When a body part comes in contact with a sharp edge, which of the following occurs?

When performing an autopsy on a victim with sharp force injuries, it is sometimes beneficial to photographically document the body as it is first seen in the autopsy room. Some pathologists refer to such photographs as "as is" photographs. Especially in homicide victims, careful evaluation for trace evidence should take place before the body is disturbed. If a sexual activity kit is required, it should be done at this time. X-rays should be taken of all areas where sharp force injuries exist to identify the presence of retained weapons or portions of weapons. A chest x-ray may also be performed at this time to evaluate for possible air embolism. The clothing should then be carefully removed, examined, and retained.

After collecting appropriate trace evidence, taking x-rays, and removing clothing, the body should be washed, so that documentation of injuries and photography can take place. Sharp force injuries should be classified as stab wounds, incised wounds, or chop wounds. The margins of a sharp force injury, whether they are stab wounds or incised wounds, are usually "continuous," but they may occasionally have an irregularity along the margin and consequently be described as "discontinuous." In addition, the margins are frequently considered "clean" or "sharp," meaning there are no associated abrasions or contusions.

Occasionally, abrasions and/or contusions occur adjacent to sharp force injuries. These may result from a variety of objects, including the handle of the weapon, such as a knife. When such injuries occur in stab wounds wherein the blade's entire length enters the body, the abrasions/contusions may be considered "hilt mark" injuries. Their presence, along with an accurate measurement of the depth of the wound during internal examination, can help the pathologist to estimate the length of the blade.

Regarding the angles (ends) of sharp force injuries, the angles may be "sharp" (coming to a point), "blunt" (having a squared-off appearance), or "indeterminate" (when a definitive ruling between sharp and blunt cannot be made). It may be useful in some cases to trace the wound margins with a pen after placing clear plastic over the wound.

When a body part comes in contact with a sharp edge, which of the following occurs?
A stab wound. Note that the left angle has a squared-off appearance and is therefore described as being "blunt," whereas the right angle comes to a point and is therefore described as being "sharp."

The location of each sharp force injury should be noted as to its specific body location, with measurement of the distance from the bottom of the foot or the top of the head, the distance from the midline or mid axillary line, and the proximity to a local landmark, such as the umbilicus, nipple, or ear, if such a landmark is nearby. The overall wound length, width, and directionality should be described, as should the appearance of the wound's margins and angles. In some cases of multiple stab wounds, it may be appropriate to group the wounds in the autopsy report provided that measurements of each individual wound have been taken and can be recovered if needed.

When a body part comes in contact with a sharp edge, which of the following occurs?
An example of a gaping stab wound with associated abrasions near the upper left angle. The presence of associated abrasions and/or contusions may result from the "hilt" or handle of a knife or other weapon. Note that the each angle of the wound is sharp.

The directionality of the "long axis" of a sharp force wound can be described as "vertical," "horizontal," or angled, with a general or specific measurement of the angulation. One method is to describe the directionality based on a clock-face configuration. For example, "the long axis of the wound runs between the 1 and 7 o'clock positions." It should be noted that, when using this method in describing incised wounds, it is not meant to imply that the "direction" of the cutting occurred from upper (1 o'clock) to lower (7 o'clock) (see more below as well as in Common Misconceptions).

Nonlinear or irregularly shaped stab or incised wounds can result from irregularly shaped or jagged weapons, from intersecting wounds, or from a twisting weapon/body interaction. The last phenomenon can result in combined stab/incised wounds. It cannot be determined based on the configuration of these wounds whether the assailant twisted the knife while it was in the body or if the victim twisted while impaled, unless there is clear evidence that the wound occurred postmortem.

In attempting to determine whether an angle is sharp or blunt, it is sometimes necessary to "reapproximate" the wound margins. In other words, the margins (edges) of the wound can be held together ("reapproximated") in order to better evaluate the angles of the wound, as shown in the photographs below.

When a body part comes in contact with a sharp edge, which of the following occurs?
A "gaping" stab wound. Note that it is difficult to determine if the angles are sharp or blunt.

