week 1 Flashcards
what is the vault of the skull
roof of cranial cavity
what is the view from above the skull called
norma verticalis
what is the view from the side of the skull called
norma lateralis
what is the view from the front of the skull called
norma frontalis
what bones compose the vault of the skull
frontal bone
parietal bone
what does the frontal bone overlie
frontal lobe of the brain
in a young child, what is the suture between the 2 halves of the frontal bone before they fuse together
metopic suture
at what age does the frontal bones tend to fuse / metopic suture disappear
around 2 years
what does the parietal bones overlie
the left and right parietal lobes of the brain
what are the bones of the skull joined together by
sutures
what is intramembranous ossification
the type of ossification when a membrane forms from the mesenchyme and mesenchymal cells differentiate into osteoblasts and lay down the bone
how are the bones in the vault of the skull laid down
intramembranous ossification
There is no cartilage precursor in the vault of the skull, the bone is laid down in membrane
what are sutures
Sutures are fibrous joints
The sutures are unossified parts of membrane
The sutures have a serrated pattern, they interlock
where is the coronal suture found
Runs from side to side coronal section
Separates the frontal bone from the two parietal bones
The word coronal refers to a crown (think of how a tiara runs from side to side as opposed to a crown going around the head)
where is the sagittal suture found
Runs from front to back
Passes from the coronal suture at the midline, back to the occipital bone at the back of the skull
separates the right and left parietal bones
can sutures be used to try and estimate the age of individuals
As people get older the sutures tend to become ossified
but it is a very inprecise way to try and tell the age of an individual
The degree of ossification varies greatly from person to person
But in general a younger person will tend to have open sutures, fibrous tissues still present whereas in older people the fibrous tissue may be replaced by bone
what is the diamond shaped opening where the metopic suture, sagittal suture and coronal suture meet in child anatomy?
anterior fontanelle
usually closes by around 18 months
what is the parietal foramen and where is it found
There are 2 little holes towards the back of the skull, one on the right and one on the left and these are called the parietal foramen
Theparietal foramen isan opening for theparietalemissary vein, which drains into the superior sagittal sinus
what is the frontal eminence
On either side of the skull the most prominent part of the upper forehead
If the frontal eminence has a similar curvature to the rest of the skull you would think that it is a male skull
if the frontal eminence has a similar curvature to the rest of the skull, what gender would you assume the skull is
male
if the curvature at the parietal eminence is more curved than the rest of the skull, what gender would you assume the skull is
female
what is the view from behind the skull called
normal occipitalis
what suture does the sagittal suture join onto at the back of the skull
lambdoid suture
what is common to see on the lambdoid suture
Common in the area of the lambdoid suture to see little islands of bone - these are called sutural bones or Wormian bones
why are sutures useful at the time of birth and within foetal life
At the time of birth the bones are quite thin and the sutures allow a little bit of movement between the skull bones to each other to allow the baby’s head to more readily pass down the birth canal in time of labour when the baby is born
Sutures are there to help with growth
what is the external occipital protuberance
The external occipital protuberance is the most posterior part of the skull
Beneath this area, moving away from the vault, you can see where muscles of the head and neck attach to the skull
what is the glabella
Theglabellais the smooth midline bony prominence between the supraciliary arches of thefrontal bone, more prominent in males, found just above the bridge of the nose
what does the frontal bone make up
the forehead and contributes to the orbital roof
how many parietal bones are there and where are they found
one on the left and the right
separated by sagittal suture
either side of midline
what part of the skull does the occipital bone contribute to
Part of the occipital bone is within the vault of the skull
part of it contributes to the base of the skull (below the level of the external occipital protuberance)
the temporal bone is made up of several parts - what are these
§ Squamous § Zygomatic process § Mastoid § Petrous § Styloid process
what is the squamous part of the temporal bone
flattened bone on the side of the vault of the skull
where is the zygomatic process found
- attached to the squamous part of temporal bone going forward and meeting the zygomatic bone
- there is a little suture between these bones that can be felt in you palpate your face in that place
what is the mastoid process
a projection that lies behind the ear
this is another feature to look for when trying to identify the gender of the skull [males tend to have fairly large mastoid processes, in females it tends to be smaller]
what is the tympanic plate
a little bone that forms along the wall of the external auditory (acoustic) meatus
where does the external auditory meatus go towards
the ear drum
where is the sphenoid bone found
Shaped a bit like a butterfly, lies on the floor of the cranial cavity across the midline
Can see the greater wing of the sphenoid bone from the norma lateralis view
what bones does the sphenoid bone come into contact with
In contact with the
- frontal,
- parietal,
- temporal and
- zygomatic bones
what is the pterion and what is it’s significance
a particularly thin area of the skull - if you get a blow to the skull in this region it can fairly easily get broken
an area along where the sutures run and they look like the letter ‘H’
Inside the cranial cavity at the point of the pterion, there is an important artery running along a groove in the bone called the middle meningeal artery
If the pterion becomes fractured it may rupture the artery resulting in an extradural haemorrhage - blood escapes from the artery to the dura mater around the brain
what is the significance of the temporal lines
There are 2 - inferior and superior
The temporalis muscle (used to close your jaw), its fibres are attached to the bone here in an area called the temporal fossa [from these lines downwards]
these lines are land marks on the side of the skull