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Embryology > Exam 4 Material > Flashcards

Exam 4 Material Flashcards

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1
Q

What do neural crest cells form in the adult?

A
  • Dorsal root ganglia and processes
  • Majority of ANS
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2
Q

What does the neural tube form in the adult?

A
  • All preganglionic autonomic fibers
  • Somatic motor fibers
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3
Q

What does mesoderm form in the adult nervous system?

A
  • Dura mater
  • Connective tissue investments of peripheral nerve fibers
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4
Q
  • What direction does the neural tube close?
  • What two portions remain open?
A
  • Cranial to caudal direction
  • Anterior neuropore (closes on day 25)
    • Becomes lamina terminalis
  • Posterior neuropore (closes on day 27)
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5
Q
  • What do the walls of the neural tube form in the adult?
  • What does the neural canal communicate with until the neuropores close?
  • What does the neural canal form in the adult?
A
  • Walls thicken to form the brain and spinal cord
  • Neural canal communicates with the amniotic cavity
  • Neural canal forms:
    • Ventricular system of the brain
    • Central canal of spinal cord
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6
Q

Ventricular zone

  • What cells form here?
  • What do they form in the adult?
A
  • Neuroblasts
  • Migrate into intermediate zone and give rise to all neuron and most glial cells of spinal cord and brain
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7
Q

What does the intermediate zone form in the adult?

A
  • Gray matter of spinal cord and brain
  • Consists of neurons and glial cells from ventricular zone
  • Forms alar and basal plates
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8
Q

What does the marginal zone form in the adult?

A
  • White matter of spinal cord and brain
  • Contains nerve fibers of neuroblasts of intermediate layer
  • Contains glial cells
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9
Q
  • What level does the neural tube develop caudally to?
  • What structure forms the sacral and coccygeal segments of the spinal cord?
  • How does this structure form and meet the neural tube?
A
  • Neural tube develops to level of 2nd sacral somites
  • Caudal eminence arises from primitive streak to form sacral and coccygeal segments of spinal cord.
  • Canalizes to blend with neural tube.
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10
Q

What does the basal plate form in the adult?

A
  • Gives rise to motor neuroblasts of ventral and lateral horns
  • Becomes ventral horn of spinal cord
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11
Q

What does the alar plate form in the adult?

A
  • Gives rise to sensory neuroblasts of dorsal horn
  • Becomes dorsal horn of spinal cord
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12
Q
  • What does the prosencephalon form in the adult?
  • What does it divide into?
A
  • Forebrain
  • Telencephalon
  • Diencephalon
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13
Q
  • What does the mesencephalon form in the adult?
A
  • Midbrain
  • Mesencephalon
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14
Q
  • What does the rhombencephalon form in the adult?
  • What does it divide into?
A
  • Hindbrain
  • Metencephalon
  • Myelencephalon
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15
Q

Ectopic corical (grey) matter

  • What is it?
  • What causes it?
  • Symptoms?
A
  • Grey matter appears in white matter
  • Caused by error in neuronal migration
  • Basis for production of seizure disorders
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16
Q

Fetal alcohol syndrome

  • What is it?
  • What causes it?
  • Symptoms?
A
  • Error in neuronal migration caused by maternal alcohol consumption during pregnancy.
  • Alcohol impairs cellular adhesion molecule, disruption of neuronal migration and cytoskeletal structures
  • Causes physical features of fetal alcohol syndrome and cognitive deficits.
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17
Q

Childhood-onset (early onset) Schizophrenia

  • What causes it?
A
  • Cortical thinning occurs in the normal pattern, but occurs at a faster pace.
  • The amount of grey matter lost correlates to severity of psychotic symptoms
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18
Q

ADHD

  • What causes it?
A
  • Delayed time course of cortical thinning.
  • Peak cortical thickness is attained later, especially in the prefrontal cortex.
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19
Q

What forms the following structures?

  • Pharyngeal arch skeletal and connective tissue components
  • Bones of neurocranium
  • Pia and arachnoid mater
  • Parafollicular cells of thyroid
  • Odontoblasts
  • Sensory ganglia of CN V, VII, IX, and X
  • Parasympathetic ganglia of the head
  • Aorticopulmonary septum (outflow tract)
A

Cranial neural crest cells

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20
Q

What forms the following structures?

