Pharyngeal Apparatus: Arches Flashcards
Pharyngeal arches
6 curved cylindrical thickenings on each side of pharyngeal duct
Components
Each consists of a mesodermal core covered on the outside by surface ectoderm and on inside by endoderm, each has its own nerve and atrial supply
Course of arch contents
Paraxial and lateral plate mesoderm neural crest cells
Time of appearance
- Appear in 4th and 5th weeks of development
- Cranial arches precede caudal ones in development and prominence
Fate (derivatives)
- Skeletal and Ligamentum derivates
- Muscular derivatives
- Nerve
1st arch
- Mandibular arch
- Consists of maxillary and mandiblular processes
2nd arch
Hyoid arch
1st arch: skeletal and ligamentous derivatives
- Maxillary process
- Mandibular process
- Ligaments
Maxillary process
Gives
1. Maxilla
2. Zygomatic
3. Part of temporal bones
Mandibular process
Gives:
Meckel’s cartilage
1. Dorsal end:
form malleus and incus
2. Ventral enemy
Forms mandible part
3. Cartilage rest degenerates
4. Most of mandible formed by membranous ossification
1 arch ligaments
- Sphenomandibular ligament
- Malleus anterior ligament
Both are formed from perichondrium of degenerated cartilage
1st arch: muscular derivatives
- Muscles of mastication
- Mylohyoid
- Anterior belly digastric
- Tensor palati
- Tensor tympani
1 arch nerve
Trigeminal nerve
2nd arch: skeletal and ligamentous derivatives
- Reichert’s cartilage
- Ligaments
Reichert’s cartilage
- Dorsal end:
Form stapes and styloid process - Ventral end:
Forms lesser horn and hyoid body upper part - Cartilage rest degenerates
2nd arch ligaments
Stylohyoid ligament is formed from perichondrium of degenerated cartilage
2nd arch: muscular derivatives
- Muscles of face
- Occipitofrontalis
- Platysma
- Stylohyoid
- Posterior belly digastric
- Stapedius
2nd arch: nerve
Facial nerve
3rd arch: skeletal and ligamentous derivatives
Greater horn and hyoid body lower part
3rd arch: muscles
Stylopharyngeus
3rd arch:nerve
Glossopharyngeal nerve
4th arch: skeletal and ligamentous derivatives
Thyroid cartilage upper part
4th arch: muscles
- Extrinsic laryngeal muscles (cricothyroid)
- Pharyngeal
- Levator palati muscles
4th arch: nerve
Superior laryngeal and pharyngeal branches of vagus nerve
6th arch: skeletal and ligamentous derivatives
Thyroid cartilage lower part and laryngeal cartilages rest
6th arch: muscles
Intrinsic laryngeal muscles
6th arch: nerves
Recurrent laryngeal branch of vagus nerve
5th arch
Either never forms in human or forms and rapidly regresses
