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Step 1 final Review > Embryo > Flashcards

Embryo Flashcards

1
Q

1st aortic arch

A

Maxillary artery

1st is max

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2
Q

2nd aortic arch

A

Stapedial artery and hyoid artery

Second = stapedial

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3
Q

3rd aortic arch

A

Common carotid artery and proximal part of internal carotid artery
C is 3rd letter

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4
Q

4th aortic arch

A

On left, aortic arch; on right, proximal part of subclavian artery
4th arch = 4 limbs

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5
Q

6th aortic arch

A

Proximal part of pulmonary arteries and (on left only) ductus arteriosus

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6
Q

1st branchial arch

A

Cartilage: Meckel cartilage, Mandible, Malleus, incus, sphenoMandibular ligament
Muscles: Muscles of mastication (temporalis, Masseter, lateral and Medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini)
Nerves: CN V2 and V3 chew
Abnormalities/Comments: Treacher Collins syndrome - 1st arch neural crest fails to migrate causes mandibular hypoplasia, facial abnormalites

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7
Q

2nd branchial arch

A

Cartilage: Reichert cartilage: Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament
Muscles: Muscles of facial expression, stapedius, Stylohyoid, platySma, posterior belly of digastric
Nerves: CN VII (facial expression). Smile
Abnormalities/Comments: Congenital pharyngocutaneous fistula - persistence of cleft and pouch -> fistula between tonsillar area and lateral neck

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8
Q

3rd branchial arch

A

Cartilage: greater horn of hyoid
Muscles: Stylopharyngeus (think of styloPHARYNGEUS innervated by glossoPHARYNGEAL nerve)
Nerves: CN IX (stylopharyngeus) swallow stylishly
Abnormalities/Comments:

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9
Q

4th-6th branchial arch

A

Cartilage: Thyroid, cricoid, arytenoids, corniculate, cuneiform
Muscles: 4th - most pharyngeal constrictors, cricothyroid, levator veli palatini. 6th - all intrinsic muscles of larynx except cricothyroid
Nerves: 4th - CN X (superior laryngeal branch) simply swallow. 6th - CN X (recurrent laryngeal branch) speak.
Abnormalities/Comments: Arches 3 and 4 form posterior 1/3 of tongue; arch 5 makes no major contributions.

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10
Q

Mnemonic for arches

A

When at the golden ARCHES, children tend to first chew (1), then smile (2), then swallow stylishy (3), or simply swallow (4), and then speak (6)

Arches are mesoderm

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11
Q

1st branchial pouch

A

Derivatives: Develops into middle ear cavity, eustachian tube, mastoid air cells
Notes: 1st pouch contributes to endoderm-lined structures of ear

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12
Q

2nd branchial pouch

A

Derivatives: Develops into epithelial lining of palatine tonsils
Notes:

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13
Q

3rd branchial pouch

A

Derivatives: Dorsal wings - develop into inferior parathyroids. Ventral wings - develop into thymus
Notes: 3rd pouch contributes 3 structures (thymus, left and right inferior parathyroids). 3rd pouch structures end up below 4th pouch structures

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14
Q

4th branchial pouch

A

Derivatives: Dorsal wings - develop into superior parathyroid
Notes:

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15
Q

Mnemonic for branchial pouches

A

Ear, tonsils, bottom to top: 1 (ear), 2 (tonsils), 3 dorsal (Bottom = inferior parathyroids), 3 ventral (To = thymus), 4 (Top = superior parathyroids).

Pouches are endoderm

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16
Q

DiGeorge Syndrome

A

3rd and 4th branchial pouch issue. No thymus or parathyroid (hypocalcemia). Also associated with cardiac defects (conotruncal anomalies).

17
Q

1st branchial cleft

A

External auditory meatus

Branchial clefts are from ectoderm

18
Q

2nd-4th branchial cleft

A

form temporary cervical sinuses, which are pbliterated by proliferation of 2nd arch mesenchyme.

Branchial clefts are from ectoderm

19
Q

Anterior 2/3 of tongue formation

A

1st and 2nd branchial (pharyngeal) arch. Thus sensation via CN V3, taste via CN VII

20
Q

Posterior 1/3 of tongue formation

A

3rd and 4th branchial (pharyngeal) arch. Thus sensation and taste mainly by CN IX, extreme posterior by CN X.

Lesion of CN IX - loss of gag reflex, loss of sensation over upper pharynx, p. tongue, tonsils, middle ear cavity, loss taste sensation over posterior 1/3 tongue.

21
Q

Motor of tongue

A

CN XII to hypoglossus (retracts and depresses tongue), genioglossus (protrudes tongue), styloglossus (draws sides of tongue up to swallow).

CN X to palatoglossus - elevates posterior tongue during swallowing.

22
Q

Taste innervation for tongue

A

CN VII, IX, X (solitary nucleus)

23
Q

Pain innervation for tongue

A

CN V3, IX, X

24
Q

Motor innervation for tongue

Step 1 final Review (3 decks)

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