ANATOMY 1 Lecture Notes - Lecture 24: Perineurium, Axon, Intercostal Space
Document Summary
Neurons = conductive cells of nervous tissue. Nerves = bundles of axons and their neuroglial cells wrapped in ct. Like skeletal muscle, consist of long cells nerve fibers (axons) Have almost identical design as skeletal muscles. Mesh of collagen fibers, fibroblasts, and macrophages surrounded by extracellular fluid. Fluid nourishes neuron and provides environment for propagation. Holds many nerve fibers together in bundle => fasciculi. Collagenous sheaths + ~15 layers of fibroblasts in collagen meshwork. Maintains osmotic environment + fluid pressure within endoneurium. Terminates by blending into ct capsules of nerve endings + muscle junctions. Bundles all fasciculi together => single nerve. + small blood vessels and lymphatic vessels for nerve. ~ 50% of cross-sectional area of nerve. => protection of nervous tissue from tensile forces of muscle movement. Spinal nerves arise from spinal cord as rootlets. Contain axons of motor neuron of cell bodies anterior regions of spinal cord grey matter. Transmit action potentials to muscles + glands of body.
