Rests on the superior aspect of the vertebral columns; composed of 22 separate bones divided into 2 groups
Bones that form a protective house for the brain
2 groups the of cranial bones
Bones that provide structure, shape and support the face and form protective housing for the upper ends of the respiratory and digestive tracts and with several of the cranial bones, form the orbital sockets for protection of the organs of sight
(Calvaria) Frontal 1 Occipital 1 Right parietal 1 Left parietal 1 (Floor) Ethmoid 1 Sphenoid 1 Right temporal 1 Left temporal 1
Frontal 1 Occipital 1 Right parietal 1 Left parietal 1
Ethmoid 1 Sphenoid 1 Right temporal 1 Left temporal 1
Nasal (right and left) 2 Lacrimal (right and left) 2 Maxillary (right and left) 2 Zygomatic (right and left) 2 Palatine (right and left) 2 Inferior nasal conchae (right and left) 2 Vomer 1 Mandible 1
Fibrous joints that connect the bones of the skull (except mandible)
With what bone(s) does the sphenoid bone articulate?
Sphenoid bone articulates with all other cranial bones
Coronal Sagittal Squamosal Lambdoidal
Suture between frontal and parietal bones
Suture on top of head between two parietal bones
Suture between temporal bone and parietal bones
Suture between occipital and parietal bones
Junction of coronal and sagittal sutures
Junction of sagittal and lambdoidal sutures
Areas of incomplete ossification in infant skulls (ex: soft spots)
At what age is adult cranial size usually achieved?
At what angle does a mesocephalic skull's petrous pyramids project anteriorly and medially from the midsagittal plane?
At what angle does a brachycephalic skull's petrous pyramids project anteriorly and medially from the midsagittal plane?
At what angle does a dolichocephalic skull's petrous pyramids project anteriorly and medially from the midsagittal plane?
Skull that is short from front to back and broad from side to side
3 regions cranial floor is internally divided into
Anterior cranial fossa Middle cranial fossa Posterior cranial fossa
Extends from the anterior frontal bone to the lesser wings of the sphenoid; associated mainly with the frontal lobes of the cerebrum
Accommodates the temporal lobes and associated nuerovascular structures and extends from the lesser wings of the sphenoid bone to the apices of petrous portions of the temporal bones
Deep depression posterior to the petrous portions of the temporal bones, protects cerebellum, pons and medulla oblongata
Vertical portion of frontal bone, forms forehead and anterior part of cranial vault
Has vertical portion (frontal squama) and horizontal portions
3 things frontal bone forms
Orbital plates Part of the roof of the naval cavity Greater part of anterior cranial fossa
6 landmarks on the frontal bone
Frontal eminences Supraorbital margins Supraciliary arches Supraorbital foramina Glabella Nasal spine
Rounded elevations on each side of the midsagittal plane of the superior portion of the squama of the frontal bone
Two arched ridges below the frontal eminences and just above the supraorbital margins that correspond in position to the eyebrows
Two openings for nerves and blood vessels in the center of the supraorbital margin (frontal bone)
Smooth elevation between the superciliary arches of the frontal bone used as centering mark
Small inferior projection of bone at the anterior edge of the ethmoidal notch of the frontal bone; superior-most component of the bony nasal septum
Situated between the two tables of the squama of the frontal bone on each side of the midsagittal plane These irregularly shaped sinuses are separated by a bony wall which may be incomplete and usually deviates from the midline
3 things the frontal squama articulates with
Parietal bones at the coronal suture Greater wing of these sphenoid bone at the frontosphenoidal suture Nasal bones at the frontonasal suture
Midpoint of the frontonasal suture
5 things the frontal bone articulates with
Right and left parietals Sphenoid Ethmoid Nasal bones Zygoma
Small, cube-shaped bone at the midsagittal plane located between the orbits
3 things the ethmoid bone consists of
Horizontal plate Vertical plate Labyrinths
4 things the ethmoid bone forms
Part of anterior cranial fossa Nasal cavity Orbital walls Bony nasal septum
Horizontal portion of the ethmoid bone that is received into the ethmoidal notch of the frontal bone; perforated by many foramina for the transmission of olfactory nerves
