Webster's New World Medical Dictionary

central auditory processing disorder
A neu-
rological disorder in which a person has difficulty
properly interpreting sounds received by the ears,
particularly the phonemes of speech. Abbreviated
CAPD. CAPD can result in difficulties with attention,
speech production, and reading.
central core disease of muscle
One of the
conditions that produces “floppy baby” syndrome.
Central core disease of muscle causes hypotonia
(low muscle tone) in a newborn baby, slowly pro-
gressive muscle weakness, and muscle cramps after
exercise. Muscle biopsy shows a key diagnostic
finding of absent mitochondria in the center of
many muscle fibers. It is caused by an abnormal
gene on chromosome 19 involving ryanodine recep-
tor 1, and is inherited as a dominant trait.
central line
An infusion tube located in or near
the heart, which is at the center of the circulatory
system. For example, a Swan-Ganz catheter with its
tip in the right atrium and ventricle of the heart is a
central line.
central nervous system
That part of the nerv-
ous system that consists of the brain and spinal
cord. Abbreviated CNS. The CNS is one of the two
major divisions of the nervous system. The other is
the peripheral nervous system (PNS), which is out-
side the brain and spinal cord. The PNS connects
the CNS to sensory organs, such as the eye and ear,
and to other organs of the body, muscles, blood ves-
sels, and glands.
central nervous system, spongy degeneration
of the
See 
Canavan disease.
central vision
A process in which millions of
cells change light into nerve signals that tell the
brain what the person is seeing. As a person reads,
drives, and performs other activities that require
fine, sharp, straight-ahead vision, light is focused
onto the macula in the center of the retina, the light-
sensitive layer of tissue at the back of the eye.
centromere
The “waist” of the chromosome that
is essential for the division and retention of the
chromosome in the cell. The centromere is a
uniquely specialized region of the chromosome to
which spindle fibers attach during cell division.