When a body part comes in contact with a sharp edge, which of the following occurs?
The same stab wound depicted in the previous image, with reapproximated wound margins. Note that reapproximation of the wound edges allows one to determine that the upper angle is blunt, whereas the lower angle is sharp.

Reapproximation of the margins can occur by simply holding the margins together; for photography, some choose to use clear tape over the wound or superglue to bind the subcutaneous tissues together.

Postmortem drying of the wound results in a darkening of the wound, with associated drying and a loss of flexibility. As such, postmortem drying can make evaluation of a wound's margins and angles difficult. Soaking the wounds with a wet towel may facilitate reapproximation of dried wounds.

When a body part comes in contact with a sharp edge, which of the following occurs?
A stab wound which has become dried out postmortem. Note the dark discoloration of the margins. Even with postmortem drying, it is possible to determine in this case that the left angle is sharp, whereas the right angle is blunt.

The pathway into or through the body should be described. A wound that goes completely through a specific body part is said to have "perforated" that part (see the following 2 images). Conversely, if the wound only goes partly into a body part, it is said to have "penetrated" that part.

When a body part comes in contact with a sharp edge, which of the following occurs?
A perforating stab wound of the arm. It could not be determined with certainty which wound represents the entrance and which represents the exit.

When a body part comes in contact with a sharp edge, which of the following occurs?
The same perforating stab wound as shown in the previous photograph. After examining and photographing the wounds, a probe can be gently inserted through the wound in order to show that the 2 skin defects connect with each other.

A description of the overall direction of the wound and its maximal depth of penetration should also occur. This is particularly important in deep stab/puncture wounds. It is appropriate to describe the direction within 3 planes, including front/back, right/left, and up/down. Pouring a radio-opaque substance into a stab wound to delineate the wound path is a technique that only works in the world of television fiction.

As in the 2 photos shown above, it is frequently impossible to differentiate entrance stab wounds from exit wounds. It should be noted that extreme care should be employed when inserting probes into wounds, such that no additional tissue damage is produced by the probe. Insertion of probes should only occur after careful examination, documentation, and photography of the "unprobed" wound.

A chop wound represents a combination of sharp and blunt force injuries, typically produced by a heavy or "powerful" object that has an edge that is somewhat sharp to very sharp, or by a sharp object wielded with a tremendous amount of force. The edge of the object creates a sharp force injury, characterized by cutting of the skin and underlying tissues, whereas the intensity of the force, or the relative "bluntness" of the object, results in associated abrasions, lacerations, and/or contusions, with or without underlying fractures. A chop wound's appearance may also aid in determining the type of weapon used, as the wounds may take on the pattern of the weapon.

When a body part comes in contact with a sharp edge, which of the following occurs?
A chop wound produced by the claw end of a crowbar.

The overall shape of a stab wound tends to mimic the object that caused the wound. As such, wounds caused by knives tend to be linear (or curvilinear). Scissors create a more triangular-shaped stab wound. Objects with a cylindrical shape cause round stab wounds, which may mimic gunshot wounds. Screwdrivers can cause cross-shaped wounds (Phillips head), rectangular wounds (standard head), or even round or square wounds (depending on the shape of the shaft).

When a body part comes in contact with a sharp edge, which of the following occurs?
Multiple stab wounds produced by a standard screwdriver. Note the rectangular shape of several of the wounds.

When a body part comes in contact with a sharp edge, which of the following occurs?
Multiple superficial punctures produced by a Phillips ("cross-shaped"/"crosshead") screwdriver.

Other sharp objects can produce patterns that correlate with the objects' shapes.

When a body part comes in contact with a sharp edge, which of the following occurs?
A superficial puncture wound complex produced by a 4-tined dinner fork.

When a body part comes in contact with a sharp edge, which of the following occurs?
A stab (puncture) wound complex produced by a barbecue fork with 2 tines.