  • Melanocytes
  • Schwann cells
  • Glial cells in peripheral ganglia
  • Chromaffin cells of adrenal medulla
  • Dorsal root ganglia
  • Sympathetic chain ganglia
  • Prevertebral sympathetic ganglia
  • Enteric parasympathetic ganglia of gut
  • Abdominopelvic parasympathetic ganglia
A

Trunk neural crest cells

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21
Q

Neuroblastoma

  • What is it?
  • What causes it?
  • Where is it commonly located?
  • Symptoms?
A
  • Neuroendocrine tumor occurring mainly in children
  • Arises from any neural crest cell element of sympathetic nervous system
  • Commonly located near or within suprarenal gland, abdomen, thorax, neck, pelvis
    • Commonly metastasizes to bone marrow, bones, and lymph nodes
  • Symptoms:
    • Bone pain and a limp
    • Unexplained fever, weight loss, irritability
    • Periorbital ecchymosis (caused by metastasis to orbits)
    • Abdominal primary tumor in 2/3 of patients causing asymptomatic abdominal mass
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22
Q

Schwannoma

  • What is it?
  • Where is it commonly located?
  • Symptoms?
A
  • Benign tumor of Schwann cells of neural crest origin
  • Commonly located near vestibular branch of CN VIII
  • Symptoms:
    • Hearing and balance problems
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23
Q

Von Recklinghausen disease (Neurofibromatosis)

  • What is it?
  • What causes it?
  • Symptoms?
A
  • Autosomal dominant disease
  • Caused by mutation on chromosome 17 that inactivates proto-oncogene RAS (tumor suppressor gene).
  • Symptoms:
    • Café-au-lait spots: Flat patches of skin that are darker than surrounding area. Usually get larger and increase in number as patient ages
    • Freckles: located in underarms and groin
    • Neurofibromas: Benign tumors usually located on or just under skin
    • Lisch nodules: Dark spots appearing in iris
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24
Q

