Module 1 - Introduction to the Central Nervous System Flashcards
What are the 3 primary germ layers in the early embryo?
- ectoderm (develops into neural structures and the epidermis) 2. mesoderm (develops into skin, bone and muscles) 3. endoderm (develops into internal organs)
What kind of brain cut is this?
Coronal
What kind of brain cut is this?
Horizontal
What kind of brain cut is this?
Sagittal
What is the longitudinal fissure?
Located along the midsagittal plane, it separates the two hemispheres
What is the largest lobe?
The frontal lobe
What separates the frontal lobe from the parietal lobe?
The central sulcus
Where is the precentral gyrus? What is it’s function?
In front of (anterior to) the central sulcus, and contains the primary motor areas
Describe the prefrontal association areas
They are concerned with functions such as emotion, motivation, personality, initiative, judgement, ability to concentrate, and social inhibitions.
What is the function of the cingulate gyrus (on the medial surface of the frontal lobe)?
Modulating emotional aspects of behavior
What does the parietal lobe do? (broadly)
Important in regulating somatosensory, language, and spatial oreintation functions
Where is the postcentral gyrus located? What is it’s function?
Behind the central sulcus, in the parietal lobe.
It is the primary somatosensory area of the cortex
What is the primary function of the temporal lobe?
Processing autory information, language, and certain complex functions.
What is the limbic lobe associated with?
Processing complex aspects of learning, memory and emotion
What are the “deep structures” of the brain?
- The basal ganglia
- limbic structures
- white matter
What are the basal ganglia? Where are they broadly located?
The basal ganglia are a group of interconnected, interacting nuclei within the forebrain, diencephalon, and midbrain.
Together, the basal ganglia play a critical role in the initiation and control of voluntary movements
What are the components of the basal ganglia?
forbrain: caudate and lenticular (putamen and globus pallidus) nuclei
diencephalon: subthalamic nucleus
midbrain: substantia nigra
Of what is the forebrain comprised?
Telencephalon and Diencephalon
Of what components is the telencephalon comprised?
- Cerebral hemispheres
- Deep structures
- Thalamus
Of what components is the diencephalon comprised?
- thalamus
- hypothalamus
- subthalamus
What structure is shown in the below image?
subthalamus
What do “projection fibers” do?
project to and from the cortex
What do “commissural fibers” do?
Connec the hemispheres
What do “association fibers” do?
Connect areas within one hemisphere
What is the largest set of commissural fibers?
The corpus callosum
Which is the largest set of projection fibers (ie fibers carrying information to and from the cerebral cortex)?
The corona radiata
What is the diencephalon?
A component of the forebrain, it consists of several sets of paired structures on either side of the 3rd ventrical: the thalamus, the hypothalamus, and the subthalamus
What is the thalamus?
A part of the diencephalon and consisting of 2 “egg-shaped” nuclear masses”
It is critical processing station for all sensory information (except olfactory) on its way to the cortext and plays key roles in processing motor information, in integrating higher order cognitive and emotional information, and regulating cortical activity. The thalamus can be considered the gatekeeper for the cortex.
What is the hypothalamus?
The hypothalamus is structurally part of the diencephalon but functionally part of the limbic system.
It plays key roles in coordinating and integrating endocrine, autonomic, and homeostatic functions.
What is the subthalamus?
The subthalamus is part of the basal ganglia and plays an important role in modulating and integrating voluntary movement and muscle tone.
Together, the midbrain and the hindbrain comprixe what?
The brainstem - the CNS division caudal to the diencephalon
Where are the cranial nerves located and what do they do?
Located in the brainstem, they provide sensory and motor information to and from the head and mediate the senses
What is the most rostral area of the brainstem?
The midbrain
Of what 2 things is the hindbrain comprised?
The pons and the medulla
Of what 5 things is the midbrain comprised?
- A large pair of cerebral peduncles on its anterior surface
- Two pairs of nuclui, the superior and inferior colliculi, on its posterior surface
- The cerebral aqueduct
- The red nucleus
- The substatia nigra
The superior colliculi are involved in visual reflexes
The inferior colliculi are an integrating centre in the auditory pathway
The cerebral aqueduct connects the third and fourth ventricles
The red nucleus and substantia nigra play roles in coordinating motor activity
What is the cerebellum and where is it located?
The cerebellum is an outgrowth of the pons and overlies the fourth ventricle.
The cerebellum has two hemispheres and a central are called the vermis, and its surface is covered by the highly folded cerebellar cortex
How is the cerebellum connected to the brainstem?
By the cerebellar peduncles that carry information to and from the cerebellum.
What is the function of the cerebellum?
The cerebellum has important roles in processing of sensory information and coordination of voluntary motor activity. More recent evidence indicates a role for the cerebellum in cognitive function as well.
How is the cerebellum attached to the brainstem?
By the cerebellar peduncles that carry information to and from the cerebellum
What are two main divisions of the peripheral nervous system?