Thick, conical process on cribriform plate of the ethmoid bone that projects superiorly from its anterior midline and serves as the anterior attachment for the falx cerebri
Vertical portion of the ethmoid bone; thin flat bone that projects inferiorly from the inferior surface of the cribriform plate and, with the nasal spine, forms the superior portion of the bony septum of the nose
Two light, spongy lateral masses of the ethmoid bone Contain ethmoid sinuses or air cells
3 groups cells of each side of the ethmoid sinuses are divided into in the labyrinths
Anterior Middle Posterior ethmoidal air cells
Two thin, scroll shaped processes the project inferiorly from each medial wall of the labyrinths of the ethmoid bone
Superior and middle nasal conchae
5 bones the ethmoid bone articulates with
Frontal Sphenoid Lacrimal Maxilla Vomer
Two square-shaped bones that have a convex external surface and a concave internal surface Form a large portion of the sides of the cranium and the posterior portion of the cranial roof by their articulation with each other at the sagittal suture in the MSP
Prominent bulge on each parietal bone near the center of external surface of each bone Point where the width of the skull should be measured to set technique because it’s the widest point of the head
5 bones the parietal bones articulate with
With each other at sagittal suture in MSP Frontal Temporal Occipital Sphenoid
Irregular, wedge-shaped bone that resembles a bat with its wings extended (somewhat) Located in base of cranium anterior to temporal bones and basilar portion of occipital Body contains two sphenoid sinuses (incompletely separated by a median septum) and anterior surface forms posterior bony wall of nasal cavity
7 things the sphenoid bone consists of
Body 2 lesser wings 2 greater wings 2 pterygoid process
Deep depression (saddle) on superior surface of body of the sphenoid bone that houses pituitary gland
Where is the sella turcica located?
Located on sphenoid bone in MSP of cranium 3/4 in (1.9 cm) anterior and superior to the level of the external acoustic meatus (EAM)
Anterior border of sella of the sphenoid
Posterior border of sella of the sphenoid that bears the posterior clinoid processes
Top borders of dorsum of the sphenoid
Posterior clinoid processes
Slanted area of bone posterior and inferior to the dorsum sellae of the sphenoid Continuous with basilar area of occipital Supports pons of the brain
Extends across the anterior portion of the tuberculum sellae of the sphenoid and ends on each side at the optic canal
Opening of the sphenoid into the apex of the orbit for the transmission of optic nerve and ophthalmic artery
Actual opening of the optic canal of the sphenoid
Triangular in shape and nearly horizontal in position; arise, one on each side, from the anterosuperior portion of the body of the sphenoid bone and project laterally, ending in sharp points Medial ends form the anterior clinoid processes
Lesser wings of the sphenoid bone
4 things the lesser wings of the sphenoid bone form
Posteromedial portion of orbital roofs Posterior portion of anterior cranial fossa Upper margin of the superior orbital fissure Optic canals
Arise from the sides of the body of the sphenoid bone and curve laterally, posteriorly, anteriorly and superiorly
Greater wings of the sphenoid bone
4 things the greater wings of the sphenoid bone form
Part of the middle cranial fossa Posterolateral walls of the orbits Lower margin of the superior orbit sulci The greater part of the posterior margin of the inferior orbital sulci
3 paired foramina situated on greater wings of the sphenoid bone
Arise from lateral portion of inferior surface of the body of sphenoid bone and medial portions of inferior surfaces of greater wings; project inferiorly and curve laterally
2 plates of bone each pterygoid process of the sphenoid consists of
Medial and lateral pterygoid laminae which are fused at their superoanterior parts
Elongated, hook-shaped process on inferior extremity of medial lamina of the sphenoid that makes it look longer and narrower than lateral lamina
2 things the pterygoid processes of the sphenoid articulate with
Palatine bones anteriorly Wings of the vomer where they enter into the formation of the nasal cavity
What does the sphenoid bone articulate with?