Pheocromocytoma

  • What is it?
  • What causes it?
  • Symptoms?
A
  • Mainly in adults 40-60 yo; release of too much epinephrine and norepinephrine
  • Caused by tumor of adrenal medulla
  • Symptoms:
    • Unexplained and paroxisitic hypertension
    • Tremors
    • Anxiety
    • Profuse sweating
    • Pallor
    • Chest pain
    • Abdominal pain
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25
**Waardenburg syndrome** * What is it? * What causes it? * Symptoms?
* Group of autosomal dominant genetic conditions * Caused by mutations in EDN3, EDNRB, MITF, PAX3, SNAI2, and SOX10 * These genes are involved with formation and development of melanocytes * Symptoms: * Congenital hearing loss * Pale blue eyes or different colored eyes (heterochromia) * Patch of white hair or hair that prematurely turns gray
26
**Craniorachischisis** * What is it? * What causes it? * Symptoms?
* Entire length of neural tube opens onto surface of head and back * Caused by incomplete closure of neural tube * Incompatible with life
27
**Anencephaly (Cranioschisis)** * What is it? * What causes it? * Symptoms?
* Infants lack functional forebrain and fail to gain consciousness * Caused by failure of anterior neuropore to close * Most infants do not survive more than a few hours after birth.
28
**Myeloschisis** * What is it? * Symptoms?
* Entire spinal cord open to body surface * Often bifid vertebral spines present
29
**Meningomyelocele** * What is it? * What causes it?
* Neural tube and meningeal membranes protrude from vertebral canal, forming fluid filled sac * Often located in lumbosacral region * Caused by failure of posterior neuropore to close
30
Risk factors for neural tube defects include...
* Maternal exposure to valproid acid (anti-seizure medication) * Vitamin A * Hyperthermia * Maternal diabetes
31
Protection against neural tube defects...
* Maternal folic acid supplementation at least 3 months prior and during pregnancy
32
**Meningocele** * What is it?
* Meningeal membranes protrude into sac but spinal cord does not * Less severe than myelomeningocele
33
**Spina bifida occulta** * What is it? * What causes it? * Symptoms?
* Skin-covered neural tube defect at level of spinal cord * Caused by failure of posterior neuropore to close * Symptoms: * Marked externally on back by: Tuft of hair, * Pigmented mole * Angioma (port-wine colored birth mak of skin) * Lipoma * Dimple * Tethered cord
34
**Encephaloceles** * What is it? * What causes it? * Symptoms?
* Skin-covered neural tube defect at level of brain * Caused by failure of anterior neuropore to close appropriately * Symptoms: * Brain tissue protruding through skull. Commonly in occipital region * Poor neurologic function and threatened survival in large encephaloceles
35
**Tethered Cord** * What is it? * What causes it? * Symptoms?
* Lower end of spinal cord is attached in a lower than normal position. Filum terminale is short and thick. * Caused by complication of open or closed neural tube defect * Symptoms: * Weakness and sensory deficits in lower extremities * Toe walking * Poor bladder control * Constipation * Symptoms caused by stretched and damaged spinal cord as vertebral column elongates
36
**(Arnold) Chiari Malformation** * What is it? * What are the four types?
* Part of cerebellum located below foramen magnum * Four types: * Type I: Extension of cerebellar tonsils into foramen magnum without involving brain stem * Most common form * Type II: Extension of both cerebellar and brain stem tissue into foramen magnum * 95% of kids with lumbar myelomeningocele have this as well * Associated with hydrocephalus * Type III: Cerebellum and brain stem protrude or herniate through foramen magnum and into spinal cord * Most severe form * Associated with encephalocele * Type IV: Incomplete or underdeveloped cerebellum. * Cerebellar tonsils located in normal position, but parts are missing
37
**Hydrocephalus** * What is it? * Symptoms? * What are the different types? * What are their causes?
* Excess CSF in the ventricle system * Symptoms: * Third and lateral ventricles are swollen with fluid * Cerebral cortex abnormally thin * Sutures of skull are forced apart allowing the calvarial bones to increase in size * Types: * Obstructive or noncommunicating hydrocephalus * Lack of communication b/w ventricles and subarachnoid space * Caused by congenital aqueductal stenosis * Caused by choroid plexus tumors that secrete too much CSF * Nonobstructive or communicating hydrocephalus * Free communication b/w ventricles and subarachnoid space, but reabsorption of CSF is impaired * Caused by obliteration of subarachnoid cisterns * Malfunction of arachnoid villi
38
**Holoprosencephaly** * What is it? * What causes it? * Symptoms?
* Incomplete separation of cerebral hemispheres * Caused by embryonic cells in median plane of the embryonic disc are destroyed during the third week * Symptoms: * Small forebrain * Lateral ventricles merge to form one large ventricle * Eyes abnormally close together or fused * Sometimes nose is lacking
