Anatomy, Head and Neck, Asterion


Article Author:
Paul Cowan


Article Editor:
Oluwaseun Adigun



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Orawan Chaigasame
Carrie Smith
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Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
12/21/2018 12:07:12 PM

Definition/Introduction

The asterion, derived from the Greek word asterion meaning “starry,” is an anatomical landmark on the human skull.  

Issues of Concern

The asterion is made up of the junction of the occipital bone, the temporal bone, and the parietal bone.  Its definition can also be a confluence of the lambdoid suture which is the junction of the occipital and parietal bones, the occipitomastoid suture, which is a junction of the occipital and temporal bones, and the parietomastoid suture, which is a junction of the parietal and temporal bones.  It is a visible landmark on the human skull seen when removal of the soft tissue from the bony surfaces has taken place.

Clinical Significance

The asterion is a clinically significant piece of human cranial anatomy primarily for its utilization as a landmark in the retrosigmoid approach to skull base surgery.  This technique is important for tumor resection from the cerebellopontine angle, such as with vestibular schwannoma removal.  A 2007 study of dried human skulls published in the Chinese Medical Journal by Xia et al., sought to provide the best location on the surface anatomy of the skull through which to drill to perform an endoscopic retrosigmoid keyhole approach in skull base minimally invasive surgery.  The authors found that a hole 2.0 cm in diameter placed at the midpoint between the tip of the mastoid and the asterion was the best location from which to access the structures of the cerebellopontine angle.[1]

The asterion also potentially plays a part in the placement of hearing implants.  In a 2018 study published in Otology & Neurotology, Arnold et al. state the need for an alternative site for implantation of the floating mass transducer of a bone conduction hearing implant, which ordinarily is implanted on the mastoid.  The authors state that for patients with prior mastoid surgery or anatomical difficulties precluding appropriate placement of the mass transducer, an alternative method should be in place.  They propose a retrosigmoid approach, using pre-operative computed tomography scanning and avoiding the sigmoid sinus by targeting a point approximately 1.9 cm posterior and 1.7 cm inferior to the asterion, and 3.3 cm posterior and 2.1 cm superior to the mastoid notch.[2]


  • Image 7313 Not availableImage 7313 Not available
    Image courtesy S Bhimji MD
Attributed To: Image courtesy S Bhimji MD

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Anatomy, Head and Neck, Asterion - Questions

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A 50-year-old male presents to the ED after being hit in the head with a blunt object from behind by an unseen attacker. He is obtunded and has significant ecchymosis posterior to the left ear, posterior and superior to the mastoid. An urgent head CT is obtained and you see a skull fracture at the point where the parietal, occipital, and temporal bones meet. What is the name of this anatomical point?



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A 45-year-old woman presents for reported hearing loss. She states that she first noticed that she had a hard time with conversations, and her daughter would yell at her for the television being too loud, which began several months ago. She has not been able to hear anything out of her right ear for the past week and is concerned. She reports that she has not been feeling sick lately and is not in any pain. Upon exam, no abnormalities are noted with the exception of a Weber test that lateralizes to the left ear and a Rinne test that demonstrates deficits in both air and bone conduction in the right ear. An MRI of her head reveals a mass at the right cerebellopontine angle. The neurosurgeon decides he wants to use a retrosigmoid approach to remove the mass. Which skull landmark will be used when deciding where to drill?



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Sutural lines meet at which of the following skull landmarks?



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Anatomy, Head and Neck, Asterion - References

References

Xia Y,Li XP,Han DM,Zheng J,Long HS,Shi JF, Anatomic structural study of cerebellopontine angle via endoscope. Chinese medical journal. 2007 Oct 20     [PubMed]
Arnold H,Schulze M,Wolpert S,Hirt B,Tropitzsch A,Zimmermann R,Radeloff A,Löwenheim H,Reimann K, Positioning a Novel Transcutaneous Bone Conduction Hearing Implant: a Systematic Anatomical and Radiological Study to Standardize the Retrosigmoid Approach, Correlating Navigation-guided, and Landmark-based Surgery. Otology     [PubMed]

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