Embryology Flashcards
Meroencephaly (anencephaly)
Failure of the anterior neuropore to close
Spina bifida cystica
failure of the posterior neuropore to close
Lissencephaly
abnormal patterning of sulci and gyri. Incomplete neuronal migration to the cerebral cortex during the 3rd and 4th months of gestation.
Grey matter heterotopia
gray matter appears in white matter, basis for seizure disorder
Neurocristopathies
neuroblastoma, Schwannoma, Neurofibromatosis, Waardenburg syndrome, pheochromocytoma, Hirschsprung’s disease, CHARGE, DiGeorge syndrome
Neuroblastoma
neuroendocrine tumor arising from any neural crest cell element of the sympathetic nervous system. Metastasizes widely in bone marrow, bones and lymph nodes.
Raccoon eyes
appear with neuroblastoma and metastasis of neuroblastoma to the skull
Schwannoma
benign tumor of Schwann cells of neural crest origin. It is most commonly located near the vestibular branch of CN VIII
Neurofibromatosis/Von Recklinghausen Disease
NF Type 1 is an autosomal dominant condition characterized by changes in skin pigmentation and tumors along nerves in skin, brain and other parts of the body
Cafe au lait spot
clinically associated with neurofibromatosis. Flat patch on skin that are darker than the surrounding area.
Pheocromocytoma
tumor in adrenal medulla. Occurs as a result of too much epinephrine and norepinephrine
Waardenburg syndrome
genetic condition that causes congenital hearing loss and changes in pigmentation of hair, skin, and eyes.
NTDs
caused by abnormal neurulation
Total Dysraphism
incomplete closure of the neural tube
Anencephaly
total dysraphism of the brain with normal function of the spinal cord
Spina Bifida Aperta/Myeloschisis
entire spinal cord is open to the body surface, bifid vertebral spines are also present
Localized spinal dysraphism
only certain regions of the neural tube remain open
Meningomyelocele
most common open NTD. Type of spina bifida in which the neural tube and its meningeal membranes protrude from the vertebral canal, forming a fluid filled sac. Aka spina bifida cystica
Risk factors for meningomeyloceles
valproic acid, vitamin A, hyperthermia, maternal diabetes
Meningocele
meningeal membrane protrudes into the sac but the spinal cord does not. Less severe than meningomyelocele
Spina bifida oculta
NTD at the level of the spinal cord. Caused by failure of the posterior neuropore to close. Often location is mid sacral and marked externally by tuft of hair, mole, angioma, lipoma, or dimple. May be associated with tethered cord
Encephaloceles
NTD at level of brain. Brain tissue protrudes through the skull. Most common location is occipital but can also be frontal.
Tethered spinal cord
lower end of spinal cord is attached in a lower than normal position. Filum terminal is short an thick.
Chiari malformation
4 types. Most common congenital anomaly that involves structural defect of cerebellum. Cerebellum is located below the foramen magnum.
Hydrocephalus
3rd and lateral ventricles are swollen with fluid, cerebral cortex is abnormally thin, and surfers of skull are forced apart
Obstructive/noncommunicating hydrocephalus
caused by lack of communication between ventricles and subarachnoid space. Commonly caused by congenital aqueduct stenosis or choroid plexus tumors that secrete too much CSF.
non obstructive or communicating hydrocephalus
free communication between the ventricles and the subarachnoid space but the reabsorption of the CSF is impaired. Common cause–> obliteration of the subarachnoid cisterns and malfunction of arachnoid villi
Holoprosencephaly
results from incomplete separation of the cerebral hemispheres and most are associated with facial abnormalities.
Dandy walker anomaly
complete agencies of the cerebellar vermis and cystic dilation of the fourth ventricle that occupies the posterior fossa.
Agenesis of Corpus Callosum
complete or partial absence of corpus callosum
Derivatives of neural crest cells
Dorsal root ganglia, majority of ANS
Derivatives of neural tube in PNS
All preganglionic autonomic fibers and somatic motor fibers
Mesoderm derivatives of PNS
Dura mater and connective tissue investments of peripheral nerve fibers
What separates the pharyngeal arches externally?
Ectoderm-lined pharyngeal clefts
What separates the pharyngeal arches internally?
Endoderm-lined pharyngeal pouches.
What does each pharyngeal arch contain?
Outer ectoderm, inner endoderm and a core of mesenchyme
Nerve of First (mandibular) pharyngeal arch
Trigeminal
Nerve of second (hyoid) pharyngeal arch
Facial
Nerve of third pharyngeal arch
Glossopharyngeal
Nerve of fourth pharyngeal arch
Superior laryngeal nerve of vagus
Nerve of sixth pharyngeal arch
Recurrent laryngeal branch of vagus
Groove between the maxillary prominence and the lateral nasal prominence
Nasolacrimal groove (cleft).
Primary (anterior) palate
formed by merging of the medial nasal prominences
Secondary (posterior) palate
formed by fusion of the palatine shelves (plates and processes)
