General anatomy of the brain Flashcards Preview

Neuroanatomy > General anatomy of the brain > Flashcards

Flashcards in General anatomy of the brain Deck (48):
1

Cerebrum

-has 4 major lobes ( frontal, temporal, parietal and occipital lobes)
-lobar surface is heavily folded forming sulci (valleys) and gyri (ridges)
-Primary (major) sulci are more invariant in their appearance than the secondary (minor sulci)

2

Central sulcus

-divides frontal lobe from the parietal lobe

3

Precentral gyrus

-primary motor cortex
-part of the frontal lobe
-homunculus represents the different parts of the body

4

Post-central gyrus

-part of the parietal lobe
-the primary somatosensory cortex with a similar homunculus representation

5

Lateral sulcus

-Sylvian fissure
-divides frontal lobe from the temporal lobe

6

Insula

- a structure sometimes regarded as the 5th lobe of the cerebrum
-located deep in the Sylvian fissure
-where primary gustatory cortex is found

7

Dorsolateral prefrontal cortex

- in between the superior and inferior frontal sulci is the middle frontal gyrus and this has the dorsolateral prefrontal cortex in it
-executive functions of the human brain

8

Cingulate sulcus

-on the medial side of the frontal lobe
-the anterior portion of the adjoining cingulate gyrus is considered to be the seat of motivation

9

Orbitofrontal cortex

-olfactory and orbital sulci are on the inferior surface of the frontal lobe
-the orbitofrontal cortex is often considered to be the seat of associative learning and decision-making

10

Primary auditory cortex

-is in the superior temporal sulcus ( in lateral sulcus)

11

Inferior parietal lobe

-made of the angular gyrus and supramarginal gyrus
-is considered to be important for visuospatial attention
-interparietal sulcus separates suiperior and inferior parietal lobes

12

Primary visual (striate) cortex

-in the calcarine sulcus in the medial occipital cortex

13

Left temporal cortex

language comprehension

14

Right hemisphere

language prosody (tonal modulation of speech)

15

Dominant hemisphere

-hemisphere contralateral to the dominant hand is the dominant hemisphere
-mediates language and speech functions
-dominance can be tested using Annette's handedness scale or Edinburgh handedness inventory
-handedness is not always same as dominance
-in 10% right handed people, the right hemisphere is dominant
-left-handed people only 20% are right hemisphere dominant, 64% are left hemisphere dominant and 16% show bilateral dominance

16

Planum temporale

-triangular region in the upper surface of the superior temporal gyrus
-important for language learning
-larger on the left than the right hemisphere in 65% brains
-it can be very asymmetrical
-reduced or reversed asymmetry in schizophrenia

17

Left Hemisphere Lesion

-aphasia
-right-left disorientation
-finger agnosia
-dysgraphia (aphasic)
-dyscalculia (number alexia)
-limb apraxia
-facial recognition

18

Right Hemisphere lesions

-visuospatial deficits
-anosognosia
- finger neglect
-dysgraphia (spatial, neglect)
-dyscalculia (spatial)
-constructional apraxia
-dressing apraxia
-facial recognition

19

Papez circuit

Limbic structures involved in emotional processing

hippocampus=> fornix==>mamilliary bodies==>mammillothalamic tract==>anterior thalamic nucleus==>genu of the internal capsule==>cingulate gyrus==> parahippocampal gyrus==> entorhinal cortex==> perforant pathway==>back to hippocampus

20

Limbic system

-described by Broca, Papez and Maclean
-after Papez circuit, this was expanded to include amygdala, septum, basal forebrain, nucleus accumbens and orbitofrontal cortex
-involved in mediation of emotional responses, influencing neuroendocrine responses and reward system regulation
-evolutionarily older than the higher cortical centres

21

Medial temporal structures

-include the hippocampus, amygdala, entorhinal and parahippocampal cortex
-plays role in memory processes
-few areas where the continuous production of new neurons is noted even in adult life
-amygdala appears crucial for fear conditioning and emotional regulation

