Viscerocranium Flashcards
The Treacher Collins Syndrome is due to bones defects (True/False)
False: it is due to bone and tissue defects.
Where do the viscerocranium, the mandible and the larynx develop from?
From the pharyngeal arches.
When do the main events in craniofacial morphogenesis occur?
Between the 4th and the 8th week. The face can be distinguished by the end of the second month.
When can we see the pharyngeal arches in the embryo? What do they give rise to?
During the 4th and 5th week. They are transient.
They give rise to bones in the cranium and pharynx as well as muscles of the face.
Main features in a 28 day embryo
Pharyngeal arches (face and neck), somites and optic and lens placodes.
Where does the mesenchyme in pharyngeal arches derive from?
From the CNCCs
What are pharyngeal arches composed of?
Cartilage, arteries, paraxial mesoderm (which will form striate muscle), cranial nerves, mesenchyme from CNCCs (which will form bone).
What do neural crest cells give rise to?
Structures such as ganglia, endocardial cushions, chromaffin cells, Schwann cells, melanocytes… but also bones and structures from the viscerocranium (which develop from the mesenchyme).
CNCCs from the forebrain migrate….
Anteriorly.
CNCCs of midbrain and hindbrain migrate…
To the pharyngeal arches.
CNCCs which migrate rostrally form the… which will develop into the…
FRONTONASAL PROMINENCE, FOREHEAD
CNCCs which migrate to the 1st PA form the…
Maxillary and mandibular prominences.
To which bones does the frontonasal prominence give rise to and how?
Frontal bone and part of the maxillary bone (primary palate) via membranous ossification.
To which bones does the mesenchyme of the maxillary prominence give rise to and how?
Squamous portion of the temporal bone, maxilla (secondary palate), palatine bone and zygomatic bone via membranous (direct) ossification.
To which bones does the mesenchyme of the mandibular prominence give rise to and how?
It gives rise to the mandible via membranous ossification.
What kind of ossification does skeleton which surrounds viscera in the neck undergo?
Either endochondral ossification or remain as cartilage.
Roof of the bony orbit
Frontal bone and lesser wing of the sphenoid
Lateral wall of the bony orbit
Zygomatic bone and greater wing of the sphenoid
Floor of the bony orbit
Maxillary bone, part of the zygomatic bone, orbital process of the palatine bone
Medial wall of the bony orbit
Lacrimal bone and orbital plate of the ethmoid bone
Foramina in the bony orbit
Supraorbital and infraorbital foramen, optic canal, superior orbital fissure, inferior orbital fissure, ethmoidal foramina and lacrimal groove.
Anatomical relation between the orbit and the maxillary sinus
The orbit is sitting on the maxillary sinus.
What is the anterior nasal aperture or piriform aperture formed of? (CROSS-SECTION)
- The centre: vomer and the ethmoid, which forms the superior and middle conchae, the uncinate process and the ethmoidal bulla with ethmoidal cells.
- The inferior conchae.
- The lateral wall: maxilla (which forms the anterior nasal spine), as well as the lacrimal, ethmoid and palatine bones.
What are the choanae?
Openings between the nasal cavities and the nasopharynx.
Lateral wall of choanae/posterior nasal aperture
Sphenoid bone
Medial wall of posterior nasal aperture/choanae
Vomer
Floor of posterior nasal aperture/Choanae
Palatine bone
Roof of posterior nasal aperture
Sphenoid bone
From which bone does the posterior nasal spine come from?
From the palatine bone
Foramen which is the main way of passage into the nasal cavity
Sphenopalatine foramen
Roof of the nasal cavity
Sphenoid, ethmoid bone (cribriform plate), frontal bone, nasal bones
Main function of Choncae
Increase surface of mucosa
Lateral walls of the nasal cavity
Frontal process of the maxilla, ethmoid bone (superior and middle conchae, uncinate process, ethmoidal bulla), lacrimal bone, perpendicular plate of the palatine bone.
Medial walls of the nasal cavity
Vomer, perpendicular plate of ethmoid, cartilaginous septum
What is the anterior cranial fossa (located above the nasal cavity) formed of?
- Middle part: crista galli and cribriform plate of the ethmoid bone
- Lateral part: frontal bone
Parts of the ethmoid bone
- Crista galli and cribiform plate
- Ethmoidal cells
- Orbital plate and perpendicular plate
- Superior and middle conchae
- Infundibulum
- Ethmoid bulla
- Uncinate process
What is the nasal placode?
Ectodermal thickening induced by the underlying forebrain that will originate the olfactory epithelium.
Apart from the frontal bone, the frontonasal prominence forms…
- Part of the tip of the nose
- Philtrum of lip (upper part of the lip)
- PRIMARY PALATE ( a part of the maxillary bone with 4 incisor teeth).
The primary palate derives from…
The frontonasal prominence
The maxillary prominence forms…
The secondary palate (the rest of the maxillary bone).
Why do primary and second palate have different innervation and irrigation?
Because primary palate derives from FNP, while secondary palate derives from the maxillary prominence.
When do primary and secondary palate fuse?
