Intro to Skull Flashcards
Two divisions of the skull/cranium
Neurocranium and viscerocranium
neurocranium
aka
two parts
cranial vault - is the bony covering of the brain and the cranial meninges
also contains proximal parts of the cranial nerves and the vasculature of the brain
Calvaria and cranial base
calvaria
portion of the neuorcranium - upper part of the cranial cavity containing the brain
neurocranium composed of?
series of eight bones
4 singular and two sets as pairs
Frontal, ethmoid, sphenoid, occipital and PAIRED TEMPORAL AND PARIETAL
Bones forming the neurocranium are developed how?
intramembranous ossification from the neural crest
endochondral ossification od cartilage = chondrocranium
*or from more than one type
Viscerocranium
aka
forms what?
consits of?
Facial skeleton, and forms from the anterior part of the cranium and consists of the bones surrounding the mouth - upper and lower jaws
surrounding the nose/nasal cavity
and compromising most of the orbits (eye sockets or orbital cavities)
15 bone *
viscerocranium bones
15 irregular bones
3 singular bones centered or lying on the midline and 6 bones occuring as bilateral pairs
3 singular bones of viscerocranium
mandible
ethmoid
vomer
6 paired bones/bilateral pairs in the viscerocranium
Maxillae inferior nasal conchae zygomatic palatine nasal lacrimal
bones in the viscerocranium mainly develop how
develop in the MESENCHYME OF THE EMBRYONIC PHARYNGEAL ARCHES
antatomical position of the skull
with reference to the orbitomeatal plane / frankfort plane
in anatomical position when the inferior margin of the orbit and the superior margin of the external acoustic meatus are in the SAME HORIZONTAL PLANE
superior view of skull - what do you see
four bones
one paired parietal R/L and the frontal bone (anterior) and the occipital lobe (posterior)
superior view of skull features
Coronal Suture sagital/ interparietal suture Lamboidal suture Bregma Lambda Frontal Eminence Parietal Eminence
Coronal Suture
separates the frontal anteriorly from the parietal lobes posteriorly
Sagital suture
separates the L/R parietal lobes
Lambdoidal suture
separates the occipital lobe from the parietal lobes (anterior) and the temporal bones (lateral)
Bregma
landmark that represents where the sagittal and coronal sutures comes together
Lambda
landmark where the sagittal and lambdoidal suture meet
frontal eminences
anterior corners of the forehead/on frontal lobe and represent the initial site of ossification of the frontal bone
Parietal eminences
prominence seen on the parietal lobe also representing the initiation site of ossification in these parietalbones
these are POSTERIORLATERAL BULGES
Posterior View Features
Sagittal suture (barely visible -but seen)
Lambdoidal suture
Lambda- where the sutures come together of the sagittal and lambdoidal
External occipital protrubence
Occipital condyles
Superior and Inferior nuchal line - areas of attachment for some neck and back muscles
mastoid process
styloid process
External occipital protrubence
most posterior aspect in the posterior view of the skull - coming out
Occipital condyles
seen on the posterior view of the skull - these are articulating points - so likely smooth for articulation purposes
Superior and Inferior nuchal line
attachment site for some neck and back muscles - help with skull movements
Mastoid process
seen on the posterior view of the skull - this is where the sternocleodomastoid connects
bones visible in posterior view
occipital, parietal, temporal
metopic suture
the frontal bone develops from two membranous ossification centers at the future sites of the frontal eminences during the seventh fetal week - at birth the right and left temporal bones are present and separated by a midline metopic or interfrontal suture
suture begins to fuse during first year of like and is usually gone by 6 years old - however remnants may remain and this is known as a metopic suture
bones in the frontal/anterior view of the skull
look at your notes
zygomatic region and keystone feature
what three bones and where support the arch
keyston of the zygomatic arch is the diamond-shaped zygomatic bone
the MAXILLA SUPPORTS ANTERIORLY
THE FRONTAL BONE SUPPORTS SUPERIOLY
THE TEMPORAL BONE SUPPORTS POSTERIORLY
zygomaticofacial forament
centrally located on the prominence of the zygomatic bone and transmits the zygomaticofacial vessels and nerve
bones of the orbit in frontal view
frontal spenoid zygomatic maxilla lacrimal ethmoid palantine
superior wall of orbital mainly made from
orbital part of the frontal bone - but near the apex - it is formed by the lesser wing of the sphenoid bone
each orbital has…
four walls and an apex
medial wall of orbit?
formed mainly from the ethmoid bone
but also has contributions from the frontal, lacrimal, and palantine bones
inferior wall of the orbit
inferior wall/ floor mainly made from maxilla and partly by the zygomatic and palatine bones.
lateral wall of orbit
mainly made from the frontal process of the zygomatic bone and the GREATER WING OF THE SPHENOID
lateral walls of the two orbits are..?
