Keyhole defect production in tubular bone.

Fracture characteristics, reported primarily for the cranium, are valuable indicators of bullet direction. A bullet striking the vault tangentially produces an irregular opening, termed a "keyhole defect." with the circular portion of the defect being the initial point of impact. Identifying this feature in tubular bone (long bone) can also demonstrate bullet direction and the position of the bone at the time of the shooting. This case study involving a tangential shot (i.e., a keyhole fracture) to the humerus demonstrates some of the same fracture mechanics seen in the cranium.

Characteristics of child abuse by anteroposterior manual compression versus cardiopulmonary resuscitation: case reports.

Lethal and sublethal injuries to infants caused by anteroposterior manual compression can be accompanied by lateral rib fractures, hemorrhage into the viscera, and when severe, rupture of large vessels and solid organs. Abusers may claim that these injuries were sustained in an attempt to perform cardiopulmonary resuscitation (CPR). The difference between injuries caused by CPR and injuries caused by inflicted anteroposterior compression is examined in one sublethal and two lethal cases.

Diameter of cranial gunshot wounds as a function of bullet caliber.

Determination of bullet caliber becomes increasingly important in homicides where the bullet is missing. In cases with entrance wounds to bone that are circular and well defined it may be tempting to measure the defect and offer suggestions about bullet caliber. For this reason, the relationship between wound diameter and bullet caliber was examined using cranial bones from autopsy cases. The minimum diameter of 35 cranial wounds produced by .22, .25, and .38-caliber bullet was measured. The relationship of minimum wound diameter to bullet caliber was examined using a one way analysis of variance. Fisher's least significant difference test revealed no significant difference between .22-caliber and .25-caliber wounds, while the .38-caliber wounds were significantly different (P < .001) from .22-caliber and .25-caliber wounds. Variation in wound size resulting from such factors as bullet shape, surface treatment, strength characteristics, loss of gyroscopic stability, intermediate targets, tangential impacts, and existing fractures are discussed. Also, the large variety of calibers available are noted as complicating the prediction of caliber from wound size. In view of these factors caution is recommended in any attempt to determine precise bullet caliber from the minimum dimensions of the cranial gunshot entrance wound.

Effects of human decomposition on bullet striations.

Five different types of bullets, representing the major materials used in centerfire handgun and rifle ammunition, were inserted into the cranial, chest and abdominal cavities, muscle and adipose tissues of a fresh cadaver. The bullets were retrieved after the body was 90% decomposed. Observation and comparison of before and after photographs let each bullet serve as its own control. Results indicate the reactivity of bullet materials and the body region are significant factors affecting the corrosion process and may obscure rifling striations.

Identification of gunpowder in healed wounds.

A woman received a contact gunshot wound to the abdomen from a .22 caliber revolver. She recovered only to succumb to another gunshot wound six months later. The initial wound was dissected and multiple intact granules of round flake gunpowder were recovered. Cross sections of granules were clearly identifiable in histologic slides. Recovery of intact powder in remote wounds has not been previously described and may help classify the ammunition and weapon used to produce the injury.

Characteristic features of entrance wounds from hollow-point bullets.

Several cases of gunshot wounds produced by hollow-point bullets showed characteristic central tags. These apparently arise from sparing of the skin surface by the hollow point cavity when the bullet strikes the skin tangentially. This unique feature may be helpful in assessing entrances of perforating wound tracks or other cases where the bullet is either not available or unknown.

Atypical gunshot exit defects to the cranial vault.

Cranial exit wounds typically display external beveling, however, variation has been noted in the literature due to keyhole phenomena and pre-existent fractures. Two cases of atypical exit morphology are presented with features mimicking blunt trauma. In both instances radial fractures created by the exiting impact allowed passage without producing exit beveling. A working knowledge of the biomechanics of bone fracture, radiographs and low power microscopy are essential elements for the proper interpretation of such exit wound fractures.

The A.B.F.O. study of third molar development and its use as an estimator of chronological age.

Radiographs depicting third molars (M3s) have been used to estimate chronological age in juvenile and adult suspects, but accuracy of the method has been in question. This study provides age benchmarks for American whites (age range: 14 to 24 years) based on cases (n = 823) drawn from diplomates of the American Board of Forensic Odontologists in the United States and Canada. Maxillary M3 formation was slightly advanced over mandibular M3s, and root formation occurred earlier in males than females. Mean and median ages for M3 formation are tabled using Demirjian's eight-grade classification. Regression formulas and empirical probabilities are provided relative to the medicolegal question of whether an individual is at least 18 years of age. The M3 is the most variable tooth in the dentition, but situations arise where M3 formation is the only usable datum for age estimation.

The meaning of an accessory projectile.