Somatic and visceral/autonomic
What is the somatic nervous system?
What is the visceral or autonomic nervous system?
Supplies and receives fibers to and from smooth muscle, cardiac muscle, and glands.
What are the 2 divisions of the Visceral or Autonomic Nervous System?
- Parasympathetic division
- sympathetic division
What is the sympathetic division of the ANS?
Important for control of ‘normal’ body functions, e.g., normal operation of digestive system
What is the sympathetic division of the ANS?
Also known as the ‘fight or flight’ division; important in helping us cope with stress
What is the organization of the spinal cord?
A continuous series of posterior rootlets, containing sensory axons, enter the posterior aspect of the spinal cord, and a continuous series of anterior rootlets, containing motor axons, emerge from teh anterior aspect of the spinal cord.
These sensory and motor axons merge together in the spinal nerves.
What do the posterior rootlets contain?
sensory axons
What do the anterior rootlets contain?
motor axons
What do the posterior and anterior rootlets merge to form?
spinal nerves
What is the bulge in the posterior root, just proximal to the point where the spinal nerve forms, known as?
Spinal ganglion - which contains the cell bodies of the sensory nerve fibers
Which two areas within the spinal cord contain increased numbers of motor neurons to supply the arms and legs?
- cervical enlargement
- lumbosacral enlargement
At uts caudal pole, the spinal cord tapers off into the [blank] and ends in the [blank], which anchors the spinal cord to the dorsum of the coccyx.
At uts caudal pole, the spinal cord tapers off into the conus medullaris and ends in the filum terminale, which anchors the spinal cord to the dorsum of the coccyx.
What is the ventricular system?
The ventricular system is a fluid filled space within the brain, which is continuous with the central canal of the spinal cord.
What is cerebrospinal fluid?
Secretion of the ependymal cells of the choroid plexus
Two lateral ventricles are associated with what?
The telencephalon (cerebral cortex, basal ganglia, hippocampus, amygdala), one in each cerebral hemisphere
What shape are the lateral ventricles?
C shaped (due to the curvature of the brain during embryonic development)
What are the three horns of the lateral ventricles?
The anterior horn
the posterior horn
the inferior horn
Describe the anterior horn of the lateral ventricles
deep in the frontal and parietal
lobes of the forebrain and anatomically associated with the basal
ganglia, in particular the head of the caudate nucleus
Where is the posterior horn of the lateral ventricles located?
The posterior
horn extends into the occipital lobe,
Where is the inferior horn of the lateral ventricles located?
In the temporal lobe
The [blank] is located in the floor of the inferior horn
The hippocampus is located in the floor of the inferior horn
The [blank] separates the two lateral ventricles
on the medial surface, such that they cannot communicate with each
other.
The septum pellucidum separates the two lateral ventricles
on the medial surface, such that they cannot communicate with each
other.
How are the lateral ventricles connected with the third ventricles?
Through the interventricular foramen (foramen of Monro)
With which part of the brain is the third ventricle associated?
The third ventrlcle is associated with the diencephalon, and the thalamus
and hypothalamus are located on either side of the third ventricle.
How is the 3rd ventricle connect to the 4th ventricle?
Through the cerebral aqueduct
With what part of the brain is the 4th ventricle associated?
The hindbrain, and it lies between the cerebellum, the pons, and the medulla.
What is parenchyma?
The functional tissue of an organ as distinguished from the connective and supporting tissue.
What is the flow of CSF?
From the lateral to the third and fourth ventricle
How does CSF flow out from the 4th ventricle?
Through the two lateral foramin (of Luschka) and through the medial foramen (of Magendie) into the subarachnoid space or into the central canal of the spinal cord
In the subarachnoid space there are regions with large amounts of CSF, what are they called?
Subarachnoid cisterns
The brain is surrounded by three layers of connective tissure, what are they called?
Meninges
What are the three meninges?
Dura mater, pia mater, arachnoid mater
What is the outermost meninge?
Dura mater - it is connected to the skull and contains the venuous sinuses
Venuous sinus
Collect oxygen depleated blood and drain it
What is the middle meninge?
The spidary middle layer is the arachnoid matter. This layer lines the dura, and bridges over the sulci on the surface of the brain.
What is the inner meninge?
Pia mater. This fine layer of tissue is directly connected to the brain parenchyma and follows all gyri and sulci
The blood supply to the brain comes from which two sources?
The internal carotid and vertebral arteries
The two vertebral arteries come together as the [blank] at the level of the brainstem
The two vertebral arteries come together as the basilar artery at the level of the brainstem
Which blood supply system supplies both the spinal cord and the brainstem?
The vertebral-basilar system
Which blood supply system supplies the forebrain?
The vertebral-basilar and internal carotid systems
The vertebral-basilar system and the internal carotid systems are joined at the base of the brain to form an arterial circle, known as [blank], from which major arteries supplying the brain arise.
