Human skull with duplicated foramen spinosum

The Curious Case of the Double Foramen Spinosum: What It Means for Your Brain Surgery

Soraya Malik in Health & Wellness November 2025 • 4 min read.

"A rare anatomical variation could impact surgical precision and blood flow. Understand the implications of bilateral foramen spinosum duplication."

Deep within the human skull, nestled within the sphenoid bone, lies a tiny but crucial opening called the foramen spinosum (FS). This small gateway serves as a passage for the middle meningeal artery (MMA), a vital blood vessel that nourishes the brain's outer layers. In most individuals, there is one foramen spinosum on each side of the skull. But what happens when nature decides to create a duplicate?

A recent case report has shed light on a rare anatomical variation: the bilateral duplication of the foramen spinosum. This means that instead of the usual single opening on each side, the skull exhibits two distinct foramina spinosa. While this might seem like a minor detail, it has significant implications for neurosurgery, blood flow dynamics, and even our understanding of human evolution.

This article will explore the fascinating world of the foramen spinosum, delve into the details of this rare duplication, and uncover why it matters for both medical professionals and anyone interested in the intricacies of the human body. Understanding this anatomical quirk can help improve surgical outcomes and provide valuable insights into the complex processes that shape our anatomy.

Decoding the Foramen Spinosum: Why Location Matters

Human skull with duplicated foramen spinosum

In humans, the foramen spinosum (FS) is found within the sphenoid bone, posterolateral to the foramen ovale (FO) and, typically, along the posteromedial aspect of the greater wing. The FS allows communication between the middle cranial and infratemporal fossae. Usually, the foramen transmits the middle meningeal artery (MMA), middle meningeal veins, and the meningeal (recurrent) branch of the mandibular nerve (nervus spinosus) [1]. The lesser petrosal nerve, usually transmitted by the foramen ovale or, occasionally, the foramen petrosum (of Arnold), may also pass through the FS [1,2].

The location of the foramen spinosum is crucial because it serves as a landmark for neurosurgeons during procedures involving the middle cranial fossa. This area of the skull base is a complex region containing vital nerves and blood vessels. Accurate identification of the foramen spinosum helps surgeons navigate this intricate landscape, minimizing the risk of damage to surrounding structures.

Surgical Navigation: The FS is a key reference point for accessing deeper structures within the skull.
Minimizing Risk: Precise identification reduces the chances of accidental injury to the MMA or nearby nerves.
Procedure Planning: Understanding the FS location aids in pre-operative planning and helps determine the best surgical approach.

The position of the FS isn't uniform across all species. The report highlights that in species evolutionarily predating humans, the FS exists within the temporal bone, the sphenosquamosal suture, or is absent altogether [3]. It is therefore thought that, during the course of human evolution, the ossification of the posterior aspect of the greater wing of the sphenoid progressively developed around the MMA [3]. Among extant great apes, the FS is absent much more frequently than in humans or fossil hominids [3]. Humans do, however, occasionally exhibit an absence or hypoplasia of the FS [1,4].

What This Means for the Future

The discovery of bilateral foramen spinosum duplication underscores the importance of recognizing anatomical variations. As medical imaging techniques advance, we are likely to encounter more of these unique presentations. Awareness of these variations and their potential clinical implications will be crucial for improving patient care and surgical outcomes.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4172/2161-0940.1000162, Alternate LINK

Title: Bilateral Duplication Of The Foramen Spinosum: A Case Report With Clinical And Developmental Implications

Journal: Anatomy & Physiology

Publisher: OMICS Publishing Group

Authors: Matthew J Zdilla

Published: 2014-01-01

Everything You Need To Know

What is the primary function of the foramen spinosum (FS) and why is its location significant?

The foramen spinosum (FS) serves as a crucial gateway within the sphenoid bone for the middle meningeal artery (MMA), middle meningeal veins, and the meningeal branch of the mandibular nerve. Its location is vital as it allows communication between the middle cranial and infratemporal fossae. It's a key landmark for neurosurgeons, aiding in surgical navigation and minimizing risks during procedures involving the middle cranial fossa.

What does it mean when there is bilateral duplication of the foramen spinosum, and why is this clinically relevant?

Bilateral duplication of the foramen spinosum refers to the presence of two distinct foramina spinosa on each side of the skull, instead of the usual single opening. This variation can complicate neurosurgical procedures and alter blood flow dynamics, with potential implications for surgical outcomes and a better understanding of human evolution.

Why is the precise location of the foramen spinosum so critical for neurosurgeons?

The precise location of the foramen spinosum is crucial for neurosurgeons as it serves as a key reference point during procedures involving the middle cranial fossa. Accurate identification helps surgeons navigate this intricate area, minimizing the risk of damage to the middle meningeal artery (MMA) or nearby nerves. This detailed understanding facilitates better pre-operative planning and selection of the optimal surgical approach.

How do variations in the foramen spinosum impact surgical procedures and patient care?

Variations in the foramen spinosum, such as bilateral duplication or absence, highlight the importance of recognizing anatomical differences. As medical imaging advances, identifying these unique presentations becomes crucial. Awareness allows medical professionals to adapt surgical approaches, reduce complications, and improve patient care. Ignoring these variations may lead to unintended damage to critical structures like the middle meningeal artery (MMA) during surgery.

How did the foramen spinosum evolve over time, and what does this tell us about human anatomy?

In species evolutionarily predating humans, the foramen spinosum exists within the temporal bone, the sphenosquamosal suture, or is absent altogether. During human evolution, the ossification of the posterior aspect of the greater wing of the sphenoid progressively developed around the middle meningeal artery (MMA). Humans occasionally exhibit an absence or hypoplasia of the FS. Understanding these evolutionary changes can provide insights into the development and function of the foramen spinosum and the middle meningeal artery.