Face, Development, and Pharyngeal Arches Flashcards
What cell type are the cartilage elements of pharyngeal arches 1,2, and 3 made of?
Neural crest cells of the mid and hind brain
What cell type are the cartilage elements of pharyngeal arches 4 and 6 made of?
Lateral plate mesoderm
All bones that are derived from pharyngeal cartilages are formed by___________.
Endochondral formation
What are the names of the cartilages that are derived from the 1st pharyngeal arche?
-meckel’s cartilage
What cartillage arises from the mandibular swelling?
Meckel’s cartilage
What is the name of the cartilage of the second arche?
Reichert’s cartilage
The laryngeal cartilages are derived from which pharyngeal arch(es)?
Arches 4 and 6
The laryngeal cartilages consists of which 5 cartilages?
- *-thyroid cartilage
- cricoid cartilage**
- arytenoid cartilage
- corniculate cartilage
- cuneiform cartilage
What cell type are the laryngeal cartilages of arches 4 and 6 derived from?
Lateral plate mesoderm
What bones arise from the first pharyngeal arche?
- incus
- malleus
- Alisphenoid
- premaxilla
- maxilla
- zygomatic bone
- Squamous part of temporal bone
Which bones are derived from meckel’s cartilage?
Incus and malleus
What bones arise from the second pharyngeal arche?
- stapes
- lesser horn of the hyoid bone
- upper portion of the body of the hyoid bone
What bones arise from the 3rd pharyngeal arche?
- lower portion of body of the hyoid bone
- greater horn of the hyoid bone
What bones arise from the 4 and 6th pharyngeal arche?
None
TRICK QUESTION
What are the rest of the facial bones formed from and how are they formed?
- neural crest cells
- intramembranous ossification
The anterior ligament of the malleus and the sphenomandibular ligament are derived from which arche?
Arch 1
The stylohyoid ligament is derived from which arche?
Arch 2
What nerve innervates the 1st pharyngeal arche?
CNV- Trigeminal N. (maxillary and mandibular division)
What nerve innervates the 2nd pharyngeal arche?
CNVII-facial N.
What nerve innervates the 3rd pharyngeal arche?
CNIX- Glossopharyngeal nerve
What nerve innervates the 4th and 6th pharyngeal arche?
CNX-Vagus N/ CN XI-Accessory n.
What tissue are the muscles of the pharyngeal arches mainly derived from?
Paraxial mesoderm derived from cranial somitomere and occipital somites
What muscles are derived from the first pharyngeal arche?
- Muscles of mastication
- mylohyoid mm.
- anterior belly of the digastric mm.
- tensor tympani mm.
- tensor veil palatini mm.
The muscles that are derived from the 1st pharyngeal arche come from which cranial somitomere?
4th cranial somitomere
What muscles are derived from the 2nd pharyngeal arche?
- muscles of facial expression
- posterior belly of the digastric mm.
- stylohyoid mm.
- stapedius mm.
The muscles that are derived from the 2nd pharyngeal arche come from which cranial somitomere?
6th cranial sometomere
What muscles are derived from the 3rd pharyngeal arche?
-stylopharyngeus mm.
The muscles that are derived from the 3rd pharyngeal arche come from which cranial somitomere?
7th somitomere
What muscles are derived from the 4th pharyngeal arche?
- cricothyroid mm
- Cricopharyngeus m.
The muscles that are derived from the 4th pharyngeal arche come from which occipital somites?
Occipital somites 2-4
What muscles are derived from the 6th pharyngeal arche?
- Laryngeal muscles (except cricothyroid- 4 arch)
- Skeletal muscles of esophagus
What tissue covers the exterior of the pharyngeal arches?
Ectodermal epithelium
What tissue is found within the pharyngeal arches?
Mesenchymal tissue
What tissue is found on the interior surface of the pharyngeal arches?
Endodermal epithelium
How many clefts are there in the embryo at week 5?
4 clefts
What happens to the first cleft during development?
-it moves towards the first pharyngeal pouch and becomes the external auditory meatus
What happens to the last three clefts during development?
- the 2nd cleft grows and then overlaps the 3rd and 4th cleft
- they form a cavity lined with ectodermal epithelium
- it holds the cervical sinus
How many pouches are seen in an embryo?
5 pouches
What happens to the 1st pouch during development?
-it joins the first cleft to form the external auditory meatus
What happens to the 2nd pouch during development?
- becomes obliterated
- what’s left of its epithelial lining will form buds with the surrounding mesenchyme
- these will become the palatine tonsils
What happens to the 3rd pouch during development?
- it will become the parathyroid glands and the thymus
What happens to the 4th pouch during development?
What happens to the 4th pouch during development?
What happens to the 5th pouch during development?
It will become the ultimobranchial body
T/F: There can be cervical cysts and fistulas formation within the 2nd, 3rd and 4th clefts as development progresses
True
What are the steps of the development of the thyroid gland?
