Skull Intro Flashcards
Cranium
The skeleton of the head aka the skull
What are the two parts of the cranium?
neurocranium and the viscerocranium
Neurocraniuma(description and contents)
The bony covering of the brain and the cranial meninges. Contains proximal part of the crainial nerves and the vasculature of the brain
Calvaria
The dome like roof of the neurocranium
Cranial base
The floor of the neurocranium
Which bones make up the neurocranium and which ones come in pairs?
Frontal, Ethmoid, Sphenoid, Occipital, Temporal(pair), & Parietal(pair)
8 total bones
How are the bones of the neurocranium formed?
- Intramembranous ossification of the head mesenchyme from the neural crest
- Endochondral ossification of cartilage(chondrocranium)
What do the bones of the viscerocranium surround or comprise?
- The mouth(upper and lower jaw)
- The nose/nasal cavity
- most of the orbits
What bones make up the viscerocranium and which come in pairs?
-mandible
-ethmoid
-Vomer
pairs:
-Maxillae
-Inferior nasal conchae
-zygomatic
-palatine
-lacrimal
-nasal
How do the bones of the viscerocranium from
Develop in the mesenchyme of the embryonic pharyngeal arches
What is considered anatomical position of the skull?
It is when the inferior margin of the orbital and the superior margin of the external acoustic meatus lie in the same horizontal plane.
What is the plane that runs horizontally from the inferior margin of the orbit to the superior margin of the external acoustic meatus called?
The orbitometal or Frankfort plane
what are the 4 bones visible from an anterior position?
Frontal, the right and left parietal, and the occipital
Coronal suture
Separates the frontal bone anteriorly and the parietal bones posteriorly
Sagittal suture
Separates the right and left parietal bones
Also called the inter parietal suture
Bregma
The intersection of the sagittal and coronal suture
Lambdoidal suture
separates the parietal and temporal bones from the occipital bone
Lambda
Where the sagittal and lambdoidal suture intersect
Frontal eminences(where and what to they signify)
The anterior corners of the forehead
They signify the initial site of ossification of the frontal bone
Parietal eminences(where and what to they signify)
the more prominent postereolateral bulges
They signify the initial site of ossification of the parietal bone
Describe frontal bone development.
The frontal bone develops from two memebranous ossification centers of the frontal eminences duing the seventh fetal week
At birth the right and left frontal bones are separated by a midline metopic, or interfrontal, suture.
It starts to fuse at age 1 then is obliterated at age 6, there maybe still some remnants left
What shape does the zygomatic area form?
An arch
What is the keystone of the zygomatic arch?
The zygomatic bone
What are the 3 bones supporting the zygomatic arch and their position?
Maxilla, anteriorly
Frontal, superiorly
Temporal, posteriorly
Zygomaticofacial foramen
Located centrally on the prominence of the zygomatic bone and transmits the zygomaticofacial vessels and nerve
Superior wall of the orbit
Basically horizontal and formed by the orbital part of the frontal bone
near the apex of the orbit it is made of the lesser wing of the sphenoid bone
median wall of the orbit
primarily made of the ethmoid bone, with parts from the frontal, lacrimal, and palatine bones.
inferior wall of the orbit
Formed mainly by the maxilla and partly by the zygomatic and palatine bones
Inferior orbital fissure
partly separates the lateral and inferior wall of the orbit
lateral wall of the orbit
formed by the frontal process of the zygomatic bone and the greater wing of the sphenoid bone. The lateral walls of the two orbits are perpendicular to each other
Supraorbital notch or foramen
located directly above the medial third of the superior margin of the orbit
Transmits the supraorbital vessels and nerves
Infraorbital foramen
located 7-8mm below the midpoint of the inferior margin of the orbital.
Communicates with the infra-orbital canal and groove in the floor of the orbit and transmits the infraorbital vessels and nerve
List the apertures of the wall of the orbit.
- Superior orbital fissure
- Inferior orbital fissure
- Optic canal
- Anterior and posterior ethmoidal foramen
Structures running through the superior orbital fissure
CN-III,IV,VI,V1
Structures running through the inferior orbital fissure
CN-V2 and the infraorbital vessels
Structures running through the optic canal
CN-II and the Ophthalmic artery
Structures running through the anterior and posterior ethmoidal foramen
Anterior and posterior ethmoid nerve, artery, and veins
Bones of the anterior cranial fossa
Frontal, ethmoid and sphenoid bones
Bones of the middle cranial fossa
Sphenoid, temporal, and parietal bones
Bones of the posterior cranial fossa
Occipital, temporal and parietal bones
What do the temporal line signify?
They represent the superior limit of the curved origin of the temporalis muscle
Pterion
The H shaped junction of the frontal, greater wing of the sphenoid, parietal and temporalis bones
