Anatomical variations and clinical implications of the artery to the lingual nerve

The pterygomandibular space is a critical anatomic area for the delivery of local anesthesia in the practice of dentistry. The neurovascular contents of this area are subject to trauma and its resultant local and systemic complications. This study of 202 cadaveric specimens reaffirms the literature as to the percent distributions of the superficial and deep routes of the maxillary artery and details for the first time the anatomic variations of the artery to the lingual nerve. This artery courses through the pterygomandibular space placing it at risk for injection trauma along with the other neurovascular contents. It has been uncommonly identified and referred to in the literature, yet it may be the first artery encountered when entering the space with a needle or during surgical intervention in the area.

Innervation of human trigeminal nerve blood vessels

Film preparations and histological sections of human trigeminal nerve impregnated with silver nitrate and treated according to Falck-Hillarp revealed a rich innervation within the intraneural blood vessels. Highly diverse and complex neural interconnections were noted in the arterioles and venules of the trigeminal ganglion capsule as well as in the epineurium and external layers of the perineurium of the trigeminal nerve branches. Neural plexuses were detected on the vessel walls within these layers. Sensory innervation of the neural blood vessels was mainly relegated to polyvalent tissue-vascular receptors with adrenergic neural plexuses encountered on the walls of the intraneural vessels.

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.