Head and Neck: Pharyngeal Apparatus Flashcards by Biraaj Mahajan

Where do neural crests migrate

Into pharyngeal arches

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What makes up the pharyngeal apparatus

Pharyngeal arch, pouch and cleft and membranes

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What does each arch contain?

Cranial Nerve
Aortic arch artery
Cartilage

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What is the pharyngeal cleft/groove?

Invagination of the ectoderm

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Pharyngeal pouch?

outpocketings of endoderm

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How do flat bones of face and skull form?

Intramembranous ossification

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What is housed in the mesenchymal core of each arch?

Neural crest cells
Paraxial mesoderm
Lateral plate mesoderm

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1st pharyngeal arch

Mandibular arch; largest

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What 2 prominences make up the 1st pharyngeal arch

Maxillary prominence

Mandibular prominence

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Does the maxillary or mandibular cartilage component remain in the adult?

The maxillary cartilage regresses (palatopterygoquadrate)

Mandibular -meckel’s cartilage remains

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Meckel’s cartilage derivatives in adult (mandibular prominence)

Incus
Malleus
*** bone develops by endochondral ossification (cartilage model first)

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Perichondrium of Meckel’s cartilage derivatives

Anterior ligament of malleus

Sphenomandibular ligament

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Maxillary prominence derivatives

Maxillary bone
Zygomatic bone
Palatine bone
Squamous portions of temporal bone

**formed by intramembranous ossification

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Mandibular prominence derivatives

by intramembranous ossification - mandible

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Muscles derived from pharyngeal arch 1

Masticatory muscles:
Temporalis, Masseter, Medial and Lateral Pterygoids
Tensor Veli Palatini
Tensor Tympani
Ant. belly Digastric 
Mylohyoid

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Cranial nerve of Arch 1

CN V - sensory to face and motor to muscles of arch 1

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Skeletal components derived from cartilage of Arch 2 - Reichert’s cartilage

Stapes
Styloid process (endochondral ossification)
Stylohyoid ligament (perichondrium derived)
Lesser horn and upper body of hyoid

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Muscles derived from Arch 2

All muscles of Facial Expression
Stapedius
Stylohyoid
Posterior belly of digastric

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Cranial nerve of Arch 2

Facial Nerve CNVII

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Innervation of Ant. Digastric

Comes from Arch 1 - so V

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Innervation of Post. Digastric

Comes from Arch 2 - so VII

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Skeletal component of 3rd Arch

Greater horn and lower half of body of hyoid bone

**remember lesser horn and upper half of hyoid bone body came from 2nd arch

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Muscle component of 3rd arch

STYLOPHARYNGEUS

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Cranial nerve of 3rd arch

CN IX -glossopharyngeal nerve

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Skeletal component of arches 4/6

Laryngeal cartilages | *thought to come from lateral plate mesoderm

Muscular component of arches 4/6 soft palate

``` Soft palate: Levator veli palatini Uvulae Palatoglossus Palatopharyngeus ```

Muscular component of arches 4/6 Pharynx

Superior, middle and inferior constrictors Palatopharyngeus Salpingopharyngeus

Muscular component of arches 4/6 Larynx

``` Cricothyroid Thyroarytenoid Posterior crico-arytenoid Lateral crico-arytenoid Transverse and oblique arytenoids Vocalis ```

Cranial nerve of Arches 4/6

Vagus Nerve CN X

Arch Artery 1

Maxillary artery

Arch Artery 2

Stapedial artery | Hyoid Artery

Arch Artery 3

MAJOR: Common carotid , ECA and proximal part of ICA

Arch Artery 4

Left -arch of aorta + l. subclavian Right - proximal r. subclavian

Arch Artery 6

Ductus arteriosus | Pulmonary arteries

Pharyngeal Pouch

associated with endoderm

Pharyngeal Pouch 1

Tubotympanic recess | *epithelial lining of tympanic cavity and Eustachian tube

Pharyngeal Pouch 2

Epithelium of palatine tonsil

Pharyngeal Cleft 1

epithelial lining of External acoustic meatus

Pharyngeal Pouch 3

complicated by developing a dorsal and ventral region dorsal: Inferior parathyroid gland Ventral: Thymus (stroma)

Pharyngeal Pouch 4

Dorsal: Superior parathyroid gland Ventral: Ultimobranchial body -> parafollicular cells

Pharyngeal membrane

Tympanic membrane

Tongue is derived from which primordial tissue

Endoderm

Anterior 2/3 of tongue comes from which pharyngeal arch

Arch 1

Arch 1 contributions to tongue formation

2 lateral swellings and 1 median lingual swelling **Lateral swellings overgrow and fuse in midline to cover the median bud

Dividing line between anterior and posterior tongue

Terminal sulcus

Which arches contribute to posterior 1/3 of tongue?

Root of tongue is formed by third/fourth arches

Anterior 2/3 of tongue innervated by which nerve

GSA: CN V | SA (taste): CN VII

Posterior 1/3 of tongue innervated by which nerve(s)

GSA and SA(taste): Arch 3- CN IX -glossopharyngeal Arch 4 - CN X

All muscles of tongue receive innervation from which cranial nerve?

CN XII - hypoglossal nerve | **except palatoglossus

Thyroid gland is derived from which primordial tissue type

Begins as a thickening of endoderm (diverticula)

What connects the foramen cecum in tongue to thyroid gland

The thyroglossal duct

Follicular vs. Parafollicular cells of thyroid origin

Follicular cells come from endoderm (thyroid) Parafollicular cells (parathyroid) come from ultimobranchial body off of 4th pharyngeal pouch

Branchial cysts/fistulas

remnants of the cervical sinus which typically regresses **typically found on anterior border of SCM

Thyroglossal cyst

remnant of thyroglossal duct between tongue and thyroid gland; always midline; sinus or fistula

First Arch Syndrome

abnormal development of first arch; Treacher Collins Syndrom Robin Sequence

Treacher Collins Syndrome

hypoplasia of zygomatic bone; mandibular hypoplasia

Robin Sequence

Triad complex: poor growth of mandible causes high, posteriorly placed tongue prevents palatine shelves fusion = cleft palate

DiGeorge Syndrome

failure of 3rd/4th pharyngeal pouch differentiation = thymus hypoplasia absence of parathyroid glands (calcium regulation problems)

Borders of the stomadeum

Upper border: Frontonasal placod Lateral borders: 2 maxillary prominences Caudal border: 2 mandibular prominences

Nasal placode

thickening of surface ectoderm; mark site of future nasal cavities

Nasal placode = olfactory placode undergoes what changes?

Invaginates to form nasal pit

What structures surround the nasal pits?

Medial and Lateral nasal prominences surround the nasal pit derived from nasal placode

What structure separates the lateral nasal prominence from adjacent maxillary prominence?

Nasolacrimal groove!

What does the nasolacrimal groove become?

Nasolacrimal duct connect medial corner of eye to inferior meatus

Which nasal prominences fuse in the midline?

Medial nasal prominences fuse to give rise to intermaxillary segment

What (3) structures does the intermaxillary segment give rise to?

Philtrum of lip Upper jaw - four incisors = premaxilla Primary palate

By what mechanism does bone develop in all of hard palate

Intramembranous ossification