A previously expended pistol casing was removed from a gunshot wound after an apparent accidental shooting. Examination of this foreign body indicated it had ridden the bore ahead of the bullet. Further investigation disclosed this as a deliberate but ignorant means to load an already loaded weapon. The assailants then fired at a passerby and killed him. Disclosure of the foreign body by X-ray, recovery and examination at autopsy were used to corroborate the circumstances and allowed charges of criminally negligent homicide to be placed.

Matching bullets to bone impact signatures.

When bone is penetrated or perforated by a bullet, the bullet's impacting surface is often uniquely modeled by the fractured bone. Reconstructing bone with simple super-imposition of the bullet's contour lines allows matching of a particular bullet to its specific bone defect.

Differentiation of hydrocephalic calf and human calvariae.

Occasionally, partial calvariae of hydrocephalic calves are found in forensic contexts and mistakenly identified as human. Such specimens can be properly identified through immunological assessment of associated soft tissue, microscopic analysis of associated hair, and morphological comparison with documented museum specimens. Morphological comparison should focus on the form of the occiput, supraorbital grooves, and bulbous vault and presence of coronal processes.

Recognition of cemetery remains in the forensic setting.

Cemetery remains exposed through vandalism or natural phenomena are frequently brought to the attention of law enforcement agents or medical examiners. Although it is often difficult to distinguish cemetery remains from those of medicolegal significance, clues to their origin may exist. Characteristics consistent with cemetery remains include physical characteristics associated with the embalming process. Characteristics indicative of cemetery remains include functional or ornamental artifacts associated with the coffin, devices used in embalming the body, and elevated levels of embalming chemicals in the soft tissue.

Methods for physical stabilization of ashed teeth in incinerated remains.

Methods for physically stabilizing the extremely fragile ashed teeth that are often encountered in incinerated human remains were investigated. Results of a questionnaire sent to forensic anthropologists and forensic odontologists disclosed that, for these two groups, the most popular methods currently used are impregnation with a solution of polyvinyl acetate or application of cyanoacrylate cement, respectively. In addition, extracted human teeth were incinerated in the laboratory and impregnated with commercially available preparations of either cyanoacrylate cement, clear acrylic spray paint, hair spray, spray furniture varnish, clear fingernail polish, quick-setting epoxy cement, Duco household cement, polyvinyl acetate polymer in acetone, or self-curing clear dental acrylic resin. Every substance tested successfully stabilized the incinerated teeth. Clear acrylic spray paint was judged the most efficacious overall because of its ease of application, availability, inexpensiveness, and rapidity of setting.

Cranial fracture patterns and estimate of direction from low velocity gunshot wounds.

Cranial trauma produced by low velocity gunshot wounds is investigated in an autopsy series. In skeletonized remains with postmortem damage, or after surgical debridement, the primary internal or external beveling may become obscured, causing difficulty with the identification of entrance and exit wounds. The morphology of associated secondary and tertiary fractures based upon the mechanics of their production is discussed as a means of establishing bullet entrance and exit sites.

Extraradicular cemental fragments in the alveolar bone of prehistoric American Indians: report of three cases.

Heretofore unreported, grossly observable structures composed of cementum were found in the superficial alveolar bone--but not attached to the tooth root--in three prehistoric American Indian skeletons from South Dakota. The macroscopic, radiographic, and histologic morphology of these fragments is described and compared with other cemental structures that occur in the alveolar process.

Elastic fibers in the anulus fibrosus of the dog intervertebral disc.

A light microscopic investigation of the anulus fibrosus in cervical intervertebral discs of the dog was conducted to ascertain the arrangement and distribution of elastic fibers. Elastic fibers were observed in all lamellae of the anulus fibrosus. However, collagenous fibers were the predominant type of connective tissue fiber, and elastic fibers were randomly dispersed among them. Intralamellar (collagenous and elastic) fibers were vertically and obliquely oriented in both superficial and deep lamellae of the anulus fibrosus. All intralamellar fibers were densely and regularly arranged in superficial lamellae, but they were more loosely organized in deep lamellae. A narrow border of interlamellar, elastic fibers was observed between broader, contiguous lamellae in the superficial zone of the anulus fibrosus. Interlamellar elastic fibers wer vertically and obliquely arranged in superficial lamellae; however, they were radially oriented in deep lamellae. The deepest lamella of the anulus fibrosus consisted of a loose, three-dimensional network of intermeshing collagenous and elastic fibers. These observations suggest that elastic fibers are integral components of the articular and shock absorption mechanisms of the anulus fibrosus, and the cervical intervertebral disc of the dog is a suitable model for experimental investigation of the role of elastic fibers in intervertebral disc herniation.

Non-carious interproximal grooves in Arikara Indian dentitions.

The dentitions of adult Arikara Indians from the Larson site (39WW2) were examined to determine the frequency and etiology of noncarious interproximal grooves. The observations included groove morphology, loci and association with dental pathology. Approximately 30% of the individuals exhibit one or more pronounced grooves. The use of dental probes in conjunction with dietary grit is the likely responsible for interproximal grooves in this population sample.