nearly perpendicular to each other
supraorbital notch/foramen
located directly above the medial third of the superior margin and transmits the supraorbital vessels and nerve
infraorbital foramen
is about 7-8mm below the midpoint of the inferior margin. it communicates posteriorly with the infra-orbital canal and groove in the floor of the orbit anf also transmits infraorbital vessels and nerves
superior orbital fissure
location of the extra occular eye muscles so CN III, IV, VI, and V1
inferior orbital fissure
V2 and infraorbital vessels
optic canal
Opthalamic artery and CN II - optic nerve
Anterior and posterior ethmoid foramen
location of the anterior and posterior ethmoidal nerve, artery, and vein
remember this is on the medial wall of the orbit
intraorbital abscess
a rare complication after a maxillary molar extraction - the orbit can be prone to infection due to its anatomical proximity to the maxillary sinus - adjacent to the floor of the orbit
OPTHALAMIC MANIFESTATION OF A DENTAL ABSCESS
the floor of the orbit and the roof of the maxillary sinus are in close proximity
could see clinically as an swollen or inflammation of the eye after an extraction in a maxillary molar
facial or anterior surface of maxilla
helps form the upper face
orbital surface of maxilla
this is the superior aspect and it forms the floor of the orbit
nasal or medial surface of the maxilla
forms the bulk of the lateral wall of the nasal cavity
infratemporal / posterior surface of maxilla
forms the anterior wall of the infratemporal region
extends into the temporal region posteriorly
maxilla processes
named based upon what they are attaching to
Frontal process of maxilla
bar of bone that projects upward from the anterosuperior aspect to contact the frontal bone above
alveolar process of the maxilla
forms the sockets and supporting bone for the maxillary teeth
zygomatic process of maxilla
on the lateral aspect and is the buttressing maxillary contribution to the zygomatic arch
palatal process of the maxilla
this is a horizontal shelf projecting from the medial aspect of the maxilla toward the midline and its opposite counterpart
HELPS FORM THE ROOF OF THE ORAL CAVITY AND FLOOR OF THE NASAL CAVITY
infraorbital foramen on maxilla
opens onto the facial surface about 7mm below the midpoint of the inferior orbital margin. it is the mouth of the infraorbital canal and trasmits to the face the infraorbital nerves and vessels
anterior nasal spine of maxilla
sharp midline anterior projection of the inferior nasal border
incisive fossa of maxilla
depressoin overlying the maxillary incisor roots
canine ridge of maxilla
prounounced, elongated elevation of alveolar bone overlying the large maxillary canine root
canine fossa of maxilla
concavity distal to the canine ridge overlying the maxillary premolar roots
extends upward to the infraorbital foramen
site of injection for local anesthesia of the premolar maxillary teeth
nasolacrimal sulcus
anterior to the maxillary hiatus and runs in a vertical direction
along with the lacrimal bone it forms the the nasolacrimal canal, which transports tears from the orbit to the nasal cavity
why when we cry our nose runs too because this is a connection to the nasal cavity
Internal View of the cranial fossa
Anterior
Middle
Posterior
T/F the parietal bone is apart of the cranial fossa
NO - not on the base
Anterior Cranial Fossa
Frontal and Ethmoid bone
Middle Cranial Fossa
Temporal and sphenoid bone
Posterior cranial fossa
Occipital and part of temporal
lateral view cranial vault region
includes forehead and temporal region
Facial region in the lateral view
includes the zygomatic, orbital, and nasal regions
infratemporal region
- General
COVERED by the RAMUS OF THE MANDIBLE
Infratemporal region importance
A lot of nerves and vessels and fibers going through this region and also another site of injection - critical to dentistry in understanding this region
bones visible in the lateral view
Frontal, Temporal, Parietal, Occipital, Sphenoid= GREATER WINGS = paired process of a single bone), Lacrimal, zygomatic, ethmoid, mandible, maxillae (paired), nasal bones
temporal lines
selected feature in the lateral view
Superior and Inferior
two curved lines that arch upward and backward from the zygomatic process of the frontal bone and travel acorss the frontal one and parietal bone, then recurve downward and forward on the parietal bone to end inferiorrly on the temporal bone
attaching for muscles of mastication
Pterion
anthropological landmark named for the H - shaped junction of the frontal, parietal, sphenoid, and temporal bones on the LATERAL ASPECT OF THE CRANIAL VAULT - IT IS THE WEAKEST PART OF THE SKULL AND VESSEL UNDERNEATH IS AT RISK
temporal fossa
slightly depressed area on the anterolateral aspect of the skull that is inferior to the temporal lines. It is filled in by the temporalis muscle
forming the posterior root of the zygomatic arch?
the zygomatic process of the temporal bone
- this is a long slender forward projecting making this posterior root of the zygomtic arch
external auditory meatus
also called canal- of the temporal bone and forms the entrance of the middle ear within the temporal bone
external occipital protrubance - in the lateral view aka
inion - occupies the central aspect of the occipital bone
Styloid process in lateral view
sharp and slender process that angles inferiorly, medially, and anteriorly
provides attachment for a number of different muscles and two ligaments
vaginal process of the temporal bone
portion of the tympanic plate that wraps itself around the base of the styloid process like a scroll
mastoid process in the lateral view
lump of bone immediately posterior and inferior to the external auditory meatus
it serves as part as the insertion of the sternomastoid muscle