Skull Flashcards
What are the 2 parts of the cranium?
Neurocranium-pneumatized bones with sinuses held by sutures
Viscerocranium-makes the facial skeleton
What are the characteristics of the neurocranium?
Consist of:
Calvaria=skull cap- dome shaped
Basicranium-basal plate
What is the orbitomeatal plane?
Plane that passes at the bottom of the orbits and encompasses the opening of the external auditory meatus
What are the craniometric points?
Nasion-junction of frontonasal and internasal sutures meet
Glabella-smooth prominence between eyebrows
Bregma- junction of coronal and sagittal sutures
Vertex-superior point of neurocranium
Lambda-junction of lamboid and sagittal sutures
Pterion-suture between frontal-sphenoid, parietal-temporal
Asterion-Star shaped located at junctions of 3 sutures parietomastoid, occipitomastoid and lambdoid
Inion-most prominent point of external occipital protuberance
What are the fontanelles?
Soft spots on head present in neonates
Clinally important to diagnose increased intracranial pressure (bulging) or dehydration (depressed)
Consist of 4 located: anterior, posterior, sphenoidal, mastoid
What are the bones of the facial aspect of the cranium?
Frontal bone Zygomatic bones Maxillae bones Nasal bone Lacrimal Mandible
What are the characteristics of the frontal bone?
Originally paired bone but fused early to form one bone
Contains frontal sinus
Orbital part forms part of the roof of the orbit
Supraorbital foramen is the passage of the supraorbital neurovasculature
Supraciliary arch more marked in men forms elevated ridge above rim
What are the characteristics of the zygomatic bones?
Form prominence of cheek bones. Articulates:
Superiorly with frontal bone
Inferiorly with maxillae
Posteriorly with zygomatic process of temporal bone
What are the characteristics of the maxillae?
Made by 2 bones united at the intermaxillary suture and together form the upper jaw. Contain several processes:
Orbital process forms infraorbital margin and the floor of the orbit
Infraorbital foramen located inferior to the orbit, contains infraorbital neurovasculature
Alveolar process includes the alveoli of the upper teeth
Zygomatic process articulates with zygomatic bone
Maxillary sinus-large pyramid shaped space that drain into the middle meatus of the nose
Piriforme aperture-opening of the nasal cavity divided in 2 halves by nasal septum
What are the characteristics of the nasal bone?
Forms superior border of piriform aperture
What are the characteristics of lacrimal bone?
Form part of the medial wall of the orbit
What are the characteristics of the mandible?
U-shaped bone articulating with the rest of the cranium via the TMJ.
Has a body and a ramus
What are the characteristics of the body of the mandible?
Forms the horizontal part of the bone with several parts
The alveolar process contains the mandibular teeth
Mental foramina located inferior to the second premolar teeth and is the passage for the mental nerves and vessels
Mental protuberance might have 1 or 2 tubercles which for the most prominent part of the chin
What are the characteristics of the ramus of the mandible?
Vertical part which meet the body to form angle of the mandible
Terminates with the coronoid process and condylar process separated by mandibular notch
The mandibular foramen is located below the notch and leads into mandibular canal which contains inferior alveolar nerve
Condylar process form the condyle for articulation with the temporal bone through the TMJ
The coronoid process serves as attachment for the temporalis
What are the characteristics of the orbits?
Contain eyeballs and accessory visual structures
Have a floor, roof, apex, medial and lateral walls
The floor is formed by the orbital process of the maxillae
The roof is formed by the orbital part of the frontal bone
The lateral wall is formed by the zygomatic bone and posteriorly by the sphenoid
The medial wall is formed by 4 bones: ethmoid, maxilla, lacrymal and sphenoid bones
What are the different types of facial fractures?
Le Fort I- Horizontal of maxillae, superior to alveolar process
Le Fort II- Oblique/vertical, posterolateral to superomedial
Le Fort III- Horizontal fracture passes through the orbit,nasal bones and concurrrent fracturing of the zygomatic arches
What are the characteristics of the lateral aspect of the cranium?
Possesses:
2 fossae- temporal and infratemporal separated by the zygomatic arch
Calvaria formed by the frontal, 2 parietal, occipital and temporal
What are the characteristics of the temporal bone?
Squamous part forms part of the lateral cranial wall
Zygomatic process forms part of the zygomatic arch with the temporal process
Tympanic part forms the external acoustic meatus
Mastoid part forms the mastoid process which serves for muscle attachment
Petrous part is not visible from the lateral view since situated deeper and contains the inner ear apparatus
What are the characteristics of the inferior view of the cranium ?
Formed by differents bones
Hard palate comprised of the maxillae and palatine
Vomer forms posters inferior aspect of the bony nasal septum
Sphenoid, temporal and occipital
What are the characteristics of the hard palate?
Posterior boundary is formed by the choanae which is the posterior nasal aperture
Incisive foramen is located in the incisive fossa and allow communication between hard palate and nasal cavity
Greater and lesser foramina allow passage of the descending palatine artery and vein as well as greater and lesser palatine nerves in the oral cavity
What are the characteristics of the sphenoid ?
Has different parts: Body Lesser wings- not seen inferiorly Greater wings Pterygoid processes Sphenoidal sinus
What are the characteristics of the pterygoid processes?
The medial plate is a posterior continuation of the lateral walls of the nasal cavities and ends inferiorly with hamulus
The lateral plate is broader than the medial wall and has a scalloped edge
The pterygoid fossa is a depression between the medial and lateral plates
What are the characteristics of the foramen ovale?
Posterior to the pterygoid process
Passage of the mandibular branch of the trigeminal nerve,
lesser petrosal nerve and accessory meningeal artery
What are the characteristics of the foramen spinosum?
Posterolateral to foramen ovale
Serves as passage for the middle meningeal artery
