Presentation 19: CNS Flashcards
Ependyma
Central canal of spinal chord, lined with ependymal cells (a specific epithelium)
Grey matter
Less myelinated neurons (less insulation)
In spinal cord made up of dorsal horn (sensory neurons) and ventral horn (motor neurons)
White matter
Contains more myelin (insulation)
In spinal chord made up of ascending (bring info to brain) and descending (bring info everywhere else) tracts
Reflex arc
Interneurons confined to spinal cord, involved in sending sensory signals straight to motor without going to the brain
Neurocoel
Hollow cavities in the brain filled with cerebro-spinal fluid which acts as a cushion and a medium of exchange
Cerebral hemispheres = lateral ventricles
Thalamus = third ventricle
Midbrain = aqueduct
Metencephalon = upper part of 4th ventricle
Myelencephalon = lower part of 4th ventricle
General components of the brain
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Prosencephalon
The forebrain
- composed of Telencephalon (cerebral hemisphere) and Diencephalon (thalamus, epithalamus, and hypothalamus)
- enlarged in birds and mammals which reflects more complex behaviors and more efficient muscle control
Mesencephalon
Midbrain
- just the mesencephalon, composed of tectum (roof, sensory function) and tegmentum (floor, motor function)
- impulses go up at cranial nerves 3-4
- contains auditory and optic lobes
- neurocoel = cerebral aqueduct
Telencephalon
Part of forebrain
Cerebral hemispheres
- neurocoel = lateral ventricle
- contains olfactory bulbs, tracts, and lobes
- higher vertebrates have sulci (grooves) and gyri (ridges)
Diencephalon
Part of forebrain
Thalamus
- Includes epithalamus (roof), thalamus (main part), hypothalamus (floor and walls)
- neurocoel = 3rd ventricle
Tela choroidea
thin membrane that lines the brain cavity and projects into brain as choroid plexus
Choroid plexus
projection of tela choroidea into brain cavity. Produces cerebro-spinal fluid which cushions the brain and acts as a medium of exchange
Rhombencephalon
Hindbrain
- split into the metencephalon (cerebellum + pons) and myelencephalon (medulla oblongata)
- Neurocoel = 4th ventricle
Metencephalon
Part of hindbrain
Made up of cerebellum and pons
- ventrally have pyramidal tracts that connect to corticospinal tracts
- neurocoel = upper part of 4th ventricle
- roof = cerebellum (dorsal outgrowth, most prominent)
Myelencephalon
Most post. part of hindbrain
Composed up of medulla oblongata
- neurocoel = lower part of 4th ventricle
Medulla oblongata
Primary component of myelencephalon
- transition from brain to medulla of spinal cord
- assoc. w/ cranial nerves 7-12
- has distinctive nuclei assoc. w/ sense organs
What are the 3 functions of the medulla oblongata?
- cluster of nuclei assoc. w/ cranial nerves
- major root of info from body to brain through ascending/descending tracts
- clusters of soma for visceral, auditory, and proprioceptive receptors (things you don’t control)
What are the 2 main functions of the cerebellum
- process all sensory input
- maintain equilibrium w/ input from inner ear to myelencephalon
Pons
Part of metencephalon
Connects cerebellum to cerebral cortex
- most prominent in mammals
Cerebellum
Dorsal outgrowth of metencephalon
- roof of 4th ventricle along with choroid plexus
- larger in birds/mammals but reduced in fishes
Tectum
Roof of mesencephalon
- Sensory function
- contain optic lobes which receive input from retinas
- contain auditory lobes, posterior optic lobes, and cochlea
- specialized into superior and inferior colliculi
Tegmentum
Floor of Mesencephalon
- Motor function
- primary place for cross of ascending and descending tracts
Epithalamus
Roof of diencephalon
- associated w/ pineal organ (photoreceptor in lampreys, endocrine organ in higher vertebrates)
Optic lobes
Part of tectum (except in mammals - telencephalon)
- receives visual input from retina
Cerebral aqueduct
Very large in anamniotes (fishes/amphibians/etc.), smaller in amniotes (birds/mammals/reptiles)
Connects cavities of the 3rd and 4th ventricles
Thalamus
Main part of diencephalon
- paired mass of nuclei forming dorsal walls get info for coordination center and receive all sensory impulses from spinal cord, midbrain, and hindbrain and sends that info to cerebral cortex
- split into ventral and dorsal sections (dorsal part is the important one)
hypothalamus
make up floor and ventrolateral walls of diencephalon
- nuclei that regulate appetite, sexual activity, temperature, water balance, and behavior (homeostasis)
- activity is enhanced by hormones released during breeding season
Cerebral cortex/hemispheres
pair of extended lobes of telencephalon
- Surface of cerebral cortex is folded to increase area forming sulci (grooves) and gyri (ridges)
Sulcus
grooves formed by folding of cerebral cortex to increase area
Gyrus
Ridges formed by folding of cerebral cortex to increase area
How are nervous tissues divided
Into Pallium and paleostriatum
- pallium divided into archipallium and paleopalleum)
Pallium
Type of nervous tissue
- Divided into archipallium and paleopalleum
- forms roof of ventricle
Paleostriatum
forms floor of the ventricle and a type of nervous tissue
What is the diversity of nervous tissues between fish, amphibia, amniota, and mammalia?
Fish: the entire cerebral hemispheres are made of paleostratium
Amphibia: oflactory and motor nuclei mostly located in the telencephelon
Amniota: Add neostriatum (new layer of tissue from paleostriatum) which allows for coordination of skeletal muscle
Mammalia: Paleopalleum and neostriatum reduced into the basal ganglia at the base of telencephalon
- expanded pallium called neopallium which = brain cortex made of grey matter
- have gyri and sulci
- have corpus callosum which connects cerebral hemispheres
Corpus callosum
Connects two cerebral hemispheres in mammals
- integrates both sensory and motor info that then responds as actions
