Slide discuss about various aspects of pharyngeal arches

1. Embryology of Pharyngeal arches, Pouches,
Clefts: Correlation with common
developmental anomalies in ENT-Head & Neck
Dr. Kripa Dongol
M.S. (ORL-HNS) , 3rd Year Resident
GMSM Academy of ENT and HN Studies
TUTH, IOM

2. ROADMAP
• Development of pharyngeal arches, pouches & clefts
• Derivatives of pharyngeal arches, pouches & clefts
• Anomalies of pharyngeal arches
• Anomalies of pharyngeal clefts
• Anomalies of pharyngeal pouches

3. Pharyngeal Arches
• Typical feature in head and neck
• Develop - early 4th wk
• Neural crest cells migrate into the head and neck region
• Neural crest cell – skeletal components

4. Pharyngeal Arches
• 1st pair arches - surface elevations lateral to pharynx
• Other arches - rounded ridges on each side of the future
head and neck regions

5. Pharyngeal Arches
• Morphologically, they resemble gills in fish
• True gills (branchia) not formed so the term pharyngeal
arches is used in humans.
• Branchial - Greek word branchia or gill
• Formation of the face, ear and neck

6. Pharyngeal Arches
• End of the 4th wk - four pairs of pharyngeal arches visible
externally
• Arches separated from each other by fissures - pharyngeal
grooves
• Numbered in craniocaudal sequence

7. Pharyngeal Arches
 Ridges between arches = Clefts and Pouches
• Clefts = outside (ectoderm)
• Pouches = inside (endoderm)

9. Pharyngeal Arches
• 1st (mandibular arch) - maxillary and mandibular prominences
• 1st pair - major role in facial development
• Maxillary process - premaxilla, maxilla, zygomatic bone, and
part of the temporal bone through membranous ossification
• 2nd arch (hyoid arch) - hyoid bone

10. Fate of Pharyngeal Arches
• 5th wk - 2nd pharyngeal arch enlarges and overgrows the 3rd &
4th arches, forms cervical sinus
• End of 7th wk - second to fourth pharyngeal grooves and the
cervical sinus have disappeared

11. Pharyngeal Arch Components
• Each arch contains
– Cartilage
– Cranial nerve
– Artery
– Muscle component
• All neural crest origin
• 6 arches, only 5 form
structures in humans
– 1, 2, 3, 4, and 6
– 5th fails to develop

12. Arch and nerve arrangement
Arch Post-trematic nerve Pre-trematic nerve
1st Mandibular nerve (V) Chorda tympani
branch of VII
2nd Facial nerve (VII) Tympanic branch of IX
3rd Glossopharyngeal (IX) -
4th&6th Superior and
Recurrent laryngeal
nerve
-

13. Fig. Nerve supply of each branchial arch

14. 1st Arch “Mandibular Arch”
• Skeletal components
– Meckel’s cartilage
• Framework for mandible
– Malleus head and neck
– Incus body and short process
– Sphenomandibular ligament
– Portion of mandible
– maxilla
• Muscles
– Muscles of mastication
– Anterior digastric
– Mylohyoid
– Tensor tympani
– Tensor veli palatini
• Nerve
– CN V (Trigeminal)
• Artery
– Maxillary

15. 2nd Arch “Hyoid Arch”
• Skeletal components
– Reichert’s cartilage
• Stapes
• Malleus manubrium
• Incus long process
• Styloid process
• Hyoid bone (lesser horn and
upper body)
• Stylohyoid ligament
• Muscles
– Facial expression, buccinator,
platysma, stapedius, stylohyoid,
posterior digastric
• Nerve
– CN VII (Facial)
• Artery
– External carotid

16. 3rd Arch
• Skeletal components
– Hyoid (greater horn and lower body)
• Muscles
– Stylopharyngeus
• Nerve
– CN IX (Glossopharyngeal)
• Artery
– Common carotid and 1st part of internal carotid

17. 4th Arch
• Skeletal components
– Thyroid, epiglottis, cuneiform cartilages
• Muscles
– Cricothyroid, Constrictors of pharynx, levator palati
• Nerve
– Superior laryngeal
• Artery
– Subclavian(right side), aortic arch(left side)

