pharyngeal apparatus
TRANSCRIPT
PHARYNGEAL APPARATUS
Dr. G.Prabavathy
Assistant Professor
Pharyngea
l
apparatus
Clinical syndromes
OBJECTIVES
Components of pharyngeal apparatus
Components and derivatives of pharyngeal arches
Components and derivatives of pharyngeal clefts
Components and derivatives of pharyngeal pouches
Clinical syndromes
Pharyngeal arches
Pharyngeal clefts
Pharyngeal pouches
Pharyngeal membranes
PHARYNGEAL APPARATUS
PHARYNGEAL / BRANCHIAL
APPARATUS
4th week of intrauterine development
PHARNGEAL ARCHES
In fourth week of development – series of surface
elevations appear in the lateral wall of primitive pharynx
caudal to stomodeum
PHARYNGEAL ARCHES
Initially there are six arches. Fifth arch is small
and rudimentary and soon disappears
Only five pharyngeal arches remain
6th arch
Arch 6
COMPONENTS OF PHARYNGEAL ARCH
A Core of mesoderm – derived from paraxial mesoderm
& neural crest cells
A Cartilaginous bar – from neural crest
A Pharyngeal arch artery – from aortic sac
A Nerve
Arrangement of post-trematic and pre-trematic
nerves
Pharyngeal arch Nerves
First arch Maxillary and Mandibular
nerves
Chorda tympani nerve
Second arch Facial nerve
Third arch Glossopharyngeal nerve
Fourth arch Superior laryngeal branch
of vagus
Sixth arch Recurrent laryngeal branch
of vagus
DERIVATIVES OF PHARYNGEAL ARCHES
Nerves of the pharyngeal arches
MUSCLES OF PHARYNGEAL
ARCHES
Pharyngea
l arch
Muscles
First arch Muscles of Mastication (Temporalis,
Masseter, Medial and Lateral Pterygoid)
Anterior belly of digastric, Mylohyoid,
Tensor tympani & tensor veli palatini
Second arch Muscles of facial expression, posterior belly
of digastric, stylohyoid, stapedius
Third arch Stylopharyngeus
Fourth arch Cricothyroid, levator palati, contrictor of
pharynx and intrinsic muscles of larynx Sixth arch
SKELETAL ELEMENTS
SKELETAL ELEMENT OF PHARYNGEAL
ARCHES
Pharynge
al arch
Skeleton Ligaments
First arch
(Meckes’s
cartilage)
Malleus, and Incus
Premaxilla, maxilla
,zygomatic bone, part of
temporal bone, mandible,
Anterior ligament of
malleus
Sphenomandibular
ligament
Second arch
(Reichert’s cartilage)
Stapes, styloid process,
Smaller cornu of hyoid bone,
superior surface of body of the
hyoid bone
Stylohyoid ligament
Third arch Greater cornu and lower part
of body of hyoid bone
Fourth arch Laryngeal cartilages (thyroid,
cricoid, arytenoids,
corniculate, cuneiform) Sixth arch
I ARCH SYNDROME
Due to lack of migration of neural crest cells into
first pharyngeal arch
Treacher collins syndrome:
Inherited autosomal dominat trait
Malar hypoplasia
Mandibular hypoplasia
Down slanting palpebral fissures
Deformed external ears
PIERRE ROBIN SYNDROME
Autosomal recessive
disorder
Micrognathia
Cleft palate
glossoptosis (posteriorly
placed tongue)
PHARYNGEAL CLEFTS
PHARYNGEAL CLEFTS
• Invagination of surface ectoderm between the
pharngeal arches
• Four pharyngeal clefts
Second arch grows rapidly downward overlaps
the second,third and fourth pharyngeal clefts –
cervical sinus
Only first pharyngeal cleft – external auditory
meatus, whereas other clefts are obliterated
Pharyngeal
Membrane
Adult derivatives
First Tympanic membrane
Second
Third
fourth
Obliterate/disappear
BRANCHIAL CYST
Remnants of second, third and fourth pharyngeal
clefts form cervical sinus
Normally cavity of cervical sinus disappears as neck
develops but it fails to obliterate – branchial cyst
Appears along ant border of sternocleidomastoid
BRACHIAL CYST AND BRANCHIAL FISTULA
BRANCHIAL FISTULA
When branchial cyst ruptures – branchial fistula
Open along ant border of sternocleidomastoid
Internal branchial fistula
External branchial fistula
LATERAL CERVICAL FISTULA
PHARNYGEAL POUCHES
PHARNYGEAL POUCHES Four pairs of pouches – evaginations of endoderm,
lining between two arches
FIRST PHARYNGEAL POUCH
First pharyngeal pouch – tubotympanic recess
Distal part of tubotympanic recess – middle ear
cavity and mastoid antrum
Proximal part – eustachian/auditory tube
SECOND PHARYNGEAL POUCH • Endoderm proliferates to Form solid buds, central core of these
buds breaks down to form Tonsillar crypts
• Part of this pouch remains as intratonsillar crypt
(crypta magna)
THIRD PHARYNGEAL POUCH
Dorsal bulbar part – parathyroid III or inferior
parathyroid gland
Ventral tubular part - thymus
FOURTH PHARYNGEAL POUCH
Dorsal bulbar part – superior parathyroid gland IV
Fifth pouch incorporated with fourth pouch – caudal
pharyngeal complex – para follicular cells or c cells
SUMMARY
Pharyngeal arches – five in number, present in lateral wall and floor of the primitive pharynx
Pharyngeal clefts- four in number, present externally between the arches, lined by ectoderm
Pharyngeal pouches – four in number, present internally between the two pharyngeal arches, lined by the endoderm
Pharyngeal membranes – four in number and located between adjacent arches
Enumerate the Derivatives of second pharyngeal
arch
Name the Derivatives of first pharyngeal arch
Explain Cervical sinus
IMPORTANT QUESTIONS 1. Stages of development of kidney
2. explain horseshoe shaped kidney
3. Congenital polycystic kidney [dec 2002]
4. Accessory renal arteries[ may 2007]
5. Ectopia vescicae[ may 2005]
6. Ectodermal cloaca[ may 2006]
7. Gubernaculum testes[ may 2006]
8. Name the sites of Ectopic testis
9. Undescended testis(cryptorchidism)
10. Epispadias and hypospadias
11. Derivates and remnants of Mesonephric duct
12. Enumerate the derivatives of Paramesonephric duct. What is unicornuate uterus[april 2002]
13. Development of uterus[nov 2010]
14. Duplication of uterus[ may 2007]
15. Give embryological basis of Bicornuate uterus