Embryology: Pharyngeal Arches Flashcards
In humans, where does the lower jaw, face and neck structures derive from
Pharyngeal arches
what are the pairs of pharyngeal arches
1,2,3,4,6
In which direction do the pharyngela arches form?
Cranial to caudal
What is the time frame for the pharyngeal arches
Begins day 22 ends early 5th week
What is a pharyngeal arch
- an expansion of tissues containing a mesenchymal core with outer ectoderm and inner endoderm
- contain:
- cartilage element
- straited muscle
- cranial nerve
- aortic arch artery
What is the outer ectoderm of the pharyngeal arch
Pharyngeal cleft/groove
What is the inner endoderm layer of the pharyngeal arch
Pharyngeal pouch
The endoderm on the pharyngeal arch is associated with
Arch cartilage
Mesoderm of pharyngeal arch associated with
Arch artery
Ectoderm of pharyngeal arch is associated with
Arch cranial nerve
Pharyngeal arch cartilages are derived from
Neural crest cells
Arch 1 Skeletal Elements
Maxillary Part: Palatopterygoquadrate bar: incus and alisphenoid
Mandibular Part: Meckel’s cartilage: malleus and sphenomandibular ligament
Arch 2 Skeletal Elements
Reichart’s cartilage: stapes, stylohyoid process, stylohyoid ligament. Lesser horns and upper rim of hyoid
Arch 3 Skeletal Elements
Greater horns, lower rim of hyoid
Arch 4 & 6 Skeletal Elements
Larynx cartilages
Arch 1 Cranial Nerve
Trigeminal Nerve ( CN V)
maxillary and mandibular divisions
Arch 2 Innervation
Facial Nerve (CN VII)
Arch 3 Innervation
Glossopharyngeal N. (CN IX)
Arch 4 innervation
Vagus Nerve (X): Superior laryngeal branch
Arch 6 Innervation
Vagus Nerve (X): Recurrent Laryngeal Branch
Arch 1 muscles
- originate from head of mesoderm
- Muscles of Mastication (temporalis, masseter, and pterygoids)
- anterior belly of digastric
- 2 “tensors”
- tensor tympani
- tensor veli palatini
Arch 2 muscles
- originate from head of mesoderm
- muscles of facial expression
- orbicularis oculi
- orbicularis oris
- risorius
- platysma
- auricularis
- frontalis
- buccinator
- posterior belly of digastric
- stylohyoid
- stapedius
Arch 3 Muscles
- originates from head of mesoderm
- stylopharyngeus
Arch 4 Muscles
- originate from occipital somites 2-4
- constrictors of the pharynx
- cricothyroid
- levator veli palatini
Arch 6 Muscles
- originate from occipital somites (1-2)
- intrinsic muscles of the larynx
Arch 1 Blood Supply
Terminal branch of Maxillary Artery
Arch 2 Blood Supply
Stapedial Artery (embryonic)
Corticotympanic Artery (adult)
Arch 3 Blood Supply
Common Carotid Artery
Root of Internal Carotid Artery
Arch 4 Blood Supply
Arch of Aorta (left side)
Right Subclavian Artery (right side)
Original Sprouts of Pulmonary Arteries
Arch 6 Blood Supply
Ductus Arteriosus
Roots of Definitive Pulmonary Arteries
development of the face occurs
Weeks 4-7
End of the 4th week development of face has
Frontal nasal prominence, maxillary prominence and mandibular prominence (arch 1)
Development of face end of 5th week has
Rupture of oropharyngeal membrane and proliferation of mesenchyme of mandibular prominence
Development of face 5th-6th week has
growth of the maxillary prominence and the formation of the nasal placode and nasal pit
What forms the nasal placode
medial nasal process and lateral nasal process & nasalacrimal groove
what is a nasal placode?????****
area of cells that aggregate
outer opening of nasal pit developed from 5-6th week
development of the face weeks 6th-7th has
Intermaxillary process, Philtrum and primary palate
formation of intermaxillary process
fusion of the medial nasal processes
Formation of philtrum and the primary palate
fusion of intermaxiallary process with maxillary prominences
Where is the philtrum located
portion just inferior to nose and superior to upper lip
Development of the face 7th week has
Nasal lacrimal duct, lacrimal sac and nasal passages and the Secondary palate
What is the oropharyngeal membrane
gut tube
describe the formation of the secondary palate
forms from maxillary palate, process grows inferiorly and then grows up to form palate shelves that fuse at the midline.
Incomplete fusion of primary/secondary palate causes
unilateral cleft lip, bilateral cleft lip or cleft plate
What failed to fuse in Unilateral cleft lip
lateral nasal and maxillary prominences (primary palate)
What failed to fuse in bilateral cleft lip
Medial process and maxillary prominence (primary palate)
What failed to fuse in cleft palate
Palatal shelves of maxillary prominence. (Secondary palate)