Although the appearance of stab wounds may indicate the shape of the weapon used, such is not necessarily the case with incised wounds; however, occasionally, the appearance of incised wounds may provide some indication as to the weapon type.

Serrated knives (those having "teeth") frequently produce wounds that are indistinguishable from nonserrated knives; however, if the serrated edge is dragged along the skin surface (usually adjacent to a stab or incised wound), multiple, small, superficial, parallel incised wounds corresponding to the serrated edge's teeth may be evident. Serrations may also be detected on underlying bony structures.

When a body part comes in contact with a sharp edge, which of the following occurs?
This stab wound of the cheek has a superficial curvilinear incised wound that trails away from the posterior margin toward the ear. Note the multiple, parallel, superficial incised wounds extending from the stab wound margins, superior to the longer incised wound. The presence of these marks indicates that the injuries were produced by a weapon with a serrated edge.

When a body part comes in contact with a sharp edge, which of the following occurs?
A sharp force injury complex of the chest. This wound was caused by the serrated-edged blade of a running electric reciprocating saw when the intoxicated operator fell onto the saw. Note the curvilinear to somewhat irregularly-shaped stab wound complex, as well as the marginal abrasions with superficial tooth-mark incisions/abrasions on the left side of the photograph.

When documenting multiple sharp force injuries, it is important to describe every wound. Most pathologists use some type of organizational scheme to keep track of the injuries. For example, some pathologists number the wounds sequentially, beginning from the wound closest to the top of the head and work downward from head to neck to trunk, ending with the arms and legs. Some pathologists describe stab wounds first and then incised wounds. Some combine the methods or use other methods. When there are numerous, similar sharp force injuries within a relatively small surface area, it is appropriate to describe the wounds together as a group or "cluster."

When a body part comes in contact with a sharp edge, which of the following occurs?
In this case with multiple stab wounds, it would be acceptable to describe the closely grouped collection of stab wounds within the central chest area as a "cluster," while providing individual descriptions of the wounds of the right side, the right chest, and the left chest near the axilla.

When a body part comes in contact with a sharp edge, which of the following occurs?
Multiple stab wounds of the back. Many pathologists would describe these wounds separately; however, some might describe them as a cluster.

"Hesitation marks" are a group of multiple, superficial, roughly parallel, incised wounds, typically present on the palmar (anterior) aspect of the wrists/forearms in suicide victims. [6] The classic case has groups of numerous, bilateral wrist hesitation marks. Hesitation marks may be seen in locations other than the wrists, including the neck, the chest, the antecubital fossa, and the inguinal area. The hesitation marks may be adjacent to a deeper, lethal wound, or they may be totally distant from the lethal wound(s).

When a body part comes in contact with a sharp edge, which of the following occurs?
Hesitation marks on the wrist of an individual who committed suicide via stab wounds of the chest.

Occasionally, no lethal sharp force wound is identified, and autopsy reveals that the cause of death is a suicidal overdose or some other type of traumatic injury. Despite the fact that the presence of hesitation marks is considered by some to be pathognomonic for suicide, it is possible for homicidal sharp force cases to have injuries that are indistinguishable from hesitations marks, although these are less likely to be on the wrists bilaterally. Multiple, superficial, roughly parallel incised wounds on the neck, adjacent to a deep, lethal incised wound, can be seen in victims of homicidal sharp force injury, particularly if torture was employed.

In victims of homicidal sharp force trauma, a frequent finding is the presence of so-called "defensive wounds" or "defense-type wounds." Classic defensive wounds in sharp force injury cases include multiple stab and incised wounds on the upper extremities, typically the fingers, hands, and forearms. These injuries occur as the victim attempts to fend off the attack by raising his or her hands and arms in a defensive posture, and they tend to be more dispersed in their distribution, as compared to hesitation wounds. [6] Similar appearing defensive wounds may occur on the lower extremities when the victim is on his or her back, raising the legs and feet to attempt to block the attack.

When a body part comes in contact with a sharp edge, which of the following occurs?
Defensive wounds of the hand/fingers.

