Neuroanatomy Class Exam 1 Flashcards
Where does the CNS bend occur?
At the cephalic flexure
Where is the Cephalic Flexure Visible?
It is visible at the junction between the brainstem and the diencephalon
What are the divisions of the brainstem?
Midbrain, Medulla, and Pons
What joins the two cerebral hemispheres?
The Corpus Callosum; this is a huge fiber bundle
What develops into the ventricular system?
The cavity of the neural tube
How does the system of ventricles connect?
The third ventricle opens into the lateral ventricle (of each hemisphere) through the inerventricular foramen. Posteriorly, the third ventricle is continuous with a narrow channel through the midbrain known as the cerebral aqueduct. This aqueduct connects with the fourth ventricle of the pons and medulla. The fourth ventricle is continuous with the central canal of the caudal medulla and the spinal cord.
What is burried deep within the lateral sulcus?
The insula is hidden within this sulcus. It overlies the site where the telencephalon and the diencephalon fuse during embryological development.
What is the circular sulcus?
The circular sulcus outlines the insula and marks its borders withe opercular areas of the cortex.
What are the four divisions of the frontal lobe?
The Superior, middle, and inferior frontal gyri. The fourth major division is the
What does the frontal lobe contain?
The frontal lobe mainly contains the motor areas.
What are the subdivions of the parietal lobe?
1) Postcentral sulcus and gyrus
2) Superior Parietal Lobule
3) Supramarginal Gyrus
4) The Angular Gyrus
5) The Precuneus (only visible on the medial surface of a sagittal cut)
What is the parital lobe mainly responsible for?
Integrates sensory information
What are the subdivisions of the Temporal Lobe?
These include the superior, middle, and inferior temporal gyri as well as the occipitotemporal gyrus and the inferior temporal gyrus. The last two are only visible medially with a sagittal cut and viewed from slightly below the brain.
What is the temporal lobe primarily responsible for?
It contains the auditory areas.
What are the subdivisions of the Occipital Lobe?
These include the lateral occipital gyri, lingual gyrus, and the Cuneus.
What is the occipital lobe mainly responsible for?
Primary responsiblity is vision
What are the subdivisions of the Limbic Lobe?
These include the Cingulate sulcus and gyrus, the Uncus, and the Parahippocampal Gyrus.
What is the Limbic Lobe primairly responsible for?
Primary responsiblity is emotion and memory processing.
What does the Diendephalon include?
The thalamus and hypothalamus.
What is the function of the thalamus and the hypothalamus?
The thalamus serves as a relay center for sensory information to the cortex. All sensory info goes through the thalamus except taste and smell. It also regulates consciousness and alertness.
The hypothalamus is responsible for autonomic actions, such as controlling body temperature, heart rate, and hunger.
Where are most cranial nerves located?
Most cranial nerves are located in the brainstem
What are the three functions of the parietal lobe?
1) Primary Somatosensory Cortex
2) Langauge Comprehension (inferior parietal lobule of one hemisphere paired with portiosns of the temporal lobe)
3) Spatial Orientation adn direction of attention
What is the interthalamic adhesion?
The point of fusion for the two thalami
What is one exception to sensory information that does not go through the thalamus?
Olfactory Information; all other information goes through the thalamus
What separates the thalamus from the hypothalamus?
The hypothalamic wall in the wall of the third ventricle.
What connects the hypothalamus to the pituitary gland?
The infundibular stalk
What is the tectum?
In the midbrain, a portion posterior to the cerebral aqueduct. Is it the roof of the cerebral aqueduct
Understand the strucure of the brainstem and surrounding structures
What forms part of the floor of the fourth ventricle?
The rhomboid foss, a depression in the brainstem. It is in the shape of a diamond.
Describe the open and closed portion of the medulla
The open medulla is the medulla at the level of the 4th ventricle, giving the impression of an open cavity. The closed medulla is caudal to the 4th ventricle.
What are the embryonic origins of the optic nerves?
Outgrowths of the Diencephalon
What is the Caudate Nucleus?
A subcortical structure that lies deep within the brain near the thalamus. Plays an important role in various higher neurological functions.
What is the function of an oligodendrocyte?
An oligodendrocyte myelinates axons of CNS neurons. They are also distinguishable because they form MULTIPLE sheets of myelin each on separate axons.
What is the function of microglia?
Microglia remove debris and infectous organisms
What are the derivatives of the neural crest?
The derivatives of the neural crest give rise to most of the peripheral nervous system (PNS) and to several non-neural cell types, including smooth muscle cells of the cardiovascular system, pigment cells in the skin, and craniofacial bones, cartilage, and connective tissue
The cerebellum is derived from what secondary brain vesicle?
The rhombencephalon gives rise to the metencephalon (and myelencephalon) and the metencephalon gives rise to the cerebellum.
