Anatomy- Skull/Face/Palate development Flashcards
What is a synchondrosis?
A join where there is a layer of hyaline cartilage between 2 joints.
It is found on growth plates. When the plate stops growing (the cartilage is converted into bone
What is an ossification centre and how many of them are there in the skull?
An ossification centre is where bone develops from.
There are 6 of them in the skull:
Parts 3 and 4 are fused by birth (intramembranous ossification)
Parts 1 and 2 fuse by endochondral ossification.
Name the fontanelles of the skull and state when they close.
Posterior fontanelle- closes at 2 months
Sphenoidal fontanelles - close at 6 months
Mastoidal fontanelles- close at 6-18 months
Anterior fontanelle- close at 2 years
Label this diagram of the fetal skull
A- Metopic suture
B-Coronal suture
C-mental symphasis
D-Anterior fontanelle
E- Saggital suture
F-Lambdoid suture
G- Coronal suture
H- posterior fontanelle.
Discuss the mental symphysis?
Normally open at birth but fuses at 1 year.
If you can still see it, the mental symphysis is fibrous.
When does the metopic suture close?
2-4 years
Label this diagram of the adult skull
A- temporal
B- zygomatic
C- maxilla
D- mandible
E- Frontal
F- Coronal suture
G- Parietal
H- Lambdoid suture
I- Bregma
J- Sagittal suture.
K- Lambda
What causes the production of the bregma?
The closure of the anterior fontanelle.
What causes the production of the lambda?
The closure of the posterior fontanelle.
Compare the fetal skull to the adult skull.
- Angle of the mandible in the fetal skull is more obtuse.
- The fetal skull has the sphenoidal fontanelle which closes over in an adult to form the pterion.
- The tempanic ring in a fetus develops into the tympanic plate in an adult.
When does the face develop?
4- 8 weeks in utero
When does the palate develop?
6-10 weeks in utero
What is a pharyngeal arch?
This is a tissue outgrowths that contribute to the structures of the face and ears.
Which pharyngeal arch is responsible for facial development?
1st pharyngeal arch:
Forms :
The trigeminal nerve
Muscles of mastication
Malleous and incus of middle ear
Meckle’s cartilage.
Name the 5 prominences that form the face?
Frontonasal prominence
Maxillary promience
Medial nasal prominence
Lateral nasal prominence
Mandibular promience.
Describe how the nose develops?
The nasal placodes form the olfactory epithelium.
The nasal promiences produce nasal pits that become the nostrils.
The medial nasal promiences fuse together to form the tip of the nose.
The lateral nasal promiences forms the wings of the nose.
The frontonasal promience forms the bridge of the nose.
Describe how the maxillary and mandibular promiences form the face?
Maxillary promience forms the cheeks
Maxillary promience fuses with the medial nasal to form upper jaw
Mandibular prominence fuses to form jaw and lower lip.
Chin is produced when the 2 mandibular promiences fuse.
Fusion of the maxillary and mandibular prominences form the corner of the mouth.
What does the palate form from?
2 parts: the primary and secondary palate.
How does the primary palate form?
The medial nasal processes form the intramaxillary processes which gives rise to the primary palate and the philtrum of the lip.
How is the secondary palate formed?
The maxillary promiences form the palatal shelves.
The palatal shelves fuse to form the secondary palate.
This seperates the nasal and oral cavities.
What causes cleft lip?
Failure of fusion of the medial nasal promience and the maxillary prominence.
What causes cleft palate?
Failure of fusion of the 2 palatal shelves.
