The question of whether a human skull can stop a knife is one that has been studied and debated extensively. At first glance, it may seem obvious that a knife would easily be able to penetrate through the bones of the skull. However, the structure and density of the skull provides more protection than might be expected. Understanding the factors involved can shed light on this morbid but fascinating issue.
The skull is composed of several bones that fit together to form a rigid protective structure around the brain. The main bones that would be relevant in stopping a knife thrust are the frontal, parietal, temporal and occipital bones. These bones vary in thickness from around 1/8 inch on the temple region to nearly 1/2 inch on the occipital region at the back of the skull.
While bone density and thickness provides the skull with considerable strength, whether it can resist penetration depends greatly on the characteristics of the knife. Factors like blade design, length, sharpness and force of the thrust will play a major role. A longer, sharper knife driven with great force will obviously have a better chance of puncturing the skull than a short, dull knife weakly jabbed.
Studies on Skull Penetration
Several scientific studies have been conducted to directly test and measure the ability of different knives to penetrate human skulls. These studies provide useful data to shed light on this question.
One study published in the Journal of Forensic Sciences in 2009 sought to determine the minimum force required to penetrate a human calvarium, the upper portion of the skull. They tested 13 different knives of varying blade designs, lengths and thicknesses against sections of parietal bone cut from 5 donated human skulls.
The researchers used a custom apparatus to guide the knife into the bone samples while measuring the force. They found that the minimum force required varied greatly depending on the knife used, ranging from 34 to over 1500 Newtons of force. Serrated blades performed better than non-serrated, and longer narrower blades required less force than short wide ones.
These findings confirm that knife characteristics significantly influence skull penetrating capability. While some knives were unable to puncture the skull at maximum force, others were able to penetrate with less than 100 Newtons, within the capabilities of a reasonably strong adult.
Another study by German researchers in 2010 came to similar conclusions. They tested 7 different knife designs against frontal and parietal bone samples from human cadavers. The narrower blades required between 1750 and 2400 Newtons to fully penetrate the frontal bones, while wider blades needed only 1100-1500 Newtons. They concluded long narrow blades were optimal for reducing penetration force.
Ballistics Gel Studies
In addition to tests directly on human bone, a number of studies have been done using ballistics gel molds cast in the shape of a human skull. Ballistics gel provides a tissue simulant that can model penetration effects.
One such study from Wayne State University aimed to test knife attacks on a simulated human head model with artificial skin, muscle and skull layers. They found many variables affected results including skill of the user and impact location, but strong determined attacks could penetrate the frontal bone in many cases.
These kinds of ballistics gel models provide a more realistic model than bare bone samples. They demonstrate that while the skull provides substantial protection, enough force from fixed-blade knives can still enable them to penetrate deeply in some cases.
Real-World Examples
Along with laboratory testing, there are many real world examples that demonstrate the complexities of attempted skull penetration with knives. While the skull can often repel an attack, this depends greatly on specifics of the situation.
In some cases, the skull does stop the knife. For example, in 2015 a Chinese man survived being stabbed in the head with an 8-inch kitchen knife which became embedded in his skull when the tip failed to penetrate through the frontal bone. The man made a full recovery after doctors safely extracted the blade.
However, plenty of other cases exist where knives were successfully driven through the skull, often with enough force to penetrate the brain. For example, a 20 year old man was killed after being stabbed through the eye socket with enough force for the knife tip to penetrate the brain.
Many factors determine outcome, including skull thickness at the impact site, angle of attack, blade thickness and knife velocity and energy at impact. Well-aimed forceful vertical attacks often have highest risk of penetration.
Skull Fracturing
Even in cases where a knife fails to fully penetrate the skull, the impact can still cause serious or fatal injury due to fracturing. As the studies show, significant force is required to puncture through the thick cortical bone, especially near the center of the skull.
However, less force is needed to fracture the skull and cause pieces of bone to fragment and displace inwards, which can lacerate the brain. Depressed fractures where bone is pushed inwards are especially dangerous.
The fracture limits depend on factors like location, bone thickness, direction of force and shape of the blade tip. But knife impacts can certainly generate enough localized force to cause fracturing even if they don’t completely puncture through the skull.
Conclusion
In conclusion, whether a human skull can stop a knife is a complex issue that depends on many variables. The thickness and strength of the bones provide substantial protection, but enough force applied skillfully with an appropriately shaped blade can successfully penetrate in some cases.
However, thick areas of the skull near the center can resist complete penetration from many knife attacks. Still, impacts that don’t puncture through may cause localized fracturing and depressed bone fragments, which can prove fatal.
Carefully controlled tests give an indication of the knife designs and amounts of force that enable skull penetration. However, real-world cases prove that outcomes vary greatly depending on the multitude of factors involved in an attack. While the skull may resist some knife assaults, it cannot be relied upon to always stop this type of threat.
| Study | Method | Key Findings |
|---|---|---|
| Journal of Forensic Sciences, 2009 | Tested 13 knives on human skull bone samples | Minimum force to penetrate varied from 34 – 1500 Newtons depending on blade. Serrated and narrow blades performed best. |
| German study, 2010 | Tested 7 knives on human skull bone samples | Narrow blades required 1750-2400 Newtons to penetrate frontal bone. Wider blades needed only 1100-1500 Newtons. |
| Wayne State University | Tested knife attacks on simulated ballistics gel head | Strong attacks could penetrate frontal bone in many cases. |
Real-World Examples of Skull Penetration
| Case | Result |
|---|---|
| Chinese man stabbed in head with 8-inch knife | Knife embedded in skull but failed to fully penetrate through frontal bone. |
| Man stabbed through eye socket into brain | Knife penetrated through thin orbital bone with enough force to reach brain. |
Conclusion
The human skull provides substantial protection against knife attacks. However, whether it can completely stop a knife depends on many factors:
- Bone thickness – Thicker areas near middle of skull more resistant
- Blade design – Long, thin blades require less force
- Impact force – Enough force can enable penetration in some cases
- Angle of attack – Vertical downward attacks often most damaging
- Skill – Precision targeting of thinner bone regions improves chances of penetration
While the skull can stop many knife assaults, complete penetration leading to fatal brain trauma can still occur under the right circumstances. However, fracturing leading to depressed bone fragments poses a major risk even when the knife fails to fully puncture through the skull.