Anatomical Terminology Because the unit we are currently studying involves the human body, it is necessary for you to familiarize yourself with some basic anatomical terminology as it relates to the human body. Directional Terms Directional terms describe the positions of structures relative to other structures or locations in the body. Superior or cranial - toward the head end of the body; upper (example, the hand is part of the superior extremity). Inferior or caudal - away from the head; lower (example, the foot is part of the inferior extremity). Anterior or ventral - front (example, the kneecap is located on the anterior side of the leg). Posterior or dorsal - back (example, the shoulder blades are located on the posterior side of the body). Medial - toward the midline of the body (example, the middle toe is located at the medial side of the foot). Lateral - away from the midline of the body (example, the little toe is located at the lateral side of the foot). Proximal - toward or nearest the trunk or the point of origin of a part (example, the proximal end of the femur joins with the pelvic bone). Distal - away from or farthest from the trunk or the point or origin of a part (example, the hand is located at the distal end of the forearm). Planes of the Body Coronal Plane (Frontal Plane) - A vertical plane running from side to side; divides the body or any of its parts into anterior and posterior portions. Sagittal Plane (Lateral Plane) - A vertical plane running from front to back; divides the body or any of its parts into right and left sides. Axial Plane (Transverse Plane) - A horizontal plane; divides the body or any of its parts into upper and lower parts. Median plane - Sagittal plane through the midline of the body; divides the body or any of its parts into right and left halves. Body Cavities The cavities, or spaces, of the body contain the internal organs, or viscera. The two main cavities are called the ventral and dorsal cavities. The ventral is the larger cavity and is subdivided into two parts (thoracic and abdominopelvic cavities) by the diaphragm, a dome-shaped respiratory muscle. Thoracic cavity The upper ventral, thoracic, or chest cavity contains the heart, lungs, trachea, esophagus, large blood vessels, and nerves. The thoracic cavity is bound laterally by the ribs (covered by costal pleura) and the diaphragm caudally (covered by diaphragmatic pleura). Abdominal and pelvic cavity The lower part of the ventral (abdominopelvic) cavity can be further divided into two portions: abdominal portion and pelvic portion. The abdominal cavity contains most of the gastrointestinal tract as well as the kidneys and adrenal glands. The abdominal cavity is bound cranially by the diaphragm, laterally by the body wall, and caudally by the pelvic cavity. The pelvic cavity contains most of the urogenital system as well as the rectum. The pelvic cavity is bounded cranially by the abdominal cavity, dorsally by the sacrum, and laterally by the pelvis. Dorsal cavity The smaller of the two main cavities is called the dorsal cavity. As its name implies, it contains organs lying more posterior in the body. The dorsal cavity, again, can be divided into two portions. The upper portion, or the cranial cavity, houses the brain, and the lower portion, or vertebral canal houses the spinal cord. Calculating Time of Death Using Algor Mortis For the first 12 hours, the body loses 0.78°C (1.4°F) per hour. After the first 12 hours, the body loses about 0.39°C (0.7°F) per hour Sample Problems Example: What is the temperature loss for someone who has been dead for 12 hours? Temperature loss = (0.78°C/ hour) x 12 hours = 9.36°C Example: Calculate the time of death if a person has been dead for less than 12 hours. If temperature loss is less than 12 hours (or less than 9.36°C) then you use the rate of 0.78°C per hour to estimate the time of death. Temperature of dead body is 32.2°C (90°F) Normal body temperature is 37°C (98.6°F) 37°C – 32.2°C = 4.8°C lost since death How long did it take to lose 4.8°C? 0.78°C/ hour x unknown number of hours = degrees lost 0.78°C/ hour x unknown number of hours = 4.8°C lost by body Solve for the unknown number of hours since death occurred: Number of hours = 4.8°C ÷ 0.78°C/ hour Number of hours = 6.1 hours Convert 0.1 hours into minutes: 0.1 hour x 60 min/ hr = 6 minutes hours since death = 6.1 hours or 6 hours and 6 minutes Example: Is the time of death more than 12 hours or less than 12 hours? Recall that if a body has been dead 12 hours or less, the body loses heat at the rate of 0.78°C/ hour. If the body has been dead 12 hours, then 0.78°C x 12 hours = 9.36°C If a body loses 9.36°C, then the person has been dead for 12 hours. If a body loses more than 9.36°C, then the person has been dead for more than 12 hours. Example: Calculate the time of death if the person was dead for more than 12 hours. If the body has lost more than 9.36°C, then you know that the victim has been dead for more than 12 hours. Recall that after 12 hours, the body loses heat at a rate of 0.39°C per hour. You need to calculate how many hours beyond the 12 hours that someone died and add it to the 12 hours. Body temperature was given as 22.2°C (72°F). 1. How many total degrees were lost from the time of death until the body was found? 37°C – 22.2°C = 14.8°C 2. Since 14.8°C is more than 9.36°C, you know that the body was dead longer than 12 hours. How much longer? 37°C – 22.2°C = total loss of 14.8°C since death 9.36°C were lost in the first 12 hours 14.8°C lost since death – 9.36°C lost the first 12 hours = 5.44°C lost after the first 12 hours 3. Recall that the rate of heat lost after 12 hours is 0.39°C per hour. You need to determine how many hours it took to lose that 5.44°C. You need to determine how many hours it took to lose that 5.44°C. (0.39°C/ hour)/ (unknown # hours) = 5.44°C lost after the initial 12 hours Solve for unknown number of hours: Unknown # hours (x) = 5.44°C ÷ (0.39°C/ hour) = 14.8 hours total time to lose 14.8°C or approximate time of death 4. First 12 hours there was a loss of 9.36°C. Next 14.8 hours there was an additional loss of 5.44°C. Therefore the victim has been dead about 26.8 hours (or approximately 27 hours) 0.8 hours x 60 min/hr = 48 minutes Calculating Portmortem Interval Using Rigor Mortis Background – In old detective movies, a dead body was often referred to as a “stiff.” The term refers to the onset of rigor mortis that follows soon after death. In this activity, you will estimate the postmortem interval by analyzing the degree of rigor of the deceased body. Postmortem interval is greatly affected by many variables. In this activity, you will make estimates based only on the state of rigor mortis. Actual postmortem interval estimates require examination of other types of evidence in combination with rigor mortis. Time after Event Appearance Circumstances death Body becomes stiff Stiffness begins with the eyelids and jaw 2 to 6 hours Rigor begins and stiffness moves muscles after about two hours then center of down body. body stiffens, then arms and legs Rigor 12 hours Peak rigor is exhibited Entire body is rigid complete Loss of rigor in small Slow loss of Rigor lost first in head and neck and last in 15-36 hours muscles first followed rigor bigger leg muscles by larger muscles Rigor totally Muscles become Many variables may extend rigor beyond the 36-48 hours disappears relaxed normal 36 hours Factors affecting Event Effect Circumstances rigor Cold temperature Inhibits rigor Slower onset and slower progression of rigor Temperature Warm Accelerates rigor Faster onset and faster progression of rigor temperature Lack of oxygen to muscle, the buildup of Aerobic exercise Accelerates rigor lactic acid, and higher body temperature Activity before accelerates rigor death Muscles fully oxygenated will exhibit rigor Sleep Slows rigor more slowly Obese Slows rigor Fat stores oxygen Body weight Body loses oxygen quickly and body heats Thin Accelerates rigor faster .