Gross Brain, Brainstem and Spinal Cord (Dennis) Flashcards
CNS
PNS
-brain and spinal cord
Everything else
Subdivisions of the brain:
Forebrain, cerebellum and brainstem
Forebrain parts…
Cerebral hemispheres and diencephalon
Gray matter:
Nuclei
Cortex
Contains cell bodies and dendrites with common function
Layers of gray matter over other parts of the CNS
White matter:
Contains axons covered with myelin
Aka fasciculus, funiculus, lemniscus, peduncle and tract
Naming neural tracts:
1st part
2nd part
Location of cell bodies where the neurons originate
Location of where axons terminate
Gyrus
Sulcus
Fissures
Ridge of cortical tissue
Groove located between gyri
Particularly deep sulci
Purpose of folding into gyri and sulci:
Increase total cortical area and total number of cortical neurons
Four sulci that divide brain into lobes:
Central sulcus - divide frontal from parietal
Lateral sulcus - divide frontal, parietal and temporal
Parietooccipital sulcus - divides parietal from occipital
Cingulate sulcus
What joins the two hemispheres of the brain?
Corpus callosum (fiber bundle)
Limbic lobe:
Strip of cortex that encircles the telencephalon-diencephalon junction
Between corpus callosum and frontal, parietal and occipital lobes
Curves around to occupy part of the medial surface of temporal lobe
What makes up the lateral surface of the frontal lobe?
Precentral gyrus, superior, middle and inferior frontal gyri
What do the precental gyrus contain?
Primary motor cortex as wells as premotor and supplementary motor areas
Important for planning and initiating voluntary movements
Broca’s area:
On inferior frontal gyrus of one hemisphere (usually left)
Prefrontal cortex:
Occupies the rest of the frontal lobe
Involved with executive function, personality, decision making, insight & foresight
What is on the parietal lobe?
Somatosensory areas. Postcentral gyrus, superior and inferior parietal lobules
Functions of the parietal lobe:
Primary somatosensory cortex on the postcentral gyrus controls processing of tactile and proprioceptive info; sensory localization
Inferior lobule involved with language comprehension
Remainder deals with spatial orientation and directing attention
Homonculus:
Map on the primary motor or primary somatosensory cortex that shows the distribution of innervation (both motor and sensory) to a particular part of the body (contralateral side)
More innervation on the face vs. back of shoulder
Be able to map the damage on the cortex based on the deficits and vice versa
What is in the temporal lobe?
Superior, middle and inferior temporal gyri
Inferior surface is made up of the broad occipitotemporal (fusiform) gyrus
Function of the temporal lobe:
Superior surface has the primary auditory cortex
Wernicke’s area on posterior surface of the superior temporal gyrus, as well as supramarginal and angular gyrus - language comprehension
Inferior surface - involved in higher order processing of visual info
Medial part - learning and memory
Limbic structures of the brain:
Composed of the cingulate and parahippocampal gyri
Anterior end of the gyrus has the uncus
Hippocampus folded in temporal lobe at the hippocampal sulcus
Amygdala lies beneath the uncus of tempioral lobe
Limbic lobe importance…
Emotional responses, drive related behavior & memory
What is the insula?
Lies in the lateral sulcus
Concealed by the lobes (open the lateral sulcus or removing the opercula to reveal the insula)
Bordered by the circular sulcus
Important for taste function
Occipital lobe has …
Lateral occipital gyri, cuneus, primary visual cortex (within the calcarine sulcus walls), visual association cortex (higher order visual processing)
Diencephalon:
Includes the thalamus, hypothalamus, epithalamus and subthalamus
Inferior surface of hypothalamus has the infundibular stalk, which connects it to the pituitary gland (2 rounded protuberances, with mammillary bodies also visible)
Which sense does not go through the thalamus?
Olfaction
Basal nuclei
Parts
Group of nuclei deep to the cerebral cortex in each hemisphere
Caudate and Lenticular nucleus (divided into putamen and globus pallidus)
-associated with movement control
What separates the Lenticular nuclei from the thalamus and caudate nucleus?
