Decorticate & Decerebrate Posturing

• What does decorticate posturing indicate?

  Damage above the red nucleus
• What does decerebrate posturing indicate?

  Damage at or below the red nucleus
• What are the main descending motor pathways?

  • Motor cortex
  • Decussation of the Pyramids
  • Internal Capsule
  • Upper Motor Neurones
• What do tectospinal pathways control?

  Head movements in response to visual stimuli
• Where do tectospinal pathways originate?

  From the superior colliculi
• What is the function of rubrospinal pathways?

  Excite flexor activity and inhibit extensor activity
• What is the primary input for rubrospinal pathways?

  Cerebellum
• What do reticulospinal pathways control?

  Coordinated movement and muscle tone
• Where do pontine reticulospinal tracts originate?

  Oral and caudal pontine reticular nuclei
• What is the role of lateral vestibulospinal tracts?

  Regulate muscle tone in posture and balance
• What is the function of medial vestibulospinal tracts?

  Contact cervical motor neurons for head position
• What characterizes decorticate posturing?

  Involuntary flexion of upper extremities
• How are the arms positioned in decorticate posturing?

  Flexed or bent inward on the chest
• What is a key feature of decerebrate posturing?

  Involuntary extension of upper extremities
• How is the head positioned in decerebrate posturing?

  Arched back
• What happens to the arms in decerebrate posturing?

  Extended by the sides and rotated internally
• What is the position of the legs in decerebrate posturing?

  Extended and rotated internally
• What causes abnormal posturing?

  Lesions that upset pathway activity balance
• What type of lesion causes decorticate posturing?

  Lesion above the red nucleus
• What type of lesion causes decerebrate posturing?

  Lesion below the red nucleus
• What are the differences between decorticate and decerebrate posturing?

  • Decorticate:
  • Damage above red nucleus
  • Flexed arms, extended legs
  • Decerebrate:
  • Damage at or below red nucleus
  • Extended arms, extended legs
• What are the two types of pathways used by the central nervous system?

  Ascending and descending pathways
• What do descending tracts carry in the central nervous system?

  Motor information in efferent nerves
• What is the function of upper motor neurons (UMN)?

  Transmit signals from the brain to spinal cord
• What do lower motor neurons (LMN) connect to?

  Peripheral muscles
• How are motor tracts in the spinal cord categorized?

  Pyramidal and extrapyramidal tracts
• What are the characteristics of pyramidal tracts?

  • Conscious control of muscles
  • Originates from the cerebral cortex
  • Supplies muscles of the body and face
• What are the characteristics of extrapyramidal tracts?

  • Unconscious, reflexive control of muscles
  • Originates from brainstem structures
  • Controls balance, locomotion, posture, and tone
• What are the two main tracts of the pyramidal system?

  Corticospinal and corticobulbar tracts
• What is the role of the corticospinal tract (CST)?


  Conscious control of body muscles
• Where does the corticobulbar tract terminate?

  In the brainstem at motor nuclei
• What is the significance of bilateral innervation in the corticobulbar tract?

  It provides redundancy for head and neck muscles
• Which cranial nerve receives only contralateral UMNs for the lower face?

  Cranial nerve VII
• What do extrapyramidal tracts control?

  Unconscious, reflexive muscle movements
• What are the four extrapyramidal tracts?

  1. Reticulospinal
  2. Vestibulospinal
  3. Rubrospinal
  4. Tectospinal
• What is the function of the medial reticulospinal tract?

  Contributes to voluntary movements
• What does the rubrospinal tract supply?

  Upper limb flexors and trunk flexors
• Where does the tectospinal tract originate?

  In the tectum of the midbrain
• What is the clinical significance of UMN lesions?

  They present with hypertonia and spastic paralysis
• How do LMN lesions present clinically?

  With hypotonia and flaccid paralysis