Chapter 7 - Gross Neuroanatomy Flashcards Preview

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Flashcards in Chapter 7 - Gross Neuroanatomy Deck (87):
1

Rostral

Anterior

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Caudal

Posterior

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Three anatomical planes of section

Midsaggital plane along the midline, other lines parallel to this are sagittal. Horizontal plane and coronal plane.

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The Cerebellum

Contains as many neurons and the cerebrum

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Dorsal Roots

Carry information from the PNS to the CNS

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Ventral roots

Carry information from the CNS to the PNS

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Dorsal Root Ganglia

One per each spinal nerve. Contains the cell body of receptors.

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Afferent neurons

Carry sensory information to the CNS. AKA sensory neurons

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Efferent Neurons

Carry information from the CNS to the body. Also known as motor neurons.

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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.

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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.

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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.

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Choroid Plexus

The ventricular system is comprised of four ventricles and filled with CSF (produced by choroid plexus tissue in ventricles).

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Computer Tomography

CT scans are x-ray images visualizing slices of tissue. Requires x-radiation (MRI does not).

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Nucleus

A collection of neurons, usually deep in the brain and distinguishable. Think about a ‘nut’ of neurons deep in the brain.

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Substantia

A group of related neurons deep in the brain, but with fuzzier borders than nuclei.

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Locus

A small, well defined group of cells in a specific location.

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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.

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Nerve

A bundle of axons in the PNS, only one collection of CNS axons is called a nerve, the optic nerve.

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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

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Commissure

Any collection of axons that connect one side of the brain with the other side

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Lemniscus

A tract that meanders through the brain like a ribbon.

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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.

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Neurelation

The process where the neural plate becomes the neural tube, occurs about 22 days after conception in humans.

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Prosencephalon

The most rostral vesicle, also called the forebrain.

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Mesencephalon

Middle primary vesicle, becomes the midbrain (aka mesencephalon).

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Rhombencephalon

The most caudal primary vesicle, also called the hindbrain. Connects to the caudal neural tube, which gives rise to the spinal cord.

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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.

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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.

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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.

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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).

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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

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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).

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Tegmentum

The tegmenum contains the black substantia nigra and red nucleus. These two things are involved in control of voluntary movement.

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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.

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Pons

The pons serves as a massive switchboard connecting the cerebrum with the cerebellum

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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).

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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.

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The Central Sulcus

Marks the boundary between the frontal lobe and parietal lobe.

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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.

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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.

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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).

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3 Telencephalic Nuclei

Basal Ganglia
Amygdala
Hippocampus

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2 Structures that differentiate from the prosencephalon

Telencephalon
Diencephalon

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Two structures that differentiate from the diencephalon

Thalamus
Hypothalamus

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4 Structures that differentiate from the telencehalon

Cortex
Basal Ganglia
Amygdala
Hippocampus

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Two structures that differentiate from the mesencephalon

Tectum (upper midbrain)
Tegmuntum (lower midbrain)

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Two structures that differentiate from the rhombencephalon

Pons
Medulla

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Coronal

Frontal

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What sense does the pons deal with

Sensory representation of face

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What does the cerebellum come from

Pons, the pons has many many projections into the cerebellum

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Midbrain has ____ fibres on its ventral side

Motor fibres

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Superior Colliculi

Upper bumps on midbrain near the cerebellum. For eye movement

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Inferior Colliculi

Lower bumps on midbrain near the cerebellum. For midbrain relay of auditory system.

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Each sense has its own _____ of the thalamus

Nuclei

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Hypothalamus' Main function

Endocrine, especially with the pituitary gland, involved in autonomic NS.

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Basal Ganglia

Part of the cerebrum, important for the initiation of movement

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Hippocampus

Learning and spacial navigation

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Central Sulcus

Divides frontal lobe (motor) from parietal (sensory)

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Sylian Fissure

Shows where language processing takes place

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Cerebral Aqueduct

Communicates between 3rd and 4th ventricles. Opens in pons (4th ventricle) and then turns into the central canal down the spinal cord

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How many ventricles and their names

Lateral ventricles (2), 3rd ventricle and 4th ventricle (total of 4)

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Dura Mater Sense

Has some receptors that can protect pain around outer layer of brain and spinal cord

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Subachnoid Space Size and features

Rather large with blood vessel projections. Also contains cerebrospinal fluid and is continious with centricles

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Choroid Plexus is Innervated with _____ to do ______

Blood vessels, to filter blood in lateral ventricles

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Contaminants in CSF

Can be detected anywhere, eg. lumbar puncture penetrates dura mater and sample will show contaminants and can detect tumor in brain

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Ectoderm will become

Brain and skin

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Mesoderm will become

Skeleton and skeletal muscle system

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Neural tube will become

Entire nervous system

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Neural crest will become

Entire PNS

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Internal capsule is a part of the _____ and relays all ____

Thalamus and sensory information

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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

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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).

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Layer IV of the neocortex

Frequently the input layer

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Layers V and VI of the neocortex

Frequently output layers

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Cortical column

Vertical unit of processing

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Brodmann

Early 20th century anatomist who stained human brains with nissl and mapped out cortical territories

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Brodmann's areas (how many)

52

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Sensorimotor areas get _____ in ____ mammals

Smaller in higher mammals

80

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.

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CT Scans

Computer tomography, slice x-rays, good for looking at brain bone trauma. Can find tissue density

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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.

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Structural MRI

Snapshot of 3D brain

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Functional MRI (fMRI)

Targets deoxygenated (hemoglobin?) to find areas that are using the most amount of energy.

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Magnetic Resonance Spectroscopy

Can target any molecule you want and show density

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Diffusion Tensor Imaging

Shows white matter density, often combined with fMRI

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PET scans

Positron Emission Tomography, measures blood supply during task (colourful!)