trochanter A pyramidal prominence that projects from the proximal (near) and medial (inside) part of the shaft of the femur. The lesser trochanter is also called the minor trochanter, the inner trochanter, and the medial process of the femur. The trochanters are points at which hip and thigh muscles attach. The greater trochanter…
The greater trochanter A powerful protrusion located at the proximal (near) and lateral (outside) part of the shaft of the femur. The greater trochanter is also called the major trochanter, the outer trochanter, and the lateral process of the femur.
trochanter One of the bony prominences toward the near end of the thighbone (the femur). There are two trochanters:
tRNA Transfer RNA.
trisomy 21 syndrome See Down syndrome.
trisomy 18 syndrome The presence of three copies of chromosome 18, rather than the normal two. Children with trisomy 18 syndrome have multiple malformations and mental retardation. They characteristically have low birth weight, small head (microcephaly), small jaw (micrognathia), malformations of the heart and kidneys, clenched fists with abnormal finger positioning, and malformed feet. The…
trisomy 13 syndrome The presence of three copies of chromosome 13, rather than the normal two. Children with trisomy 13 syndrome are profoundly mentally retarded and have multiple malformations, commonly including scalp defects, hemangiomas (blood vessel malformations) of the face and nape of the neck, cleft lip and palate, malformations of the heart and abdominal…
trisomy The presence of three copies of a chromosome rather than the normal two. The most common trisomies in newborns are trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), and trisomy 21 (Down syndrome).