ALL other cranial bones and the zygoma
Bone situated at posteroinferior part of cranium
2 things the occipital bone forms
Posterior half of cranial base Greater portion of posterior cranial fossa
4 parts of the occipital bone
Squama Two occipital condyles Basilar portion
Saucer-shaped, being convex externally; curves posteriorly and superiorly from foramen magnum and is curved from side to side
2 things the squama of the occipital bone articulates with
Parietal bones at lambdoidal sutures Mastoid portions of temporal bones at occipitomastoid sutures
Extend anteriorly, one on each side of the foramen magnum of the occipital bone; articulate with C1 and make it able to move head
Curves anteriorly and superiorly to its junction with the body of the sphenoid In an adult, this part of the occipital bone fuses with the body of the sphenoid bone, resulting in the formation of a continuous bone
Large aperture/opening through which inferior portion of medulla oblongata passes as it exits cranial cavity and joins spinal cord
Prominent process on external surface of squama of the occipital, midway between its summit and the foramen magnum; corresponds in position with internal occipital protuberance
External occipital protuberance/inion
Project anteriorly, one from each side of squama of the occipital, for articulation with atlas of c-spine Part of each lateral portion curves medially to fuse with basilar portion and complete the foramen magnum and part of part of it projects laterally to form the jugular process
On the inferior surface of the curved parts, extending from the level of the middle of the foramen magnum anteriorly to the level of its anterior margin, reciprocally shaped condyles articulate with superior facets of the atlas Only bony articulations between the skull and neck
Found at anterior ends of the condyles of the occipital and transmit hypoglossal nerves
Emissary veins pass through these parts of the occipital
Anterior portion of occipital bone contains a deep notch that forms part of this
2 reasons jugular foramen of the occipital is an important large opening
Allows blood to drain from the brain via internal jugular vein Lets three cranial nerves pass through it
4 things the occipital bone articulates with
Two parietals Two temporals Sphenoid Atlas (C1)
Irregular in shape bones that are situated on each side of the cranial base between the greater wings of the sphenoid and occipital bone
2 things the temporal bones form
Large part of the middle cranial fossa Small part of the posterior cranial fossa
5 things the temporal bones consist of
Squamous portion Tympanic portion Styloid process Zygomatic process Petromastoid portion
Thin upper portion of temporal bone, thinnest area of skull; forms part of side wall of cranium
Slender, pointed bone of variable length projecting inferiorly from the temporal bones, anteriorly and slightly medially from inferior surface of tympanic portion
Mastoid and petrous portions of the temporals which contains the organs of hearing and equilibrium/balance
Prominent arched process on the squamous portion of the temporals that projects anteriorly to articulate with zygomatic bone of the face and complete the zygomatic arch
Rounded eminence on inferior border of zygomatic process of the temporals, forms anterior boundary of mandibular fossa
Part of the temporals that receives condyle of mandible to form temporomandibular joint (TMJ)
Located below squama and in front of mastoid and petrous portions of temporal bone Forms anterior wall, inferior wall, and part of the posterior walls of the external auditory meatus (EAM)
What size is the external auditory meatus (EAM) of the temporals?
EAM approximately 1/2 in (1.3 cm) in length and projects medially, anteriorly and slightly superiorly
Forms the inferior posterior part of temporal bone and is prolonged into the conical mastoid process Usually contains air cells, which vary greatly in size, number and pneumatization
2 things the mastoid portions of the temporals articulate with
Parietal bone at its superior border through the parietomastoid suture Occipital bone at its posterior border through the occipitomastoid suture, which is contiguous with the lambdoidal suture
Conical process projecting from mastoid portion of the temporals that varies considerably in size, depending on its pneumatization and is larger in males than in females
Conical or pyramidal in shape and is the thickest and densest portion of cranium Contains the organs of hearing and balance From its base at the squamous and mastoid portions of the temporals, it projects medially and anteriorly between the greater wing of the sphenoid and the occipital to the body of the sphenoid, with which its apex articulates Internal carotid artery in carotid canal enters the inferior aspect of the petrous portion, passes superior to the cochlea, then passes medially to exit the petrous apex
Ragged foramen near petrous apex of the temporals the carotid canal opens into; contains internal carotid artery
Located at the center of posterior aspect of petrous portion of the temporals, transmits the vestibulochochlear and facial nerves
Internal acoustic meatus (IAM)
Upper border of petrous portion of the temporals
5 things the temporal bone articulates with
Parietal Occipital Sphenoid Zygoma Mandible
6 lines starting from EAM
Orbitomeatal line (OML) Infraorbitalmeatal line (IOML) Glabellomeatal line (GML) Acanthiomeatal line (AML) Mentomeatal line (MML) Inter pupillary line (IPL)
Line from outer canthus to EAM, used most often
Line from infraorbital margin to EAM, second most used
Infraorbitalmeatal line (IOML)
Line from glabella to EAM
Glabellomeatal line (GML)
Line from acanthion to EAM
Acanthiomeatal line (AML)
Line from mental point to EAM
Perpendicular line between pupils of eyes (not at EAM)
Inter pupillary line (IPL)
Part position for lateral (right or left) cranium
MSP of head parallel to IR IPL perpendicular to IR IOML parallel to transverse axis of cassette; IOML also should be perpendicular to the front edge of the cassette
CR of lateral (right or left) cranium
Perpendicular to center of IR Enters 2 in (5 cm) superior to EAM
3 evaluation criteria of lateral skull
Superimposed orbital roofs and greater wings of sphenoid Superimposed TMJs Sella turcica in profile
Patient and part position for PA/PA axial cranium (Caldwell method)
Forehead and nose resting (maybe) on table or upright OML perpendicular to IR plane MSP perpendicular to IR IR centered to nasion
Perpendicular, exits nasion
CR for PA axial of cranium (Caldwell method)
Angled 15 degrees caudad Exits nasion
3 evaluation criteria of PA/PA axial cranium (Caldwell method)
Equal distance from lateral borders of skull to lateral border of orbits Symmetric petrous ridges Entire cranial perimeter showing three tables of squamous bone
What is the difference between the petrous ridges on the PA and PA axial cranium (Caldwell method) projection?
