Anatomic investigation of the labyrinthine artery

Objective: To observe the origin, the course and the location of the labyrinthine artery[LA], and to investigate the spacial relationship between LA and facial nerve and vestibulocochlear nerve (VCN).

Methods: The specimens including 49 sides cerebellopontine angle (CPA) and internal acousticmeatus (IAM) infused with red galatin into artery were dissected and observed under operating microscope.

Results: LA arised from anterior inferior cerebellar artery (AICA) (83.6%), or basilar artery (BA) (12.3%) or vertebral artery (VA) (4.1%). AICA formed a loop in cerebellopontine angle (CPA) or internal acoustic meatus (IAM). The loop was located in the extra-meatus of IAM (28.6%), or at the opening of the IAM (18.4%), or in intrameatus of IAM (36.7%). AICA passed over ventral side of VII and VIII cranial nerves (18.4%) or across between VII and VIII cranial nerve root (81.6%). LA was a mono-arterial (51.1%), or bi-arterial (40.8%), or tri-arterial (4.1%) vessel. The calibre of LA was (0.18 +/- 0.05) mm. In CPA and IAM, facial nerve located anteroinferior to VIII cranial nerve, but the location of VCN was posteriolaterally. LA most commonly coursed between VII and VIII. LA divided into anterior vestibular artery, vestibulocochlar artery and cochlear artery. On the base of IAM, the facial nerve situated in anterosuperior, but cochlear nerve in anteroinferior and vestibular nerve in posterosuperior.

Conclusions: LA was a mainly artery supplied to facial nerve, VCN and vestibulocochlear organs. Once LA is damaged, facial weakness (or paralysis), vertigo or hearing loss would be developed.