Lesson 3 Flashcards
Thalamus and Hypothalamus (Diencephalon)
- SHET + third ventricle
- almost completely hidden from the surface of the brain
- midline strcture with symmetrical right and left halves
Diencephalon
Roof of the 3rd Ventricle
Superior Border of the Diencephalon
Mnemonics: MOITH
Mammilary Bodies
Optic Chiasm
Infundibulum
Tuber Cinerium
Hypothalamus
Inferior Border of the Diencephalon
Mnemonic: L-IC 👅
Internal Capsule
Lateral Border of the Diencephalon
Thalamus
Hypothalamus
Stria Medullaris Thalami
Medial Surface of the Diencephalon
- Small groove on the lateral wall of the slim 3rd ventricle
- separates the: thalamus and epithalamus (dorsally) and hypothalamus and subthalamus (inferiorly)
Hypothalamic Sulcus
- large mass of gray matter on either side of the third ventricle
- connected by inter thalamic adhesion
(aka masa intermedia/commissure) - complex and highly organized
- connected to cerebral cortex for information is processed and integrated
Thalamus
- “Great relay station” (for ascending tracts; all sensory and motor; EXCEPT FOR OLFACTORY)
- detect and appreciate crude sensations
- w/ several nuclei (projects to the I/L side of the cerebral cortex)
Functions of Thalamus
- covers upper surface of the thalamus
- from lateral surface of the thalamus to cerebral cortex
Stratum Zonale (AKA Thalamic Radiations)
- bifurcates ventrally and divides the thalamus (gray matter) into three parts:
L,A,M
Internal Medullary Lamina
- close to the internal capsule
- layer of myelinated fibers on the lateral surface of the thalamus
External Medullary Lamina
- Counterpart: Limbic system
- receive information from the limbic system
Anterior Thalamaic Nucleus
Function of Anterior Thalamic Nucleus
Episodic Memory and Emotions
Afferent Fibers of Anterior Thalamic Nucleus
Cingulate Gyrus
Hypothalamus
Mammillary Bodies
Efferent Fibers of Anterior Thalamic Nucleus
Cingulate Gyrus
Hypothalamus
- Counterpart: Limbic System and Area 9, 10, 11, 12
- Receive and integrate information from the limbic system
Dorsomedial Thalamic Nucleus
Afferent Fibers of Dorsomedial Thalamic Nucleus
Olfactory Areas
Amydala
Cingulate Gyrus
Area 9, 10, 11, 12
Efferent Fibers of Dorsomedial Thalamic Nucleus
Cingulate Gyrus
Area 9, 10, 11, 12
Functions of of Dorsomedial Thalamic Nucleus
Prefrontal: memory association
Limbic: Integrates sensory, motor, visceral, and olfactory information and relates it to emotional state
4 Major Divisions of Lateral Thalamic Nucleus
Ventral Anterior
Ventral Posterior
Dorsal and Lateral Dorsal Thalamic Nucleus
Medial and Lateral Geniculate Body
Ventral Anterior (Lateral Thalamic Nucleus)
Motor relay nuclei
Ventral Anterior Counterpart and Efferent Fiber of Ventral Anterior
Area 6 and 8
Afferent Fibers of Ventral Anterior
Area 6, Basal Ganglia, Reticular Formation, Other Thalamic Nucleus
Afferent Fibers of Ventral Lateral
Cerebellum, Red Nucleus, Ventral Anterior Fibers
Ventral Lateral Counterpart and Efferent Fibers of Ventral Lateral
Area 4
Ventral Posterior
Sensory nuclei
Ventral Posteromedial Counterpart and Efferent Fibers
M: Mukha
Area 3,1,2
Afferent Fibers of Ventral Posteromedial
Trigeminal Lemniscus and Gustatory Area
Ventral Posterolateral Counterpart and Efferent Fibers
Area 3,1,2
Afferent Fibers of Ventral Posterolateral
Medial Lemniscus, Spinal Lemniscus
Dorsal/Lateral Dorsal Thalamic Nucleus Subdivisions
- Lateral Dorsal
- Lateral Posterior
- Pulvinar
Dorsal/Lateral Thalamic Nucleus Counterpart
Multimodal: Association areas (connections with parietal and part of occipital lobes)
Afferent Fibers of Dorsal/Lateral Thalamic Nucleus
