1.1: Embryology Flashcards
What do the pharyngeal arches contribute to?
Much of the face and neck
When do the pharyngeal arches develop?
In weeks 4 and 5
What are the names of the pharyngeal arches?
They are number 1, 2, 3, 4, and 6 There is no 5
Describe the order of the pharyngeal arches (anatomically and how they develop)
1 is most cranial They develop in this order
What are the components of the pharyngeal arches?
- Mesenchymal Core - Neural Crest Cells - Cranial Nerve Component - Aortic Arch Component
What layers of the mesoderm make up pharyngeal arches?
All layers
Describe the structure of the pharyngeal arches (what separates them?)
The arches are separated by clefts (ectoderm) and pouches (endoderm)`
Name the cranial nerves that are associated with each pouch?
Pouch 1 = CN V (Trigeminal, Only mandibular and maxillary) Pouch 2 = CN VII (Facial) Pouch 3 = CN IX (Glossopharyngeal) Pouch 4 and 6 = CN X (Vagus) Cranial nerves 5, 7, 9 and 10
Describe Arch 1: Bone
Different from the others - divided into two components: The maxillary process of the 1st arch contributes to - Maxilla - Zygoma - Part of temporal The mandibular process of the 1st arch contributes to - Mandible - Two ossicles (Incus and malleus)
Describe Arch 1: Muscle
Muscles of mastication Anterior Belly of Digastric Mylohyoid Tensor Timpani (Middle Ear) Tensor Palatini (Involved in palate)
Describe Arch 1: Nerves
Supplied by Cranial Nerve 5 (Trigeminal) V1 = Opthalamic V2 = Mandinbular V3 = Maxillary Provides sensory supply to the skin of the face
Describe Arch 2: Bone
Stapes Styloid Process of Temporal Bone Stylohyoid Ligament Lesser Horn of Hyoid Upper Part of Hyoid Body
Describe Arch 2: Muscle and Nerve
Muscles of Facial Expression Stapedius Stylohyoid Posterior Belly of Digastric Auricular Muscles All supplied by VII (Facial Nerve)
Describe Arch 3: Bone Muscle Nerve
Greater horn of hyoid Lower part of hyoid Stylopharyngeus Muscles Glossopharyngeal nerve (IX)
Describe arches 4 and 6:
There are no bony components Gives rise to the laryngeal cartilages Muscles: 4: Cricothyroid, Levator Palatini and Pharyngeal Constrictors Supplied by Superior Laryngeal Nerve (From Vagus X) 6: Intrinsic laryngeal Supplied by recurrent laryngeal Nerve (From Vagus X)
What is the only muscle innervated by glossopharyngeal nerve?
Stylopharyngeus
What are pouches?
Pouches are the indentations in the ENDODERM between adjacent arches
Describe pouch 1?
This engulfes the bony structures of arch 1 and 2 to give us the middle ear cavity, the eustachian tube and contributes to the tympanic membrane
Describe pouch 2?
Becomes the palatine tonsil