What are the components of the pharyngeal apparatus?
In the pharyngeal arches, what do the neural crest and paraxial mesoderm give rise to, respectively?
NC: CT components
Paraxial Mesoderm: Muscles
Each arch has its own ___________ and _______________.
cranial nerve and blood supply (aortic arch artery)
How many arches initially develop? How many are there in the end?
6 initially, but arch 5 regresses, leaving 1-4 and 6
The pharyngeal pouches are internal evaginations of what kind of pharyngeal _____________.
How many Pharyngeal pouches are there?
What are the skeletal derivatives of Arch 1?
1.– viscerocranium (malleus, incus) and connective tissues of face
What are the muscular derivatives of Arch1?
a.Muscles of mastication (temporalis, masseter, medial and lateral pterygoids)
b.Also: anterior belly of digastric, mylohyoid, tensor tympani, tensor veli palatini.
What nerve innervates Arch 1?
Trigeminal nerve (CN V3)
The oropharyngeal membrane develops between the two processes of the first arch. What is it composed of?
Outer layer of ectoderm and inner layer of endoderm
The oropharyngeal membrane ruptures by day 26 to allow communication between what structures?
Pharynx and oral cavity
What is the innervation of Arch 2?
What is the innervation of Arch 3?
What is the innervation os arch 4?
What is the innervation of the fifth arch?
Slide says "mostly regresses", so take away is who cares.
What is the innervation of Arch 6?
Vagus nerve, primarily by the recurrent larygeal nerve
The entire face comes from what arch?
What are the 3 prominences of Arch 1? What does this mean for the associated cranial nerve?
This is why the trigeminal nerve has three branches
What are the skeletal derivatives of Arch 2?
a.Stapes, styloid process of temporal bone
b.Stylohyoid ligament; lesser horn and superior portion of body of hyoid
What nerves contain SVE's?
What are the muscular derivatives of Arch 2?
a.Muscles of facial expression
b.Also: stylohyoid, posterior belly of digastric, stapedius
Innervation of Arch 2?
Facial nerve, CN VII
What is the skeletal derivative of Arch 3?
1.greater horn and inferior portion of body of hyoid bone.
What is the muscular derivative of arch 3?
What is the skeletal derivative of Arch 4?
with 6th arch, forms all laryngeal cartilages.
What is the innervation of Arch 4?
Vagus nerve (CN X)
What are the muscular derivatives of arch 4?
muscles of pharynx; cricothyroid
What are the muscular derivatives of Arch 5?
What are the skeletal derivatives of Arch 6?
1.with 4th arch, forms all laryngeal cartilages.
What are the muscular derivatives of arch 6?
1.laryngeal muscles (except cricothyroid); skeletal muscle of esophagus
What is the innervation of Arch 6?
Recurrent laryngeal nerve from the Vagus (CN X)
Which cleft contributes to an adult structure? What structure is it?
A.First cleft contributes to formation of the external ear.
The remnants of clefts 2-4 form what?
The cervical sinus, which is later obliterated
What is the destiny of pouch 1?
A.contributes to formation of the middle ear and auditory tube.
What does pouch 2 form?
Stroma of the palatine tonsil, tonsillar fossa
What does pouch 3 form?
1.Dorsal portion: inferior parathyroid glands
2.Ventral portion: thymus
What does pouch 4 form?
1.Dorsal portion: superior parathyroid glands
2.Ventral portion: ultimobranchial body (see development of thyroid gland below)
What does the ultimobranchial body develop into?
Parafollicular cells of the thyroid
The thyroid gland is derived from a median endodermal thickening of what?
The thyroid gland descends along the pharynx into the neck, remaining connected to the tongue via what? When does this connection degenerate?
Thyroglossal duct - degerenates by week 7
The superior opening of the thyroglossal duct remains as the what?
~50% of individuals will have what structure that is a remnant of the distal thyroglossal duct?
Pyramidal lobe of the thyroid
From what arches does the tongue develop?
What does the first pharyngeal arch form in the tongue?
body (anterior 2/3) of tongue (GSA from trigeminal n.)
What does the third arch form in the tongue?
the root (posterior 1/3) of tongue (GVA from glossopharyngeal n.)
What does the 4th arch form in the tongue?
the epiglottic region of tongue (GVA from vagus n.)
What is the muscular component of the tongue derived from?
Paraxial mesoderm of occipital somites
What cranial nerves can be tested with the tongue?
What CN provides the anterior 2/3 of the tongue with sensation? What fiber types?
GSA (general sensation from epithelium of ectodermal origin)
What nerve provides sensory information from the posterior 1/3 of the tongue?
What fiber types do this?
GVA - (sensory nerve from epithelium of endodermal origin)
What provides sensory innervation to the epiglottis?
Patients may have remnants ectopic thyroid or parathyroid tissue. Where may these be found?
1.Remnants of thyroid tissue can remain along the course of migration.
2.The parathyroids also undergo a migration and are highly variable in their location.
What causes a lateral cervical cyst? Where are these found?
The cervical sinus fails to degenerate. These cysts are found along the anterior border of the SCM.
What leads to a branchial fistula?
What are the two types?
1.Branchial fistulas occur when second arch fails to overgrow the third and fourth arches.
The cervical sinus retains a connection with the surface (external fistula).
In rare cases, the lateral cervical cyst can open into the pharynx (internal fistula).
What are thyroglossal cysts the remnant of?
Where are they located?
1.Always located on or near midline of the neck.
Remnant of the thyroglossal duct
What is a commonality of nerual crest cell defects?
Cranio facial defects
A newborn female presents with difficult nursing and an inability to completely close her eyes. She is diagnosed with congenital facial nerve palsy. The nerve associated with which pharyngeal arch is affected in this patient?
What cranial nerve?
What are 3 defects of neural crest cells?
1.Treacher Collins Syndrome, Robin Sequence, DiGeorge Anomaly
DiGeorge syndrome arises from what?
Deletion on long arm of chromosome 22
What are 4 presentations of Digeorge Syndrome?