anatomy Flashcards
what is a synchondrosis?
A primary cartilaginous joint – Mainly found in the developing skeleton (e.g. growth plates).
Adult example – between first rib and sternum. Hyaline cartilage between the two bone surfaces with very little movement permitted.
where would you expect to see the Spheno-occipital synchondrosis?
Between the sphenoid and occipital bones – allows growth in the base of the skull.
what is an ossification centre?
An ossification centre is the STARTING POINT FOR BONE GROWTH.
Some bones in the skull develop from several ossification centres, which later fuse into a single bone.
The first ossification centre to appear is the primary ossification centre.
How many ossification centres does the occipital bone develop from?
Usually 6 ossification centres – parts 3 & 4 (see image) usually fused by birth
What is a fontanelle and why are these important structures in the developing skull?
Membranous areas “soft spots” between bones of the calvarium (neurocranium). Allow for compression and overlap of bones during birthing - head can appear slightly distorted for several days following birth.
Also important for continued rapid growth of brain after baby is born.
What is a fontanelle and why are these important structures in the developing skull?
Membranous areas “soft spots” between bones of the calvarium (neurocranium). Allow for compression and overlap of bones during birthing - head can appear slightly distorted for several days following birth.
Also important for continued rapid growth of brain after baby is born.
How many fontanelles are there and when does each close?
1x Anterior, 1x Posterior, 2x Mastoid (posterolateral), 2x Sphenoidal (anterolateral)
Approx. Closure Pattern (all postpartum)
Between 1-3 months - Posterior Fontanelle
By around 6 months - Sphenoidal (anterolateral) Fontanelle
Between 6-18 months - Mastoid (posterolateral) Fontanelle
By around 2 years - Anterior Fontanelle
the difference/relationship between sutures and fontanelles? Are sutures just the joinings made by the fontanelle gaps?
Sutures are tough fibrous joints between cranial bones - with little to no movement between bones.
Fontanelles are membranes covering the brain that haven’t yet turned to bone (ossified) – they allow movement/overlapping of the bones during birth and rapid expansion of the brain and skull following birth. When the bones grow together and fuse, they are replaced by sutures.
label the adult skull below
.
label the fetal skull below
label the skulls below
when does face features develop in utero?
4-8 weeks
when does palate forms in utero
6-10 weeks
when is the earliest bone to be laid in skull and what it is?
6-7 weeks
and its mandible
what forms out of 1st pharyngeal arch?
Trigeminal nerve (CN V)
Muscles of Mastification
Malleus
Incus
Meckel’s cartilage
what forms out of 2nd pharyngeal arch?
facial nerve (VII)
muscles of facial expression
hyoid
what forms out of 3rd pharyngeal arch?
glossopharyngeal nerve (IX)
stylopharyngeus
common carotid artery
hyoid
what forms out of 4th and 6th pharyngeal arch?
vagus nerve (X)
muscles of pharynx and larynx
aortic arch
laryngeal cartilages
what are pharyngeal arches?
ridges or outgrowth
formed during embryogenesis
centre is made out of neurocrest cells and mesenchyme
each arch has internal rod
has striated muscle that goes to develop into muscle
what is meckel’s cartilage and what forms around it?
acts as a jaw support during early development, and a template for the later forming jaw bones.
mandible forms around it
how many facial prominences are there and name them?
5
frontonasal
paired maxillary
paired mandibular
tell me about frontonasal prominence
it overlies developing forebrain
and forms the forehead and bridge of the nose
tell me about medial nasal province
forms midline nose
philtrum upper lip
tell me about lateral nasal prominence
forms aloe of nose
