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Spina Bifida with Meningocele
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Cards (192)
Section 1
(50 cards)
Spina Bifida with Meningocele
Vertebral arches did not form The sac contains CFS Minor loss of function
When does myelination of axons begin?
4th month tracts become myelinated as they begin to function
Formation of Spinal Nerves
Nerve fibers of the basal plate grow outward to form ventral roots Neural crest cells migrate to form dorsal root ganglia - central processes of the DRG grow inward to the dorsal horns - distal process grow outward to form dorsal roots Ventral and dorsal roots come together to form spinal nerve
Spina Bifida Occulta
Occurs in the lumbar and sacral areas Incomplete fusion of the vertebral arches Tuft of hair over the defect Usually no spinal cord involvement (may be asymptomatic) May not be found until adulthood
Pharyngeal Arch Endoderm
covers medial, inside component, including the pouches
Cerebellum Development
Derived from thickenings of the alar plates of the metencephalon Neuroblast --> deep cerebellar nuclei --> cerebellar cortex These swellings grow on each side and fuse to cover the rostral portion of the 4th ventricle By the 12th week, the vermis and hemispheres have formed, followed by the flocculonodular lobe
Midbrain (mesencephalon) derivatives
mesencephalon --> midbrain + aquaduct
Pharyngeal Arch Mesoderm forms...
skeletal muscle, arch arteries, nerve
Meningohydroencephalocele
Meninges, brain tissue, and ventricular lumen protrude from the skull
Diencephalon Development
Derived from the alar plate Swellings give rise to the thalamus, hypothalamus, and epithalimus As the thalamus develops, there is often a fusion on the mideline (the interthalamic adhesion or massa intermedia)
Forebrain (prosencephalon) derivates
Telencephalon --> Cerebral hemispheres + Lateral ventricles Diancephalon --> Thalami, etc. + 3rd ventricle
Pharyngeal Arch Ectoderm
covers lateral, outside component, including the clefts
1st Pharyngeal Arch Artery
Maxillary artery - branched distribute to all of the muscular and bony area that come from that arch
Neural tube layers
Neuroepithelial layer - innermost Mantle layer - middle layer Marginal layer - outermost layer * develops from inside to outside
Pharyngeal Arch Neural Crest forms...
bone, cartilage, connective tissue, neurons, smooth muscle
Pineal Gland (epiphysis) development
develops from the roof plate of the diencephalon
Adenohypophysis (anterior pituitary) development
develops at week 4 from outpocketing of the of stomodeum ectodem (Rathke's Pouch) separates from oral cavity at week 6
Meningoencephalocele
Meninges and brain tissue protrude from the skull
Spina Bifida with Meningomyelocele
Vertebral arches did not form The sac contains spinal roots and/or the spinal cord Moderate to severe loss of function - more LOF if higher up
Neuralation
Fusion of the neural fold occurs cranially and caudally, creating cranial and caudal neuropores
Schwann cells develop from
neural crest cells
Secondary Pharyngeal Cartilage (Reichert's Cartilage)
Dorsal end - stapes , styloid process Intermediate - regresses and perichondrium forms stylohyoid ligament Ventral part - lesser horn on hyiod and upper half of the hyoid body
Mesencephalon Alar Plate gives rise to...
Neuroblasts --> superior and inferior colliculi (tectum)
Sulcus limitans
separates the basal and alar plates
Spinal Cord formation
mantle layer differentiates into dorsal and ventral swellings Basal Plate (ventral swelling) - ventral horn of spinal cord (motor) Alar Plate (dorsal swelling) - dorsal horn of the spinal cord
1st Pharyngeal Arch forms what?
Mesenchyme around the ventral part - mandible (mandibular) Dorsal end -incus, malleus (mandibular) Intermediate part - anterior ligament of the malleolus, sphenomandibular ligament
Ectodermal Placodes
Local thickening in the embryonic ectodermal layer Constitute a primordial group from which a sense organ or ganglion develops
1st Pharyngeal Arch (maxillary) forms what bones?
pre-maxilla, maxilla, zygoma, squamous temporal bone, palatine bone, vomer
Adult spinal cord stops where?
around L3
Mesencephalon Basal Plate gives rise to...
