Chapter 7 - Gross Neuroanatomy Flashcards
Rostral
Anterior
Caudal
Posterior
Three anatomical planes of section
Midsaggital plane along the midline, other lines parallel to this are sagittal. Horizontal plane and coronal plane.
The Cerebellum
Contains as many neurons and the cerebrum
Dorsal Roots
Carry information from the PNS to the CNS
Ventral roots
Carry information from the CNS to the PNS
Dorsal Root Ganglia
One per each spinal nerve. Contains the cell body of receptors.
Afferent neurons
Carry sensory information to the CNS. AKA sensory neurons
Efferent Neurons
Carry information from the CNS to the body. Also known as motor neurons.
The Visceral PNS
The autonomic nervous system, It consists of the neurons that innervate the internal organs, blood vessels and glands. Relay information like pressure and oxygen levels. Command the contraction and relaxation of smooth muscle.
Cranial Nerves
There are 12 pairs of cranial nerves which arise from the brain stem and innervate mostly within the head. They were numbered by Galen from anterior to posterior. Some are part of the CNS and some are part of the somatic or visceral PNS. Many cranial nerves contain a cocktail of different axons that perform different functions.
The Meninges
Three membranes that protect the CNS from the overlying bone. The outermost layer is the dura mater, a tough inelastic bag that surrounds the brain and spinal cord. Under the dura mater is the arachnoid membrane, a blood vessel riddled membrane. If a blood vessel bursts here a pool of blood can develop between the arachnoid membrane and dura mater, called a subdural hematoma. A hematoma can compress the CNS and impair function, pressure is relieved by drilling a hole to drain (sometime called trepanning). The third layer is called the pia mater (gentle mother), it is thin and adheres closely to the brain, blood vessels in this membrane also dive into the brain tissue. There is a salty fluid (CSF - Cerebrospinal fluid) filled space between the pia mater and arachnoid membrane called the subarachnoid space.
Choroid Plexus
The ventricular system is comprised of four ventricles and filled with CSF (produced by choroid plexus tissue in ventricles).
Computer Tomography
CT scans are x-ray images visualizing slices of tissue. Requires x-radiation (MRI does not).
Nucleus
A collection of neurons, usually deep in the brain and distinguishable. Think about a ‘nut’ of neurons deep in the brain.
Substantia
A group of related neurons deep in the brain, but with fuzzier borders than nuclei.
Locus
A small, well defined group of cells in a specific location.
Ganglion
Ganglia are collections of neurons in the PNS, can be thought of as ‘knots’ of neurons. Only one structure labelled ganglia exists in the CNS, the basal ganglia.
Nerve
A bundle of axons in the PNS, only one collection of CNS axons is called a nerve, the optic nerve.
Bundle
A collection of axons that run together but do not necessarily have same origin or destination. Capsule - A collection of axons that connect the cerebrum with the brain stem
Commissure
Any collection of axons that connect one side of the brain with the other side
Lemniscus
A tract that meanders through the brain like a ribbon.
Ectoderm
Part of an early embryo disk, the entirety of the nervous system and skin is derived from this layer. It turns into the neural plate at about 17 days from conception in humans. It then forms a neural groove, which eventually fuses to produce a neural tube. At this point the entire CNS is a sheet of cells on this wall. The neural crest is a bit of neural ectoderm that gets pinched off in forming the neural tube, it is lateral to the neural tube and will form the entirety of the CNS.
Neurelation
The process where the neural plate becomes the neural tube, occurs about 22 days after conception in humans.
Prosencephalon
The most rostral vesicle, also called the forebrain.
Mesencephalon
Middle primary vesicle, becomes the midbrain (aka mesencephalon).
Rhombencephalon
The most caudal primary vesicle, also called the hindbrain. Connects to the caudal neural tube, which gives rise to the spinal cord.
Forebrain Differentiation
For graphical representation see pg. 184. The prosencephalon splits off into four vesicles, one pair is called the telencephalic vesicles and the others are the optic vesicles.
Optical Development
The optic vesicle will differentiate into an optic stalk and optic cup. The optic stalk will become the optic nerves and the optic cups will become retinas. This means that the optic nerve and retinas are part of the CNS rather than the PNS.
Telencephalon
The two telencephalon vesicles that form will become the two hemispheres of the cerebrum. It grows posteriorly, meaning that they will reach back towards the hindbrain. Olfactory bulbs will develop from the telencephalon. The walls of the telencephalon differentiate into two structures, the cerebral cortex and the basal telencephalon (also the amygdala). The diencephalon differentiates into the thalamus and hypothalamus. See graph in notes of Lecture 5 for this.
The lateral and third ventricle
The lateral ventricles are surrounded on the dorsal side by the telencephalon while the third vesicle is surrounded by the diencephalon (which the telencephalon and the optic vesicles branch out of).
Midbrain differentiation
The midbrain differentiates into an upper and lower part. The tectum (upper) and the tegmentum (lower). The CSF filled space inbetween constricts into a narrow channel called the cerebral aqueduct. The cerebral aqueduct connects rostrally to the third ventricle of the diencephalon
Colliculus
The tectum of the midbrain differentiates into four bumps. Two are called the superior colliculus (optic tectum controls eye movement) and two are called the inferior colliculus (channels input from ear to thalamus).
Tegmentum
The tegmenum contains the black substantia nigra and red nucleus. These two things are involved in control of voluntary movement.
Hindbrain Differentiation
The hindbrain differentiates into the pons, cerebellum (from the rhombic lips) and medulla oblongata. The cerebellum and pons develop from the rostral half of the hindbrain (metencephalon) and the medulla develos from the caudal half (myencephalon). The CSF tube here becomes the fourth ventricle which is continuous with the cerebral aqueduct of the midbrain.