18. 6th Arch
• Skeletal components
– Cricoid, arytenoids, corniculate
• Muscles
– All intrinsic muscles of larynx (except cricothyroid)
• Nerve
– Recurrent laryngeal
• Artery
– Pulmonary artery on right
– Ductus arteriosus on left

20. Branchial Clefts and Pouches
• 4 clefts and 4 pouches

21. Pouches
• 1st Pouch
– Eustachian tube, middle ear, mastoid, inner layer of
tympanic membrane
• 2nd Pouch
– Palatine tonsils bed, root of tongue, foramen cecum
• 3rd Pouch – ventral and dorsal wings
– Ventral wing – Thymus
– Dorsal wing – Inferior parathyroid glands

22. Pouches
• 4th Pouch
– Superior parathyroid glands
– Parafollicular C-cells of thyroid gland
• 5th Pouch
– Contributes to Ultimobranchial bodies (Parafollicular C-
cells)

24. Migration of parathyroids & thymus
• Thymus - migrates in a caudal and a medial direction, pulling
the inferior parathyroid with it
• Increased proportion of anomalies of position of the inferior
parathyroid gland.
• Migration is complete at the end of the 7th week.

26. Migration of parathyroids & thymus
• Superior parathyroid gland – usually above the inferior
thyroid artery and behind the recurrent laryngeal nerve
• Inferior gland - usually below the inferior thyroid artery
and in front of recurrent laryngeal nerve.

27. Pharyngeal Clefts
• Dorsal portion of 1st cleft – EAM (separated from the first
pouch by the tympanic membrane)
• 3rd month – meatal plug, 7th month – dissolve – if persist :
EAC atresia
• Second arch overgrows the second, third and fourth clefts,
forming the cervical sinus which then resorbs

28. Development of external ear
• 6 mesenchymal proliferations at the dorsal ends of the 1st
and 2nd pharyngeal arches, surrounding the first
pharyngeal cleft
• These swellings (auricular hillocks), three on each
side of the external meatus, later fuse and form the
definitive auricle

29. Development of external ear
• Hillock 1- anterior portion of the ear lobe, hillock 2 - tragus
and hillock 3 - ascending helix.
• Of the second arch hillocks, 4 and 5 produce the anti-helix
and the helix, with 6 - posterior lobule.
• Incomplete fusion of the hillocks - clefts and hypergenesis -
tubercles, tags and polyotia
Anotia Microtia

30. Preauricular tags Polyotia Abnormal folds
Bat ear Lop ear Macrotia

31. Development of tongue
Ant. 2/3  2 lingual & midline tubercular impar
Post. 1/3  3rd pharyngeal arch
Post. Most 4th arch
Muscles  occipital somites
General sensation ant. 2/3  lingual n of V3
Taste frm ant. 2/3  corda tympani of VII
General n taste frm post. 1/3  CN IX
Post.most  CNX

32. • Thyroid enlage behind tubercular impar- floor of the pharynx
and develops caudally.
• It enlarges and becomes bilobed at end of 7th week.
• The tract usually atrophies, caudal end remains as a pyramidal
lobe.
• Failure of the tract to involute - thyroglossal cyst
• The hyoid bone, developing later, may entrap a portion of the
thyroid duct or draw it caudally, leaving the duct dorsal to the
bone

34. Branchial anomalies
• Result from improper development of the branchial
apparatus (Cyst, sinus or fistula)
• Cyst – Part of branchial groove or pouch become separated
from the surface and fails to resorb
• Sinus - Branchial groove or pouch fails to resorb & remains
open onto its epithelial surface
• Fistula – Passes from skin externally to pharynx or larynx
internally

35. Branchial anomalies
• A persistent cleft - external sinus, a blind ending opening onto
the skin.
• A persistent pouch will cause an internal sinus
• Persistence of both cleft and pouch will cause a fistula with an
internal and external opening

36. 1st Arch Anomalies
• Involves malformations of eyes, ears, palate and mandible
• 3 main manifestations of “First Arch Syndrome”
– Treacher Collins Syndrome
– Pierre Robin Syndrome
– Goldenhar Syndrome

37. Treacher Collins Syndrome
• Mandibulofacial dysostosis
• Inherited AD
• Features
– Midface, zygomatic and mandibular hypoplasia
– Ear anomalies: microtia, anotia, stenotic or atresia of EAC,
malformation of malleus and incus (CHL)
– Eye anomalies: coloboma of lower lids, down-slanting
palpebral fissures
– Cleft palate (35%)
– Normal intelligence

