GROSS ANAT OF THE NERV SYSTEM Flashcards
What are the components of the CNS?
BRAIN: Forebrain (Telencephalon, Diencephalon), Brain Stem (Midbrain, Pons, Medulla), Cerebellum; SPINAL CORD: Cervical, Thoracic, Lumbar, Sacral, Coccygeal
What are the components of the PNS?
The nerves that connect your CNS to the rest of your body. Cranial nerves (Origin = brain stem, Exceptions CN I and II); Spinal nerves (Origin = spinal cord)
Define afferent signals/information.
Neuronal projections to a neuron, group of neurons or central nervous system.
AFFERENT ARRIVES!
Define efferent signals/information.
Neuronal projections from a neuron, group of neurons or central nervous system.
EFFERENT EXITS!
What is the difference between the autonomic and somatic nervous systems?
Autonomic (unconscious visceral motor); Somatic (conscious motor and sensory)
What are 3 functions of the nervous system?
- Sensory (afferent) = sensory receptors detect stimuli and transmit information to the brain or spinal cord; 2. Integrative function = interneurons analyze and integrate sensory information; 3. Motor function (efferent) = motor neurons initiate actions in effectors.
What is the CNS?
Brain and spinal cord
What is a nucleus?
A group of neurons within the CNS with similar function, connectivity, and neurotransmitters
What is a tract?
A bundle of axons traveling together within the CNS
What is a synapse?
A point of connection/communication between neurons
What is afferent?
Arriving information
What is efferent?
Exiting information
What is the PNS?
Cranial nerves and spinal nerves
What is a nerve?
A bundle of axons (plus associated connective tissue and blood vessels) located outside the brain and spinal cord
What is a ganglion?
A group of neurons outside of the CNS with similar function, connectivity and neurotransmitters
What is the somatic nervous system?
Afferent and efferent systems that regulate motor innervation of skeletal muscle and relay sensory information from the external environment
What is the autonomic nervous system?
Efferent systems that regulate motor innervation of smooth muscle and glands
What is the visceral sensory system?
Afferent sensory information from the internal environment (hollow organs)
What are the components of the somatic nervous system?
Somatic sensory neurons (Afferent) convey information from sensory receptors; Somatic motor neurons (Efferent) convey information from the CNS to skeletal muscles.
What are the components of the autonomic nervous system?
Sensory neurons (Afferent) convey information from visceral organs; Autonomic motor neurons (Efferent) convey information from the CNS to smooth muscle, cardiac muscle, and glands.
How are neurons classified?
Nervous tissue is comprised of neurons and neuroglia. Neurons are excitable, postmitotic, and highly variable; Neuroglia support, nourish, and protect neurons.
What are the important characteristics of neurons?
Neurons are highly specialized cells with organelles. Key components include cell body/soma, Nissl bodies, dendrites, axons, and terminal boutons.
What is the function of an axon?
The axon carries electrical impulses away from the neuron’s cell body and toward other neurons, muscles, or glands.
What is the function of a dendrite?
Dendrites receive electrical or chemical signals from other neurons.
What are the 3 types of neurons in vertebrates?
- Multipolar = 1 axon, many dendrites; 2. Bipolar = 1 axon and 1 main dendrite; 3. Pseudo-unipolar = 1 process exits the soma and splits.
What are the components of a synapse?
- Electro-chemical impulse travels along axon; 2. Presynaptic neuron releases neurotransmitters; 3. Neurotransmitters bind to receptors on postsynaptic neuron; 4. Electro-chemical impulse continues.
What are the 4 types of glia found in the CNS?
- Astrocytes = contact capillaries and neurons; 2. Oligodendrocytes = myelinate axons; 3. Microglia = phagocytes; 4. Ependymal Cells = line ventricles and produce CSF.
What are the 2 types of glia found in the PNS?
- Schwann cells = myelinating cells; 2. Satellite cells = surround neuron cell bodies and support.