Why does damage to a sensory area on the left cerebral cortex cause deficits on the right?
Second order sensory axons cross the midline on the way to the thalamus
What does the falx cerebri separate?
The two cerebral hemispheres
What does the tentorium cerebelli separate?
The Occipital Lobes and the Cerebellum
What is the cingulate gyrus?
An important part of the limbic system, the cingulate gyrus helps regulate emotions and pain. It is also involved in predicting and avoiding negative consequences
What is the Epidural Space?
Space between the bone of the skull and the dura. Site of epidural hematomas.
What does the interventricular foramen connect?
It connects the lateral ventricles and the third ventricle.
What do the median and lateral apertures accomplish?
The median aperture is an opening in the roof of the fourth ventricle; it drains CSF into the cisterna magna
The lateral apertures drain CSF into the subarachnoid space. They are right below the median aperture.
Where are Choroid Plexus Cells NOT found?
In the anterior horns of the Lateral Ventricle
What are lower motor neurons?
Fibers that convey messages to skeletal muscles
What are primary afferent neurons?
Primary afferents are sensory neurons (axons or nerve fibers) in the peripheral nervous system that transduce information about mechanical, thermal, and chemical states of the body and transmit it to sites in the central nervous system.
Do the axons of lower motor neurons cross the midline?
No, the axons of lower motor neurons leaving the CNS do NOT cross the midline
What is the mode of travel for somatosensory pathways?
Most somatosensory pathways (the expections are taste and smell) cross the midline and pass through the thalamus which relays the information to the cerebral cortex.
From which side of the body does each half of the cerebellum receive information?
The ipsilateral side
What is the primary function of the cerebellum?
Interpret sensory information to coordinate movement
Do somatosensory pathways from the periphery to the cerebellum pass through the thalamus?
No, it goes directly to the cerebellum. Can involve as few as two neurons.
What is the corticospinal tract?
A collection of fibers that descend from cell bodies in motor areas of the cerebral cortex and terminate in the spinal cord. Commonly referred to as upper motor neurons.
How does the basal nuclei and cerebellum work to induce movement?
They have few or no outputs of their own, so they influence the motor areas of the cerebral cortex. When these two are damaged, the motor areas and lower motor neurons remain intact - movment may be slow or uncoordinated but there is no loss of strength
Do corticospinal axons cross the midline?
Just as the somatosensory pathways cross the midline between the periphery and the cerebral cortex, so to deos the corticospinal tract. Thus, damage to one half will cause deficits in the contralateral side.
Is a relay in the thalamus required for outputs from the motor cortex?
No, single neurons with very long axons project all the way from motor cortex to the contralateral half of the spinal cord.
The Basal Nuclei of one side inderectly affect movements of which side of the body?
The contralteral side of the body is affected.
How does the cerebellum work?
To accomplish fine motor tasks, the cerebellum has input from the cerebral cortex and somatosensory input from the ipsilateral side of the body. Cerebellar outputs return to motor cortex, affecting corticospinal activity; this requires a stop in the thalamus. The final element in the general pattern of cerebellar connectivity is dictated by the fact that one side of the cerebellum is related to the ipsilateral side of the body. Because one side of the forebrain is related to the contralateral side of the body, this means that pathways interconnecting the cerebellum and forebrain must cross the midline. Because cerebellar outputs are directed toward motor cortex (via the thalamus), cerebellar damage causes problems with movement but not with sensation.
Which two meninges are continuous with each other?
The Arachnoid and Pia; sometimes referred to as the leptomeninges
Which meningeal layer is attached to the skull?
The Dura is attached to the inner surface of the skull
Which meningeal layers are separated by CSF?
The arachnoid and pia
Is there a “real space” on either side of the cranial dura?
No, because one side is attached to the skull and the other is attached to the arachnoid
What are the two potential spaces assoicated with the dura?
The subdural and epidural spaces.
What is a potential space?
A potential space is a space that only exists pathologically. For example, a potential space is made when blood forces a space to be made (epidural hematoma).
What are dural folds?
Dural folds are double layered folds of dura that reflect back on themeselves. It is where the inner dural layer separattes from its external counterpart and protrudes into the cranial cavity.
The mainn two are the falx cerebri and the tentorium cerebelli
What does the tentorium cerebelli separate?
Separates the superior surface of the cerebellum from the occipital and temporal lobes, defining supratentorial and infratentorial compartments within the cranial vault. The supratentorial compartment contains the forebrain, and the infratentorial compartment (or posterior fossa ) contains the brainstem and cerebellum.
What is the tentorial notch?
A space in the tentorium cerebelli through which the brainstem passes.
What are dural venous sinuses?
