Ccd Embryology

Front 1

State the components of the pharyngeal arches

Back 1

1. Mesnchymal core- paraxial and lateral plate mesoderm and neural crest cells. Striated muscle (mesoderm)
2. External ectodermal lining
3. internal endodermal linign
4. arch specific cranial nerve ( from neural crest cells and neuroectoderm placodes )
5. arotic arch artery

Front 2

Importance of neural crest cells and development

Back 2

we have skeletal and cartillagenous coimponents derived from these, they have to migrate from the neural folds to their location and there is potential for this to go wrong.

Front 3

What is treacher collins syndrome and its characterisitcs

Back 3

Lack of neural crest cells in the pharyngeal areas leading to a host of problems. Affected due to 1st pharyngeal arch where mandible is derived from

1. Down slanting palperbal fissures
2. lower eyelid colobomas
3. microtia
4. zygomatic and mandibular hypoplasia.
5. malformed ear ossicles
6. mostly affects first phayrngeal arch structures
7. 
   

Front 4

how does treacher collins affect mandible

Back 4

mandibular condyle severly effected, abnormal TMJ - Retrognathia

- results in a bird like appearance

Front 5

What causes treacher collins

Back 5

genetic condition affecting the TOCF1 gene, which encodes the treacle protien thats expressed in neural folds as neural crest cells. NCCs are forming and migrating

- mutations in TOCF1 associated with increased apoptosis of neural crest precursors and decreased proliferation of NCC's

Front 6

What is digeorge anomaly

Back 6

1. 22q11.2 deletion syndrome
   
2. mild facial malformations- smll mouth, philtrum, micrognathia
3. total or partial agenesis of derivatives of 3rd and 4th pouches, thymys and parathyroid.
4. cardiac abnormalties - persistis truncus aretriousis

Front 7

cause of digeorge anomaly

Back 7

deletion on chromosome 22 leads to imparied neural crest cell migration.

Front 8

Where does the face develop from and when

Back 8

develops from 5 prominences that appear in week 4, 2 maxillary, 2 mandibular and one frontonasal prominence. the prominences are dervied from neural crest cells and surround the stomodeum

Front 9

what happens during week 5 of facial development

what do the prominences do

what is formed

Back 9

1. nasal pits form week 6, and the fronto nasal prominence.
   
2. maxillary prominences grow medially and compress the medial nasal prominence which fuse in the midline to form the intermaxillary segment,
3. upper lip formed by medial and maxillary nasal prominences and lower lip formed by mandibular prominences that fuse in the midline

Front 10

medial nasal prominences fuse to form what

Back 10

1. intermaxillary segment composed of
   
2. philtrum, maxilla with 4 incisors and primary palate

Front 11

secondary palate is derived from what

Back 11

maxillary prominences

Front 12

Explain how the palate forms

Back 12

1. medial walls of maxillary promence extend to form palatine shelves
   
2. palatine shelves directed towards either side of the tongue- vertical position
3. they then elevate to horizontal position and fuse in midline with primary palate to form definitve palate.
4. incisive formane marks midline boundary between primary and secondary palate.

Front 13

Cleft lip and palate. different types

Back 13

• B- affectiing the lip and primary palate and posterior clefts
• can be unilateral or bilateral
• can involve both anterior and posterior defects

Front 14

severity of celft lip palate

Back 14

• cleft lip with or without palate, 1 in 700 births, failure of medial nasal and maxillary prominences to fuse. can be complete or incomplete.

Front 15

Complications of cleft lip palate

Back 15

varies in severity, caused by failure of palatine shelves to fuse, complications include feeding and speech.

Front 16

Causes of celft lip palate

Back 16

1. can be genetic - Van der woude syndrome IRF6 mutation. most common cause
   
2. Environmental - teratogents (smoking anticonvulsants vit A)
3. environmental mechanial - mandibular dysplasia preventing tongue to drop and palatine shelves to elevate assciated with treacher collins syndrome

Front 17

Pierre robin sequence

Back 17

often seen in treacher colins, micrognatihia results in posterio displacement of tongue (glossoptosis) and prevents lowering of tongue.

Front 18

hypodontia causes

Back 18

affects secondary dentition, failure of permanent tooth buds to form from the dental lamina

Front 19

hyperdontia causes

Back 19

hyperproliferation of dental lamina resulting in scond permanent tooth bud , less common and associated with other cranial malformations.

Front 20

State what the Notochord, paraxial , intermediate and lateral plate mesoderm go on to form

Back 20

1. Notochord- Induces neuralation first step in the development in the CNS.
2. Paraxial mesoderm forms somites- skeletal muscle , dermis and vertebraee
3. intermediate mesoderm forms - genitourinary system
4. lateral plate forms - splits into parietal and visceral layers, forming linings of body cavities, peritoneum and smooth muscle of the gut wall.