39
**Dandy Walker Anomaly** * What is it? * Symptoms?
* Complete agenesis of cerebellar vermis and cystic dilation of fourth ventricle * Symptoms: * Hydrocephalus * Occipital prominence form large cystic dilation of fourht ventricle in posterior fossa
40
**Agenesis of Corpus Callosum** * What is it? * Symptoms?
* Complete or partial absence of corpus callosum * Symptoms: * May be asymptomatic * Seizure and mental deficiency common
41
**Lissencephaly** * What is it? * What causes it? * Symptoms?
* Smooth cerebral surface * Caused by incomplete neuronal migration to cerebral cortex * Symptoms: * Apnea * Poor feeding * Abnormal muscle tone * Microcephaly in first year * Seizures * Profound mental retardation * Mild spastic quadrplegia
42
What structures arise from the first pharyngeal arch?
* Trigeminal nerve (CN V) * Tensor tympani * Malleus * Incus
43
What structures arise from the second pharyngeal arch?
* Facial nerve (CN VII) * Stapedius muscle * Stapes bone
44
What structures arise from the third pharyngeal arch?
* Glossopharyngeal nerve (CN IX)
45
What structures arise from the fourth pharyngeal arch?
* Superior laryngeal branch of vagus nerve (CN X) * Laryngeal cartilages
46
What structures arise from the sixth pharygneal arch?
* Recurrent laryngeal branch of vagus nerve (CN X) * Laryngeal cartilages
47
What structures arise from the first pharyngeal pouch?
* Auditory (eustachian) tube
48
What structures arise from the second pharyngeal pouch?
* Palatine tossils * Tonsillar fossa
49
What structures arise from the third pharyngeal pouch?
* Inferior parathyroid gland * Thymus
50
What structures arise form the fourth pharyngeal pouch?
* Superior parathyroid gland * Ultimobranchial body (Parafollicular C cells of thryoid gland)
51
What structure arises from the first pharyngeal groove?
* External auditory meatus
52
**Pharyngeal (Branchial) Fistula** * What is it? * What causes it? * Symptoms
* Abnormal canal that runs from skin surface to lumen of pharynx or to cervical (branchial) cyst * Fistula runs along SCM and passes between internal and external carotid arteries * Caused by failure of 2nd pharyngeal arch to completely grow caudally over 3rd and 4th arches, leaving cervical sinus in contact with skin surface * Symptoms: * Intermittent discharge of mucoid material from a small opening in the side of neck, just anterior to the sternocleidomastoid muscle.
53
**Pharyngeal (Branchial) Cyst** * What is it? * What causes it?
* Painless swelling in neck along anterior border of SCM * Usually do not become apparent until late childhood/early adulthood * Caused by remnant of parts of cervical sinus and/or the second pharyngeal groove that persist, forming cyst.
54
What structure arises from the first pharyngeal membrane?
Tympanic membrane
55
**Treacher Collins Syndrome** * What is it? * What causes it? * Symptoms
* Type of first arch syndrome * Caused by autosomal dominant gene * Caused by insufficient migration of neural crest cells into first arch * Symptoms: * Underdeveloped zygomatic bones * Down-slanting palpebral fissures * Mandibular hypoplasia * Defects of lower eyelid * Deformed external ears * Abnormalities of middle and internal ears (sometimes) * Cleft palate (sometimes)
56
**Pierre Robin sequence** * What is it? * What causes it? * Symptoms
* Autosomal recessive disorder; type of first arch syndrome * Caused by insufficient neural crest cell migration to first arch * Symptoms: * Hypoplasia of mandible * Cleft palate * Defects of eye and ear
57
**DiGeorge Syndrome (CATCH 22)** * What is it? * What causes it? * Symptoms
* Developmental defects of neural crest-derived tissues (Neurocristopathy) * Caused by genetic deletions on long arm of one of two 22nd chromosomes * Symptoms * Minor craniofacial defects: small jaw, low-set ears, auricular abnormalities, cleft palate, hypertelorism * Total or partial agenesis of thymus, parathyroid glands, parafollicular cells (derivatives of 3rd and 4th pharyngeal pouches) * Cardiovascular anomalies: truncus arteriosus, tetralogy of Fallot, interrupted aortic arch CATCH: Cardiac anomalies, Abnormal facies, Thymic aplasia, Cleft palate, Hypoparathyroidism - hypocalcemia
58
**Congenital hypothyroidism** * What is it? * What causes it? * Symptoms
* Thyroid hormone deficiency during fetal life and present at birth * Caused by severe iodine deficiency, thyroid agenesis, or abnormalities involving biosynthesis of thyroid hormone * Symptoms * Dry, rough skin * Excessive sleeping * Reduced interest in nursing * Poor muscle tone * Low or hoarse cry * Infrequent bowel movements * Exaggerated jaundice * Low body temperature * In the case of thyroid agenesis, symptoms include: * Larger anterior fontanel * Persistence of posterior fontanel * Umbilical hernia * Large tongue
59