38. Treacher Collins Syndrome

39. Treacher Collins Syndrome
Features
Downward slanting
palpebral fissures
Lower eyelid colobomas
Hypoplastic supraorbital rims
Mandibular
hypoplasia
Auricular malformation
Malar hypoplasia

40. Pierre Robin Syndrome
• Sequence of :
– Micrognathia (small mandible)
– Glossoptosis (posterior displacement/retraction of tongue)
Upper airway obstruction
– Cleft palate (U-shaped)
– Primary defect - poor growth of the mandible - posteriorly
placed tongue that fails to drop from between the palatal
shelves, preventing their fusion

41. Pierre Robin Syndrome
Features
• Cleft palate  Glossoptosis  Micrognathia

42. Pierre Robin Syndrome
Otolaryngological Considerations
• Airway compromise
– Upper airway obstruction
– Feeding, aspiration
• Hearing loss
– Otitis media most common
(60%)
 Associated syndromes
 Stickler (18-25%)
 Velocardiofacial (7-15%)
 Treacher Collins (5%)
 Hemifacial microsomia (3%)

43. Goldenhar Syndrome
Oculoauriculovertebral Dysplasia
• No single genetic locus
• Disturbed neural crest cells at 30-45 days gestation
• First and second branchial arch
• Hemifacial microsomia when no internal organ
or vertebral disruption

44. Goldenhar Syndrome
Features
• Hemifacial microsomia
• Mandibular hypoplasia
• Microstomia
• Epibulbar lipodermoids
• Upper eyelid coloboma
• Vertebral anomalies
(spina bifida,
hemivertebra)

45. Goldenhar Syndrome
Features
Hemifacial microsomia
Epibulbar dermoid
Mandibular
hypoplasia
Microtia and preauricular tags/pits
Upper eyelid
coloboma

46. • OMENS
– Orbital distortion
– Mandibular hypoplasia
– Ear anomaly
– Nerve (facial) involvement
– Soft-tissue deficiency
• “Plus” to include additional anomalies
– Cardiac
– Skeletal
– Pulmonary
– Renal
– Gastrointestinal
Goldenhar Syndrome
Classification Scheme

47. Goldenhar Syndrome
Otolaryngological Considerations
• Hearing loss
– More conductive than sensorineural
– Ossicular abnormalities
– Microtia
• Aberrant facial nerve course
• Surgical craniofacial reconstruction

48. 2nd Arch Anomalies
• Malformed auricle
– Microtia
• Ossicular malformation
– Stapes
– CHL
• Muscular asymmetry of face
• Hyoid malformation
– lesser horn and upper body

49. 3rd Arch Anomalies
• Hyoid anomalies
– Lower body
– Greater horn
• Aneurysm of carotid artery

50. 4th Arch Anomalies
• Laryngeal stenosis
• Laryngoptosis (low position of larynx)
• Chondromalacia
• Double aortic arch
• Pulmonary artery sling
– Left pulmonary artery originates from right pulmonary
artery
– Slings around right main-stem bronchus

51. First Branchial Cleft Anomalies
• Preauricular sinuses, cysts , Collaural fistula, EAC atresia
or stenosis

52. First Branchial Cleft Anomalies
• Periauricular sinuses and cysts
- Usually preauricular sinus with opening just infront of
ascending limb of helix
- Asymptomatic, infection
- Excision of cyst / sinus with tract (caution – facial nerve)

53. Collaural fistula
• < 5 % of branchial cleft anomalies
• Failure of resorption of ventral part of 1st branchial cleft
• Fistula runs from EAC or tragal notch to neck between
angle of mandible and sternocleidomastoid muscle
• In some cases, a skin-covered band runs from the floor of
the meatus to the umbo
• Track – starts from below auricle between angle of mandible
and sternocleidomastoid muscle  through parotid
(medial/lateral or through facial nerve) opens into EAC

54. 1st Branchial Cleft Cyst
• Work Classification
– Type I
• Preauricular mass or sinus
• Ectoderm
• Sinus tract is anterior and medial to the EAC
– Preauricular region  Lateral to CN VII  Parallels EAC
 Ends in EAC or middle ear
– Type II
• More common than Type I
• Ectoderm & Mesoderm
• Presents at the angle of mandible or submandibular region
– Angle of mandible  Lateral or medial to CN VII  Ends
in concha or bony-cartilaginous junction of EAC.

