Veterinary Histology and Embryology

MUSCLE SPINDLES (Neuromuscular spindles)

• In voluntary muscle, sensory nerves end in end bulbs and muscle spindles. The muscle spindles, is a cylindrical elongated structure within which are one or several muscle fibres, connective tissue blood vessels and myelinated nerve fibres.
• The whole is enclosed in a connective tissue capsule, which is pierced, at various points by one or more nerve fibres.
• The thicker myelinated sensory fibres lose their myelin, as they branch repeatedly within the spindle.
• The axons terminate in close opposition to the sarcolemma of the enclosed muscle fibres.
• The muscle fibres of the muscle spindle are thinner, richer in sarcoplasm and have more nuclei.