The pharyngeal apparatus consists of pharyngeal arches, pouches, grooves, and membranes that form in the developing embryo and contribute to structures in the head and neck region. The arches support the pharynx walls and give rise to skeletal, muscular, vascular and nerve components. The pouches form diverticula that develop into structures like the tonsils, thymus and parathyroid glands. Pharyngeal anomalies can result if parts of the apparatus that normally disappear persist.

1. DEVELOPMENT OF HEAD AND
NECK
PHARYNGEAL APPARATUS

2. PHARYNGEAL APPARATUS
• CONSISTS OF---
• 1 PHARYNGEAL/BRANCHIAL ARCHES
• 2 PHARYNGEAL/BRANCHIAL POUCHES
• 3 PHARYNGEAL/BRANCHIAL GROOVES
• 4 PHARYNGEAL/BRANCHIAL MEMBRANES
• THESE PRIMITIVE EMBRYONIC STRUCTURES
CONTRIBUTE GREATLY TO THE FORMATION OF
HEAD & NECK

3. PHARYNGEAL APPARATUS
• PHARYNGEAL ANOMALIES RESULT FROM
PERSISTENCE OF PARTS OF PHARYNGEAL
APPARATUS THAT NORMALLY DISAPPEAR
• OROPHARYNGEAL MEMBRANE ,FORMED
DURING THE THIRD WEEK,SEPARATES THE
STOMODEUM FROM PRIMITIVE PHARYNX
• OROPHARYNGEAL MEMBRANE RUPTURES ON
ABOUT DAY 26

6. PHARYNGEAL ARCHES
• BEGIN TO DEVELOP EARLY IN THE 4th WEEK
WHEN NEURAL CREST CELLS MIGRATE INTO
FUTURE HEAD & NECK REGION
• INITIALLY EACH ARCH CONSISTS OF A CORE OF
MESENCHYME COVERED EXTERNALLY BY
ECTODERM AND INTERNALLY BY ENDODERM
• THE MESENCHYME IS DERIVED FROM---
• 1 PARAXIAL MESODERM
• 2 LATERAL MESODERM
• 3 NEURAL CREST CELLS

7. PHARYNGEAL ARCHES
• THE ARCHES SUPPORT THE LATERAL WALLS OF
THE CRANIAL PART OF THE FOREGUT [ THE
PRIMITIVE PHAYRYNX ]
• STOMODEUM [PRIMTIVE MOUTH ] APPEARS AS A
SLIGHT DEPRESSION OF SURFACE ECTODERM
• STOMODEUM COVERED BY OROPHARNGEAL
MEMBRANE
• PHARYNX COMMUNICATES WITH THE AMNIOTIC
CAVITY WHEN OROPHARYNGEAL MEMBRANE
RUPTURES

8. PHARYNGEAL ARCHES
• FIRST PAIR APPEARS LATERAL TO THE
DEVELOPING PHARYNX
• OTHER ARCHES APPEAR AS ROUNDED
ELEVATIONS ON EACH SIDE OF THE PHARYNX
• BY THE END OF THE 4th WEEK 4 WELL
DEFINED PAIRS OF ARCHES ARE VISIBLE
EXTERNALLY
• 5th & 6th PAIR OF ARCHES ARE RUDIMENTARY
AND NOT VISIBLE EXTERNALLY

9. PHARYNGEAL ARCHES
• ARCHES ARE SEPARATED FROM EACH OTHER BY
GROOVES
• ARCHES AND GROOVES ARE NUMBERED
CRANIOCAUDALLY
• PHARYNGEAL ARCH COMPONENTS
• 1 SKELETAL COMPONENT
• 2 MUSCULAR COMPONENT
• 3 ARTERIAL COMPONENT
• 4 NERVE COMPONENT

21. PHARYNGEAL POUCHES
• PRIMITIVE PHARYNX WIDENS CRANIALLY
WHERE IT JOINS THE MOUTH
• NARROWS CAUDALLY AS IT JOINS THE
OESOPHAGUS
• ENDODERM OF PHARYNX LINES THE
INTERNAL ASPECT OF ARCHES
• THE ENDODERM PASSES INTO BALLOON LIKE
DIVERTICULA ---THE POUCHES

27. PHARYNGEAL POUCHES
• PAIRS OF ARCHES DEVELOP IN A CRANIOCAUDAL
SEQUENCE
• THE 1st PAIR OF POUCHES LIES B/W 1st & 2nd ARCHES
• FATE OF PHARYNGEAL POUCHES
• FIRST POUCH
• EXPANDS INTO TUBOTYMPANIC RECESS WHICH GIVES
RISE TO---
• 1 TYMPANIC CAVITY
• 2 MASTOID ANTRUM
• 3 AUDITORY TUBE WHICH CONNECTS THE TYMPANIC
CAVITY WITH THE PHARYNX

28. PHARYNGEAL POUCHES
• FATE OF POUCHES
• SECOND POUCH
• LARGELY OBLITERATES AS PALATINE TONSIL
DEVELOPS
• PART OF THE CAVITY REMAINS AS
INTRATONSILLAR CLEFT
• ENDODERM PROLIFERATES AND GROWS INTO
THE SURROUNDING MESENCHYME WHICH LATER
DIFFERENTIATES INTO LYMPHOID TISSUE

29. PHARYNGEAL POUCHES
• FATE OF POUCHES
• THIRD POUCH
• EXPANDS AND FORMS---
• 1 SOLID DORSAL BULBAR PORTION---FORMS
INFERIOR PARATHYROID GLAND
• 2 HOLLOW ELOGATE VENTRAL
PORTION---FORMS THYMUS

30. PHARYNGEAL POUCHES
• FATE OF POUCHES
• FOURTH POUCH
• EXPANDS AND FORMS---
• 1 DORSAL BULBAR PORTION---FORMS SUPERIOR
PARATHYROID
• 2 VENTRAL ELONGATE PORTION---FORMS
ULTIMOBRANCHIAL BODY WHICH FUSES WITH THYROID
GLAND AND GIVES RISE TO PARAFOLLICULAR CELLS
• FIFTH POUCH
• RUDIMENTARY AND BECOMES PART OF FOURTH POUCH

31. PHARYNGEAL GROOVES
• FOUR GROOVES OR CLEFTS ARE PRESENT IN
THE NECK REGION OF THE EMBRYO FROM 4th
to 6th WEEK
• ONLY 1st GROOVE EXISTS AS EXTERNAL
ACOUSTIC MEATUS
• OTHER GROOVES COME TO LIE IN A SLIT LIKE
DEPRESSION ---THE CERVICAL SINUS
• THESE GROOVES NORMALLY OBLITERATE AS
THE NECK DEVELOPS

32. PHARYNGEAL MEMBRANES
• TEMPORARY STRUCTURES
• APPEAR IN THE BOTTOM OF PHARYNGEAL
GROOVES ON EACH SIDE OF THE NECK DURING
THE 4th WEEK
• FORMED WHEN EPITHELIA OF A GROOVE
[ECTODERM] AND A POUCH [ENDODERM ]
APPROACH EACH OTHER SEPARATED BY
MESENCHYME
• ONLY 1st MEMBRANE GIVES RISE TO THE
TYMPANIC MEMBRANE