DIENCEPHALON & BRAINSTEM

what are the main functions of the diencephalon

• sensory relay and processing

• homeostasis & autonomic regulation

• motor integration

• endocrine regulation

• circadian rhythm regulation

• limbic and behavioral functions

what is the anatomical relationship of the diencephalon

• located b/w the cerebral hemispheres and brainstem

• surrounds the third ventricle

what are the key structures of the diencephalon

• epithalamus

• thalamus

• subthalamus

• hypothalamus

location of the diencephalon

most dorsal portion of the diencephalon

what are the structures of the epithalamus

pineal gland and habenula

what are the functions of the epithalamus

secretion of melatonin

regulation of circadian rhythms and sleep-wake cycles

reward processing

behavioral responses

location of subthalamus

inferior to the thalamus

what are the structures of the subthalamus

subthalamic nucleus

what are the functions of the epithalamus

• regulates motor control

• interacts with basal nuclei

location of thalamus

• central portion of the diencephalon

• superior to the hypothalamus

• forms the lateral walls of the 3rd ventricle

what are the characteristics of the thalamus

• paired thalamus

• interthalamic adhesion (massa intermedia)

• lateral genticulate body (visual relay nucleus)

• medial genticulate body (auditory relay nucleus)

what are the functions of the thalamus

• gateway to the cerebral cortex

• relays nearly all sensory info EXCEPT OLFACTION

• participates in motor and limbic circuits

what is the thalamus the “gateway” to

the cerebral cortex

location of hypothalamus

inferior and anterior to the thalamus

forms the floor anad inferolateral walls of the third ventricle

what are the structures of the hypothalamus

hypothalamus

mammillary bodies (inf. surface of hypothalamus)

infundibular stalk (infundibulum)

what is the infundibulum

connects the hypothalamus to the pituitary gland

what are the functions of the thalamus

• maintains homeostatis

• regulates the sutonomic nervous system

• controls endocrine function through the pituitary gland

what arises from the midbrain

mesencephalon then the midbrain

what arises from the hindbrain

metecephalon → pons and cerebellum

myelencephalon → medulla

location of brainstem

located within the posterior cranial fossa

what does the brainstem connect

forebrain to the spinal cord

what are the structures of the brainstem

midbrain

pons

medulla oblongata

what are the functions of the brainstem

• pathway for ascending and descending CNS pathways

• houses cranial nerve nuclei 3-12

• contains centers involved in respiration, cardiovascular function and regulation of consciousness

location of the midbrain

most rostral portion of the brainstem

what does the midbrain connect

the forebrain to the pons and cerebellum

what are the structures of the midbrain

• cerebral punduncles

• interpeduncular fossa

• superior colliculi

• inferior colliculi

• superior cerebellar peduncle

• cerebral aqueduct

• substantia nigra

• red nucleus

what are the functions of the midbrain

• visual reflexes

• auditory reflexes

• eye movement control

• motor control and movement regulation

• transmission of ascending and descending pathways

what is on the anterior surface of the midbrain

• cerebral peduncles (crus cerebri)

• interpeduncular fossa

• CN 3 emergence

what are the cerebral peduncles (crus cerebri)

• paired bundles of white matter located on the anterior surface of the midbrain

• it contains pathways connecting the cerebral hemispheres to the brainstem and spinal cord

what is the interpeduncular fossa

a midline depression located b/w the cerebral peduncles

what is the CN 3 emergence

an emergence from the interpeduncular fossa on the ventral surface of the midbrai

what is a peduncle

a large bundle of nerve fibers that serves as a connection between different regions of the brain

what is on the posterior surface of the midbrain

• superior colliculi

• inferior colliculi

• superior cerebellar peduncle

what is the superior colliculi

paired rounded elevations on the dorsal surface of the midbrain

what is the inferior colliculi

paired rounded elevations inferior to the superior colliculi

what does the superior cerebellar peduncle connect

connects the cerebellum to brainstem

what are the deep structures of the midbrain

• substantia nigra

• red nucleus

what is the substantia nigra

pigmented nucleus located deep within the midbrain that is part of the basal ganglia motor system

what is the red nucleus and what is it involved in

• nucleus located deep within the midbrain

• involved in motor control

what is the location of the pons

between the medulla and the midbrain

what are the structures of the pons

• basal pons

• middle cerebellar peduncles

• basilar groove (anterior surface)

• fourth ventricle (posteriorly)

what are the functions of the pons

• communication between the cerebrum and cerebellum

• participates in sensory and motor processing

• contributes to respiratory and autonomic regulation

• contains cranial nerve nuclei

what is the cranial nerve that the pons contains

CN 5-8

what is the location of the medulla oblongata

• the most caudal portion of the brainstem

• is continuous with the spinal cord

what are the structures of the medulla oblongata

• pyramids

• pyramidal decussation

• olives

• inferior cerebellar peduncle

• contributes to the floor of the fourth ventricle

what is the pyramidal decussation

the crossing of descending motor fibers

what are the olives

paired structures lateral to the pyramids

what does the inferior cerebellar peduncle connect

medulla and cerebellum

what are the functions of the medulla oblongata

• conduction of ascending and descending pathways

• contains cranial nerve nuclei

• participates in autonomic regulation

what cranial nerves does the medulla oblongata contain

IX

X

XI

XII

Location of reticular formation

central core of the brainstem

structures of the reticular formation

diffuse network of interconnected neurons extending throughout the brainstem

functions of the reticular formation

• movement

• pain modulation

• autonomic regulation

• arousal and consciousness