7. Cranium Flashcards
What bones are part of the axial skeleton?
-Skull bones
-Auditory ossicles (ear bones)
-Hyoid bone
-Ribs
-Sternum
-Bones of the vertebral column
What are the 2 divisions of the cranial bones?
- Calvaria (Skull Cap)
- Floor or Base
What does the Calvaria consist of?
4
-1 Frontal bone
-1 Occipital bone
-2 Parietal bones
-2 outer plates of compact bone and inner layer of spongy or trabecular bone called Diploë (red bone marrow)
What does the floor or base consist of?
- 1 Ethmoid bone
- 1 Sphenoid bone
- 1 Occipital bone
- 1 Frontal bone
- 2 Temporal bones
What are the 3 regions of the **base **of the skull?
- Anterior Cranial Fossa
- Middle Cranial Fossa
- Posterior Cranial Fossa
What does the Anterior Cranial fossa contain?
Houses frontal lobe of cerebrum
What does the middle cranial fossa house?
Houses temporal lobes of cerebrum
What does the posterior cranial fossa house?
Houses cerebellum, pons, medulla oblongata
What are the parts of the frontal bone?
two
- Vertical part (frontal squama)
- Horizontal part
What does the vertical part of the frontal bone contain(2), and what does it form?
-Contain the frontal sinuses, and frontal squama
-Forms the forehead and anterior part of cranial vault
What does the horizontal part of the frontal bone make up?
three
-Orbital plates
-Part of roof of nasal cavity
-Greater part of floor of anterior cranial fossa
What are the benefits of the orbital plates for an MRT?
How we determine the tilt side to side of the skull (no tilt when head straight)
What is the glabella?
(Smooth elevation between superciliary arches)
What are the articulations of the frontal bone?
six
-Parietal bones (right and left)
-Sphenoid
-Ethmoid
-Nasal bones
-Nasion
-Zygoma
PENNZS
What landmarks on the parietal bones make up the widest portion of the skull?
Parietal eminences marks the widest portion of the skull
What are the articulations of the parietal bone?
five
-Frontal
-Temporal
-Occipital
-Sphenoid
-Opposite parietal bone
What forms the posterior cranial fossa?
Occipital bone
Where is the location of the occipital bone on the skull?
Situated at the posteroinferior part of skull
What are the four parts of the occipital bone?
1.Squama
2.Two occipital condyles
(Where C1 articulates with skull)
3.Basilar portion
What are the landmarks located on the occipital bone?
6
-External Occipital Protuberance (Inion)
-Nuchal Lines
-Foramen Magnum
-Hypoglossal canals (Hypoglossal nerve)
-Jugular Foramen
-Foramen Lacerum
What does the internal jugular vein do?
Internal Jugular vein drains venous blood from brain
What are the articulations of the occipital bone?
-Atlantooccipital joint -C1
-Parietal bones
-Temporal
-Sphenoid
What forms the atlantooccipital joint? What movement does this allow?
Occipital condyles form this (allows us to say no)
What sections of the cranium does the temporal bone form?
-A large part of the middle cranial fossa and a small part of the posterior cranial fossa
-Forms the inferior lateral parts of skull
What portions/bones does the temporal bone consist of?
1.Squamous portion
2.Tympanic portion
3.Petrous ridges or pyramids
4.Mastoid process
What important landmarks are located on the temporal bone?
-Carotid Canal (Internal carotid artery)
-Jugular Foramen
-Foramen Lacerum
-EAM
-Internal Auditory Canal
(vestibulocochlear and facial nerves (7&8)
What parts of the cranium does the sphenoid form?
-Forms part of anterior and middle cranial fossa
-Keystone bone of the cranial floor
What does the sphenoid bone consist of?
1 Body
2 lesser wings
2 greater wings
2 pterygoid processes
What part of the cranium does the ethmoid form?
-Part of anterior portion of the anterior cranial fossa
-Medial wall of the orbits
-Superior portion of bony nasal septum
and sidewalls of nasal cavity
Where is the ethmoid bone located?
-Anterior to the sphenoid and posterior to nasal bones
Whatare the landmarks on the ethmoid bone
five
1.Cribriform Plate
2.Crista Galli
3.Perpendicular Plate
4..Lateral Masses
5.Middle nasal conche
What does the cribriform plate contain?