-develops as an epithelial proliferation in the floor of the pharyngeal gut between the tuberculin impar and the copula(foramen cecum)
-this then forms a downgrowth known as the thyroid diverticula
-As the thyroid migrates it descends to different levels:
. Anterior to hyoid bone
. Anterior to trachea
How does the thyroid gland descend to its final position?
-descends through the thyroglossal canal
What tissue is the thyroid gland made from?
Endodermal lining of the pharynx
T/F: A cyst can develope within the thyroglossal duct that the thyroid gland used to descend to its normal position
True
How is the anterior 2/3rd of the tongue formed?
-proliferation of mesoderm forms a tuberculin impar and lateral lingual swelling which forms the anterior 2/3rd of the tongue
How is the root of the tongue formed?
-caudally, the copula from the 2nd arche and hypobranchial eminance from the 3rd and 4th arche form the root of the tongue
How is the epiglottis formed?
-formed from the 4th and 6th arches
Which nerve provides general sensory to the anterior 2/3rd of the tongue?
CNV3-Mandibular N.
Which nerve innervates the taste buds on the anterior 2/3rd of the tongue?
CNVII- Facial N. (chorda tympani)
Which nerve innervates the root of the tongue?
CNIX (glossopharyngeal)
Which nerve innervates the anterior of the epiglottis?
CNX- Vagus N.
Chart of branchial arch and what they derive
Branchial arche and its structures
Picture of muscles of branchial arches
Branchial arch and its structures
Fate of clefts and pouches
Mesenchyme for formation of head region is derived from
Paraxial mesoderm (somites/somitomeres), lateral plate mesoderm, neural crest, placodes
Muscles of mastication
Temporalis, masseter, and pterygoids
Mandibulofacial dysostosis AKA
Teacher Collin’s syndrome or FIRST ARCH SYNDROME
Mandibulofacial dysostosis
Autosomal dominant w/ variable penetrance - caused by lack of migration of neural crest into pharyngeal arch 1; produces various facial anomalies (deafness due to malformation of ossicles); normal intelligence but may be mistaken due to deafness
Muscles of hyoid arch
Stapedius, stylohyoid, posterior belly of digastric, auricular, and muscles of facial expression
Adult derivatives of pharyngeal pouch 1
Epithelial lining of auditory tube and middle ear cavity; tubotympanic recess (lateral/distal = tympanic/middle ear cavity; medial/proximal = auditory/eustachian tube)
Adult derivatives of pharyngeal pouch 2
Epithelial lining of palatine tonsils crypts (medial = tonsillar fossa, surface epi of palatine tonsil; lateral = degenerates)
Adult derivatives of pharyngeal pouch 3
Inferior parathyroid gland and thymus (dorsal = inf. parathyroid; ventral = thymus); things move caudally
Adult derivatives of pharyngeal pouch 4
Superior parathyroid gland, contribute to parafollicular cells of thyroid (dorsal = parathyroid; ventral = degenrates; ultimobranchial body = C-cells/parafollicular cells); things move caudally
•Most somitomeres develop to somites, except where?
In the head
The _________ contributes primary to the 1st pharangeal arch, while the __________ contributes primarily to arches 2,3,4 and 6.
Midbrain
Hindbrain
Are their somitomeres in the head?
NO
Cranial neural crest cells play an imporant role in the development of what structures?
Thymus
Thyroid
Parathyroid
Ear development
Which mesoderms make the head and neck muscles?
Occipital lateral plate mesoderm
Paraxial Mesoderm
Components of the initial pharangeal arches
- A membrane (ectoderm and endoderm)
- A mesenchymal core (mesoderm and neural crest)
- An internal pouch (endoderm)
- An external cleft/groove (ectoderm)
The primitive oral cavity is known as __________
Stomodeum
*By the end of week 4, the stomodeum is bound by oropharyngeal membrane and 5 facial swellings
Which swelling of the mandibular arch gives rise to the forehead and temples?
Frontonasal process
Which facial swelling of the mandibular arch gives rise to the upper jaw
Maxillary process
Which facial swelling of the mandibular arch gives rise to the lower jaw?
Mandibular swelling
Nose development
- Nasal pit
- Raised rim due to mesenchymal proliferation
- Formation of lateral and medial nasal processes
- Ectoderm at floor of nasolacrimal groove (lateral nasal process and adjacent maxillary process) invaginates into underlying mesenchyme
- Formation of nasolacrimal duct and lacrimal sac
- Duct drains into inferior meautus of nose
- Postnatal drainage of excess tears
- Lateral and medial nasal processes migrate toward each other and fuse to form the intermaxillary process/segment
- Frontonasal process forms forehead, dorum and apex of nose.