10th week
At which level do primary and secondary palates fuse?
At the level of the incisive foramen.
Medial nasal prominences fuse forming…
The tip of the nose
What happens if the FNP (primary palate) and the maxilla (secondary palate) do not fuse properly?
Facial clefts are developed.
Facial cleft which occurs in 1/1000 births
Cleft lip
Facial cleft in which both lip and maxillary bone have a cleft (it extends to incisive foramen)
Cleft palate
Facial cleft because of incorrect fusion of maxillary processes between them
Isolated cleft palate
Facial cleft in which the lacrimal canal is not formed at all, nasal prominences due not fuse correctly
Oblique facial cleft
Mandibular prominence gives rise to…
The mandible
In the mandible, in the distal region, what kind of ossification do we find?
Menckel’s cartilage undergoes endochondral ossification to form the symphysis.
What kind of ossification do we find in the middle region of the mandible?
Meckel’s cartilage degenerates and osteoblasts differentiate directly from the mesenchyme of the 1st pharyngeal arch (intramembranous ossification).
Orientation of the heads of the mandible
Their main axis forms an angle of 130 degrees.
Mandible foramina
Mental and mandibular foramen
Temporomandibular joint is a…
Symphysis (hyaline cartilage and fibrocartilage)
What happens when the jaw opens more than 15 degrees?
Condylar process (from the TMJ) gets displaced from the fosa anteriorly and there is a forward movement of the articular disc.
To which 2 little ossicles does the 1st pharyngeal arch give rise to?
Malleus and incus (auditory structures) (ENDOCHONDRAL OSSIFICATION)
2nd pharyngeal arch gives rise to…
Stapes, styloid process (ENDOCHONDRAL OSSIFICATION) and stylohyoid ligament
What kind of ossification does the hyoid bone undergo?
Endochondral ossification
The superior part of the hyoid derives from…
2nd arch
The inferior part of the hyoid derives from…
3rd arch
4th pharyngeal arch gives rise to…
Epiglottis and thyroid cartilage
6th pharyngeal arch gives rise to…
The cricoid cartilage
Problems in the migration of CNCCs and the formation of the mesenchyme give rise to craniofacial defects (affecting bones) such as…
Treacher Collin Syndrome and Robin Sequence (alteration in 1st arch), as well as Velocardiofacial syndrome (heart is also affected because of problems in the formation of endocardial cushions).
When do we start to recognise pharyngeal arches individually?
Beyond the 5th week
What does the sphenopalatine foramen connect?
The nasal cavity and the pterygopalatine fossa.
Skeletal congenital malformations in the bones of the face usually present as isolated malformations, without any external or visible defects (T/F)
False
The mandible originates from
1st PA
The placodes are thickenings of the ectoderm induced by the developing brain that will give rise to specialized sensory organs (T/F)
True
The ethmoid bone ossifies via endochondral ossification (T/F)
True
The striate muscles of the face, pharynx and larynx derive from non-condensed paraaxial mesoderm (T/F)
True
The sphenoid bone ossifies via membranous ossification (T/F)
False
When does the face of the embryo largely form?
during the 2nd month of development
The facial skeleton derives from cranial neural crest cells (T/F)
True
The inferior concha is part of the ethmoid bone (T/F)
False
Indicate the CORRECT statement regarding the primary palate:
- it derives from the intermaxillary segment
- it is formed from the maxillary bone of each side
- it is posterior (or caudal) to the incisive foramen
- it is an isolated bone that forms early in development but later dissapears
- it derives from the intermaxillary segment
Every structure we need to chew is give by… PA
1st
Trigeminal nerve is given by … PA
1st
Incus and malleus are developed from … PA
1st
Temporal bones are developed from… PA
1st
Zygomatic bone are developed from… PA
1st
Maxilla (upper jaw) is developed from … PA
1st
Mandible (lower jaw) is developed from … PA
1st
Name the three muscles developed from the 1st PA used for chewing
Temporalis, pterygoid and masseter
Name the muscles that blocks the chewing noise and is derived from the 1st PA
Tensor tympani
Muscles used for swallowing which derive from the 1st PA
Tensor veli palatini, mylohyoid muscles, anterior belly of digastric.
PA arch involved in forming facial expressions
2nd PA
Nerve derived from the 2nd PA
Facial nerve
Styloid process is derived from… PA
2nd
Hyoid bone is derived from…PA
2nd
Stapes are derived from…PA
2nd
Muscles that help in swallowing derived from 2nd PA
Posterior belly of the digastric, stylohyoid.
Muscles that anchors stapes and is derived from 2nd PA
Stapedius
Nerve coming from the 3rd PA
Glossopharyngeal
Bone and muscle derived from 3rd PA
Hyoid bone and stylopharyngeus muscle
Superior laryngeal from vagus nerve comes from … PA
4th
Recurrent laryngeal from vagus nerve comes from… PA
6th
From which pharyngeal arches do laryngeal cartilages come from?
4th and 6th
Muscles from 4th PA
Levator palatini, pharyngeal constrictors, and crycothyroid