Flashcards in 1.2 Development of the Head and Neck Deck (38):
What are the pharyngeal archs?
A system of mesenchymal proliferations in the neck region of the embryo
How many arches develop and how many are in the adult?
1-6 develop, number 5 regresses, so 5 are left in the adult
What structures are associated with each arch?
Artery, nerve, vein and cartilage bar
What is a pharyngeal arch made up of?
Mesoderm core with 1 half surrounded by ectoderm and 1 half surrounded by endoderm
How does the neural tube develop?
The notochord signals the overlying ectoderm to thicken. The edges elevate and curl in to form a tube.
Name the 3 vesicles the anterior end of the neural tube turns into
Describe the formation of pharyngeal clefts and pouches
As the embryo grows, clefts appear between the arches. The arches are then engulfed by the growing embryo and so are inside the body. They are then referred to as pharyngeal pouches.
Which areas of the brain do CNIII- XII develop from?
Midbrain and hindbrain
Which nerves are the 'nerves of the pharyngeal arches'?
CN V, VII, IX and X
What type of fibres do the nerves of the pharyngeal arches have and what do they innervate?
Both sensory and motor functions
They innervate the derivatives of the pharyngeal arches
Where is the facial skeleton derived from?
1st pharyngeal arch
Where are the muscles of mastication derived from?
1st pharyngeal arch
Where are the muscles of facial expression derived from?
2nd pharyngeal arch
What structure does the 3rd pharyngeal arch innervate?
What structures does the 4th pharyngeal arch innervate?
Cricothyroid, Levator palatini
What structures does the 6th pharyngeal arch innervate?
Intrinsic muscles of the larynx
What is the nerve of the 1st arch called?
What does the Trigeminal nerve innervate?
Muscles of mastication
Sensory innervation to the face and lining of mouth and nose
What is the nerve of the 2nd arch called?
What does the facial nerve innervate?
Muscles of facial expression
Taste buds of anterior 2/3rds of tongue
What is the nerve of the 3rd arch called?
What does the Glossopharyngeal nerve innervate?
Stylopharyngeus and sensory innervation to posterior 1/3rd of the tongue
What is the nerve of the 4th and 6th arch?
4th branch= superior laryngeal nerve
6th branch= recurrent laryngeal nerve
What does the 1st arch cartilage develop into?
Divides into maxillary and mandibular prominences. Mandibular becomes Meckel's cartilage and becomes malleus and incus in the ear. Also provides the template for the mandible
What does the second arch cartilage develop into?
Stapes (in middle ear)
Lesser cornu and the upper body of hyoid bone
What does the 3rd arch cartilage develop into?
Greater cornu and lower body of hyoid bone
What do the 4th and 6th arches cartilage develop into?
Thyroid, arytenoid and cricoid
What is the fate of the 1st arch artery?
What is the fate of the 2nd arch artery?
What is the fate of the 3rd arch artery?
What is the fate of the 4th arch artery?
Left: Arch of aorta
Right: Brachiocephalic artery
What is the fate of the 6th arch artery?
Which nerve becomes hooked around the arch of the aorta?
Recurrent laryngeal nerve
What is the fate of the 1st pharyngeal pouch?
Tympanic cavity and auditory tube
What is the fate of the 2nd pharyngeal pouch?
What is the fate of the 4th pharyngeal pouch?
What is the fate of the pharyngeal clefts?
The 2nd cleft grows downwards to cover all the other clefts. The 1st cleft is the only one which remains.