Development of the Brain, spinal cord and cranial nerves Flashcards
What does the ectoderm give rise to?
The skin, CNS (Brain and spinal cord), PNS *peripheral nerves) pituitary gland, teeth and nose mucosa
What does the mesoderm give rise to?
GI tract, heart, RBC, skeletal muscles, heart and mesenchyme cells that give rise to the bone and cartilage.
What does the endoderm give rise to?
Digestive tract and Lungs
How does the mesoderm form?
During gastrulation process on day 16. The cells of the ectoderm in contact with the endoderm proliferate and move across to form the primitive streak which confirms bilateral symmetry in the embryo. The proliferating cells invaginate into the cephalic end of the primitive streak called the primitive node and displace the hypoblast which forms the mesoderm.
What is the primitive node?
The primitive node is at the cephalic end of the primitive streak.
What is the primitive pit?
The slightly elevated area around the primitive node called the primitive pit.
Where does the nervous system develop from the trilaminar disc?
The ectoderm.
What is the process of neuralation?
Notochord stimulates the ectoderm differentiates-> neuroectoderm differentiates -> neural epithelial cells which form a thickened layer called the -> neural plate which changes shape and folds inward to create neural folds with a neural groove. The neural groove -> neural tube when the neural folds converge. Before the neural folds fuse, parts of the neural tube separate and migrate as neural crest cells to form the spinal cord and cranial nerves
What does the neural crest give rise to?
The PNS(cranial nerves and spinal nerves) and the spinal cord.
What does the neuroectoderm give rise to?
Tissue of the nervous system.
What does the paraxial mesoderm give rise to?
The somites which are the dermis, skeletal muscle, cartilage tendons and vertebrae
What are somites?
Precursor mesodermal paired cells on either side of the notochord that gives rise to the dermis, skeletal muscle, cartilage, tendons and vertebrates
How does the spinal cord develop?
The neural tube has 3 zones: the matrix, marginal and mantle zone. The marginal zone gives rise to cells called neuroblasts and glioblasts which migrate into the mantle zone and form two plates.
The alar plate forms the dorsal side of the neural tube and contains the afferent sensory neurons which later becomes the grey matter of the spinal cord. The basal plate forms the ventral portion of the neural tube which contains the efferent motor neurons and forms the white matter of the spinal cord. The basal and alar plate are separated by the sulcus limitans. The sulcus limitans extends from the spinal cord to the rostral mdbrain.
What is the ventral medial fissure?
The ventral horn of the spinal cord formed by the basal plate bulge.
What is the dorsal septum?
The dorsal horn of the alar plate fusing together.
What is the meninges?
The three-layer membrane that protects both the spinal cord and brain. Inner layer is pia mater, middle layer is a web like structure called the arachnoid and the tough outer layer is the dura mater.
What is the dura mater?
Tough Outer layer of tissue which protects the brain and spinal cord. It arises from the paraxial mesoderm that surrounds the neural tube
What is the pia mater?
Inner delicate layer directly surrounding the brain and spinal cord. It arises from neural crest cells.
What is the arachnoid mater?
Web like tissue which forms the middle layer of the meninges. It arises from neural crest cells.
What is the conus medullaris?
Terminal end of the spinal cord at level L1 but the neural tube continues beyond this
How do the cranial nerves develop?
Cranial nerves derive from neural crest cells and thickened patches of ectoderm called the ectodermal placodes.
Neural crest cells separated from the neural tube and ectodermal patches break away from the ectoderm and they migrate through the embryo in the cranium and trunk and divide into the cranial nerves, pharyngeal arches, skeletal tissue and connective tissue components, sensory ganglia of cranal nerve 5, 6, 7, 9 and 10 AND THE
What cranial nerve does pharyngeal arch 1 give rise to?
Cranial nerve 5- trigeminal nerve
What cranial nerve does pharyngeal arch 2 give rise to?
Facial nerve- cranial nerve 7
What cranial nerve does pharyngeal arch 3 give rise to?
Glossopharyngeal nerve -cranial nerve 9
What cranial nerve does pharyngeal arch 4 and 6 give rise to?
Vagus nerve
What are the special sensory cranial nerves?
Olfactory, optic and vestibulocochlear
WHat is the somatic efferent nerves?
Trochlear, abducens, hypoglossal and oculomotor nerve which are homologous with the ventral roots of the spinal nerves
What do neural crest cells give rise to in the trunk?
Schwann cells, chromaffin cells of adrenal medulla and sympathetic chain ganglia.