The maxillary prominence gives rise to:
Lateral part of upper lip
Upper jaw
Secondary palate
The intermaxillary process (lateral and medial nasal process) gives rise to:
Middle part of the philtrum of upper lip
Middle part of upper jaw and associated gums
Primary plate
The lateral nasal process gives rise to:
Alae of nose
Mouth and lips development
- oropharyngeal membrane ruptures
- Forms embryonic mouth (connection to foregut)
- Mandibular processes merge and give rise to lower jaw, lower lip, and lower part of face
Mandibular processes merge and give rise to …
lower jaw, lower lip, and lower part of face
Cheek development
- In the 2nd month, the mouth is reduced to its final width due to fusion of lateral portions of maxillary and mandibular swellings to create the cheeks
- Primitive lips and cheeks are invaded by pharnygeal arch 2 mesenchyme, giving rise to facial muscles
Development of the primitive choana and primary palate
- oronasal membrane rupture, connection of primitive nasal cavities with oral cavbivty is primitive choana
- Floor of nasal caivty formed by posterior extension of intermaxillary process frorm the primary palate
Tongue development
- 1st pharayngeal arch forms medial swelling: medial tongue bud
- Lateral swellings of 1st arch: distal tongue buds
- Expand to overgrow median tongue bud
- Forms anterior 2/3rds of the tongue
What embrological structures developments into the anterior 2/3rd of tongue
Lateral swellings of 1st arch: distal tongue buds
Which embrologic structure develops into the copula?
2nd pharngeal arch develops midline swelling: copula
In weeks 5 and 6, the copula is overgrown by midline swelling of 3rd and 4th pharyngeal arched called ________. This structure becomes what?
Hypopharyngeal eminence
*The posterior part of the tongue
How is the epiglottis formed?
Fold of 4th pharyngeal arch
Line of fusion between anterior 2/3 and posterior 1/3 of tongue is marked _________-
Terminal sulcus
Most pharyngeal arch cartilage forms from neural crest cells of _________ and _________ regions but cartilages from 4th and 6th arches apparently develop from _______________.
Midbrain; hindbrain; lateral plate mesoderm
What is formed from the Meckel’s cartilage (of the mandibular swelling)?
Malleus and Incus
Sphenomandibular ligament
Anterior malleolar ligment
What is formed from the Reichert’s cartilage (of the 2nd arch cartilage)?
Stapes
Styloid process
Stylohoid ligament
Lesser horns of the hyoid bone
Upper half of hyoid body
Do the laryngeal cartilages ossify?
No. They can make our thyroid cartilage and our cricoid cartilage.
*Derived from 4th and 6th arch cartilage
3rd arch cartilage contributes to…
Lower half of the hyoid body
Greater horns of the hyoid
The 4th and 6th arch cartilages contribute to
The laryngeal cartilages
Which type of cranium forms the base of skull?
Cartilagenous neurocranium
What gives rise to the striated muscles of pharyngeal arches?
The mesenchyme of somatic mesoderm
What are the muscles of mastication?
Temporalis
Deep part of masseter muscle
Lateral pterygoid muscle
Superficial part of masseter muscle
Medial pterygoid
Where do the muscles of massication insert?
All insert into the mandible
Which muscles develop from the 2nd arch?
Muscles of facial expression
Stylohyoid
Posterior belly of digastric
Stapedius
Which muscles are dervied from the 3rd arch?
Stylopharyngeus
Which muscles develop from the 4th arch?
Muscles of phaynx except stylophangeus
Superior, middle, and inferior pharyngeal constrictors
Muscles of soft palate (except tensor veli palatini)
Cricotyroid muscles
Cricopharyngeus
Which musces develop from the 6th arch?
Laryngeal muscles (except cricothyroid_
Skeletal muscles of esophagus
What arteries develop from each arch?
1st- Maxillary artery
2nd- Stapedial artery and hyoid arterty
3rd- Common Carotid artery
4th
- Left- Part of the aortic arch
- Right- proximal part of right subclavian
6th- Pulmonary artery
What do the 1st pharyngeal cleft and pouches give rise to?
The tympanic cavity of the middle ear
External acoustic meatus
True or false. Cyst formation in development of pharyngeal cleft 1 usually results in hearing loss.
False
Which pharyngeal clefts are usually obliterated?
2,3,4
What do the 3rd and 4th pharayngeal pouches form?
3rd
- Dorsal
- Inferior parathyroid glands
- Ventral
- hymus
4th
- Dorsal
- Superior parathyroid glands
- Ventral
- Ultimobranchial body (C cells of thyroid gland)
Hypoplasia of 3rd and 4th arches can also disrupt the 1st and 2nd arches, leading to what additional findings?
Micrognathia
Cleft palate
Hearing loss
Abnormal deveipment of parts of the 1st pharangeal arch can lead to which rare complexes?
- Treacher Collins Syndrome- problem with maxilla and mandible
- Pierre Robin syndrome- problem with mandible
