NSIII Diencephalon, Brainstem, Cerebellum

• Cerebellum

  • Day to day function
  • 10% of brains volume but 50% of the total neurons
  • Connected to brainstem via “peduncles”
  • Motor coordination and balance
  • Where body is in space to everything around you
• The cerebellum has similar features to the cerebrum
• Gross anatomy of the cerebellum

  • A cortex with grooves (fissures) and ridges (folia)
  • Deep nuclei
  • 2 hemispheres with lobes
  • Ventral “vermis” = worm
  • Info comes in, synapses and then gets released
• Lobes and hemispheres of the cerebellum

  • Vermis
  • Lateral hemisphere
  • Flocculonodular lobe
• Vermis 

  • Axial control 
  • Things along the midline/torso
• Lateral hemisphere

  • Appendicular control
  • Limbs
• Flocculonodular lobe

  • Eye movements
• Cerebellar peduncles

  • Sits at the level of the pons (brainstem) and is connected via 3 peduncles
• Peduncles are highways

  • Superior peduncle = output
  • Middle and inferior peduncle = input
  • Vision, vestibular (balance), proprioception (where body is in space)
• Cerebellum integrates sensory information (vision, vestibular, proprioception) to modulate motor output

  • Important for complex movement
• Basal ganglia = basic motor 

  • Ex. running straight
• Cerebellum = piggy-backs off motor function

  • Ex. running through a forest
• The cerebellum controls white and grey matter
• Parts of the diencephalon

  1. Thalamus
  2. Hypothalamus
  3. Pituitary gland (posterior)
• Thalamus 

  • Gatekeeper for sensory information - selective attention
  • Relay nuclei
  • Takes in information, makes a decision about it, sends it to cortex
  • Cortical input: determine which info is sent to cortex
• Selective attention

  • Making a decision about what information is going to reach the cortex
• Anterior thalamus

  • Balance basal ganglia + cerebellum
• Posterior thalamus

  • Vision and hearing
• Lateral thalamus

  • Touch, pressure, proprioception
  • Temperature and pain
• Hypothalamus

  • Maintain homeostasis
  • ANS regulation - HR, BP, RR, digestive motility, pupil size, temperature regulation
• Posterior pituitary gland

  • Secrete hormones - oxytocin, vasopressin
• Most cranial nerves come from the brainstem

  • 4 nerves about the pons
  • 4 nerves in the pons
  • 4 nerves below the pons
• The brainstem consists of:

  1. Midbrain
  2. Pons
  3. Medulla 
• Midbrain

  • Connects “hindbrain” (pons, medulla and cerebellum) with the forebrain cortex
  • Key structures:
  • Superior colliculus
  • Inferior colliculus
  • Substantia nigra
  • Cranial nerves: III, IV
  • Cerebral peduncles
  • Corticospinal motor tracts
• Superior colliculus: visual reflexes (tracking)
• Inferior colliculus: auditory integration
• Substantia nigra: dopamine production (basal nuclei)
• Pons

  • Transmit information from cerebrum to cerebellum and medulla
  • Transmit sensory information from periphery to brain
  • Cranial nerves: V - VIII
  • Relay nuclei from cortex to cerebellum via cerebellar peduncles
• Medulla

  • Continuous with spinal cord
  • Anterior = motor
  • Posterior = sensory
  • Pyramid (center)
  • Olive (lateral)
  • Cranial nerves: IX - XII
  • Pyramidal decussation
  • Corticospinal motor tracts
• Basilar artery comes off the pons
• Cranial nerves

  • 12 pairs total
  • Considered part of the PNS
  • Spinal nerve equivalent
  • Information can be:
  • Sensory 
  • Motor
  • both
• CN I

  • Olfactory
  • Olfaction
  • Extends through the cribriform plate of the ethmoid bone
  • Strong connection to limbic system = memory
  • sensory
• CN II

  • Optic
  • Vision
  • Sensory
• CN III

  • Oculomotor
  • Eye muscles
  • Motor
• CN IV

  • Trochlear
  • Superior oblique motor
  • Motor
• CN V

  • Trigeminal
  • Face sensation
  • Both (sensory and motor)
  • Sensory = to face
  • Motor = muscles of mastication (chewing)
  • Proprioception
• What are the 3 branches of the trigeminal nerve

  1. Ophthalmic (V1)
  2. Maxillary (V2)
  3. Mandibular (V3)
• CN VI

  • Abducens
  • Lateral rectus motor
  • Motor
• CN VII

  • Facial
  • Muscles of facial expression and taste
  • Both (sensory + motor)
  • Sensory = taste buds (anterior ⅔)
• CN VIII

  • Vestibulocochlear
  • Balance and hearing
  • Sensory