Cerebral Cortex and Other Thalamic Nuclei
Efferent Fibers of Dorsal/Lateral Thalamic Nucleus
Association Areas
Medial Geniculate Body Counterpart
M: Marinig
Area 42: Association Auditory Area
Area 22: Superior Temporal Gyrus
Lateral Geniculate Body Counterpart
L: Labo
Area 17: Primary Visual Area
Area 18, 19: Secondary Visual Area
Afferent Fibers of Medial Geniculate Body
Lateral Lemniscus, Inferior Colliculus
Efferent Fibers of Medial Geniculate Body
Superior temporal gyrus
Afferent Fibers of Lateral Geniculate Body
Optic Tract
Efferent Fibers of Lateral Geniculate Body
Visual Cortex
- involved in activation of cortext from brain stem
- involved in: (Mnemonics: RF SI C)
Reticular formation, sensorimotor integration, consciousness
Intralaminar nuclei
Participates in sensorimotor
coordination, cognition (e.g. attention,
arousal), and pain processing
Centromedian nuclei
Subserve autonomic, motor, sensory, behavioral, cognitive, and mood-related functions
Reticular nucleus
Nucleus:
● Lateral Geniculate
● Medial Geniculate
● Ventral Posterolateral
● Ventral Posteromedial
Functions:
Involved in relaying and modifying sensory signals from the body, face,
retina, cochlea, and taste receptors
Sensory
Ventral Anterior
Ventral Lateral
Convey motor information from the cerebellum and globus pallidus to
the precentral motor cortex
Motor
Anterior
Dorsomedial
Dorsomedial nucleus receives
input from the olfactory cortex and amygdala regions and projects
reciprocally to the prefrontal cortex
and the hypothalamus
Limbic
Reticular
Centrum Medianum
Intralaminar
Has demonstrated interaction with
cortical motor areas, the caudate nucleus, the putamen, and the cerebellum
Intralaminar
● Immediate C/L hemianesthesia = altered
sensation/half doesn’t have sensation
● Abnormal nociception (pain reception)
○ Burning, stabbing, throbbing, or
tingling pain
○ Hyperalgesia
■ Enhanced sensitivity to pain
○ Allodynia
■ Pain or non-painful stimuli
■ Pain due to a stimulus that
does not normally provoke
pain (e.g. brush of a feather)
○ Hyperesthesia
■ Increased sensitivity to stimuli
of different kinds
● Abnormal thermal sensation
○ Discomfort with the temperature
system
Thalamic Pain Syndrome (aka Dejerine-Roussy Syndrome / Central Post-Stroke Pain Syndrome)
Responsible for regulating endocrine, metabolic, autonomic, and emotional functions
It serves as the center of the limbic system
Important for maintaining homeostasis
Hypothalamus
Anterior: Preoptic area
Lateral: Internal capsule
Caudal: Merges with the midbrain
Hypothalamus Anatomical Boundaries
where the optic nerves cross
Optic chiasm
involved in hormonal regulation
Tuber cinereum and Infundibulum
important for memory processing
Mammillary bodies
contains small blood vessels supplying the brain
Posterior perforated substance
allowing it to regulate physiological and emotional responses effectively
● Visceral and somatic structures
● Retina
● Olfactory mucous membrane
● Inner ear
● Frontal lobe of Cerebral Cortex
● Hippocampus
● Amygdaloid complex
● Tegmentum
● Dorsomedial and midline nuclei
Afferent Fibers of Hypothalamus
maintain homeostasis and regulate bodily functions
● Preoptic nuclei
● Anterior nuclei
● Posterior nuclei
● Lateral nuclei
● Mammillary body
● Hypothalamic nuclei
Efferent fibers of hypothalamus
The hypothalamus is composed of small nerve cells arranged into distinct nuclei, which regulate different physiological functions.
Hypothalamic Nuclei
receives afferent bers from
the retina (intensity of light) and thus influence activities of the
hypothalamic nuclei
Suprachiasmatic nucleus (“intrinsic
clock”)