Neuroblasts --> nuclei in the tegmentum (CN III, IV, etc)
Mantle Layer
Forms grey matter - local CNS neurons
1st Pharyngeal Arch Nerve
Trigeminal (CN V) - ophthalmic branch (V1) - maxillary branch (V2) - mandibular branch (V3) * trigeminal sensory for entire face
Marginal Layer
Forms white matter - myelinated peripheral axons
Spinal Meninges formation
mesenchyme and neural crest cells --> leptomeninges --> Dura, Arachnoid, Pia mater CSF is formed at week 5 and fills the subarachnoid space
Neuroepithelial Layer
Ventricular zone/Ependymal layer Gives rise to neurons and most glia Gives rise to ependymal epithelium of the ventricular system
Neural Crest Cells
Derived from lateral edges of the neural folds that lose attachment with the neural tube as it closes These cells migrate to give rise to the PNS and ANS - dorsal root ganglia - sympathetic ganglia - schwann cells - meninges
Roof and Floor plates of developing spinal cord
allow for information to pass from one side of the spinal cord to the other not neurons, just pathways
Neuropores
communicate freely with the amniotic cavity cranial pore closes at day 25 caudal pore closes at day 27
Meningocele
Meninges protrude from the skull
Hindbrain (rhombocephalon) derivatives
Metacephalon --> Pons + Cerebellum + Upper part of 4th ventricle Myelencephalon --> medulla + lower part of the 4th ventricle
1st Pharyngeal Arch Muscles
Muscles of mastication - Temporalis - Masseter - Medial & lateral pterygoids Accessory muscles of mastication - Mylohyoid - Anterior belly of digastric - Tensor veli palatini - Tensor tympani (ear)
Telencephalon Development
develops cerebral hemispheres from inside out from alar plate sulci and gyri form as it grows out
Anecephaly
failure of cranial neuropore closure leads to failure of cranial vault formation, causing brain tissue degeneration detected by fetal ultrasound Risk decreased by Folic acid usually lack telencephalon usually survive for a few hours remaining structures covered by a thin membrane
Alar and Basal Plates in the Brainstem
Alar plates move laterally Sulcus limitans is now on the floor of the 4th ventricle Basal is still motor; alar is still sensory * motor and sensory nuclei appear at week 4
Spina bifida with myeloschisis
Caudal neuropore fails to close
Development of Neural Tube Flexures (week 4)
Midbrain (mesencephalic) flexure - This is the only flexure that persists in the adult Pontine flexure - At the junction of the metencepalon and the myelencephalon Cervical flexure - At the junction of the myelencephalon and the spinal cord
Neurohypophysis (posterior pituitary) development
derived from neuroectoderm of the diencephalon
After the midbrain flexure, ventral is what direction?
Inferior
Parasympathetics Development
Preganglionic parasympathetic fibers are in CN III, VII, IX, and X and S2-S4 spinal nerves Postgnaglionic parasympathetic fibers are derived from neural crest cells migrating to the target structure
Oligodendrocytes develop from
glioblasts that form from Neuroepithelial cells
Section 2
(50 cards)
5th Pharyngeal Pouch
Never develops Controversy concerning possible development of ultimobranchial body
epiglottis originates from
4th pharyngeal arch
paired viscerocranium bones
maxilla zygomatic nasal lacrimal palatine inferior nasal conchae
Pyramidal Lobe
Persistence of the thyroglassal duct present in 50% of people
3rd Pharyngeal Arch Nerve
Glossopharyngeal (CN IX)
2nd Pharyngeal Pouch
Palatine tonsillar fossa Endoderm forms the surface epithelium and lining of tonsillar crypts At 12-20 weeks, lymphoid tissue invades the endoderm and forms the palatine tonsils
Parts of the developing skull
Neurocranium (membranous) Chondrocranium (cartilagenous) Viscerocranium (membranous)
Bifid Tongue
tongue buds fails to fuse
6th Pharyngeal Arch Nerve
Recurrent laryngeal nerve of vagus (CN X)
microcephaly
born with reduced head size due to reduced brain growth ** skull only grows in response to brain growth
Craniostenosis
a malformation of the skull due to the premature closure of the cranial sutures
4th Pharyngeal Pouch
Dorsal bud - Superior parathyroid glands Ventral bud - Ultimobranchial body --- Fuses with the thyroid gland --- Disseminates within thyroid to become parafollicular C cells (secrete calcitonin)
External Ear
formed from 6 hillocks - 1-3 from 1st arch - 4-6 from 2nd arch ** starts in neck area and ascends
Skull Development
