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Embryology > Exam 4 Material > Flashcards

Exam 4 Material Flashcards

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
Q

Waardenburg syndrome

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
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26
Q

Craniorachischisis

  • What is it?
  • What causes it?
  • Symptoms?
A
  • Entire length of neural tube opens onto surface of head and back
  • Caused by incomplete closure of neural tube
  • Incompatible with life
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27
Q

Anencephaly (Cranioschisis)

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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.
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28
Q

Myeloschisis

  • What is it?
  • Symptoms?
A
  • Entire spinal cord open to body surface
  • Often bifid vertebral spines present
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29
Q

Meningomyelocele

  • What is it?
  • What causes it?
A
  • 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
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30
Q

Risk factors for neural tube defects include…

A
  • Maternal exposure to valproid acid (anti-seizure medication)
  • Vitamin A
  • Hyperthermia
  • Maternal diabetes
31
Q

Protection against neural tube defects…

A
  • Maternal folic acid supplementation at least 3 months prior and during pregnancy
32
Q

Meningocele

  • What is it?
A
  • Meningeal membranes protrude into sac but spinal cord does not
  • Less severe than myelomeningocele
33
Q

Spina bifida occulta

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
Q

Encephaloceles

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
Q

Tethered Cord

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
Q

(Arnold) Chiari Malformation

  • What is it?
  • What are the four types?
A
  • 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
Q

Hydrocephalus

  • What is it?
  • Symptoms?
  • What are the different types?
    • What are their causes?
A
  • 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
Q

Holoprosencephaly

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
Q

Dandy Walker Anomaly

  • What is it?
  • Symptoms?
A
  • 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
Q

Agenesis of Corpus Callosum

  • What is it?
  • Symptoms?
A
  • Complete or partial absence of corpus callosum
  • Symptoms:
    • May be asymptomatic
    • Seizure and mental deficiency common
41
Q

Lissencephaly

  • What is it?
  • What causes it?
  • Symptoms?
A
  • 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
Q

What structures arise from the first pharyngeal arch?

A
  • Trigeminal nerve (CN V)
  • Tensor tympani
  • Malleus
  • Incus
43
Q

What structures arise from the second pharyngeal arch?

A
  • Facial nerve (CN VII)
  • Stapedius muscle
  • Stapes bone
44
Q

What structures arise from the third pharyngeal arch?

A
  • Glossopharyngeal nerve (CN IX)
45
Q

What structures arise from the fourth pharyngeal arch?

A
  • Superior laryngeal branch of vagus nerve (CN X)
  • Laryngeal cartilages
46
Q

What structures arise from the sixth pharygneal arch?

A
  • Recurrent laryngeal branch of vagus nerve (CN X)
  • Laryngeal cartilages
47
Q

What structures arise from the first pharyngeal pouch?

A
  • Auditory (eustachian) tube
48
Q

What structures arise from the second pharyngeal pouch?

A
  • Palatine tossils
  • Tonsillar fossa
49
Q

What structures arise from the third pharyngeal pouch?

A
  • Inferior parathyroid gland
  • Thymus
50
Q

What structures arise form the fourth pharyngeal pouch?

A
  • Superior parathyroid gland
  • Ultimobranchial body (Parafollicular C cells of thryoid gland)
51
Q

What structure arises from the first pharyngeal groove?

A
  • External auditory meatus
52
Q

Pharyngeal (Branchial) Fistula

  • What is it?
  • What causes it?
  • Symptoms
A
  • 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
Q

Pharyngeal (Branchial) Cyst

  • What is it?
  • What causes it?
A
  • 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
Q

What structure arises from the first pharyngeal membrane?

A

Tympanic membrane

55
Q

Treacher Collins Syndrome

  • What is it?
  • What causes it?
  • Symptoms
A
  • 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
Q

Pierre Robin sequence

  • What is it?
  • What causes it?
  • Symptoms
A
  • 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
Q

DiGeorge Syndrome (CATCH 22)

  • What is it?
  • What causes it?
  • Symptoms
A
  • 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
Q

Congenital hypothyroidism

  • What is it?
  • What causes it?
  • Symptoms
A
  • 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
Q

Ectopic thyroid gland

  • What is it?
  • What is the most common type?
A
  • 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
Q

Thyroglossal duct cysts and sinuses

  • What are they?
  • What causes them?
  • Symptoms
A
  • 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
Q

Oblique facial cleft

  • What is it?
  • What causes it?
A
  • Nasolacrimal ducts remain as open grooves on face
  • Caused by failure of maxillary prominence and lateral nasal process from fusing
62
Q

Cleft lip

  • What is it?
  • What causes it?
  • In what sex is it more common?
A
  • 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
Q

Cleft palate

  • What are the types?
  • What are their causes?
  • What teratogens can cause them?
  • What sex are they more common in?
A
  • 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
Q

Which portion of the tongue derives from what pharyngeal arch? What are their innervations?

A
  • 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
Q

What does the ectodermal otic placode form in the adult?

A

Inner ear

66
Q

What do the first and second pharyngeal arches, cleft, and pouches form in the adult?

A

External and middle ears

67
Q

Congenital Hearing Loss (Deafness)

  • What are the two types and their individual causes?
  • What is the overall cause?
A
  • 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
Q

CHARGE syndrome

  • What are the symptoms?
  • What causes it?
A

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
Q

The proximal parts of the hyaloid vessels form what in the adult?

A

Central artery and vein of retina

70
Q

Anophthalmia

  • What is it?
  • What causes it?
A
  • Absence of eye
  • Caused by the failure of the optic vesicle to form
71
Q

Coloboma

  • What is it?
  • What causes it?
A
  • 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
Q

Congenital Cataracts

  • What is it?
  • What causes it?
A
  • Opacities of the lens, usually bilateral.
  • Most common causes include congenital infections (rubella), trisomy 21, galactosemia, maternal diabetes
73
Q

Retina detachment

  • What can cause it and why?
A
  • Various types of trauma can cause it because two layers of retina never fuse firmly
74
Q

Congenital glaucoma

  • What is it?
  • What causes it?
A
  • 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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