Pharyngeal Arches B&B Flashcards
what are the three components of the pharyngeal apparatuses?
- Pharyngeal arches - bilateral mounds
- pharyngeal clefts - invaginations between the mounds (arches), outside of embryo made of ectoderm
- Pharyngeal pouches - depressions between the mounds (arches), inside of embryo made of endoderm
What is contained in each of the pharyngeal arches? (3)
- Core of mesenchyme connective tissue that gives rise to cartilage/bones and muscles.
- Neural crest cells which migrate to the center and give rise to cranial nerves.
- An artery which forms the aortic arches.
What are the bones of the first pharyngeal arch?
- maxillary process —> maxilla, zygomatic bone
- mandibular process —> mandible, Meckel’s cartilage (becomes incus and malleus in adults)
what does embryonic Meckel’s cartilage become in adults? from which pharyngeal arch is it derived?
first pharyngeal arch (part of mandibular process), becomes incus and malleus (inner ear) in adults
What are the muscles of the first pharyngeal arch?
muscles of mastication (this makes sense because the mandible develops from the first arch!)
- temporalis (on temporal skull)
- pterygoids (side of jaw)
- masseter (side of jaw)
- mylohyoid (connects mandible to hyoid)
- anterior digastric (below jaw)
- tensor tympani (ear)
- anterior 2/3 of tongue
which cranial nerves are derived from the first pharyngeal arch?
mandibular and maxillary divisions of the trigeminal nerve (this makes sense because the mandible/maxilla are derived from the first arch!)
sensory to face + motor to muscle of mastication (which also derive from first arch! woah!)
what blood vessel derives from the first pharyngeal arch?
maxillary artery
this makes sense because maxilla/mandible/muscles of mastication all derive from first arch!
Which bones are derived from the second pharyngeal arch? (3)
“Reichert’s cartilage” becomes:
1. stapes (ear)
2. styloid process of temporal bone
3. lesser horn of hyoid
from which pharyngeal arch is Reichert’s cartilage derived and what does it become? (3)
second pharyngeal arch, becomes:
1. stapes (ear)
2. styloid process of temporal bone
3. lesser horn of hyoid
What are the muscles of the second pharyngeal arch?
- muscles of facial expression
- stapedius (ear)
- auricular muscles (ear)
- stylohoid
- posterior digastric (under jaw)
which nerve is associated with the second pharyngeal arch?
facial nerve which makes sense because the muscles of facial expression derive from the second arch!!
Which arteries are associated with the second pharyngeal arch?
- stapedial artery - embryonic vessel, involutes in development
- hyoid artery - embryonic vessel, develops into small branch of internal carotid
which bone, muscle, nerve, and artery are associated with the third pharyngeal nerve?
bone: hyoid (body and greater horn)
muscle: stylopharyngeus (connects styloid process to pharynx)
nerve: glossopharyngeal (IX) (mixed)
arteries: common carotid + proximal internal carotid
from which pharyngeal arch does the common carotid artery derive?
Third pharyngeal arch
which pharyngeal arch does not persistent humans?
Fifth pharyngeal arch
Which nerve innervates both the fourth and sixth pharyngeal arches?
vagus nerve
4th: superior laryngeal branch
6th: recurrent laryngeal branch (loops around aorta)
what cartilage develops from the 4th and 6th pharyngeal arches?
both arches fuse to form larynx cartilage - thyroid, cricoid, arytenoid, corniculate, cuneiform
what muscles develops from the 4th and 6th pharyngeal arches?
laryngeal muscles (this makes sense because the larynx cartilage also derives from these arches!)
4th: cricothyroid, levator palatini, pharyngeal constrictors
6th: intrinsic muscles of larynx (besides cricothyroid)
which arteries are derived from the 4th and 6th pharyngeal arches?
4th: aortic arch (left) + proximal right subclavian artery (right)
6th (“pulmonary arch”): proximal pulmonary artery (right/left) + ductus arteriosus (left)
from which pharyngeal arch does the aortic arch derive?
4th pharyngeal arch (left)
on the right, becomes proximal right subclavian artery
from which pharyngeal arch does the right subclavian artery derive?
4th pharyngeal arch (right)
on the left, becomes aortic arch
from which pharyngeal arch does the proximal pulmonary arteries and ductus arteriosus derive?
6th pharyngeal arch - “pulmonary arch”
from which pharyngeal arch are the following nerves derived?
a. facial
b. trigeminal
c. vagus
d. glossopharyngeal
1st: trigeminal (CN V, 5)
2nd: facial (CN VII, 7)
3rd: glossopharyngeal (CN IX, 9)
4th/6th: vagus (CN X, 10)
which nerves develop from the following pharyngeal arches?
1st
2nd
3rd
4th/6th
1st: trigeminal (CN V, 5)
2nd: facial (CN VII, 7)
3rd: glossopharyngeal (CN IX, 9)
4th/6th: vagus (CN X, 10)
which structures (on a large scale) are associated with the 1st, 2nd, 3rd, and 4th/6th pharyngeal arches?
1st —> maxilla/ mandible
2nd —> hyoid
3rd —> hyoid
4th/6th —> larynx
from which pharyngeal arches are the following arteries derived?
a. common/internal carotid
b. aortic arch (left)
c. ductus arteriosus/ pulmonary artery
a. common/internal carotid - 3rd pharyngeal arch
b. aortic arch (left) - 4th pharyngeal arch
c. ductus arteriosus/ pulmonary artery - 6th pharyngeal arch
Treacher Collins Syndrome
failure of neural crest cell migration to first pharyngeal arch
underdeveloped facial bones (mandibular hypoplasia, micrognathia, absent/small ears, glossoptosis)
may lead to difficulty breathing due to airway obstruction by tongue
baby with abnormal facial features struggling to breath may have an abnormally developed _____ pharyngeal arch
first pharyngeal arch —> Treacher Collins Syndrome
underdeveloped facial bones (mandibular hypoplasia, micrognathia, absent/small ears, glossoptosis)
may lead to difficulty breathing due to airway obstruction by tongue
from which pharyngeal arches does the tongue and it’s innervation derive?
anterior 2/3: 1st/2nd arches, sensation via CN V (trigeminal, 1st arch), taste via CN VII (facial, 2nd arch)
posterior 1/3: 3rd/4th arches, sensory via CN IX (glossopharyngeal, 3rd arch), taste via CN X (vagus, 4th arch)
motor: CN XII (hypoglossal) with tiny bit from CN X
