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CNS Anatomy > Embryology > Flashcards

Embryology Flashcards

1
Q

Mention sources of mesenchymal core of pharyngeal arches

A
  1. Paraxial mesoderm which forms musculature
  2. Migrating neural cest cells which form skeletal element or arch cartilage
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2
Q

Internal grooves of pharyngeal arches are called……, while external are called……

A

Pharyngeal pouches
Pharyngeal clefts

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3
Q

Mention structures invading each pharyngeal arch

A

An aortic arch connecting aortic sac with corresponding dorsal aorta
An cranial nerve from adjacent hindbrain

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4
Q

1st arch divides into 2 prominences with are….

A

Ventral mandibular
Dorsal maxillary

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5
Q

Mention derivatives of 1st pharyngeal arch

A

Skeletal element forms 2 cartilages Meckle’s ventral cartilage and dorsal cartilage in maxillary prominence. Both disappear leaving incus and malleus near the developing ear
Mesenchymal element around Meckle’s cartilages gives mandible by membranous ossification, sphenomandibular ligament, spine of sphenoid and anterior ligament of malleus
Mesenchyme in maxillary process gives maxilla, zygomatic bone, palatine and squamous temporal bones by squamous ossification.
It gives all muscles supplied by mandibular brach of trigeminal + the nerve itself. The aortic arch leaves the maxillary artey

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6
Q

Enumerate derivatives of the 2nd pharyngeal arch

A
  1. Reichert’s cartilage gives stapes, styloid process, stylohyoid ligament, lesser cornu and upper part of body of hyoid.
  2. Gives all muscles supplied by facial nerve and the nerve itself
    3.stapedial Artery
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7
Q

Mention derivatives of the 3rd pharyngeal arch

A
  1. Great cornu and lower part of body of hyoid
  2. Stylopharngeus and CN IX
  3. CCA and ICA, ECA arises as sprout
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8
Q

Mention derivatives of the 4th pharyngeal arch

A
  1. All laryngeal cartilages ex cricoid and epiglottis
  2. Cricothyroid, levator palati & pharyngeal constrictors
  3. Superior laryngeal of vagus
  4. Arch of aorta on left, arch of subclavian on right
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9
Q

Mention derivatives of the 6th pharyngeal arch

A

Cricoid, laryngeal muscles except cricothyroid, recurrent laryngeal nerve of vagus, proximal parts on right and left sides gives pulmonary A., distal part disappears on left and remains on right as ductus arteriosus.

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10
Q

GR, Occurrence of 1st arch syndromes

A

Due to insufficient migration of neural crest cells to 1st pharyngeal arch

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11
Q

Describe the following:
1. Treacher Collins syndrome
2. Pierre Eobin syndrome

A
  1. AD, underdeveloped zygomatic bone, defet of lower eyelids, deformed external ear
  2. Mandible hypoplasia, eye&ear defects, cleft palate
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12
Q

Describe fate of 1st pharyngeal cleft

A

It persists and forms external auditory meatus and outer surface of tympanic membrane. The auricle develops from 6 hillocks that appear around ex aud meatus and latet fuse together.

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13
Q

The mesoderm of …..proliferates amd covers ……clefts till it fuses with ……., forming…….that later disappears

A

2nd arch
2nd, 3rd, 4th
Ectodemal coveing of 6th arch
Cervical sinus

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14
Q

Explain the following abnormalities:
1. Preauricular cyst
2. Branchial cyst
3. Branchial fistula

A
  1. Failure of fusion between hillocks of auricle
  2. Failure of obliteration of cervical sinus may be found at any point along anterior border of sternomastpid
  3. May be external due to failure of fusion of 2nd and 6th arch OR external due to rupture of cervical sinus into 2nd pouch establishing communication with the interior of the pharynx
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15
Q

Mention derivatives of 1st pharyngeal pouch

A

Tubotympanic recess, its distal part widens forming lining of tympanic cavity, antrum of mastoid, inner surface of tympanic membrane., while its proximal part remains narrow forming Eustachian tube

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16
Q

Mention derivatives of 2nd pharyngeal pouch

A

Its endodermal lining proliferates forming buds which penetrate the surrounding mesoderm forminh epithelium of palatine tonsils invaded by lymphoid tissue in 5th to yth months. Part remains as tonsillar fossa. Its dorsal part may share in tubotympanic recess

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17
Q

Mention derivatives of 3rd pharyngeal pouch

A

Its distal part forms inferior parathyroid glands and ventral part forma thymus gland which later move to their positions. Thymus is invaded by lymphoid tissue in 3rd intrauterine month.

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18
Q

Mention derivatives of 4th pharyngeal pouch

A

Its dorsal part, the superior parathyroid glands
Its ventral part, a part of thymus gland that disappears

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19
Q

Mention derivatives of 5th pharyngeal pouch

A

Caudal pharyngeal complex, forms ultimobtanchial body, that forms parafollicular cells (C cells) that produce calcitonin

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20
Q

Describe Die George syndrome

A

3rd and 4th pharyngeal pouches failed to develop, no thymus or parathroids, deformed mouth and nasal celfts. CVS abnormalities

21
Q

The olfactory placodes appear during…..

