A cross section of a bundle of nerve fibers. Axons (orange) are wrapped in myelin (purple); an extension of the membrane of glial cells. Myelin has high lipid content, and acts to insulate the axons, causing them to transmit nerve impulses much faster.
A Rare Glimpse of Leonardo da Vinci’s Anatomical Drawings - Three studies, one on a larger scale, of a man's right arm and shoulder, showing muscles; three studies of a right arm; a diagram to illustrate pronation and supination of the hand.
A cross-section of muscle tissue, surrounded by the extracellular tissue that acts as the connective tissue. Each muscle fiber is joined together by the connective tissue to make up the complete muscle