When a body part comes in contact with a sharp edge, which of the following occurs?
A defensive injury on the hand of a homicide victim.

On internal examination, pathologists should describe the pathway of each sharp force injury. In cases of multiple homicidal stab wounds, it is not uncommon for many of the wounds to remain relatively superficial, without penetration of body cavities or internal organs. Occasionally, multiple wound pathways arise from a single skin injury. Presumably in such instances, the weapon simply hit the same location more than once, or the weapon was thrust in and out of the same skin entrance site.

The maximal depth of penetration of each wound should be noted, remembering that, because of the elasticity and flexibility of tissues and organs (and even the rib cage), the depth of penetration does not necessarily mean that a weapon must be that same length. It is entirely possible for a knife with a 3-inch-long blade to produce a wound that is 4 or 5 inches deep. When "hilt mark" injuries surround a stab wound, their presence indicates that the blade was inserted to its maximum possible depth; however, as just stated, because of the elasticity of skin, subcutaneous tissues, and internal tissues, the depth measurement of the wound can still be greater than the blade length. Obviously, it is also possible for a 3-inch-long blade to penetrate less than 3 inches.

The pathway for each wound should be documented, taking note of all organs injured, as well as the direction of the wound. As noted earlier, it is common for many pathologists to provide 3 directions for each wound. For example, a stab wound may have traveled from right to left, upward, and from front to back. Another stab wound might have gone from back to front, slightly downward, without any significant right/left deviation. Other pathologists choose to measure or estimate the angle of each wound, in reference to various anatomic planes.

When a body part comes in contact with a sharp edge, which of the following occurs?
A stab wound of the inferior vena cava, as well as an associated total transection of the abdominal aorta.

All associated internal injuries should be documented, including accumulations of blood (hemothorax, hemopericardium, hemoperitoneum, retroperitoneal hemorrhage, mediastinal hemorrhage), air embolism, pneumothorax, and evidence of aspirated blood. Radiographs (x-rays) and special dissection techniques may be utilized to identify and document air embolism and/or pneumothoraces. In sex-related homicides, a layered anterior neck dissection should be performed to rule out concurrent strangulation.

When a weapon producing a sharp force injury makes contact with cartilage (or bone), the cartilage (or bone) may sustain injuries that have specific tool-mark impressions that correspond to the weapon. If such markings are unique and detailed enough, tool-mark examiners in the crime laboratory may be able to "match" an injury to a particular weapon. Pathologists should remove the area of cartilage (or bone) containing the tool-mark impressions and retain the tissue in formalin for subsequent analysis.

When a body part comes in contact with a sharp edge, which of the following occurs?
A sharp force injury of the anterior, cartilaginous portion of a rib. Examination of the cut surface using a dissecting microscope may reveal tool marks that can be compared to the suspected weapon.

Special dissection techniques used to evaluate for the presence of an air embolism are described in the next section.

Radiologic examination of the sharp force injury victim is an important part of the forensic evaluation of such cases. Radiologic identification of broken-off portions of weapons, such as knife blades, helps to avoid injury during the autopsy, and subsequent "matching" of the weapon fragments may be possible.

When a body part comes in contact with a sharp edge, which of the following occurs?
Stab wound with broken-off blade remaining in body.

When a body part comes in contact with a sharp edge, which of the following occurs?
X-ray showing a retained knife blade.

When a body part comes in contact with a sharp edge, which of the following occurs?
Broken-off knife blade removed from a body at autopsy.

Chest x-rays performed before autopsy on victims of sharp force trauma may reveal an "air-embolism" within the right side of the heart, seen as a radiolucent (dark) area.

When a body part comes in contact with a sharp edge, which of the following occurs?
A chest x-ray showing an air embolism within the heart. Note the radiolucent (dark) area within the right side of the heart (arrows).

