Embryology Of The Head And Neck Flashcards
How much of the embryo does the head and neck form in the 4th week?
The head is mostly featureless but makes up half the embryo
Generally, what do the pharyngeal arches form?
The brain, heart and great vessels and special sensory organs
What are the pharyngeal arches?
How are they named?
They are a system of mesenchymal arches in the neck reach - each one has an associated artery, nerve and cartilage bar
There are 5 numbered 1-6 (no 5th in humans)
What is the frontonasal prominence?
A prominence located between 2 areas of thickened ectoderm
It is prominent because the brain lies underneath
Contains neurocrest cells critical for development of the head and neck
What is the 3 vesicle stage of the neural tube?
Prosencephalon = forebrain Mesencephalon = midbrain Rhombencephalon = hindbrain
Spinal chord
Which part of the neural tube are the cranial nerves derived from?
All cranial nerves except 1 and 2 are derived from the mid or hind brain
What pharyngeal arches are the facial skeleton, muscles of mastication and muscles of facial expression derived from?
Facial skeleton - derived from frontonasal prominence and 1st arch
Muscles of mastication - 1st arch
Muscles of facial expression - 2nd arch
(Explains the different innervation)
Which arch is the trigeminal nerve derived from?
What does it innervate?
The first arch
Sensory to the skin of the face and lining of the mouth and nose
Motor to muscles of mastication and muscles derived from mandibular process
Which arch is the facial nerve derived from?
What does it innervate?
The 2nd pharyngeal arch
Mostly motor - to muscles of facial expression
Sensory to taste buds in anterior 2/3 of the tongue
Which arch is the glossopharyngel nerve derived from?
What does it innervate?
The 3rd pharyngeal arch
Innervates stylopharyngeus muscle
Sensory to posterior 1/3 tongue
Which arch is the vagus nerve derived from?
What does it innervate?
4th arch - the superior laryngeal nerve
Supplies the crocothyroid and constrictors of the pharynx
6th arch - the recurrent laryngeal nerve
Supplies the intrinsic muscles of the larynx
What is Meckel’s cartilage?
The 1st pharyngeal arch divides into the mandibular and maxillary prominence
The mandibular prominence develops into meckels cartilage which forms a template for the mandible
What type of ossification occurs in the mandible?
Membranous ossification
What is Reicherts cartilage?
The cartilage of the 2nd pharyngeal arch
Contributes to middle ear development and forms styloid process, upper 1/2 of hyoid bone
What do the aortic arches 1-6 form?
1st and 2nd arches disappear
3rd arch = internal carotid
4th arch = arch of aorta and brachiocephalic
6th arch = pulmonary arch