Front 21

What are neural crest cells derived from

Back 21

derived from neuroectoderm, as neural folds elevate and fuse cells at lateral edge sperate from the neural tube, neural crest cells. they migrate laterally and ventrally dispersing widely and differentiating into a variety of structures throghout the body sometimes referred to as the 4th germ layer.

Front 22

when do pharyngeal arches appear and how to they look when viewed

Back 22

appear in week 4, there are 5 arches, form in a craniocaudal cuccession, seperated by pharyngeal clefts and internal pharyngeal pouches . evolved from gill arches of fish therfore somtimes called branchial arches, give rise to many structures of the head and neck.

Front 23

skeltal derivatives of 1st arch are

Back 23

2 parts mandibular and maxillary, Direct ossification of mesenchyme- maxillae, zygomatic, squamous portion of temporal bone and mandible.

- from maxillary cartillage- alisphenoid and incus. from meckels cartillage- malleus.

Front 24

musculature derivatives from 1st pharyngeal arch-

and whats its nerve and artery

Back 24

1. muscles of masticatin
2. mylohyoid
3. anterior belly of digastric
4. tensor veli palatani
5. tensor tympani
6. innervated by maxillary and mandibular divisions of trigeminal nerve,
7. artery - maxillary (1st aortic arch)

Front 25

skeletal derivatives of second arch

Back 25

1. from reicherts cartillage - stapes, styloid process, lesser horns and upper rim of hyoid. Stylohyoid ligament.
2. overlaps with some structures from 1st arch

Front 26

musculature derivates of 2nd arch

innervation and artery

Back 26

1. muscles of masticaiton
2. posterior belly of digastric
3. stylohyoid
4. stapedius

innervated by facial nerve

artery is stapedial artery (foetal)

Front 27

what is persistent stapedial artery

Back 27

occurs 1-2 in 10,000 usually asymptomatic, usually regresses as its foetal but if remains it can pulse next to eardrum causing noise.

Front 28

Derivatives of 3rd arch

Back 28

1. skeletal - greater horn and lower rim of hyoid
2. musuculature- stylopharyngeus
3. nerve - glossopharyngeal
4. common carotid artery of internal coritid

Front 29

derivates of 4th and 6th arch

Back 29

1.skeletal - laryngeal cartillages,

1. musculature is constrictors of the pharynx , cricothryoid, levator veli palatini, intrinsic muscles of the larynx.
2. nerve - superior laryngeal branch of vagus (4th ) recurrent branch of the vagus (6th)
3. arteries - 4th arch of aorta , left subcalvian.
4. 6th artery suuply - ductus arteroisus and pulmonary arteries.

Front 30

endoderma nd pharyngeal arches contribute to the mucous membrane and glands of the

Back 30

tongue,

1st arch- anterior 2/3

2nd arch - part of copula

3rd arch - mucosa of most posterior 1/3 tongue

4th arch - small apart of psterior tongue and epiglottis

Front 31

what is ankyloglossia-

Back 31

failure of regression of attachement of ventral surface of the tongue to the floor of the mouth. leading to ankyloglossia

Front 32

what else contributes to structures of the head and neck

Back 32

4 pharyngeal clefts, 4 pharyngeal pouches in lateral wall of pharynx.

Front 33

only which cleft contributes to defintive structures

Back 33

only 1st pharyngeal cleft contributes to definitive structures.

1st cleft - external auditory meatus and part of tympanic membrane -------------------3 pharyngeal clefts are obliterated by expanding 2nd arch which fuses caudally with epicardial cartillage.

Front 34

what are cervical (branchial) cysts

Back 34

swelling present on lateral surface of the neck that are remnants of the 2nd , 3rd and 4th clefts.

Front 35

derivatives of the pharyngeal pouches

Back 35

1st pouch - tympanic cavity and auditory tube

2nd pouch - palatine tonsil

3rd- inferior parathyroid gland and thymus

4th - superior parathyroid gland and ultimobranchial body

Front 36

thyroid gland first appears here

Back 36

in week 4 as an endoderm proliferation in the foramen caecum

Front 37

how does the thyroid gland migrate

Back 37

it migrates into the neck along the thyroglossal duct, joined by the ultimobranchial body derived from the 4th pharyngeal pouch - c cells.

- foramen caecum persists in adult and thyroglossal duct degnerates.

Front 38

what is a thryoglossal cyst

Back 38

• occur in the midline of the neck around the hyoid bone or thyroglossal duct.
  
• aberrent thyroid tissue may also be located along the path of the thyroglossal duct