arachnoid definition
Medical Definition of subarachnoid. 1  1: situated or occurring under the arachnoid membrane subarachnoid hemorrhage. 2  2: of, relating to, or involving the subarachnoid space and the fluid within it subarachnoid meningitis. Arachnoid Mater. The arachnoid mater is the middle of three layers that make up the meninges, or membranes, that surround the spinal cord and brain. The dura mater is the outermost layer of the meninges. The innermost layer that contours closely to the many folds and crevices of the brain is called the pia mater. any wingless, carnivorous arthropod of the class Arachnida, including spiders, scorpions, mites, ticks, and daddy-longlegs, having a body divided into two parts, the cephalothorax and the abdomen, and having eight appendages and no antennae. Compare insect. adjective. Definition of subarachnoid. : of, relating to, occurring, or situated under the arachnoid membrane subarachnoid hemorrhage. 1. a delicate fibrous membrane forming the middle of the three coverings of the central nervous system. In life, the arachnoid (specifically the arachnoid barrier cell layer) is tenuously attached to the externally adjacent dura mater (specifically the dural border cell layer), and no natural space occurs at the dura-arachnoid interface. Arachnoid mater. The arachnoid mater is one of the three meninges, the protective membranes that cover the brain and spinal cord. The arachnoid mater is a derivative of the Neural crest mesectoderm in the embryo. Contents. resembling a spider's web. 2. of or belonging to the arachnids. 3. Anatomy. of or relating to the arachnoid membrane. 4. Botany. formed of or covered with long, delicate hairs or fibers. 1: situated or occurring under the arachnoid membrane subarachnoid hemorrhage. 2: of, relating to, or involving the subarachnoid space and the fluid within it subarachnoid meningitis. Anatomy. the serous membrane forming the middle of the three coverings of the brain and spinal cord. Compare dura mater, meninges, pia mater. Origin of arachnoid. Definition of arachnoid. 1  1 : of or relating to a thin membrane of the brain and spinal cord that lies between the dura mater and the pia mater. 2  2 : covered with or composed of soft loose hairs or fibers.
Of or relating to a thin membrane of the brain and spinal cord that lies between the dura mater and the pia mater.