PA projection shows orbits filled w/petrous ridges PA axial (Caldwell) demonstrates petrous pyramids lying in lower third of orbit
Patient and part position for AP/AP axial of cranium
Provides similar but magnified image when patient can’t be positioned for PA or PA axial projection, supine MSP and OML perpendicular to IR
CR of AP/AP axial of cranium
Perpendicular or 15 degrees cephalic for AP axial Enters nasion
Patient and part position for AP axial of cranium (Towne method)
Supine or seated erect MSP centered to midline MSP perpendicular to midline of IR OML or IOML perpendicular (if they can’t get OML perpendicular, then use IOML) IR top border level w/skull vertex
CR of AP axial of cranium (Towne method)
Directed thru foramen magnum OML = 30 degrees caudal IOML = 37 degrees caudal Enters 2.5 in (6.3 cm) above the glabella & passes through the level of the EAM
What degree difference is there between OML and IOML
How do you compensate distance for when the tube is angled?
Have to compensate distance for tube angle greater than or equal to 15 degrees by bringing distance of tube down. For every 5 degrees, bring tube down 1 in
3 evaluation criteria for AP axial of cranium (Towne method)
Equal distances from lateral border of skull to lateral margin of foramen magnum Symmetric petrous ridges Dorsum sellae and posterior clinoid processes visible with foramen magnum
Patient position for PA axial of cranium (Haas method)
Prone or seated upright MSP centered to midline Shoulders in same horizontal plane
Part position for PA axial of cranium (Haas method)
Forehead and nose on table MSP perpendicular OML perpendicular to IR
CR of PA axial of cranium (Haas method)
Directed cephalad at 25 degree angle to OML Enters at a point 1.5 in (3.8 cm) below external occipital protuberance (inion) Exits 1.5 in (3.8 cm) superior to nasion
2 evaluation criteria for PA axial of cranium (Haas method)
Equal distances from lateral borders of skull to lateral margins of foramen magnum on both sides Projection of dorsum sellae and posterior clinoid processes within foramen magnum
Patient and part position for SMV projection of cranium (Schuller Method)
Success depends on placing the IOML as nearly parallel within the plane of the IR as possible and directing the CR perpendicular to the IOML Seated upright or supine (torso elevated if supine) MSP centered to midline IOML parallel with IR MSP perpendicular to IR
CR of SMV projection of cranium (Schuller Method)
Through sella turcica perpendicular to IOML Enters MSP of throat between angles of mandible Passes through a point 3/4 in (1.9 cm) anterior to level or EAM Center IR to CR
4 evaluation criteria for SMV projection of cranium (Schuller Method)
Equal distance from lateral border of skull to mandibular condyles Symmetric petrous pyramids Superimposition of mental protuberance over anterior frontal bone, indicating full neck extension Mandibular condyle anterior to petrous pyramids
On lateral aspect of skull junction of parietal bone, squamosal suture and greater wing of sphenoid which overlies middle meningeal artery
At junction of occipital, parietal and mastoid portion of temporal bone
2 of the fontanels are situated in the MSP at the superior and posterior angles of the parietal bones
Anterior fontanel Posterior fontanel
Located at junction of the two parietal bones and the frontal bone at the bregma Close during the 2nd year of life
Lambda, posteriorly and in MSP Normally close in the 1st and 3rd months after birth
2 fontanels on each side at the inferior angles of parietal bones
Sphenoidal fontanels Mastoid fontanels
Found at site of pterion Normally close in the 1st and 3rd months after birth
Found at asteria Close during the 2nd year of life
Where do the top of the petrous pyramids lie?
Approximately at the level of an external radiography landmark called the top of ear attachment (TEA)