External Brain Morphology Flashcards
Describe the thalamus
Large number of individual nuclei, each with a specific function
Major function is to relay information to the cortex via projections from these nuclei
Almost* all information destined for the cortex must go through the thalamus
Describe the hypothalamus
Large number of individual nuclei, each with a specific function
Functions as a CNS center for the regulation of autonomic and endocrine activity
Maintains internal homeostasis; involved in limbic system
What is the tectum?
Area dorsal to the cerebral aqueduct of Sylvius
Superior and inferior colliculi are involved in visual and auditory reflexes respectively
What is the pineal gland?
A midline structure lying above the superior colliculi
What is the clinical significance of lesions in the supratentorial space or pineal gland?
Can press on the tectum and close off the cerebral aqueduct
Causing non-communicating hydrocephalus
What is the tegmentum?
Area extending ventrally from the aqueduct to the substantia nigra
Contains Oculomotor nerve complex, trochlear nucleus/nerve, and red nucleus
What does the basal portion of the tegmentum consist of?
Substantia nigra - motor system
Crus cerebri - Descending pathways course through this structure
What is the function of the cerebellum?
Roles in balance, equilibrium, muscle tone, coordination and on-going movement etc.
What does each hemisphere of the cerebellum consist of?
A cortex (with folia and fissures)
Underlying white matter
Deep nuclei
What is the midline area of the cerebellum called?
Vermis
What are the three lobes of the cerebellum?
Anterior lobe - receives afferent input from spinal cord
Flocculonodular lobe - input from the vestibular system
Posterior lobe - input from cerebral cortex, voluntary movement coordination
What is the pons?
Bridges the brain to the cerebellum - receives input from the cortex via the CST and projects to the cerebellum
What can the pons be subdivided into?
Dorsal tegmental zone - contains CN V, VI, and VII nuclei
Ventral/basal zone - containing pontine nuclei and CST fibers
Describe the medulla
Both ascending and descending pathways pass through
Contains vital respiratory and cardiovascular centers
CN IX, X, XI, XII nuclei are located here
Clinical note* tonsilar herniation presses on the medulla
What lies just below the optic nerve? (inferior brain view)
Median eminence of hypothalamus
Infundibulum
Mamillary bodies
Cerebral peduncle
What are the lobes of the cerebral cortex and what are the sulci that divide them?
Frontal, Temporal, Parietal, Occipital
Lateral sulcus (sylvian)
Central sulcus (Rolandic)
What are the three types of functional areas of the cerebral cortex?
Primary sensory/motor
Secondary, supplementary or “higher order” sensory/motor
Association areas - highest order, involved in integration of information
What are the structural divisions of the cortex?
Neo-cortex - most of the human brain
Allocortex - consists of paleo- and archi-cortex
Transition cortex
What is Brodmann’s Area 4?
Precentral gyrus - primary motor cortex
Somatotopically organized - areas with the finest motor movement have the largest representation in the cortex
What is Brodmann’s Area 6?
Consists of supplementary and premotor areas
Contributes to the CST
What is Brodmann’s Area 8?
Controls conjugate eye movements to the contralateral side
Lesion causes both eyes to deviate to the side of the lesion
What are Brodmann’s Areas 44 and 45?
Aka Broca’s area - critically involved in the motor production of language
Broca’s aphasia- caused by damage to this part of the brain
Left hemisphere is uniquely organized to process language
What is the prefrontal association cortex?
Parts of the superior, middle, and inferior frontal gyri - excluding areas 6 and 8
Plays multiple roles in cognitive behavior, especially executive functions like decision making and problem solving
What is the limbic association cortex?
Consists of the orbitofrontal cortex and parts of the temporal lobe
Involved in personality and social behavior
What is the function of the temporal lobe areas of the limbic association cortex?
Learning and memory
What are the main sulci and gyri within the parietal lobe?
Pstcentral sulcus/postcentral gyrus
Intraparietal sulcus
Surpamarginal and angular gyri
What are Brodmann areas 1, 2, and 3?
Postcentral gyrus - primary somatosensory cortex
Have four separate body representations where the different submodalities of sensation are kept separate
What separates the the superior parietal lobule and the inferior parietal lobule?
Intraparietal sulcus
What type of areas are parts of areas 2 and 5?
Higher order somatosensory areas
Lesions in these areas produce somatosensory agnosias
What areas make up the posterior parietal cortex?
Areas 5 and 7
Play a major role in integrating visual and somatosensory information
What two important gyri/areas are located in the inferior parietal lobule and what is their function?
Supramarginal gyrus - area 40
Angular gyrus - area 39
In the dominant hemisphere these gyri are important for the perception and interpretation primarily of written language
Lesions may cause alexia and agraphia
What are the main sulci/gyri located within the occipital lobe?
Calcarine cortex - made up of the cuneus and lingual gyri above and below the calcarine fissure respectively
What is area 17?
Calcarine cortex/primary visual cortex
Visuotopically organized
What are areas 18 and 19?
Higher order visual orders
Lesions can produce visual agnosias
How is the temporal lobe divided?
Superior and inferior temporal sulci divide the lobe into superior, middle, and inferior temporal gyri
What is area 41?
The primary auditory cortex on the transverse temporal gyri of Heschl
Tonotopically organized to represent the basilar membrane - with disproportionate representation to sounds devoted to speech
Why don’t unilateral lesions in the areas around the primary auditory cortex usually produce significant auditory agnosias?
There are many bilateral connections of auditory structures below the cortex
Instead, there will just be bilateral diminuation with greater loss contralateral
What is Wernicke’s area?
Posterior part of the superior temporal gyrus (part of area 22) in the dominant hemisphere
Necessary for the interpretation of spoken language
What is Wernicke’s aphasia?
Lesions in Wernicke’s area that cause the patient to be unable to understand spoken language
Can speak fluently, but speak nonsense