22

Basal ganglia

-basal ganglia are a group of gray matter nuclei forming the largest subcortical structure in the brain
-they are involved in planning an dprogramming of movement and also have a role in the processes by which an abstract thought is converted into voluntary action
-consists of the striatum (made up of the caudate nucleus and putamen) and pallidum ( globus pallidus)
-putamen and globus pallidus are sometimes called lenticular/ lentiform nucleus

23

Striatum

-made of caudate nucleus and putamen
-part of the basal ganglia

24

Lenticular/lentiform nucleus

-putamen and globus pallidus

25

Subthalamic nuclei and the substantia nigra

-functionally related to the basal ganglia but are not considered part of the basal ganglia

26

Corticostriatal projection

-basal ganglia receives crucial inputs from the glutamategic corticostriatal projection

27

Circuits involving the basal ganglia

-described by Alexander
-motor circuit
-oculomotor circuit
-dorsolateral prefrontal circuit (executive)
-anterior cingulate circuit (motivation)
-lateral orbitofrontal circuit (social intelligence)

28

OCD

-basal ganglia dysfunction: volumetric changes and higher blood flow to the caudate nuclei. Increased caudate metabolism in untreated subjects reduces after effective treatment

29

Tourette's syndrome

-basal ganglia dysfunction: striatal dopaminergic dysfunction

30

Huntington chorea

-basal ganglia dysfunction: degeneration of the striatum (mainly caudate nucleus) and selective loss of GABAergic neurons

31

Wilson's disease

-basal ganglia dysfunction: copper deposits in the lenticular nuclei

32

CO poisoning

-basal ganglia dysfunction: acute bilateral anoxic damage to basal ganglia

33

Hemiballismus

-basal ganglia dysfunction: subthalamic nucleus damage (especially in infarction)
-flailing limb movements

34

Parkinsonism

-depigmentation of substantia nigra
-Lewy bodies are seen
-Striatal overactivity associated with bradykinesia

35

Fahr's disease

-'Fahr too much ccalcium in the basal ganglia'
-progressive calcium desposition in the basal ganglia
-early onset cases present with schizophreniform psychoses and caratonia
-later onset cases exhibit dementia and choreoathetosis

36

Thalamus

-large oval mass of grey matter nuclei in the subcortical region, relaying all types of sensory information onto cortex (except olfaction)
-it also relays cerebellar and basal ganglia imputs to the cerebral cortex
-plays a crucial role in the filtering of sensory information in preparation for cortical processing

37

Anterior thalamus

-part of the limbic system
-receives the mamillothalamic tract and fornix and connects to the cingulate cortex
-thus it relays information from hypothalamus and hippocampus onto the frontal cortex

38

Pulvinar

-associated with visual attention
-sleep spindles are generated in the reticular nucleus f the thalamus

39

Hypothalamus

-regulates physiological functions such as eating, drinking, sleeping and temperature regulation
-hypothalamus has chemoreceptors that respond to variations in glucose levels, osmolarity, acid balance etc
-it plays a major role in neuroendocrine control

40

Ventromedial hypthalamus

-acts as the satiety centre
-animals with a lesion of the ventromedial hypothalamus hyperphagia and obesity are noted

41

Lateral hypothalamus

-the feeding centre

42

Cerebellum

-important role of preparing a motor plan and predicting balance needed between muscle groups to carry out the intended action smoothly
-cerebellar lesions produce ataxia and coarse intentional tremors along with hypotonia, past pointing and pendular knee jerk
-may have a cognitive role

43

Cognitive dysmetria

-Andreasen
-refers to the difficulty in coordinating and monitoring the process of receiving, processing and expressing information that could result from disrupted cortico-cerebellar circuitry in schizophrenia

44

Brainstem

-midbrain, pons and medulla
-9 out of 12 cranial nerves enter or exit the brain from the brainstem

45

Midbrain

-consists of superior (conjugate gaze control) and inferior colliculi (auditory source localisation)

46

Substantia nigra

-also located in the midbrain along with the periaqueducal grey matter
-important role in vocalisation and freezing response to threat and in pain suppression

47

Pons

-positioned beneath the cerebellum and surrounds the upper half of the 4th ventricle

48

Medulla

-surrounds the inferior part of the 4th ventricle and is continuous with the spinal cord