Head and Neck Embryology Flashcards
How many somites form in the human embryo, what do they form from and what do they become?
33 form from paraxial mesoderm. They then go on to help form the cranial skeleton.
What are the branchial/pharyngeal arches, where do they arise from and what do they go on to form?
Arches that form around the future mouth and pharynx and support the primitive pharynx. They go on to form the face and neck.
How many pharyngeal arches develop?
Six arches develop but the fifth one disappears so arch one, two, three, four and six are left.
What nerve does each pharyngeal arch develop into?
One-Mandibular Branch of Trigeminal Nerve
Two-Facial Nerve
Three-Glossopharyngeal Nerve
Four-Superior Laryngeal Branch of Vagus Nerve
Six-Recurrent Laryngeal Branch of Vagus Nerve
How can you tell which arch produces which facial muscle? Give an example.
The nerve supply to that muscle corresponds to the arch that the nerve came from, therefore the muscle came from that same arch.
Orbicularis oris is supplied by facial nerve so that means it develops from arch two.
Name four other structures developing from the pharyngeal arches
Part of Pituitary gland
Thyroid gland
Tongue
Parathyroid glands
From what five prominences does the face develop from?
Frontonasal process
Two maxillary processes
Two mandibular processes
What is associated with a cleft lip?
Cleft palate
By what process is the cranial vault (flat bones) formed by?
Membranous ossification
By what process is the base of the skull (irregular bones) formed by?
Endochondral ossification
From what is the viscerocranium formed from?
From branchial arches and sensory capsules
Why are the sutures of the skull necessary in neonates?
Allows for skull deformation through the passage of the vaginal canal.
What do sensory capsules form from and what do they turn into?
They form from mesoderm of somites of the head and neck. They form from cartilage and then ossify into bones around the nose, eye and ear and the viscerocranium.
