Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «S»:
Spinal muscular atrophy
Spinal muscular atrophy: A genetic disease characterized by progressive loss of lower motor neurons (anterior horn cells) in the spinal cord, resulting in symmetric muscle weakness and atrophy. The onset of the progressive muscle weakness ranges greatly in age from before birth to adulthood. The mus...
Spinal nerve: One of the nerves that originates in the spinal cord.
There are 31 pairs of spinal nerves. They consist of the 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve....
Spinal stenosis: Narrowing of the spaces in the spine, resulting in compression of the nerve roots or spinal cord by bony spurs or soft tissues, such as disks, in the spinal canal. This occurs most often in the lumbar spine (in the low back) but also occurs in the cervical spine (in the neck) and l...
Spinal tap: Also known as a lumbar puncture or "LP", a spinal tap
procedure whereby spinal fluid is removed from the spinal canal for
the purpose of
diagnostic testing. It is particularly helpful in the diagnosis of
of the central nervous system, especially infections, ...
Spindle cell: A cell that is tapered at both ends....
Spindle neuron: A large neuron tapered at both ends that is only found in humans and great apes and so is thought to be a relatively recent evolutionary addition to the nervous system. Spindle neurons are confined to the anterior cingulate cortex, a region of the brain that plays a role in emotion, ...
Spine: 1) The column of bone known as the vertebral
column, which surrounds and protects the spinal cord. The spine can
be categorized according to level of the body: i.e., cervical spine
(neck), thoracic spine (upper and middle back), and lumbar spine
(lower back). See also vertebral column. 2...
Spine, slipped: See: Spondylolisthesis....
Spinocerebellar: Pertaining to the spinal cord and the cerebellum, as in spinocerebellar ataxia (ataxia with cerebellar malfunction)....
Spinocerebellar ataxia: Ataxia with malfunction of the cerebellum....
Spinous process: A slender projection from the back of a vertebra to which muscles and ligaments are attached....
Spiral CAT scan
Spiral CAT scan: A conventional computerized axial tomography scan (CAT scan or CT scan) is an x-ray procedure which combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body. A ...
Spiral fracture: A fracture, sometimes called a torsion fracture, in which a bone has been twisted apart.
Spirochete: A microscopic bacterial organism in the
Spirochaeta family. Spirochetes have a worm-like, spiral-shaped form,
and wiggle vigorously when viewed under a microscope. Treponema
pallidum, the cause of syphilis, is a particularly well-known member
Spirometry: A test of the air capacity of the lung. The test utilizes a machine called a spirometer to measure the volume of air inspired and expired by the lungs....