Exam 2: face/oral cavity Diagram

What does branchial resemble?

Fish gills

On what day does the neural tube form?

On the 20th day

On what day does the pharyngeal arches appear?

On the 26th day

What does gastrulation define?

Anterior, posterior, dorsal, and ventral axes

What happens during the neurulation stage?

The formation of the neural plate, neural tube and neural crest cells

What is neural tube?

It is what becomes the central nervous system (brain, spine)

What are neural crest cells?

It is what becomes the peripheral nervous system

What is stomodeum?

A primitive mouth

What is buccopharyngeal membrane?

A thin membrane that forms a septum between the primitive mouth and pharynx

What happens to the buccopharyngeal membrane at day 26?

It breaks down to connect the oral cavity to the endodermal lining of pharynx and larynx

What happens at the end of the 4th week?

Pharyngeal arches appear

How many arches are visible on the 4th week?

4 pairs of arches

Which pharyngeal arch is rudimentary?

The 5th and 6th arches

What are the arches separated by?

Grooves/clefts

What do the arches resemble?

Finger-like structures or protrusions

What are the grooves between the adjacent folds known as?

Pharyngeal grooves

Internally in the pharynx what corresponds with the pharyngeal grooves?

Pharyngeal pouches

What develops in each pharyngeal arch?

Artery, nerve, cartilage

What does each pharyngeal arch contain?

Artery, nerve, cartilage, neural crest cells

Most structures of the face, oral cavity, and frontonasal bulge develop from which arch(es)?

The 1st and 2nd arches

Most structures of the neck develop from which arches?

The 2nd, 3rd, and 4th arches

What does the cranial neural crest cells (CNCCs) create?

Majority of craniofacial bones: frontal, nasal, maxilla, mandible, zygomatic, sphenoid, temporal, hyoid, malleus, incus, stapes

What determines the maxilla and mandible?

Expression of the endothelin 1 (EDN1) and distal-less homeobox (Dlx) transcription factors

Where doe neural crest cells migrate to?

To the core of each pharyngeal arch

What are neural crest cells later called?

Mesenchymal cells

What are the cranial nerves of the pharyngeal arches?

· Pharyngeal arch 1 => trigeminal (CN V)

· Pharyngeal arch 2 => facial (CN VII)

· Pharyngeal arch 3 => glossopharyngeal (CN IX)

· Pharyngeal arch 4,6 => vagus (CN X)

What are the skeletal structures of pharyngeal arch 1?

Maxilla, mandible, malleus, incus

What are the ligament structures of pharyngeal arch 1?

Sphenomandibular, anterior malleus

What is the cartilage of pharyngeal arch 1?

Meckel's cartilage

What is the cartilage of pharyngeal arch 2?

Reichert's cartilage

What are the skeletal structures of pharyngeal arch 2?

Stapes, styloid process, upper body hyoid, lesser cornu

What is the ligament of pharyngeal arch 2?

Stylohyoid ligament

What are the skeletal structures of pharyngeal arch 3?

Lower body hyoid, greater cornu

What are the skeletal structures of pharyngeal arch 4,6?

Laryngeal cartilage

What does Meckel's cartilage provide?

Support for the developing mandible

What makes Meckel's cartilage in the pharyngeal arch 1?

Mesoderm and cranial neural cells

What does the facial nerve (VII) innervate?

Facial muscles, taste buds from tongue, and glands from lacrimal, submandibular and sublingual (except parotid)

What is the purpose of cartilage?

Serves as a template for bones and ligaments

What is the purpose of the cranial nerve IX?

It supplies sensory and motor information to stylopharyngeus

What does the hyoid bone resemble?

A horseshoe shape

Which of the cranial nerves is the longest?

The vagus nerve (X)

Which cranial nerve represents the main component of the parasympathetic nervous system?

The vagus nerve (X)

How is the laryngeal cartilage formed?

The fusion of the 4th and 6th pharyngeal arch

What are the adult structures descended from the pharyngeal arch 1's cartilage?

Malleus, incus, template for mandible

What are the adult structures descended from the pharyngeal arch 2's cartilage?

Stapes, styloid process, upper body of hyoid (lesser cornu)

What are the adult structures descended from the pharyngeal arch 3's cartilage?

Lower hyoid (greater cornu)

What are the adult structures descended from the pharyngeal arch 4/6's cartilage?

Laryngeal cartilages of thyroid, cricoid, cuneiform, corniculate

What descends from the pharyngeal arch 1's pouch?

Pharyngotympanic tube

What descends from the pharyngeal arch 1's groove/cleft?

External acoustic meatus

What descends from the pharyngeal arch 1's membrane?

Tympanic

What descends from the pharyngeal arch 2's pouch?

Palatine tonsil

What descends from the pharyngeal arch 3's pouch?

Inferior parathyroid, thymus

What descends from the pharyngeal arch 4/6's pouch?

Superior parathyroid, parafollicular cells

What is tonsillitis?

Bacterial/viral infections of the tonsils

What are the 5 facial prominences?

Frontonasal, medial nasal, lateral nasal, maxillary mandibular

How is the nose and nasal cavities formed?

2 nasal placodes develop in symmetry => nasal pits => nasal cavity

What are the nasal pits separated by?

The stomodeum

What is macrostomia?

An abnormality that causes a wider than normal mouth => "joker" face from batman

How is macrostomia caused?

It results from failure of fusion of maxillary and mandibular process.

What is microstomia?

An abnormality that causes a narrower than normal mouth

Midbrain

Medial nasal process

Lateral nasal process

Nasal pit

Maxillary process

Mandibular process

Second arch

Forebrain