Scalp acupuncture is widely used in clinical practice, and there is still a lack of systematic studies on its nerve pathways and mechanism of action. Scalp acupoints are innervated by the trigeminal nerve which is also involved in the regulation of the leptomeninges and related arterioles nourishing the cerebral cortex. Animal experiments and human trials have shown that scalp acupuncture can exert an effect through the shortcut between the axon reflexes from the primary neurons in the trigeminal ganglion (its axon branches may separately innervate scalp acupoints and the leptomeninges directly regulating nutrient and active substances in brain tissue) and the secondary neurons of the trigeminal nucleus caudalis (head and face acupoints interact with afferents of brain tissue through presynaptic dorsal root reflex and postsynaptic neurogenic responses and convergence), which may have regulatory and therapeutic effects on intracranial tissue.