Forensic Medicine Handout PDF 2024

= Subcutaneous (small and firm due to dense fibrous strand). = Subgaleal (large & soft limited by attachment of occipitofrontalis). =Subperiosteal (limited to one bone e.g. cephalhematoma in newly born). Cut wound. Laceration (contused wound) caused by h...

= Subcutaneous (small and firm due to dense fibrous strand). = Subgaleal (large & soft limited by attachment of occipitofrontalis). =Subperiosteal (limited to one bone e.g. cephalhematoma in newly born). Cut wound. Laceration (contused wound) caused by heavy blunt instrument, simulate cut wound, edges are linear but everted and contused with crushed hair ends. Cut –laceration caused by heavy sharp instrument. Fass or axe. Firearm wound (exit & or inlet). Skull Fractures Types of skull fractures: A) Fissure fracture: Causative object: Heavy blunt instrument with considerable momentum e.g. stick, stone, blow by fist, falls may occur in the vault or base of the skull. Characters: Linear, with no bone defect, wide at point of impact (high energy absorption), occurs at site of impact and extends between& along lines of anatomical weakness: Frontal fracture (e.g. head-on RTA) often radiates into anterior cranial fossa. Temporal fracture (e.g. blow to side of head) often radiates into middle cranial fossa. Occipital fracture (e.g. backwards fall) often radiates into posterior cranial fossa. Subtypes: a) Polar fracture: Occurs when head is supported at the most bulging poles. b) Diastatic fracture: fissure fracture causing separation of sutures. c) Ring fracture: At foramen magnum due to a fall onto the feet or onto the top of the head. d) Fracture base: Occurs due to blow to the face, extension from vault fracture, or fall on heals or buttocks. Fracture base is suspected when the following symptoms are present: a) CSF otorrhea and rhinorrhea. b) Bilateral black eyes c) Battle's sign d) Epistaxis or bleeding from the ear. B) Depressed fracture: Causative object: Heavy blunt object with localized sticking surface area with considerable momentum e.g. head of hammer, stone. C) Comminuted Fracture: Spider's web: Causative object: Heavy blunt object with wide striking surface area and considerable momentum e.g. falls from heights. D) Cut fracture: Caused by heavy sharp object e.g. chopper, axe or fass. E) Compound Skull Fracture: The scalp is cut, and the skull is fractured 35  Clinical presentation of skull fractures: a) Concussion. b) Compression. c) Concussion passing to compression with lucid interval if associated with extradural hematoma. d) Death (if there is a diffuse brain injury or brain laceration). Healing of Skull Fractures: 1. Fissure: if the edges are not separated: completely healed in 3 months. If edges are separated by tissues edges smoothen in 3months. 2. Bone defect in the vault heals by membrane formation. It starts after 3months & completely closes the defect in 12months. Intracranial Haemorrhage (ICH) There are 4 types of ICH: 1. Extradural (epidural) haemorrhage (EDH) always traumatic: Site: Arterial blood accumulates between the Dura and the inner skull table. They are always unilateral. Bleeder: Middle meningeal artery as it passes upwards within a groove in the temporal bone usually associated with fracture. In 15% of cases no fracture is identified. This accumulation can be immediate or delayed. Clinical picture: a. Concussion passing to compression with lucid interval. Or b. Cerebral compression. D.D. heat hematoma 2. Subdural haemorrhage (SDH): Traumatic (More common than EDH): Site: Blood accumulates between the Dura and Arachnoids. Bleeders: bridging veins which cross the Dura to the brain surface. Cause: sudden jarring or rotation of the head (often a trivial blow or fall) causes movement of the brain relative to the Dura which leads to shear and tear of these veins (inertial trauma). Types: a) Acute blood accumulates immediately after the injury. b) Sub acute: after several hours. c) Chronic: (weeks or months) due to repeated minor trauma to the head more common in elderly (brain atrophy widens the gap), children (shaking injury as part of the child abuse syndrome) and alcoholics (frequent unprotected falls and prolonged bleeding times). Chronic SDH is presenting with: persistent headache, fluctuating drowsiness, confusion and memory changes. 36  PM: thin layer of coagulated blood with different colors and granulation tissues invading it at different sites. 3. Subarachnoid haemorrhage (SAH): ▪ Pathological, (2nd most common cause of sudden unexpected death due to disease). Causes: due to rupture of an aneurysm (common in females), congenital malformation or extension of intracerebral hemorrhage. (Site: At base of the brain). ▪ Traumatic: Usually associated with contusion and laceration of the brain surface (site: parietal, temporal, under surface of frontal poles). Rarely due to a kick or blow to the side of the neck which ruptures the vertebral artery as it enters the cranial cavity (traumatic basal SAH). 4. Intracerebral haemorrhage(ICH): ▪ Pathological: Due to hypertension, eclampsia, drug abuse, rupture of an aneurysm, arteriovenous malformation (AVM), anticoagulant, bleeding diathesis, hemorrhagic necrosis (e.g., tumor, infection), or venous outflow obstruction (e.g., cerebral venous thrombosis). ▪ Traumatic: Rupture of blood vessels in brain substance due to shearing stress or extension from surface contusion. Brain Injuries A) Localized Brain Injury: contusion and laceration. Cerebral contusion is of 2 types: "Coup type" contusions: Due to acceleration of the head from blow causing contusion at the point of impact or due to skull deformation. Contre-coup: Opposite to the site of impact due to deceleration of the head where the brain glides over the irregular, jagged contours of the skull. B) Diffuse Brain Injuries: 1-Concussion It is a clinical state of transient loss of conscious due to temporary nerve cell dysfunction with no visible physical damage. Cause: it is due to jarring of the brain inside the skull. Clinical picture: o Mild confusion or dazing which are temporary. 37  o Brief loss of conscious which won't last more than 15min (