55. Collaural fistula
 Presentation
• Discharge of epithelial or
sebaceous debris from opening
/ infection
 Investigation
• Radioopaque sinogram using
water-soluble contrast will
demonstrate the extent of the
track
• MRI
 Surgical excision - superficial
parotidectomy

56. Second Branchial Cleft Cysts
• Most Common (90%) branchial anomaly
• Failure of the cervical sinus to close may potentially
communicate with different branchial pouch
• Branchiooto-renal syndrome
• Congenital opening on the lower neck, anterior to
sternomastoid

57. Second Branchial Cleft Cysts
• Upper 2/3 & lower 1/3rd junction of SCM, deep to platysma,
lateral to IX, X, XII, between the internal and external
carotid and terminate in the tonsillar fossa
• Discharge / Infection
• Contrast sinogram to delineate track
• Surgical excision – step ladder incision

60. Third Branchial Cleft Cysts
• Rare (<2%)
• Similar external presentation to 2nd BCC
• Internal opening is at the pyriform sinus, then courses
cephalad to the superior laryngeal nerve through the
thyrohyoid membrane, medial to IX, lateral to X, XII,
deep/posterior to internal carotid
• Appearance - acute suppurative thyroiditis
• Left side
• Diagnostic delay
• Treatment - Endoscopy of the piriform fossa and
complete excision of the track

62. 4th Branchial Cleft Cyst
• Very rare
– ~ 200 cases reported in the literature
• Also associated with recurrent thyroid abscesses
• Theoretical path of tract:
– Low in neck (anterior to SCM) , Deep to common carotid
 Loops around aortic arch on the left (subclavian on
the right) lateral/superficial to CN IX Deep to
superior laryngeal nerve  Superficial to recurrent
laryngeal nerve  Opens into lower pharynx/pyriform
sinus
• Removal of a fourth branchial arch fistula - include excision
of the thyroid tissue to remove the whole tract

63. Fig. Fourth branchial cleft cyst

64. Work-up
• Ultrasound
• Round mass with uniform low echogenicity and lack of internal
septations
• Advantages: No radiation, no sedation for children, low cost
• CT
• Homogeneous lesion with low attenuation centrally and a
smooth enhancing rim
• Often part of the work-up
• More radiation, higher cost, may require sedation (children)

65. Work-up
• MRI
– Hypointense on T1 and hyperintense on T2
– Advantages: No radiation
– Disadvantages: Sedation for children, very expensive
• Fluroscopic fistulography or CT fistulography
– Inject radiopaque dye into the fistula or sinus to delineate course
• Barium swallow esophagography
– Help locate fistula tract in type 3 and 4 anomalies
• FNA

66. Treatment – Infected Cyst
• Antibiotics
– Should cover respiratory flora and Staph aureus (broad
spectrum)
– Cover 2-4 weeks
• Abscess
– Consider needle aspiration to drain
• May work without causing as much scaring as I&D
– I&D if needle aspiration doesn’t work
• Once infection cleared, operate

67. Treatment - Surgical
• Complete surgical excision of tract and cyst
• 1st cysts
– Must identify facial nerve as tract is usually
associated with it
– If possible, wait till 2 years of age
• Mastoid tip defined
• Facial nerve larger and deeper
• Controversy: waiting can lead to more infections  more
scar  more difficult surgery
– Lacrimal probes can help locate tract

68. Second Branchial Cleft Anomaly
 Treatment
Surgery
Complete surgical excision of cyst and tract
Elliptical cervical incision
» Encompassing external sinus opening
Second ‘step-laddered’ incision
» Sinus excision
» Better exposure to pharynx
Methylene Blue
» Injected externally into the sinus tract
Lacrimal probe
» Fistula excision

69. Treatment - Surgical
• 3rd and 4th cysts
– Must identify the recurrent laryngeal nerve as closely
associated (will be deep to tract)
– Removal of ipsilateral thyroid lobe is advocated to
ensure complete removal of tract
– Perform DL to examine pyriform sinus