Pons
The pons serves as a massive switchboard connecting the cerebrum with the cerebellum
Medullary Pyramids
Most axons which terminate here enter caudally from the pons, originating in the cerebral cortex and part of the corticospinal tract. Each pyramidal tract (corticospinal tract) crosses from one side of the midline to the other. Crossing is called decussation and this crossing is called pyramidal decussation. This crossing explains why the left cortex is responsible for the right side of the body and vice versa. The medulla is a major station for sensory input and damage to it usually leads to anesthesia (sense loss).
Spinal cord Differentiation
This is straightforward and ends up with a bone encased system. Spinal grey matter surrounds the spinal canal and is divided into three zones, the dorsal horn (afferent axons), the intermediate zone (interneurons), and the ventral horn (efferent axons). White matter columns extend from the dorsal (back) side of the spinal cord.
The Central Sulcus
Marks the boundary between the frontal lobe and parietal lobe.
Layers of the Cerebral Cortex
Layer 1 is separated from the pia mater by a layer that lacks neurons (molecular layer). At least one layer contains pyramidal cells that emit large dendrites, called apical dendrites that extend up to layer 1 where they form multiple branches.
Three Cortex and Rhinal Fissure
There are three cortex, hippocampus, olfactory cortex and neocortex (only found in mammals). The neocortex is separated from the olfactory cortex a sulcus called the Rhinal fissure.
Korbinian Brodmann
Constructed a cytoarchitectural map of the neocortex. Each area having common cytoarchitecture is given a number. Different areas have different functions (structure affects function).
3 Telencephalic Nuclei
Basal Ganglia
Amygdala
Hippocampus
2 Structures that differentiate from the prosencephalon
Telencephalon
Diencephalon
Two structures that differentiate from the diencephalon
Thalamus
Hypothalamus
4 Structures that differentiate from the telencehalon
Cortex
Basal Ganglia
Amygdala
Hippocampus
Two structures that differentiate from the mesencephalon
Tectum (upper midbrain)
Tegmuntum (lower midbrain)
Two structures that differentiate from the rhombencephalon
Pons
Medulla
Coronal
Frontal
What sense does the pons deal with
Sensory representation of face
What does the cerebellum come from
Pons, the pons has many many projections into the cerebellum
Midbrain has ____ fibres on its ventral side
Motor fibres
Superior Colliculi
Upper bumps on midbrain near the cerebellum. For eye movement
Inferior Colliculi
Lower bumps on midbrain near the cerebellum. For midbrain relay of auditory system.
Each sense has its own _____ of the thalamus
Nuclei
Hypothalamus’ Main function
Endocrine, especially with the pituitary gland, involved in autonomic NS.
Basal Ganglia
Part of the cerebrum, important for the initiation of movement
Hippocampus
Learning and spacial navigation
Central Sulcus
Divides frontal lobe (motor) from parietal (sensory)
Sylian Fissure
Shows where language processing takes place
Cerebral Aqueduct
Communicates between 3rd and 4th ventricles. Opens in pons (4th ventricle) and then turns into the central canal down the spinal cord
How many ventricles and their names
Lateral ventricles (2), 3rd ventricle and 4th ventricle (total of 4)
Dura Mater Sense
Has some receptors that can protect pain around outer layer of brain and spinal cord
Subachnoid Space Size and features
Rather large with blood vessel projections. Also contains cerebrospinal fluid and is continious with centricles
Choroid Plexus is Innervated with _____ to do ______
Blood vessels, to filter blood in lateral ventricles
Contaminants in CSF
Can be detected anywhere, eg. lumbar puncture penetrates dura mater and sample will show contaminants and can detect tumor in brain
Ectoderm will become
Brain and skin
Mesoderm will become
Skeleton and skeletal muscle system
Neural tube will become
Entire nervous system
Neural crest will become
Entire PNS
Internal capsule is a part of the _____ and relays all ____
Thalamus and sensory information
Topographic Connectivity
Sometimes called point to point connectivity. Pathways between sense organs to the thalamus and then to cerebral cortex. Projecting to cells that are caudal (close) to each other and at a higher level
4 Kinds of cortex
Neocortex (6 layers)
Olfactory cortex
Hippocampal Cortex (misnomer)
Entorhinal Cortex (inbetween hippocampal and neocortex, relays between them, involved in memory, especially during sleep and dreams).
Layer IV of the neocortex
Frequently the input layer
Layers V and VI of the neocortex
Frequently output layers
Cortical column
Vertical unit of processing
Brodmann
Early 20th century anatomist who stained human brains with nissl and mapped out cortical territories
Brodmann’s areas (how many)
52
Sensorimotor areas get _____ in ____ mammals
Smaller in higher mammals
Angiogram
Basically x-ray of blood vessels. Major blood vessel layout very similar from person to person. Can find intracranial Berry aneurysms with this, these form at junctions between blood vessels.Usually harmless but fatal if they hemorrhage.
CT Scans
Computer tomography, slice x-rays, good for looking at brain bone trauma. Can find tissue density
MRI
Magnetic Resonance Imagining. Protons of water in brain excited to higher energy state by radio waves. When radio waves are stopped the protons give off detectable resonance energy.
Structural MRI
Snapshot of 3D brain
Functional MRI (fMRI)
Targets deoxygenated (hemoglobin?) to find areas that are using the most amount of energy.
Magnetic Resonance Spectroscopy
Can target any molecule you want and show density
Diffusion Tensor Imaging
Shows white matter density, often combined with fMRI
PET scans
Positron Emission Tomography, measures blood supply during task (colourful!)