**Ectopic thyroid gland** * What is it? * What is the most common type?
* Undescended thyroid gland located along course of thyroglossal duct * Lingual thyroid tissue is most common type * Ectopic thyroid gland is only thyroid tissue present, so must be careful not to misdiagnose as thyroglossal duct cyst and remove the only thyroid tissue present
60
**Thyroglossal duct cysts and sinuses** * What are they? * What causes them? * Symptoms
* Cysts: Occur anywhere along course of thyroglossal duct * Caused by failure of portion of thyroglossal duct to atrophy and regress * Usually asymptomatic unless they become infected * Thyroglossal duct sinus forms after infeciton of cyst and perforation of skin * Usually opens in median plane of neck, anterior to laryngeal cartilages
61
**Oblique facial cleft** * What is it? * What causes it?
* Nasolacrimal ducts remain as open grooves on face * Caused by failure of maxillary prominence and lateral nasal process from fusing
62
**Cleft lip** * What is it? * What causes it? * In what sex is it more common?
* Small gap or indentation in upper lip that may continue to nose * Caused by failure of intermaxillary segment to fuse with maxillary prominences * More common in males
63
**Cleft palate** * What are the types? * What are their causes? * What teratogens can cause them? * What sex are they more common in?
* Complete or partial anterior cleft * Involves tissues anterior to incisive foramen * Caused by failure of lateral palatine processes to fuse with primary palate * Posterior cleft palate * Involves tissues posterior to incisive foramen * Caused by failure of lateral palatine processes to fuse with each other and with nasal septum * Complete Cleft palate * Caused by failure of lateral palatine processes to fuse with each other, the nasal septum and primary palate * Teratogens * Alcohol * Vitamin A derivatives * Corticosteroids * More common in females
64
Which portion of the tongue derives from what pharyngeal arch? What are their innervations?
* Body of tongue * Arises from first pharyngeal arch * Innervation: Trigeminal nerve * Root of tongue * Arises from second, third, and fourth pharyngeal arches * Innervation: Glossopharyngeal nerve (nerve of arch 3) and Vagus nerve (nerve of arch 4) * Epiglottis * Arises from posterior part of fourth pharyngeal arch * Innervation: Superior laryngeal nerve from vagus
65
What does the ectodermal otic placode form in the adult?
Inner ear
66
What do the first and second pharyngeal arches, cleft, and pouches form in the adult?
External and middle ears
67
**Congenital Hearing Loss (Deafness)** * What are the two types and their individual causes? * What is the overall cause?
* Two types: * Conductive hearing loss: Results from malformations in external and/or middle ear * Sensorineural hearing loss: Arises from defects in inner ear, vestibulocochlear nerve, or auditory regions of brain * Caused by either: * Genetic cause (syndromic): associated with other anomalies * Isolated defect (non-syndromic): attributed to environmental factors, including in uteror viral infection (cytomegalovirus, rubella) and neonatal exposure to aminoglycoside antibiotics (gentamycin, tobramycin)
68
**CHARGE syndrome** * What are the symptoms? * What causes it?
Symptoms: * Coloboma of eye * Heart defects * Atresia of choanae * Retarded growth and development * Genital and urinary anomalies * Ear anomalies and hearing loss Caused by: * Inner ear defects: Labyrinthine aplasia, reduction in number of cochlear turns, semicircular canal defects * Abnormal development of middle ear * External ear abnormalities * IMPORTANT: Significant malformations of external ear should raise suspicions about potential abnormalities elsewhere in body.
69
The proximal parts of the hyaloid vessels form what in the adult?
Central artery and vein of retina
70
**Anophthalmia** * What is it? * What causes it?
* Absence of eye * Caused by the failure of the optic vesicle to form
71
**Coloboma** * What is it? * What causes it?
* Defect in the inferior sector of the iris or a notch in the pupillary margin, giving the pupil a keyhole appearance. * A typical coloboma of the iris results from failure of closure of the retinal fissure during the sixth week. * A simple coloboma is frequently hereditary and is transmitted as an autosomal dominant characteristic.
72
**Congenital Cataracts** * What is it? * What causes it?
* Opacities of the lens, usually bilateral. * Most common causes include congenital infections (rubella), trisomy 21, galactosemia, maternal diabetes
73
**Retina detachment** * What can cause it and why?
* Various types of trauma can cause it because two layers of retina never fuse firmly
74
**Congenital glaucoma** * What is it? * What causes it?
* Abnormal elevation of intraocular pressure due to an imbalance between the production of aqueous humor and its outflow. * Caused by abnormal development of the canal of Schlemm or the trabecular drainage system. * Can be caused by rubella infection during pregnancy.

Embryology (2 decks)

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