Spasticity

Increased involuntary muscle contraction (the opposite of hypotonicity). Spasticity is a condition in which certain muscles are continuously contracted. This contraction causes stiffness or tightness of the muscles and may interfere with movement, speech, and manner...

Speculum

An instrument for enlarging the opening of any canal or cavity in order to facilitate inspection of its interior. An instrument for enlarging the opening of any canal or cavity in order to facilitate inspection of its interior.

Sphenoid Sinus

Either of two irregular cavities in the body of the sphenoid bone that communicate with the nasal cavities. Sinus (cavity lined with mucosa) that lies directly behind the nose and in front of the pituitary gland – the back wall of which makes up the anterior...

Spinal Fluid

Also known as cerebrospinal fluid. Clear colorless liquid secreted by the choroid plexus of the lateral, third, and fourth ventricles, and contained within the ventricular system of the brain and spinal cord and within the subarachnoid space. See cerebrospinal...

SRIF

Somatotropin release inhibiting factor (same as GHRIH). Often referred to as somatostatin. A number of drugs to treat GH excess act like this native hypothalamic hormone.