A

5th week

22
Q

Enumerate derivatives of the intermaxillary segment

A
  1. Labial component, philtrum of lips
  2. Jaw component, part of upper jaw carrying 4 incisors
  3. Palatal component, 1ry palate
23
Q

There is a solid rod between maxillary promenince and lateral nasal prominence that later gives rise to……, that open into …..and expanded cranially forming…..

A

Nasolacrimal duct
Lateral nasal wall
Lacrimal sac

24
Q

Lateral parts of upper lip are derived from……while philtrum…..

A

Maxillary prominences
Frontonasal prominence

25
Q

Maxillary and mandibular prominences fusw from……

A

Lateral to medial to decrease side of stomodeal fissure

26
Q

Explain and describe the following abnormalities:
1. Oblique facial cleft
2. Macro- or microstomia
3. Rare midline anomalies

A
  1. Failure of fusion between maxillary prominence and lateral nasal prominence, lacrimal duct persists as open furrow usually accompanied by cleft lip on the same side.
  2. Over or underfusion of maxillary and mandibular prominences
  3. Median cleft lip, cleft lower jaw, cleft nose. More common are minor degrees of cleft chin and micrognathia.
27
Q

Development of CNS begins in…..

A

3rd week

28
Q

Mention parts of neuro-ectoderm and its derivatives.

A

Neural plate: brain and spinal cord + all motor neurons + all preganglionic autonomic fibers
Neural crest: parts of PNS, sensory neurons and ganglia, autonomic ganglia and postganglionic nerves
Ectodermal placodes, sensoty ganglia of cranial nerves + parts of organs of ss (eye lens + inner ear)

29
Q

….trigggers formation of neural plate

A

Notochord

30
Q

Raised Edges of neural plate forms…..then it invaginates forming…..

A

Neural folds
Neural groove

31
Q

Ant neuropore closes in….while post…..

A

25th
27th

32
Q

Cranial parts of neural folds expand forming….., its cavity forms….., while the caudal narrow part forms…… it cavity forms…..

A

3 brain vesicles
Brain ventricles
Spinal cord
Central canap

33
Q

Neuroepithelial cells differentiate into…….

A

Neuroblasts then gliablasts then ependymal cells

34
Q

Mention layers of the neural tube and their derivatives

A
  1. Inner ependymal (germinal) zone, lining of central canal and ventricles
  2. Intertmediate mantle zone, gray matter
  3. Outer marginal zone devoid of cell bodies, white matter
35
Q

Mention stages of neuroblast development

A

Have central process extending to the lumen
Apolar
Bipolar
Multipolar

36
Q

Describe embryology of myelination starts in 4th month and is not completed till 2nd year after birth. Motor before sensory. Oligodendroglia centrally and Schwann cells peripherally.

A

starts in 4th month and is not completed till 2nd year after birth. Motor before sensory. Oligodendroglia centrally and Schwann cells peripherally.

37
Q

Derivatives of spongioblasts are……

A

Astrocytes
Oligodendroglia

38
Q

The sites for crossing of commissural fibets between rt & lt are……

A

Ventral lamina
Dorsal lamina

39
Q

In neural tube, ……contains sensory neurons while…..contains motor neurons, separated by……

A

Dorsolateral lamina
Ventrolateral lamina
Sulcus limitans

40
Q

GR: Formation of cevical and lumbar enlargements of the cord

A

Nerve cells accumulate in the regions which innervate the limb buds

41
Q

Neurons opposite sulcus limitans in spinal cord develop into……

A

The lateral horn in the thoracolumbar region (sympathetic) and sacral region (parasympathetic)

42
Q

GR: Formation of posteromedian sulcus and anteromedian fissure

A

PMS: occlusion of dorsal part of the central canal
AMF: bulging of 2 basal laminae more than the floor plate.

43
Q

During….., the spinal cord fills the vertebral column, at birth it ends at……while in adults ends at…..

A

3rd month
Opposite L3 vertebra
Opposite upper border of L2

44
Q

Spina bifida is moat common in segments….., its most common type is…..(cystica)

A

L5-S1
Meningomyelocele

45
Q

Rachischisis of brain is called……, can be detected by……

A

Anencephaly
Inc alpha fetoprotein during amniocentesis

46
Q

Mention the two earliest flexures in brain development and describe them

A
  1. Cephalic flexure separating between fore-brain and mid-brain
  2. Cervical flexure at junction of hindbrain and spinal cord
    Both are ventrally concave
47
Q

Pontine flexure forms….., it differs from the previous ones by…..

A

4th ventricle
Its convexity is forward and it does not affect the head.

48
Q

Mention developmental changes that occur to rhomencephalon

A
  1. The cavity dilates forming the 4th venticle and the lateral walls rotate around the floor plate like opening a book, basal lamina becomes medial, alar lamina becomes lateral
  2. Remains of sulcus limitans are seen in adult brain in floor of 4th ventricle
49
Q

Mention derivatives of basal lamina

A

Motor nuclei in 3 columns:
1. General visceral efferent (parasympathetic)
2. Special visceral efferent (pharyngeal arches)
3. General somatic efferent (myotomes)

CNS Anatomy (19 decks)

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