Limbic System and Diencephalon Quiz

Limbic System

• The hippocampus is an extension of the cerebral cortex in the medial temporal lobe, projecting to the fornix.
• It's involved in converting short-term to long-term memories.
• The fornix is a white matter pathway carrying hippocampal axons to other brain regions.
• The amygdala mediates fear, connecting to olfactory tracts, septal nuclei, diencephalon, and midbrain.
• Phobias might stem from early amygdala responses before the hippocampus was fully developed.
• Post-traumatic stress disorder can affect the hippocampus and long-term memory, triggering flashbacks.

Diencephalon

• The diencephalon surrounds the third ventricle.
• It stretches from the optic chiasm to the mammillary bodies.
• Structures visible on the inferior surface include: the optic chiasm, optic tracts, tuber cinereum, infundibulum, and pituitary gland.
• Mammillary bodies are gray matter protuberances with a white matter capsule.
• The thalamus relays sensory information (except smell).
• The thalamus is divided into medial-posterior, lateral-posterior, and anteriorsuperior divisions.
• These divisions contain nuclei for various functions. The anterior and medial posterior divisions are involved in memory and emotional state.
• The lateral posterior division involves sensory and emotional information.
• The lateral geniculate nucleus (LGN) is a visual relay center.
• The medial geniculate nucleus (MGN) is an auditory relay center.

Brainstem

• The brainstem connects the spinal cord to the diencephalon and cerebrum.
• It houses reflex centers for respiration, cardiovascular function, and consciousness and contains nuclei for cranial nerves III through XII.
• The brainstem includes the medulla oblongata, pons, and midbrain.
• The medulla oblongata is located between the pons and spinal cord.
• It contains the pyramids which are the major efferent tracts.
• The pons is above the medulla and below the midbrain.
• It primarily consists of transverse fibers (corticospinal, corticobulbar, etc) used in the corticospinal pathway.
• The midbrain connects the pons to the diencephalon.
• It contains the superior and inferior colliculi.

Reticular Formation

• The reticular formation is a network of nerve cells running through the brainstem.
• It receives sensory information from several areas and transmits efferent information.
• The reticular formation contributes to consciousness and arousal states, and regulates cardiovascular and respiratory control.

Cerebellum

• The cerebellum is located below the occipital lobe of the cerebrum.
• It receives sensory information about body position and movement and sends signals to adjust and coordinate movements.
• The cerebellum has two hemispheres connected by the vermis.
• It contains several lobes, including the anterior, posterior, and flocculonodular lobes.
• The cerebellar cortex is organized into three layers.
• The cerebellum receives input via climbing and mossy fibers and sends output through efferent cerebellar fibers.

Spinal Cord and Ascending/Descending Tracts

• The spinal cord is the most caudal part of the central nervous system, extending from the medulla oblongata to the lumbar region.
• It contains 31 spinal nerve pairs.
• The spinal cord is divided into anterior and posterior median fissures internally.
• The grey matter forms a butterfly-like shape within the spinal cord and contains cell bodies of neurons.
• The white matter surrounds the grey matter, and contains ascending and descending tracts of myelinated axons.
• Ascending tracts carry sensory information from the periphery to the brain.
• Descending tracts carry motor commands from brain to the periphery.
• Specific ascending tracts, such as the spinothalamic tract, carry sensory information about pain, temperature, and touch; another important ascending tract is the dorsal column-medial lemniscus.
• The spinothalamic system is responsible for carrying temperature and pain information from the body's periphery to the brain.
• The dorsal column-medial lemniscus carries sensory input on fine touch, vibration, and proprioception.
• Ascending pathways (e.g., spinothalamic, dorsal column-medial lemniscus) are important in sensory perception.
• Descending pathways (e.g., corticospinal) are involved in motor control.