1. Development of pharyngeal arches Flashcards
(44 cards)
The pharyngeal arches first appear as tissue bulges that are separated by ____
clefts (as the cranial neuropore closes)
Other name for pharyngeal arches?
Brachial/gill arches
Pharyngeal arches are made up of which embryo layers?
Mesoderm core (source: mesoderm and neural crest) Endoderm (as an internal endoderm pouch) Ectoderm (as external cleft)
With further development each arch gives rise to
dis1nct sets of structures in _______ ___ ________
With further development each arch gives rise to
dis1nct sets of structures in head and neck
What is the stomodeum?
The stomodeum, also called stomatodeum or stomatodaeum, is a depression between the brain and the pericardium in an embryo
Is the precursor of the mouth and the anterior lobe of the pituitary gland.
Which 3 prominences are found at the 1st pharyngeal arch?
Frontonasal prominence
Maxillary prominence: Upper and smaller
Mandibular prominence: Lower and larger
Note: the stomodeum is closed by the oropharyngeal membrane at 24 days.
What does the mesenchyme core within the pharyngeal arches form?
Muscle (branchial muscles)
Cartilage element
Artery
Cranial nerve
Difference between pharyngeal cleft and pouch?
Pharyngeal clefts are external + ectoderm
Pharyngeal pouchs are Internal + endoderm
Origins of the pharyngeal arch core?
Paraxial mesoderm
Neural crest
What are somitomeres?
Ill defined “segments” of paraxial mesoderm in the head region rostral to somites
Paraxial mesoderm migrates into pharyngeal arches and elsewhere to form….
mostly muscle tissue of the head ( plus some connective tissue and bone)
What are ectodermal placodes?
Thickening of ectoderm that help give rise to sensory neurone/ganglia (V, VII, IX and X)
How does the neural crest give rise to pharyngeal arch?
From ventral flow around the placodes.
Gives rise to: Mesenchyme (bone, cartilage, ligaments) ganglia and nerves.
Which pharyngeal arch gives rise to the muscles of mastication (+ extra)?
Arch 1: Temporalis, masseter, mylohyoid, anterior belly of diagastric, tensor tympani, tensor veli palati
Which pharyngeal arch gives rise to the muscles of facial expression (+ extra)?
Arch 2: Facial expression (Frontalis, orbicularis oculi, orbicularis oris, buccinator) Posterior belly of digastric Stylohyoid Stapedius
Which pharyngeal arch gives rise to the muscle stylopharngeus?
Arch 3
Which pharyngeal arch gives rise to the muscles of.. -Constrictors -The soft palate -Lev v palatini -Cricothyroid -Layrnx musculature (+somites)?
Arches 4-6
I.e. all muscles of pharynx apart from sytlopharyngeus (which is formed from 3rd arch) + all muscles of palate (apart from tensor veli palatini)
4th arch –> pharynx and palate muscles
6th arch–> larynx muscles
Which cranial nerve arises from the pharyngeal arches?
Arch 1 = Trigeminal nerve
Arch 2= Facial nerve
Arch 3 = Glossopharyngeal nerve
Arch 4 = Superior laryngeal branch of Vagus nerve
Arch 6= Recurrent laryngeal branch of Vagus nerve
Which pharyngeal arch gives rise to the maxillary artery?
Arch 1
Which pharyngeal arch gives rise to the corticotympanic artery?
Note: Embryonic term is “stapedial artery”
Arch 2
Which pharyngeal arch gives rise to the common and internal carotid arteries?
Arch 3
Which pharyngeal arch gives rise to part of aortic arch and part of right subclavian artery?
Arch 4
LHS arch –> Part of aortic arch
RHS arch –> Part of RHS subclavian artery
Which pharyngeal arch gives rise to the part of left pulmonary artery and part of right pulmonary artery?
Arch 6
LHS arch –> part of left pulmonary artery
RHS arch –> part of right pulmonary artery
Name the skeletal structures and ligaments produced from the 1st pharyngeal arch?
Skeletal structures (from neural crest cells):
- Mandible
- Maxilla
- Malleus
- Incus
- Zygomatic
Ligaments:
- Ant lig of malleus
- Sphenomandibular ligament
