The blood supply of the hypoglossal nerve and its relevance to carotid endarterectomy.

Since the hypoglossal nerve is liable to injury during carotid endarterectomy and similar procedures, its blood supply was examined in microinjection studies of human cadavers. The nerve is supplied by arteries that arise from the ascending pharyngeal artery as it exits from the hypoglossal canal, the occipital artery as the nerve passes under its branch to the sternomastoid muscle, direct branches from the external carotid artery, and branches from the ascending pharyngeal artery just near the bifurcation of the common carotid artery. Within and close to the tongue, the nerve is supplied by branches from the lingual artery. Damage to the vessels supplying the nerve may account for some cases of hypoglossal palsy after carotid endarterectomy. Possible mechanisms are ischaemia, thermal or electrical injury from diathermy current conducted to the nerve, or intraneural haematoma from rupturing one or more of these fine vessels.