Common diseases: ischemic-hypoxic encephalopathy, cerebrovascular diseases with extensive cortical damage and trauma, etc. Typical signs: flexion of the upper extremities, extension of the lower extremities, “flexion of the elbows, inversion of the shoulders, extension of the legs and ankles”. The midbrain and pontine superior reticular activation system are not damaged, and there may be unconscious swallowing movements and wake-sleep cycles. Common manifestations: the eyes can open and close unconsciously, and the eyeballs can move. The pupil-to-light reflex and corneal reflex are present. Increased muscle tone of the limbs and positive pathological reflexes. Sucking reflex, strong grip reflex, and tense neck reflex may be present. Unconscious swallowing may occur with feeding, but there is no spontaneous movement. There is no conscious response to external stimuli. Urinary and fecal incontinence. Wake-sleep cycle is present. Decerebrate ankylosis Common disorders: midbrain damage, posterior cranial fossa lesions, hypoxia or hypoglycemia, typical signs: coracoacusis, tonicity of extremities, increased muscle tone. “Elbow extension, internal rotation of the shoulder and forearm, and straightening of the lower limbs”. Basis of pathogenesis:Decerebral tonicity is mainly a reflexive hypertonicity of the extensor muscles, which is an overstretched detrusor reflex. The excessive detrusor reflex is mainly caused by the interruption of the connection between the red nucleus and the inferior structures of the midbrain. Downward inhibitory influences from above the red nucleus are blocked, the activity of the reticular inhibitory system is reduced, and the central response of the spinal cord above the ? motor neuron inhibitory impulses are diminished, while the cerebellum, the vestibular nucleus and the reticular formation have a reduced response to ? The motor neurons’ easy-going impulses still exist, thus causing tonic spasms in the extensor muscles of the trunk and limbs. Common manifestations: Impaired consciousness manifests as waking coma, where the patient appears to be awake but has no conscious activity, does not respond to verbal stimuli, and is diaphoretically incontinent, similar to decortical tonicity. Movement disorders were manifested by tonic extension of the limbs, angular torso, irregular breathing, and generalized tonic muscle spasms. Disease regression: improvement. The extensional tonicity gradually changes to upper limb flexion, inversion, and internal rotation. This indicates that the lesion is gradually confined above the midbrain level and the disease is improving. Deterioration: The state of unconsciousness is comatose, and the extensional tonicity gradually changes into delayed paralysis, indicating that the lesion has spread below the pontocerebrum and the condition gradually develops into a state of near death. Summary: 1. Both are caused by severe diffuse lesions in the brain, so it is often impossible to locate the exact site of the lesion; 2. Decortical ankylosis is mainly at the level of the cerebral cortex, while decortical ankylosis is mainly at the level of the midbrain, the latter being more severe. Decerebral ankylosis: coracobrachialis, extensional ankylosis of all four limbs.