develops from mesenchyme around the developing brain - Neurocranium - Viscerocranium
4th Pharyngeal Arch Nerve
Superior laryngeal branch of vagus (CN X)
3rd Pharyngeal Arch Cartilage forms
lower half of the body of the hyoid and the greater horn
2nd Pharyngeal Arch Arteries
Hyoid artery Stapedial artery
3rd Pharyngeal Pouch
Endothelium of dorsal diverticula - Inferior parathyroid glands Endothelium of ventral diverticula - Lobule of thymus Diverticula become detached from the wall and migrate caudally - Thymus comes to lie in the superior mediastinum
Microglossia
whole tongue develops from 2nd arch; it overgrows
unpaired viscerocranium bones
ethmoid vomer mandible hyoid
Oxycephaly (Acrocephaly)
premature closing of lambdoid and coronal suture head assumes cone shape, upward growth ** most severe
6th Pharyngeal Arch Muscles
Intrinsic Larynx Muscles - Lateral cricoarytenoid - Thyroarytenoid - Transverse and oblique arytenoids - Posterior cricoarytenoid - (Cricothyroid is 4th arch)
Branches of the Facial Nerve
temporal, zygomatic, buccal, mandibular, cervical "Two Zebras Bit My Cookie"
6th Pharyngeal Arch Artery
Aortic Arch - Left: Pulmonary artery and ductus arteriossus - Right: Pulmonary Artery
Thyroid Development
thickening of pharynx floor at week 4 becomes thyroid diverticulum thyroid descends to the hyoid and thyrocartilage Connects to the tongue by thyroglossal duct (degenerates by week 10)
6th Pharyngeal Arch Cartilages
Cricoid cartilage Arytenoid cartilages Corniculate cartilages Cuneiform cartilages * All have to do with larynx and vocal folds
Cranial Nerve I
Olfactory
Tongue Development
elevation on floor of pharynx, rostral to foramen cecum it separates into two tongue buds from the 1st arch - medial (tuberculum impar) - 2 laterals just distal to the medial at the same time, an elevation develops caudal to foramen cecum from the 2, 3, and 4 arch. This forms the posterior 1/3 of the tongue
Pharyngeal Clefts (or grooves)
4 pharyngeal clefts - all but 1st cleft overgrown by the 2nd arch to form cervical sinus, which then disappears at week 7 1st cleft invades mesenchyme and forms the external auditory meatus and ectoderm of the tympanic membrane
4th Pharyngeal Arch Muscles
Pharyngeal constrictors (superior, middle, inferior) Cricothyroid Muscle
Marcoglossia
hypertrophy of the muscles of the tongue, treatment - cut down and reform a smaller tongue
What forms if the cervical sinus doesn't close?
Pharyngeal Cleft Cysts
Neurocranium (a protective case around the brain)
Membranous Neurocranium - flat bones of the skull - intramembranous ossification - neural crest cells and paraxial mesoderm Cartilaginous Neurocranium (chondrocranium) - base of skull - endochondral ossification - paraxial mesoderm and neural crest cell
2nd Pharyngeal Arch Muscles
All muscles of facial expression Stapedius muscles Stylohyoid muscle Posterior belly of digastric
Bones posterior to the Sella Turcica
derived from paraxial mesoderm
Viscerocranium
skeleton on the face surround the mouth and nose completely surrounds part of the orbits (eyes)
4th Pharyngeal Arch Cartilage
Thyroid Cartilage
1st Pharyngeal Pouch
Elongates into the tubotympanic recess Distal part contacts the 1st cleft and forms the endoderm of the tympanic membrane The tubutympanic recess becomes: - Tympanic cavity - Mastoid antrum Connection of the recess with the pharynx becomes the auditory (eustachian) tube
4th Pharyngeal Arch Artery
Aortic Arch - Left: Aortic arch - Right: Right subclavian
3rd Pharyngeal Arch Artery
Aortic Arch - common carotid - external carotid - proximal internal carotid
Function of Fontanelles
allows the head to change shape to pass through the birth canal allows for growth of the brain and the skull through the infants first year
2nd Pharyngeal Arch Nerve
Facial Nerve (CN VII)
Tongue tie (Ankyloglossia)
Frenulum extends all the way to tip of the tongue, preventing newborns from suckling
Plagiocephaly
Anterior (coronal), posterior (lambdoid), or unilateral
Scaphocephaly
premature closure of sagittal suture extensive growth to front and back of head ** most common form
Macrocephaly/ Hydrocephaly
** not necessarily pathologic Megalencephaly (enlarged brain) Hydrocephalus (CSF on the brain) Cranial hyperostosis (bone overgrowth) ** check when head circumference is more than 2 standard deviations above the mean
3rd Pharyngeal Arch Muscular Component
Stylopharyngeus muscles
Bones anterior to the Sella turcica...
