Midbrain + Diencephalon Flashcards
Basal plates develop into what in the adult midbrain?
Edinger-Westphal nucleus
Occulomotor nucleus
The red nucleus and substantia nigra descend from what in development?
Alar plates
What are the 3 segment of the midbrain?
Tectum
Tegmentum
Basis pedunculi
What is the basis pedunculi? What does it contain?
Anterolateral section of midbrain, Cerebellar peduncle
Substantia nigra and crus cerebri
What is the crus cerebri?
Descending motor efferent pathways
The rostral limit of midbrain on ventral surface is?
The caudal limit on ventral surface is?
Exit of crura cerebri and (caudal limit of) mammillary bodies
Where crus cerebri enter pons
Dorsal surface limits of midbrain?
Rostral: rostral limit of superior colliculi
Caudal: caudal limit of inferior colliculi
What is the role of the SUPERIOR colliculi?
Receives visual, auditorium and somatosensory input
Produces motor response to direct head and eyes towards stimulus.
- (Projects to colliculospinal tract to cervical SC to control neck muscles)
What is the role of inferior colliculus?
Receives auditory input from hindbrain
Sends auditory info to superior colliculus and thalamus
What is the role of the red nucleus?
Motor nucleus, associated with cerebellum Parvocellular and magnocellular output Important in development Corticospinal more important in adults ( also has high iron content = red)
What is the role of the midbrain locomotor area?
Stimulates pattern generator to unite locomotion
Regulates pattern an speed of movement
What is the role of the Periaqueductal grey?
Descending pain modulation
Contains opioid neurones
What do the somatic motor and visceral motor components of the Occulomotor nerve innervate?
Somatic - extraocular muscles
Visceral - sphincter and ciliary muscles (pupil constriction: parasympathetic)
The medial longitudinal fasciculus gives VESTIBULAR input to which nerves?
III, IV and VI
Which is the only cranial nerve to exit from dorsal surface?
Trochlear (IV)
Which nerve controls the lateral rectus muscle?
Abducens (VI)
Where is the abducens nucleus located?
Hindbrain
Which nerve has a crossed pathway and innervates the superior oblique muscle?
Trochlear
Describe the response of visceral motor nerve III
Bilateral response:
Direct light reflex in IPSILATETAL eye
Consensual reflex in CONTRALATERAL eye
(Pupil constriction - parasympathetic)
Where does the substantia nigra (SNC) project to?
Striatum
Where does the ventral tegmental area project to?
What are these pathways and what are they involved in?
1) ventral striatum - mesolimbic pathway - reward + addiction
2) frontal cortex - mesocortical pathway - memory + arousal
What type of neurones are VTA projections?
Dopaminergic
What disorder is caused by loss of dopaminergic pathways from VTA to frontal cortex?
Schizophrenia
What disorder is caused by loss of dopaminergic pathway from SNC to striatum?
Parkinson’s
What disorders are caused by loss of dopaminergic pathway from VTA to ventral striatum?
Drug addiction
OCD
ADHD
What the 3 main components of the diencephalalon?
Thalamus
hypothalamus
Epithalamus
What is the role of the EPITHALAMUS?
Connects limbic system to other brain areas
Contains pineal gland –> melatonin - circadian rhythms
(Also contains habenula)
Another structure in the diencephalic is the reticular nucleus. What is it’s role?
GABAergic input to thalamus
Brain wave activity
What are the functions of the MEDIAL hypothalamus?
- Autonomic
- Endocrine
- Homeostasis
- Survival behaviours (reproduction, feeding, defence etc)
What are the functions of the LATERAL hypothalamus?
Sleep and wakefulness
Is there a neural connection between the hypothalamus and the anterior pituitary or posterior pituitary?
Posterior
Which hypothalamic nucleus produces oxytocin?
Paraventricular
Which hypothalamic nucleus produces vasopressin?
Supraoptic
What causes Benedikt’s sydrome? What does it cause?
Damage to tegmentum - Occulomotor nucleus and red nucleus
–> inappropriate eye movement and Cerebellar ataxia