What cells are responsible for myelination in the CNS?
Oligodendrocytes
What cells are responsible for myelination in the PNS?
Schwann Cells
What cell type lines the ventricles?
Ependymal cells
Which cells migrate into the CNS and are not derived from the neural crest or neural tube?
Microglia
What cell types form the blood-brain barrier?
Astrocytes
What is the main component of gray matter?
Gray matter contains neurons and their proximal dendrites (no myelin)
What is the main component of white matter?
White matter contains myelinated axons and myelinating oligodendroglia.
What is a synapse?
A site of communication between two neurons.
What is a sulcus?
A groove in the brain.
What is a gyrus?
A bump in the brain.
How many lobes make up the cerebral cortex?
Frontal, Parietal, Occipital, Temporal, Limbic, Insula
What are the anatomical landmarks that separate the different cortical lobes?
Parieto-occipital sulcus, central sulcus, lateral fissure.
What is the anatomical landmark that separates the cerebral hemispheres?
The superior sagittal sulcus.
What are the 3 meningeal layers, superficial to deep?
Dura mater, Arachnoid mater, Pia mater
What creates cerebrospinal fluid, and where is it found?
Choroid plexus in the lateral ventricles.
What absorbs cerebrospinal fluid, and where is it found?
Arachnoid granulations in the arachnoid mater.
What are the functions of the meningeal layers?
Dura mater = tough protection; Arachnoid mater = CSF circulation; Pia mater = follows brain surface.
What subdivisions of the lateral ventricle are associated with the lobes?
Frontal - anterior horn; Temporal - inferior horn; Occipital - posterior horn; Parietal - body.
Which ventricle is found within the diencephalon?
Third ventricle.
Which ventricle is found within the brain stem?
Fourth ventricle.
What is the path of cerebrospinal fluid through and out of the ventricles?
Choroid Plexus secretes CSF into ventricles, drains to subarachnoid space, circulates, and is absorbed by arachnoid granulations.
What two arteries are the main contributions to the cerebral vascular circle?
Internal carotid (anterior areas) and Vertebral (posterior areas).
What larger artery is the source of these arteries?
Internal carotid branches from common carotid; Vertebral branches from subclavian.
What are the 3 main branches of the cerebral vascular circle?
Anterior cerebral (ACA), middle cerebral (MCA), posterior cerebral (PCA).
From which artery does the right subclavian branch?
The right subclavian branches from the brachiocephalic artery.
From which artery does the brachiocephalic branch?
The brachiocephalic branches from the aortic arch.
From which artery does the left subclavian branch?
The left subclavian branches from the aortic arch.
What are the three main branches of the cerebral vascular circle?
- Anterior cerebral (ACA) - supplies the medial aspect of the frontal & parietal lobes.
- Middle cerebral (MCA) - supplies the lateral aspect of the frontal, parietal, & temporal lobes.
- Posterior cerebral (PCA) - supplies the medial & lateral aspects of the occipital lobe & a portion of the medial aspect of the temporal lobe.
From what germ layer does the nervous system arise?
The nervous system arises from the ectoderm.
What mesodermal structure induces the neural plate?
The notochord induces the neural plate.
What happens if the anterior neuropore fails to close?
Failure of the anterior neuropore to close results in anencephaly.
What happens if the posterior neuropore fails to close?
Failure of the posterior neuropore to close results in spina bifida.
What forms the ventricular system?
The ventricular system forms from the lumen within the neural tube.
Why are there two lateral ventricles?
The two lateral ventricles form from the developing hemispheres of the brain.
Where is the neural crest formed?
The neural crest is formed as it separates from the neural tube.
What types of cells does the neural crest become?
The neural crest becomes:
- Dorsal root ganglia neurons
- Autonomic ganglia neurons
- Pia mater (meninges)
- Schwann cells (peripheral nerves)
- Satellite cells (peripheral ganglia)
- Melanocytes (skin)