derived from neural crest cells
4 grades of microtia (small ear)
Grade 1 - smaller than normal, mostly normal anatomy Grade 2 - Part of the ear looks normal, usually the lower half (canal opened or closed) Grade 3 - small peanut shaped skin and cartilage (no canal - aural atresia) Grade 4 - complete absence of the external eat and canal ** deformed ear - hillock defect ** deformed canal - 1st cleft defect * usually just in one ear
Inner Ear Development
otic placodes form at 4th week invaginates into mesenchyme and detaches from ectoderm becoming the otic vesicle Otic vesicle divides into 2 --- utricular portion (utricle, semicircular canals, and endolymphatic duct) --- saccular portion (saccule and cochlear duct (becomes cochlea))
Section 3
(50 cards)
Calvarium
skull vault
Cranial Nerve X
Vagus
Cranial Nerve XI
Spinal Accessory
Fates of lateral nasal swellings
sides of nose, including alae (flare of nostril)
Fate of medial nasal swellings
Bridge/tip of nose Part of Nasal septum Intermaxillary segment of the face
Facial formation time span
weeks 4-10
Tentorial notch
Triangular opening in the tentorium cerebelli through which the brainstem extends from the posterior into the middle cranial fossa
What structures form the choroid plexus
fusion of the pia mater and the ependymal cells
Cranial Nerve VII
Facial
Fates of the maxillary process
Upper lip (lateral to philtrum) Midface Secondary palate
Cranial Nerve III
Oculomotor
Components of the "deep face"
palate nasal passages oral cavity
tentorium cerebelli
separates cerebrum from cerebellum
Ependymal cells
glial cells that line the ventricles of the brain
3 major mechanical events of palatogenesis
Migration of sufficient neural crest Coordinated development and merging of facial primordia Coordinated interaction between facial primordia and the developing tongue
falx cerebri
separates the two cerebral hemispheres
diaphragma sellae
small circular fold of dura that forms the roof of the sella turcica perforated in the middle for infundibulum (pituitary stalk to pass)
5 facial primordia
1 frontal process (not from arches) 2 maxillary processes 2 mandibular processes
Posterior Cleft
Cleft Palate or Cleft Uvula posterior to the incisive foramen usually medial
Arachnoid graulations (arachnoid villi)
pieces of arachnoid that project into the sinuses and allow CSF to be absorbed into venous bloodstream
Causes of clefting
Genetics Environmental --- Vitamin A + analogues like Accutane --- Dilantin (anticonvulsant) --- Phenobarbital (epileptic anticonvulsant)
Components of midface
maxilla zygomatic zygomatic temporal squamous temporal regions
Steps of Palatogenesis
Large bulging tongue blocks the merging of the palatine shelves until it is developmentally ready Tongue recedes to allow the palatine shelve to merge
Incisive Foramen
hole at the tip of the primary palate
Nasal Passages
develops when nasal pits sink into the face From nares (tip of nostril) to choanae (deep end of nasal passages)
Why is palatogenesis important?
So you can breathe while you eat Babies would have to relatch every few seconds
Facial maturation time span
weeks 9 - adulthood
Cranial Nerve IX
Glossopharyngeal
Midline Cleft
Medial nasal swelllings did not merge correctly often includes grooved of cleft nose (bifid nose)
Cranial Nerve II
Optic
Fates of frontal process
Forehead Bridge/tip of the nose Part of nasal septum
Cranial Nerve VI
Abducens
Sensory innervation of the dura
primarily the trigeminal nerve small contribution by C1-3
Cranial Nerve V
Trigeminal
Holoprosencephaly
A spectrum of craniofacial anomalies related to maldevelopment of the forebrain during weeks 3-5 results and varying levels of midline malformations (mild to life threatening)
Components Intermaxillary Segment of the face
Philtrum Premaxilla Primary palate
Flow of blood into the cranial cavity
External carotid artery Internal carotid artery Vertebral artery
Fate of the Mandibular process
Lower Face Lower Lip
Facial Cleft
runs from medial canthus of eye to upper lip nasolacrimal duct usually exposed to the surface RARE
Cranial Nerve VIII
Vestibulocochlear
Circle of Willis
circulatory anastomoses between the anterior cerebral, middle cerebral, and posterior cerebral arteries
Cranial Nerve XII
Hypoglossal
Nasolacrimal Grooves
separates each maxillary process from the lateral nasal swellings sinks into face during development becomes lacrimal collecting system collecting and drainage system, to drain tears towards nose (does not include the lacrimal gland)
falx cerebelli
separates the two hemispheres of the cerebellum
What structures are induced by ventral forebrain formation?
Frontal process Nasal placodes
causes of holoprosencephaly
Genetic Environmental - tobacco - radiation - hyperthermia - fetal alcohol syndrome
Cranial Nerve IV
Trochlear
Location of nasal placodes
Frontal process
Clefting
failure of the facial primordia to merge and/or fuse most common group of craniofacial malformations
Anterior Cleft
Cleft Lip or Cleft Jaw anterior to the incisive foramen usually lateral
Section 4
(42 cards)