-Horizontal plate
-Contains foramina (olfactory nerves 1)
Where is the Crista Galli located? What attachment does it make up?
-Sits on cribriform plate
Attachment for Falx Cerebri
What does the falx cerebri do?
Is a membrane that separates hemispheres of brain
What bone forms the superior part of the bony nasal septum
Perpendicular Plate
What part of the ethmoid contains the ethmoid sinuses?
Lateral masses
What two things does the lateral masses form?
-Form the superior and middle nasal conchae
-Form the medial wall of orbits
What makes up the zygomatic arch?
Zygomatic process (temporal bone) + Temporal process (zygomatic bone
What portion of the temporal bone creates the Zygomatic process, Mandibular fossa, and Condyle of mandible
Squamous portion
What forms the TM joint?
The condyle of mandible articulating with mandibular fossa
What portion of the temporal bone consists of the EAM and Styloid process
Tympanic portion
What does the hyoid bone hangs off of?
Styloid process on Tympanic portion of the temporal bone
What portion of the temporal bone consists of the mastoid process
Mastoid portion
What bone/landmark contains mastoid air cells that communicate with space in the middle ear
The mastoid process located on the mastoid portion of the temporal bone
What portion of the temporal bone contains the cochlea and semi-circular canals?
Petrous portion
What is another name for Petrous portion and which way does it project?
-Called petrous ridges or pyramids
-Project anteriorly and medially
What is the thickest, densest bone in skull?
Petrous portion of the temporal bone
What is the landmark for the top petrous ridges?
Top of Ear Attachment (TEA)
What part of the sphenoid forms posterior bony wall of nasal cavity?
The body
What is on the superior surface of the body on the sphenoid?
Sella Turcica
What houses the pituitary gland (hypophyseal fossa)?
Sella turcica
What is the anterior border of the sella turcica called?
Tuberculum sellae
What is the posterior border of the sella turcica called?
Dorsum sellae
What is the top borders of dorsum of the sella turcica called?
Posterior clinoid processes
Where do the pons sit against?
pons sits against the clivus
What are the 2 parts of the lesser wings on the sphenoid?
Triangular and horizontal
What do the lesser wings of the sphenoid form?
four
- posteromedial portion of the roofs of the orbits
- optic foramen and the optic canals
- upper margin of the superior orbital fissures
- anterior clinoid processes
What does the optic nerve and ophthalmic artery pass through?
Optic foramen
What do the greater wings of the sphenoid form?
Three
- posterolateral walls of the orbits
- Lower margin of the superior orbital fissures
- Part of the middle cranial fossa
What 3 foramens does the greater wings contain?
- Foramen Ovale
- Foramen Rotundum
- Foramen Spinosum
What does the Pterygoid processes of the sphenoid form?
-Inferior processes off the sphenoid body and greater wings
-Forms the posterolateral region of nasal cavity
What are the 3 types of skulls and what are their degrees?
Mesocephalic skull (47 degrees)
Brachycephalic skull (54 degrees)
Dolichocephalic skull (40 degrees)
What bones form the anterior cranial fossa?
- orbital part plates (frontal bone)
- Ethmoid bone
- lesser wings and anterior part of the body
What are the 4 sutures of the skull?
Coronal
Saggital
Lamboidal
Squamosal
Where is the coronal suture located?
Between frontal and parietal
Where is the sagittal suture located?
Superior mdiline between pariatal
Where is the lambdoidal suture located?
Posteriorly between occipital bone and both parietal bones
Where is the squamosal suture located?
Lateral part of skull between parietal and temporal bones
What is the Bregma?
Where coronal and sagittal sutures meet, between the frontal and two parietal bones.
What is the Lambda?
Posterior end of sagittal suture
What is the Pterions (Right and Left)?
Junction of the parietal, temporal, and greater wing of sphenoid
Landmark for the middle meningeal artery
What is the Asterions (Right and Left)?
Posterior to the ear where the squamosal, saggital, and lambdoidal sutures meet
What are some important landmarks located on the frontal bone?
five
-Frontal eminences
-Supraorbital margins
-Superciliary arches
-Supraorbital foramina
-Glabella