Circle of Willis
The internal carotid artery enters the skull through what?
The carotid canal
What is gray matter?
Cortex/nerve cell bodies
What is white matter?
Medullary center/fibers
What are the three kinds of white matter fibers?
- Association fibers (confined to the same hemisphere)
- Comissural fibers (cross hemispheres; e.g., corpus callosum)
- Projection fibers (to and from the cortex)
Identify the:
a. anterior commissure
b. third ventricle
c. thalamus
d. hypothalamus
e. mammillary body
f. hypothalamic sulcus
Identify the:
a. putamen
b. thalamus
c. body of lateral ventricle
d. caudate nucleus
e. globus pallidus
f. horn of lateral ventricle
g. third ventricle
Identify the:
- thalamus
- midbrain
- pons
- medulla
Identify the:
- optic tract
- mammillary bodies
- cerebral peduncles
- basal pons
- olives
- pyramids
Identify the:
- thalamus
- midbrain
- pons
- medulla
Identify the:
- superior colliculus
- inferior colliculus
- cerebellar peduncles
- 4th ventricle
- fasciculus gracilis
- fasciculus cuneatus
Identify the below aspects of the anterior cerebellum:
- flocculus
- middle cerebellar peduncle
- superior cerebellar peduncle
- nodule
- vermis
- inferior cerebellar peduncle
- tonsil
Identify the olfactory nerve (CN I)
Identify the optic nerve (CN II)
Identify the oculomotor nerve (CN III)
Identify the trochlear nerve (CN IV)
Identify the trigeminal nerve (CN V)
Identify the abducens nerve (CN VI)
Identify the facial nerve (CN VII)
Identify the vestibulocohlear nerve (CN VIII)
yellow
Identify the glossopharyngeal nerve (CN IX)
dark blue
Identify the vagus nerve (CN X)
green
Identify the hypoglossal nerve (CN XII)
turquoise
Identify the accessory nerve (CN XI)
Where does CN II (optic) exit the brainstem?
Optic tract
Where does the CN II (occulomotor) exit the brainstem?
Anterior to the cerebral peduncles
Where does CN IV (trochlear) exit the brainstem?
Just below the inferior colliculus (posterior brainstem)
Where does CN V (trigeminal) exit the brainstem?
Middle of the pons, anterior view
Where does CN VI (abducens) exit the brainstem?
Superior to the pyramids, directly inferior to the pons
Where does CN VII (facial) exit the brainstem?
inferior to the pons, superior to the pyramids
Where does CN VII (vestibulocochlear) exist the brain stem?
inferior to the pons, superior to the pyramids
Where does CN IX (glossopharyngeal) exit the brain stem?
inferior to CN VII (facial), superior to CN IX (glossophayngeal), and caudal to the olives
Where does CN X (vagus) exit the brainstem?
inferior to CN VIII (glossopharyngeal) and caudal to the olives
Where does CN XII (hypoglossal) exit the brainstem?
rostral to the pyramids and caudal to the olives
What are the 2 layers of dura mater?
- Outer: periosteal layer of dura.
- inner: meningeal dura
What is above the periosteal layer of dura?
epidural space
What runs through the epidural space?
Middle menigeal artery
what is between the mengingeal layer of dura and the arachnoid?
subdural space
What runs from the venuous sinus to the subarachnoid space?
The bridging vein
What are the 4 places that the inner dural layer folds in on itself (dural reflections)?
- falx cerebri
- falx cerebelli
- tentorium cerebelli
- diaphragma sellae
Where is the:
- third ventricle
- lateral ventricle.
- cerebral aqueduct
- Fourth ventricle
What secretes CSF?
The epithelium of the choroid plexus (found in all 4 ventricles)
What pushes the flow of CSF? Where does it flow?
Newly formed CSF
From the lateral, to the third, to the 4th ventricle
What is a subarachnoid cistern?
The width of the subarachnoid space varies because of the irregular contours of the brain. Regions that contain more susbtantial amounts of CSF are called subarachnoid cisterns
This is a sagital view of vantricles. Label the:
- anterior horn of lateral ventricle
- body of lateral ventricle
- posterior horn of lateral ventricle
- inferior horn of lateral ventricle
- 3rd ventricle
- cerebral aqueduct
- 4th ventricle
- Foramina of Luschka
- Foramen Magendie
- Central canal of spinal cord
Where does CSF exit the 4th ventricle to enter the central canal of the spinal cord (subarachnoid space)?
Through the 2 lateral foramina (foramina of Luschka), and the 1 central foramen (foramen Magendie)
What cut of brain is this?
Coronal
What cut of brain is this?
horizontal
Where is the:
- body of the lateral ventricle
- third ventricle
- posterior horn of lateral ventricle
Where is the:
- body of the lateral ventricle
- third ventricle
- inferior horn of lateral ventricle
