Definition It isany condition thatleads to: - reduction of the oxygensupply to the blood and the tissues below the the normal physiologicallevel (hypoxia). - elevation of CO2 in the blood (hypercapnia). **Hypoxiameans (lowoxygen) whileanoxiameans (withoutoxygen).
Types of anoxia: (1) Anoxicanoxia: - Ambient. - Central. - Paralytic. - Mechanical (violent asphyxia). - Obstruction of the blood flow to the lungs. (2) Anemicanoxia: - Chemicallycombinedhemoglobin. - Hemolysis. - Hemorrhage. (3) Stagnant anoxia. (4) Histotoxicanoxia.
Stages of mechanicalanoxia or violent asphyxia: Three stages: (1) Stage of forced respiration: - It is due to stimulation of the respiratory center. - Clinicalpicture: DYSPNEA (2) Stage of convulsions: - It is due to cerebral irritation. - Clinicalpicture: CONVULSIONS, CYANOSIS, HYPERTENSION, LOSS OF CONSCIOUSNESS, CONSTRICTED PUPILS. (3) Stage of paralysis: - Clinicalpicture: LOSS OF CONSCIOUSNESS, FLACCID MUSCLES & LOST REFLEXES, DEEP CYANOSIS, DILATED PUPILS, IRREGULAR BREATHING (Cheyne-Stokes respiration). **Deathoccurs in about 5 minutes..
General postmortempicture of mechanicalanoxia: - Deepcyanosis. - Proptosis of the eyeballs. - Bloody frothfrom the nose and mouth. - Congested face withpetechialhemorrhage all over. - Dark violet or blue extensive hypostasis. ** All these are externalsigns N.B: Blood isdark and fluid in consistancy due to increased CO2 and fibrinolysisrespectively.
Hanging Definition: It is the mechanicalanoxicdeath due to suspensionof the body from the neck by a ligature. Causes of death: - Cerebralischemia. - Vagal cardiac inhibition. - Mechanicalanoxia. - Transection of the spinal cord (judicialhanging).
Post-mortem picture: (1) General (2) Specialfeatures - Protrusion of the tongue. - Dribbling of saliva. - Hypostasis of the lowerhalf of the body. - Neck signs: .Elongated and the headistilted to the opposite side of suspension point. .Ligature marks (HIGH UP in the neck, OBLIQUE, INCOMPLETE, has an IMPRINT of the ligature). ** Homicidal, suicidal or accidental
Strangulation Definition: It is the mechanicalanoxicdeathcaused by constriction of the neck by a ligature occluding the air passages fromoutside. Causes of death: - Mechanicalanoxia. - Reflex cardiac inhibition. - Delayededema of the glottis and choking.
Postmortempicture of strangulation: (1) General (2) Specialfeatures All are neck signs: - Ligature marks: . Low in the neck below the thyroid cartilage. . Transverse. . Complete. . Deep all through. . Abrasions and contusions taking the shape of the ligatingmaterial. - Inward fracture of the hyoidbone and the thyroid cartilage maybefractured. - Contusions and lacerations of the neck muscles. **Homicidal, suicidal or accidental
Throttling «Manual strangulation» Definition: It is the mechanicalanoxicdeathcaused by constriction of the neck by the hand occluding the air passages fromoutside. Causes of death: - Mechanicalanoxia. - Reflex cardiac inhibition. - Cerebralanoxia. - Delayedglotticedema and choking.
Postmortempicture: (1) General (2) Specialfeatures All are neck signs - Multiple contusions and fingernail abrasions. - Inward fracture of the hyoidbone (itis the mostcommon cause of hyoidbone fracture) and fracture of the thyroid cartilage. - Contusions of the deep tissues of the neck. ** Homicidal, suicidal or accidental
Smothering Definition: It is the mechanicalanoxicdeathcaused by occlusion of the externalrespiratoryopenings by the hand or soft objects. Causes of death: Mechanicalanoxia Postmortempicture of smothering: (1) General (2) Specialfeatures - Multiple contusions and fingernail abrasions. - Contusions in the buccal mucosa. - Ventral hypostasis in cotdeath. ** Homicidal, suicidal or accidental
Traumatic asphyxia: Overlaying Definition: It is the mechanicalanoxicdeath due to mechanical pressure by a heavyobject on the chestwith or without abdominal compression leading to prevention of respiratorymovements. Causes of death: - Mechanicalanoxia. - Injury to vital organs.
Postmortempicture (1) General (2) Specialfeatures - Contusions and abrasions of the chest and abdomen. - Fracture ribs. - Rupture of internalorgans. - Line of demarcationbetween the discoloredupper part of the body and the lower part. ** Homicidal, suicidal or accidental
Choking Definition: It is the mechanicalanoxicdeathcaused by occlusion of the respiratory passages frominside. Causes of death: - Reflex cardiac inhibition - Mechanicalanoxia Types: - Pathological - Non-pathological **Homicidal, suicidal or accidental
Drowning Definition: It is the mechanicalanoxicdeath due to submersion of the respiratoryopeningsunder water. Causes of death: - Direct causes: mechanicalanoxia - Indirect causes: . Reflex cardiac inhibition due to vagal stimulation . Head injury or other fatal injuries.
Posrmortempicture of drowning - Sure externalsigns: . Froth . Cadavericspasm - Probable externalsigns: . Related to anoxicanoxia: cyanosis . Related to presence of the body in water: skin is pale&wet Goose skin Washerwoman skin Postmortem injuries . Affection of postmortem changes due to presence in water: Cooling, hypostasis, adipocere, putrefaction **Homicidal, suicidal or accidental