Organization Of The Nervous System 1 Flashcards
What are the components of the central nervous system?
Brain (enencephalon)
Spinal Cord
What are the components of peripheral nervous system?
Cranial nerves
Spinal nerves
What are the components of the brain?
Hindbrain (rhombencephalon)—> medulla oblangata, pons, cerebellum —> fourth ventricle
Midbrain(mesencephalon)—> cerebral aqueduct
Forebrain (prosencephalon)—> telencephalon, diencephalon (thalamus, hypothalamus, epithalamis, subthalamus)
What are the cranial nerves?
- Olfactory nerve
- Optic nerve
- Oculomotor nerve
- Trochlear nerve
- Trigeminal nerve
- Abducens nerve
- Facial nerve
- Vestibulocochlear nerve
- Glossopharyngeal nerve
- Vagus nerve
- Accessory nerve
- Hypoglossal nerve
How many types of each spinal nerve occurred?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Contrast grey matter in the brain and the spinal cord
Brain
• Cortex (cerebral, cerebellar)
• Central nuclei (basal nuclei, amygdala, hypothalamic nuclei, thalamic nuclei, cranial nerve nuclei, cerebellar nuclei)
Spinal Cord
• Spinal cord grey matter (H-shape)
Contrast the white matter of the spinal cord and brain
Brain
• Cerebral white matter
• Commissural fibers (corpus callosum)
• Association fibers (uncinate fasciculus)
• Projection fibers (thalamocortical projections)
Spinal Cord
• Ascending fiber tracts (anterolateral system, DCML tract)
• Descending fiber tracts (corticospinal tract)
Summarize brain embryogenesis
Day 0: fertilization forming zygote (in the ampulla of the fallopian tubes)
Day 1-5: zygote travels to the uterus and divides to become morula (16 cells), and then blastocyst Day 6: implantation of blastocyst in the uterus
Day 7-14: bilaminar embryonic disc develops (hypoblast and epiblast)
Week 3-4: gastrulation, notogenesis, and neurulation
Week 5-8: organogenesis
Describe the development of the primary brain vesicles
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Developed after 4 weeks
How are the secondary brain vesicles formed?
Prosencephalon -telencephalon and diencephalon
Mesencephalon still mesencephalon
Rhombencephalon- metencephalon & myelencephalon
Formed after 5 weeks
What are the adult derivatives of the telencephalon?
Brain structure- cerebrum
Cavity- lateral ventricles
What are the adult derivatives of the diencephalon?
Brain structure- diencephalon(thalamus, hypothalamus, epithalamus, subthalamus)
Cavity- third ventricle
What are the adult derivatives of the mesencephalon?
Brain stem: midbrain
Cavity: caudal brain
What are the adult derivatives of metencephalon ?
Brain structure: brain stem: pons
Cerebellum
Cavity: fourth ventricle
What are the adult derivatives of myelencephalon?
Brain structure: brain stem: medulla oblangata
Cavity: fourth ventricle
What does the neural tubr develop into after 3 weeks?
Cranial part abd caudal part
Cranial part guve the primary brain vesicles
What does the telencephalon become?n
Telencephalon (cerebrum, endbrain – derived from the rostral prosencephalon)
• Cerebral hemispheres
• Cerebral cortex
• Basal ganglia
• Lateral ventricles
• Foramina of Monro (interventricular foramina), which connect the lateral ventricles with the diencephalic third ventricle
. • Closely tied to olfactory nerves
What does the diencephalon form?
Diencephalon (interbrain – derived from the caudal prosencephalon) • Thalamus • Hypothalamus (and pituitary) • Subthalamus • Epithalamus • Third ventricle • Cranial nerve II
What does the mesencephalon (midbrain) form?
Mesencephalon (midbrain)
• Tegmentum (floor: including cerebral peduncles or crus cerebri)
• Tectum (roof: corpora quadrigemina or superior and inferior colliculi)
• Cerebral aqueduct
• Cranial nerves III and IV
What does the metencephalon become?
Metencephalon (derived from the rhombencephalon)
• Pons
• Cerebellum (cerebellar hemispheres and vermis)
• Rostral fourth ventricle
• Cranial nerves V - VIII
What does the metencephalon become?
Myelencephalon (derived from the rhombencephalon)
• Medulla oblongata
• Caudal fourth ventricle
• Foramina of Magendi (“M” for medial) and Luschka (“L” for lateral) communicate between the fourth ventricle and the subarachnoid space
• Central canal of the medulla is continuous with the spinal central canal
• Cranial nerves IX - XII
What are the adult derivatives of neural crest cells?
Peripheral ganglia
Schwann cells
Afferent nerve cells
What is the adult derivative of neural tube?
Preganglionic Autonomic fibers
Somatoc motor neurons
What are the adult derivatives of the mesoderm?
Emdoneurium, perineurium, and epineureium
Describe the organization of the peripheral nerves
Endpneurium
Connective tissue surrounding each axon
Perineurium:
connective tissue surrounding fascicles (group of axons)
Epineurium:
connective tissue surrounding the nerve
Describe the communications between the CNS & PNS
Flow of information between CNS – PNS with efferent and afferent pathways
Efferent Communications:
• All somatic motor neurons have the origin in the CNS
• All autonomic preganglionic neurons have the origin in the CNS
Afferent Communications:
• All sensory nerve fibers have the origin in the dorsal root ganglia or cranial nerve ganglia
What is the transitional zone?
Transitional Zone: Redlich-Obersteiner’s Zone
a.k.a. Glial-Schwann Junction
Boundary between the CNS and PNS
• Between cranial nerves and the brain
• Between the spinal nerves and the spinal cord
There is a transition from Schwann cell myelin to oligodendrocyte myelin
At this point occur the neurovascular compression syndromes in the cranial nerves (e.g. trigeminal neuralgia)