70. Endoscopic Cauterization of Pyriform Sinus
Opening
• Literature describes this for treatment of 4th sinus tracts,
but has been performed with 3rd cleft anomalies
• Recommendation
– Performed alone
– Performed with surgical resection of cyst and tract

71. Endoscopic Cauterization of Pyriform Sinus
Opening
• Verret et al.,2004
– Performed endoscopic cauterization of sinus in 10
children with 4th branchial cleft anomalies (no
surgical excision!)
• Dilated sinus opening with balloon catheter 
cautery with electrocautery ball coagulator
• 7 showed no recurrent disease after 3 years
• 3 lost to F/U

72. 1st Pouch Anomalies
• Atretic eustachian tube -> recurrent OM
• ET diverticuli
• Absence
– Tympanic cavity
– Mastoid antrum

73. 2nd Pouch Anomalies
• Thyroglossal duct cyst
– Failure of ablation of TGD
– Most common congenital neck mass
– Anywhere from base of tongue to upper mediastinum
– Typical finding
• Cystic lesion at or just below hyoid in midline that
moves with swallowing and tongue protrusion
– Sites
– Base of tongue
– Intralingual
– Suprahyoid
– Infrahyoid  most common
-Prethyroid
-pretracheal

74. Thyroglossal Duct Cyst
– May contain thyroid tissue
• Potentially the only functioning thyroid
– Perform U/S or CT to look for thyroid and to assess lesion
– Treatment – surgical
– Excision : 85% recurrence vs Sistrunk’s : 2-8 %
– Modified Sistrunk’s operation
– May contain cancer
• 1%
• Papillary carcinoma

75. Thyroglossal Duct Cyst

76. 2nd Pouch Anomalies
• Lingual Thyroid
– Failure of decent of thyroid -> atopic
• 90% of cases at the base of tongue (lingual thyroid)
– 4:1 female:male
– Usually not noted until teenage or young adult
– Asymptomatic (most cases); dysphagia, airway
compromise
– Reddish mass (well vascularized) at base of tongue

77. Lingual Thyroid
– Hypothyroidism – 70% of cases
– 2/3 cases – only functioning thyroid tissue
• Thyroid function study prior to treatment
– Treatment
• Asymptomatic – Monitor
• Symptomatic
– Excise +/- transplant tissue into muscles of neck
– Radioiodine therapy (destroys all thyroid tissue)
• Usually require lifelong thyroid replacement

78. Lingual Thyroid

79. Lateral cervical (or branchial) cysts
• Developmental failure of branchial apparatus
• Peak age incidence – 3rd decade
• Cyst lining – Stratified squamous epithelium, 10% respiratory
epithelium
• 80%- lymphoid tissue in wall, straw coloured fluid with
cholesterol crystals

80. Lateral cervical (or branchial) cysts
• Theories of aetiology –
a) Branchial apparatus theory – Remains of branchial
pouches or clefts. Later age at presentation.
b) Cervical sinus theory
c) Thymopharyngeal duct theory – Remnants of connection
between thymus and 3rd branchial pouch. But no persistent
thymic duct found.
d) Inclusion theory – (most accepted) Epithelial inclusions
within lymph node. Lymphatic tissue in wall of cyst,
Reported – Parotid, pharynx. Constant position of cyst in
neck (against)
TIBC

81. Lateral cervical (or branchial) cysts
 Cl / f :
• Anterior to the upper 1/3 of
sternocleidomastoid in young
adults.
• Persistent or Intermittent swelling
• Cystic or firm
• 40% cases – URTI preceed
• Infection
 Investigations
- USG neck, FNAC, CT scan neck

82. Fig. CT scan and HPE finding of branchial cyst

83. Lateral cervical (or branchial) cysts
• Treatment – Surgical excision

84. 3rd and 4th Pouch Anomalies
• DiGeorge Syndrome
– Congenital absence of thymus and parathyroids
– Partial deletion of chromosome 22
– CATCH -22
• Cardiac anomalies
• Abnormal facies
• Thymic aplasia
• Cleft palate
• Hypocalcemia
– Tetany and impaired cellular immunity (T-cells)

85. 3rd and 4th Pouch Anomalies
• Accessory or undecended parathyroid glands
• 10% > 4 parathyroids, 3% <4 parathyroids
• Thymic cysts

86. Fig. a) Normal position and b) Ectopic position of parathyroids

87. THANK YOU