Internal capsule (thick sheet of fibers, x shaped)
Central white matter: Arcuate fibers Longitudinal/association fasciculi Projection tracts Corpus callosum Anterior commissure
- connect cortical areas within the same sulci/gyri
- connect cortical areas within the same hemisphere
- connect cortical areas within other body regions
- interconnects the two cerebral hemispheres
- commissural fibers to/from temporal lobe (esp. inferior parts)
Internal capsule fiber groups/limbs:
Anterior limb Genu Posterior limb Sublenticular limb Retrolenticular limb
Capsule has own vascular supply so prone to infarcts
What artery supplies most of the internal capsule?
What artery supplies the retrolenticular and some of posterior limb?
Lenticulostriate arteries (off of Middle Cerebral) Anterior choroidal arteries
Brainstem parts and major function:
Midbrain, pons, medulla
Roles in CN function, conveys info to and from forebrain
Midbrain:
Has the tectum (roof) of the midbrain
Superior and inferior colliculi (bumps posterior to cerebral aqueduct)
Paired cerebral peduncles
Pons:
Protruding basal pons
Pontine tegmentum forms part of floor of 4th ventricle
Medulla:
Rostral open portion containing part of 4th ventricle
Caudal portion continuous with spinal cord
Cerebellum anatomy:
Surface made up of transverse ridges called folia
Prominent fissures divide it into lobes and lobules
White matter in medullary center composed of afferent and/or efferent fibers
Cerebellum function and damage:
Functions in sensory info processing and influences motor neurons
Damage results in equilibrium, postural control and coordination abnormalities
Posterior rootlets
Anterior rootlets
Enter SC via posterolateral sulcus
Leave SC via anterolateral sulcus
Rootlets become roots > become spinal nerves
Posterior horn of the spinal cord: Substantia gelatinosa Body Lissauer's tract Clark's nucleus (posterior thoracic nucleus)
- Region of gray matter that caps the posterior horn
- interneurons & projection neurons that transmit somatic & visceral sensory info
- white matter located between substantia gelatinosa and surface of SC
- cells on medial surface of base of posterior horn (T1-L2) that has role in postural and sensory processing
Anterior horn of the spinal cord:
Cell bodies of lower motor neurons that supply skeletal muscle, CNS control over body movements
Anterior horn of the spinal cord:
Intermediate gray matter
-Collection of various projection neurons, sensory interneurons and interneurons
What forms the lateral horn of the spinal cord:
-Preganglionic T1-L3 neurons in the intermediolateral cells column
Axons leave via ventral roots
Sacral parasympathetic nucleus (s2-s4) does not form a distinct lateral horn
Lamina of the spinal cord gray matter:
I
II
III - VI
- Marginal zone. Thin layer of gray matter covering the substantia gelatinosa
- aka substantia gelatinosa
- forms the body of the posterior horn
Lamina of the spinal cord gray matter: VII VIII IX X
- intermediate gray matter and includes extensions into anterior horn
- interneurons zones of the anterior horn
- contains clusters of motor neurons embedded in anterior horn
- zone of gray matter surrounding the central canal
Lamina function Marginal zone (I) Substantia gelatinosa (II) Body of posterior horn (III-VI)
- spinothalamic tract cells
- transmission of pain and temp info
- sensory processing
Lamina function:
Clarke’s nucleus (VII, level T1-L2)
Intermediolateral column (VII, level T1-L3)
Sacral parasympathetic neurons (VII, level S2-4)
Posterior spinocerebellar tract cells
Preganglionic sympathetic neurons
Preganglionic parasympathetic neurons > pelvic viscera
Lamina function: Accessory nucleus (Medulla-C5, IX) Phrenic nucleus (IX, C3-5)
Motor neurons > SCM and trapezius
Motor neurons > diaphragm
What work together to convey info to and from the CNS?
Primary afferents and lower motor neurons
Primary afferents terminate in the CNS on second order neurons
Usually ipsilateral
Second order neurons:
Relay signal from the primary afferents to a target in the CNScan cross the midline of the body (via the thalamus to the third order neuron)
Third order neurons
Relay message to final target in specific cortical area
Cortex decides on given output
Naming of the tracts indicates … (not absolute, but in general)
First part of the name is origin and last part is the destination
1. If ascending or descending (corticospinal vs. spinocerebellar)
2. Location of the cell body of origin (cortex vs. spinal cord)
Location where the axons will terminate (spinal cord vs. cerebellum)
