Head and Neck development Flashcards
When does the bilateral pharyngeal apparatus start to form?
Four to five weeks post fert
Pharyngeal clefts
External aspect between arches (ectoderm)
Pharyngeal pouch
internal aspect between arches. There are four well defined arches, the fifth is reabsorbed. (endoderm)
Pharyngeal membranes
2 layered structures of ectoderm and endoderm
What is in the mesenchymal core of the arches?
Paraxial mesoderm, nc cells, and lateral plate mesoderm.
What does each pharyngeal arch contain?
A cartilaginous skeletal component(nc cell derived) connective tissue (nc cells) and muscle component (paraxial) a cranial nerve and a aortic arch artery
Intramembranous bone formation
Bone develops in WELL vascularized mesenchyme. No cartilage model. Makes flat bones of face and skull
Intra cartilaginous bone formation
Bone forms from pre-existing cartilage model, SOME bones of the pharyngeal apparatus are made this way
What are the two prominces of the 1st pharyngeal arch
Maxillary and Madibular
Describe the cartilagenous component of the maxillary promincence of the 1st arch
The cartilage is called the palatopterygoquadrate (HOLY FUCK THAT IS A WORD) and the cartilage regresses and leaves no adult remnant
Describe the cartilagenous component of the mandibular prominence of the 1st pharyngeal arch
It is called Meckel’s cartilage and it makes a large contribution to the face, it leaves SOME adult structures
What does meckel’s cartilage give rise to? and how?
Incus, malleus, by endochondral ossification
What does the perichondrium of Meckel’s cartilage form?
Anterior ligament of malleus, and Sphenomandibular ligament
What does intramembranous ossification form in the maxillary prominence of the 1st arch?
Squamous portions of temporal bone, maxillary bone, zygomatic bone, palatine bone
What does intramembranous ossification form in the mandibular prominence of the 1st arch
Mandible
What are the muscle components of the 1st pharyngeal arch?
the FOUR muscles of mastication, the Tensor veli palatini (sounds like martini lol) and tensor tympani. Anterior belly of the digastric. Mylohyoid.
What is the nerve component of the first pharyngeal arch
Mandibular branch of the TRIGEMINAL (nerve V) nerve supplies the muscles. Sensory supply to skin of face is through opthalmic, maxillary, and mandibular branches of CN V as well
What does Reichert’s cartilage of the second arch give rise to?
Stapes, the styloid process, stylohyoid ligament, lesser horn and upper body of hyoid bone
What muscles come form the 2nd arch?
Muscles of facial expression, stapedius, stylohyoid, posterior belly of the digastric
skeletal component of 3rd pharyngeal arch
Lower part of the BODY and greater horn of the hyoid
muscle component of 3rd arch
the ONLY one is the stylopharyngeus
Nerve component of 3rd arch
CN IX Glossopharyngeal nerve
nerve component of 2nd arch
Facial nerve VII
Skeleton of 4th and 6th arches
never as large as other arches, they merge together. They form laryngeal cartilage from lateral plate mesoderm, cartilage does not ossify
Muscles of arches 4 and 6
muscles of soft palate, pharynx, intrinsic muscles of larynx, muscles of upper esophagus. Myoblasts of 6th arch become intrinsic laryngeal muscles
Nerve component of arch 4 and 6
Vagus Nerve
where do pharyngeal arch muscles come from?
from cranial paraxial mesoderm and occipital somites
what is the fate of pharyngeal arch arteries
they are modified to form definitive arteries of the upper thorax neck and head