Pharyngeal "Branchial" Arches

1. Pharyngeal (Branchial)
Apparatus
(Page 59)
Dr. Sherif Fahmy

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3. Dr. Sherif Fahmy

4. Pharyngeal (Branchial) Arches
• They are 6 mesodermal thickenings on both sides of
pharynx.
• They appear in the 4th
and 5th
weeks.
• Arches are covered with ectoderm (externally) and
lined with endoderm (internally).
• Arches are separated from each other by 4 clefts on
outer surface which is covered with ectodermal
cells.
• Arches are separated from each other by 5 pouches
on inner aspect (cavity of pharynx) which are lined
with endodermal cells.
Dr. Sherif Fahmy

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7. Processes of the 1st
arch
First arch has 2 processes:
1- Maxillary process.
2- Mandibular process.
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8. Dr. Sherif Fahmy
Mandibular process
Maxillary
process
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9. Maxillary process
Mandibular process
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10. Maxillar
y
process
Mandibular
process
2nd
arch
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11. Maxillary
process
Mandibular
process
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12. Structure of each arch
• Each arch is composed of
mesodermal (mesenchymal) cells
that give rise to bones, cartilages
and muscles.
• Each arch has an arterial supply
which is called aortic arch.
• Each arch has a cranial nerve.
Dr. Sherif Fahmy

13. Cranial Nerve Related
to Pharyngeal Arches

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Dr. Sherif Fahmy

15. Each arch has a nerve supply:
-Mandibular & Maxillary n. supplies
derivatives of 1st
arch.
-Facial n. supplies derivatives of 2nd
arch.
-Glossopharyngeal n. supplies derivatives
of 3rd
arch.
-Superior laryngeal br. of vagus supplies
derivatives of 4th
arch.
-Recurrent laryngeal n. supplies
derivatives of 6th
arch.
N.B. Pre-trematic nerve crosses from one arch
to other, e.g. chorda tympani n.(branch of
facial n.) supplies anterior 2/3 of tongue.

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Ectoderm
Endoderm
Cleft
Pouch
Cartilage
Aortic
arch
Nerve supply
Floor of pharynx
Coronal section of neck showing
structure of pharyngeal arches
Thickened
mesoderm
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18. Cleft
Pouch
Cartilage
Nerve supply
of the arch
Aortic arch
Pretrematic nerve
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19. Derivatives of
Pharyngeal Arches

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21. Fate of Pharyngeal Clefts
• Clefts are present on outer surface between
the arches, covered with ectoderm.
• Dorsal part of first cleft forms external
auditory meatus and outer layer of ear drum.
• Downward growth of 2nd
arch will cover the
other clefts with a space inbetween called
cervical sinus.
• Cervical sinus becomes smaller till it is
completely obilterated. Dr. Sherif Fahmy

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23. Fate of Pharyngeal Pouches
Arch Ventral partVentral part Dorsal partDorsal part
First pouch Occupied by
developing tongue.
Tubo-tympanic recess
that gives rise to midlle
ear & Eustachian tube
Second pouch Occupied by
developing tongue
Palatine tonsile
Third pouch Thymus gland Inferior parathyroid
gland
Fourth pouch Unknown Superior parathyroid
gland
Fifth pouch Ultimo-branchial
body which form
parafollicular cells
in thyroid
Dr. Sherif Fahmy

25. Congenital Anomalies
• Ectopic thymic present in neck
• Ectopic parathyroid tissue especially inferior
parathyroid gland.
• Branchial cyst: Remenant of cervical sinus.
• Branchial fistula: Remenant of cervical sinus
that communicates with skin through extenal
fistula, while if it communicates with pharynx
it forms internal fistula.
Dr. Sherif Fahmy