The capsule encloses small areas of muscle-tendon junctions. Free nerve endings intertwine among collagen bundles. Afferent fibers are activated by tension on muscle-tendon created by strong muscle contraction and inhibits the motor neurons that supply the muscle. The underlying sarcolemma is highly folded. The space between the axolemma and the sarcolemma is the primary synaptic cleft.
Sarcolemmal foldings form many secondary synaptic clefts.
The axon terminal stores secretory vesicles containing acetylcholine. Autonomic postganglionic-effector junctions Autonomic postganglionic fibers frequently form a series of swellings along their course. These varicosities contain mitochondria and numerous synaptic vesicles and may release neurotransmitter within the connective tissues. Diffusion is required for the neurotransmitter to reach the target cells. Alternatively, the fibers may lie within a groove on the surface of smooth muscle and make a 'synapse en passant' .