At the attached edges of dural folds, the two layers are normally separated to form venous channels, called dural venous sinuses, into which the cerebral veins empty
Name the Venous Sinuses
1) Superior sagittal sinus: Found along the attached edge of the falx cerebri
2) Transverse Sinus: found along the posterior line of the attachment of the tentorium cerebelli
3) Straight Sinus: along the line of attachment of the falx cerebri and tenroium cerebelli to each other
4) Confluence of Sinuses: where all these sinuses meet, near the interal occipital protuberance
What is the middle meningeal artery?
A branch of a maxillary artery. Ramifies over most of the lateral surface of the cerebral dura and supplies blood to parts of the dura.
Ophthalamic Artery
Provides blood to the dura anteriorily
Which arteries provide blood to the dura posteriorily?
The occipital and vertebral
Where are the meningeal veins and arteries located?
In the periosteal layer
Cerebromedullary Cistern
the space between the inferior surface of the cerebellum and the posterior surface of the medulla. Contains a large amount of CSF
Pontine Cistern
is located around the anterior surface of the pons and medulla and is continuous posteriorly with the cerebellomedullary cistern
Interpeduncular Cistern
is located between the cerebral peduncles and contains the posterior part of the cerebral arterial circle
What are the differences between cranial and spinal meninges?
What causes an epidural hematoma?
Tearing of meningeal arteries.
What causes a subdural hematoma?
Tearring of veins where they enter venous sinuses. In the attached picture, notice how extensive and wide these are compared to epidural hematomas. The picture at right details a shift of midline structures (such as the ventricles) as a result of the buildup of pressure.
Herniations within the Brain
Depending on where pressure builds up in the brain, certain herniations across taut reflections such as the falx cerebri can occur.
What is the intervenntricular foramen?
Connects the lateral ventricles to the third ventricle
What is the cerebral aqueduct?
The cerebral aqueduct connects the third and fourth ventricles
What are the 5 parts of the lateral ventricle?
1) Anterior Horn (frontal lobe)
2) Body (in frontal and parietal lobes)
3) Posterior Horn (projects into the occipital lobe)
4) Inferior Horn (curves inferiorily and anteriorily into the temporal lobe)
5) Atrium (where the posterior and inferior horns meet)
How does the Caudate Nucleus relate to the ventricles?
Its enlarged head forms the lateral wall of the anterior horn. The smaller body forms most of the lateral wall of the body of the ventricle. Its tail lies in the roof of the inferior horn.
Where does the third ventricle lie?
It is the midline cavity of the diencephalon
What is the anterior end of the third ventricle?
The third ventricle ends anteriorily at the Lamina Terminalis
What is the general location of the fourth ventricle?
It is sandwiched between the cerebellum posteriorily and the pons and rostal medulla anteriorily
What is the rhomboid fossa?
The rhomboid fossa is the shallow, diamond shaped depression on the dorsalsurface of the pons and medulla oblongata that forms the floor of the fourth ventricle
What is the median aperture?
A hole in the inferior medullary velum of the fourth ventricle; connects the fourth ventricle to the cerebellomedullary cistern)
What is choroid plexus?
Vascular membranous material contained in all four ventricles. This secretes most of the CSF
Descirbe the movement of CSF
Lateral ventricles –> interventricular foramen –> third ventricle –> cerebral aqueduct –> median/lateral apertures –> cisterna magna and pontine cistern
What is a multipolar neuron?
Multiple dendritic projections from the cells body and almost always an axon as well. Most neurons follow this structure.
What is a pseudounipolar neuron?
Neurons which have one extension from their cell body. That one extension then splits into multiple (see picture).
What is the dorsal gray matter?
Synonymous with the posterior horn, it is the alar plate of the neural tube. It contains derivatives for SENSORY processing
What is the ventral gray matter?
Synonymous with the anterior horn, it contains the basal plate. It has derviatives for MOTOR neurons.
What are the three primary vesicles (from rostral to caudal)?
1) Prosencephalon
2) Mesencephalon: leads to the midbrain
3) Rhombencephalon: leaders to the brainstem and cerebellum. This also merges with the caudal portion of the neural tube
What does the Mesenecephalon develop into?
The midbrain; the top most part of the brainstem. Contains the tegmentum, colliculi, and the cerebral peduncles.
What does the Metencephalon develop into?
The pons and cerebellum
What does the neural tube look like after secondary neurolation?
What is special about the neural tube cavity?
The cavity persists as the ventricular system of the adult brain and the central canal of the spinal cord.
Be aware what the neural tube and surrounding structures look like
Be aware what the neural tube looks like as represented by a picture
What is the lamina terminalis?
The lamina terminalis is a thin sheet of gray matter and pia mater that attaches to the upper surface of the chiasm and stretches upward to fill the interval between the optic chiasm and the rostrum of the corpus callosum.
In relation to the choroid plexus, where are the endothelial cells and what do the constitute?
These cells form the blood-CSF barrier. They are located around the blood capillary to form fenestrations.
The epithelial cells are closest to the ventricle side.