The presence of an air embolism may help to explain why a death might occur relatively rapidly, without extensive external or internal loss of blood. When a relatively large-caliber vein is severed, the continued pumping action of the heart can cause a vacuum-type effect, such that large volumes of air are sucked into the vein. When the air reaches the heart, a "vapor-lock" effect can occur, resulting in cessation of blood flow. This phenomenon can help to explain why, in certain cases, there is not a large amount of blood present externally or internally.

In order to confirm the suspicion of an air embolism within the right side of the heart, pathologists can carefully cut an approximately 4-5-inch × 4-5-inch "window" out of the anterior aspect of the chest wall, overlying the pericardial sac. Some prefer to remove the chest plate in the usual fashion. In either case, care should be taken to avoid disruption of large blood vessels, which can potentially cause air to enter the vessels artifactually.

The heart sac should be opened anteriorly, such that the pericardial cavity can be filled with water, so that the heart is totally submerged. Once submerged, a needle or scalpel blade can be used to puncture the right atrium of the heart. If an air embolism is present, bubbles will escape from within the right atrium. The pathologist can use a water-filled, inverted graduated cylinder to "catch" the air bubbles in order to measure the amount of air trapped within the heart (see the image below).

When a body part comes in contact with a sharp edge, which of the following occurs?
Checking for an air embolism at autopsy. In this photo, the chest plate was removed very carefully before filling the heart sac with water. An inverted water-filled graduated cylinder is being used to collect and measure the escaping air.

If a pneumothorax is visualized on chest x-ray (a radiolucency), or if one is otherwise suspected at autopsy, the pathologist can utilize a technique similar to that described for air embolism in the preceding paragraphs. During reflection of the chest skin, subcutaneous tissues, and muscles, the side "flaps" of the chest wall should be dissected laterally, farther than normal, such that "pockets" are formed between the rib cage and the outer flaps of reflected skin, subcutaneous tissue and muscle.

Care should be taken not to penetrate the rib cage/intercostal muscles during reflection. The pockets can then be filled with water. The pathologist can then perforate a submerged intercostal region (with a scalpel or needle) and look for air bubbles escaping from the pleural cavity. Measurement utilizing a water-filled, inverted graduated cylinder to "catch" the bubbles is possible, as described with air embolism above.

Depending on the case, it may be difficult for pathologists to identify specific vascular injuries. This is particularly difficult with high neck injuries and certain extremity injuries. One method that can aid in identification of vascular injuries makes use of a simple syringe filled with water. The syringe can be inserted into a portion of the blood vessel proximal to the area of concern. A relatively tight seal must be made around the syringe end. This can be accomplished with ones fingers, sutures, or a clamp. When the water is injected into the vessel, visualization of water escaping from the area of concern can be evidence that the vessel was indeed injured. If no water escapes, there is likely no injury. If water does escape, the pathologist should dissect the tissues further and visually identify the injury.

If available for examination, the weapon used or suspected to have been used in a sharp force injury case can be examined, taking care not to compromise trace evidence or contaminate the weapon or the body. When examining a weapon, such as a knife, one should note if the blade is "single-edged" (having a single sharp edge, with the opposite edge being "blunt," or squared-off), "double-edged" (having 2 sharp edges), a combination of single and double edges (usually, these combination blades have 2 edges toward the tip and then become single-edged as the blade approaches the handle), and whether or not the blade is serrated (having teeth).

It is also important to note the length of the blade (measured from the base, where the handle begins, to the tip), the width of the blade (from one edge to the opposite edge), and the thickness of the blade. It should be noted that the terminology used to describe the dimensions of the knife and the wound do not correspond with one another. In other words, when comparing a stab wound to the weapon, the thickness of the blade produces the width of the wound, the width of the blade produces the length of the wound, and the length of the blade produces the depth of the wound.

Recognizing this, it should be noted that wound width does not necessarily equal blade thickness, wound length does not necessarily equal blade width, and wound depth does not necessarily equal blade length; because of the elasticity and flexibility of human tissues, as well as the fact that the weapon can move within the wound path, the wound width, length, and depth may actually be smaller or larger than the corresponding dimensions of the weapon.