The Inion Is Not A Reliable Superficial Surgical Landmark of The Torcula In Posterior Fossa Craniotomies

Elisha Harry Otieno, Philip Mwachaka, Paul Odula, Isaac Cheruiyot, Jeremiah Munguti
Department of Human Anatomy, University of Nairobi.
Correspondence to: Elisha Harry Otieno, Department of Human Anatomy, University of Nairobi. Email: Telephone: 07034117582.


Background: Sub-occipital craniotomies are used in surgical approaches into the posterior cranial fossa. The inion is used as an extracranial landmark of the torcula in burr hole placement. However, inadvertent damage to the torcula and the related sinuses has been reported due to variant intracranial location of the torcula. These injuries lead to severe bleeding with adverse consequences. This study aimed at determining the position of the torcula in relation to the inion.

Methods: Patients and methods: 40 adult open skulls were obtained from the Department of Human Anatomy, University of Nairobi. Positional relationship between the inion and the torcula was assessed and torcula-inion distance measurements taken, where relevant, using a manual Vernier Caliper (accurate to 0.01 mm).

Results: The torcula was at the same level with the inion in half of the cases (50%), below it in 12 cases (30.0%), and above in 8 cases (20.0%). The position of the torcula above the inion ranged from 0.38-2.40cm and below it from 0.75-2.45cm.

Conclusion: The torcula lies either at the level of or below the inion in 80% of the cases. The surgeon should augment this physical landmark with radiographs to avoid iatrogenic injuries.

Key words: Inion, Posterior fossa, Craniotomies.

Ann Afr Surg. 2020; 17(3):***

Conflicts of Interest: None

Funding: None

© 2020 Author. This work is licensed under the Creative Commons Attribution 4.0 International License.


The Annals of African Surgery is the official publication of the Surgical Society of Kenya.


All content copyright © 2020 Annals of African Surgery.

ISSN (print): 1999-9674; ISSN (online): 2523-0816

Main Office Location: Menelik Medical Centre, Menelik Road, off Ngong Road, Nairobi. First floor.

Telephone: +254715260499



The content on this site is intended for health professionals. Advertisements on this site do not constitute a guarantee or endorsement by the journal, Association, or publisher of the quality or value of such product or of the claims made for it by its manufacturer.

  • Twitter
  • Facebook Social Icon
  • LinkedIn