Chapter 11

The lateral masses contain the ethmoid ________________ and help to form the medial walls of the _______ and the lateral walls of the ______________.

- air cells or sinuses - orbits - nasal cavity

The central portion of the sphenoid is the ________, which lies in the midline of the floor of the cranium and contains the _________________.

- body - sphenoid sinus

The canals of the sphenoid begin in the center as the _____________________, which leads on each side to an ________________, which ends at the _________________, or the opening into the orbit.

- chiasmatic or optic groove - optic canal - optic foramen

Of the structures of the ethmoid bone, in the sagittal view, the smaller _______________ and _________________ project superiorly, while the larger _____________________ extends inferiorly and forms the upper portion of the bony nasal septum.

- crista galli and cribriform plate - perpendicular plate

The altantoccipital joint forms a pair of ________ joints that allow movements in what directions?

- ellipsoid - flexion, extension, and limited lateral flexion and rotation

What lies below the orbital plates? What lies above them?

- facial bones - anterior part of the floor of the brain case

The first opening in the sphenoid, the ________________, and the second opening, the __________________, are seen as small openings on superior and oblique views of the sphenoid.

- foramen rotundum (29) - foramen ovale (28)

When seen from the lateral view, the temporal bones are situated between the ___________________ anteriorly and the _______________ posteriorly.

- greater wing of sphenoid - occipital bone

Extending laterally from the body to either side are 2 pairs of wings. The smaller pair, termed the ______________, are triangular and are nearly horizontal, ending in 2 processes.

- lesser wings

The second portion of the temporal bones is the area posterior to the EAM, the __________________, which contains a prominent _______________, or _______.

- mastoid portion - mastoid process, or tip

Directly medial to the lateral pterygoid processes, are 2 ____________________, or plates, which end inferiorly in small hooklike processes, called the ________________.

- medial pterygoid processes - pterygoid hamuli

The third main portion of the temporal bones is the dense _________________, which is also called the ___________________, or ______________; it houses the organs of hearing and equilibrium, including the mastoid air cells.

- petrous portion - petrous pyramid - pars petrosa

In the sagittal view of the sphenoid bone, its ______________________ are seen extending down and forward to end with a small pointed process called the ___________________. Inferior and slightly anterior to the sella turcica is a hollow-like body area, which houses the __________________.

- pterygoid processes - pterygoid hamulus - sphenoid sinus

The articulations or joints of the cranium are called ____________ and are classified as ____________ joints.

- sutures - fibrous

Inferior to the zygomatic process and just anterior to the external auditory (acoustic) meatus (EAM) is the __________________________, into which the mandible fits to form the _________________________.

- temporomandibular (TM) fossa - temporomandibular joint (TMJ)

How many bones does the frontal bone articulate with and what are they?

1. R parietal 2. L parietal 3. sphenoid 4. ethmoid

How many bones does the occipital bone articulate with and what are they?

1. R parietal 2. L parietal 3. R temporal 4. L temporal 5. sphenoid 6. atlas (C1)

What 4 structures can be found on the inferior aspect of the frontal bone?

1. SOMs (below A) 2. superciliary ridges (A) 3. glabella (G) 4. frontal tuberosities (above G)

Compared to the parietal bones, where are the following located: 1. frontal bone? 2. occipital bone? 3. temporal bones? 4. greater wings of the sphenoid?

1. anterior 2. posterior 3. inferior 4. inferior and anterior

How many bones do the parietal bones articulate with and what are they?

1. frontal 2. occipital 3. temporal 4. sphenoid 5. opposite parietal

What are the 4 bones of the calvarium (skullcap)?

1. frontal 2. right parietal 3. left parietal 4. occipital

How many cranial bones does the ethmoid bone articulate with and what are they?

1. frontal 2. sphenoid

How many bones does each temporal bone articulate with and what are they?

1. parietal 2. occipital 3. sphenoid

What are the 4 bones of the floor of the cranium?

1. right temporal 2. left temporal 3. sphenoid 4. ethmoid

When looking at the temporal bones from the front, they are divided into 3 sections:

1. squamous 2. mastoid 3. petrous

What makes an infant's skull different than an adult's?

1. the infant skull is very large in proportion to the rest of the body or facial bones 2. at birth, ossification of the cranial bones is incomplete

There are ____ cranial bones and ____ facial bones in the skull.

8 14

What 2 modalities can be used deformities of the sella turcica from the presence of a lesion?

CT and MRI

When viewing the temporal bones from above (superiorly), the single occipital bone resides between them, and this also gives another view of the thickest, densest portion of the bones, the petrous portion. It also shows the petrous pyramids projecting anteriorly and toward the midline from the area of the _______.

EAM

Which bones of the skull are paired, and form part of the roof and lateral walls of the cranium? They are roughly square and have a concave internal surface.

R and L parietals

The paired ____________________ are complex structures that house the delicate organs of hearing and balance.

R and L temporal bones

After birth, some regions of the skull do form sutures, however the areas that are slower to ossify are called ___________.

fontanels

The large opening at the base of the occipital bone through which the spinal cord passes as it leaves the brain is called the

foramen magnum ("great hole")

The last sphenoid foramina, the __________________, is a small rounded opening that is seen on the superior view.

foramen spinosum

The squamous portion of the temporal bones is quite thin and is the most vulnerable portion of the entire skull to

fractures

If viewed from the front, this bone is the most readily visible, and contributes to the formation of the forehead and the superior part of each orbit. This bone consists of 2 parts.

frontal bone

The sagittal view of the cranium also shows a large cavity of the frontal bone called the ___________________, which is located posterior to the glabella.

frontal sinus

On each side of the squamous portion of the frontal bone above the supraorbital groove is a larger, rounded prominence termed the

frontal tuberosity (eminence)

The __________ is the smooth, raised prominence between the eyebrows just above the bridge of the nose.

glabella

The _________________ of the sphenoid extend laterally from the sides of the body and form a portion of the floor of the cranium and a portion of the sides of the cranium.

greater wings

The sella turcica partially surrounds and protects a major gland of the body, the ______________________.

hypophysis cerebri (pituitary gland)

Near the center of the petrous pyramid on the posterior surface just superior to the jugular foramen is an opening or orifice called the ____________________, which serves to transmit the nerves of hearing and equilibrium.

internal acoustic meatus

Why is the supraorbital groove (SOG) important in positioning?

it corresponds to the floor of the anterior fossa of the cranial vault, which is also the level of the *orbital plate*, or highest level of facial bone mass

Posteriorly, the _______________ suture separates the 2 parietal bones from the occipital bone.

lambdoidal

The 2 _____________________ are suspended from the undersurface of the cribriform plate on each side of the perpendicular plate.

lateral labyrinths (masses)

Projecting downward from the inferior surface of the body of the sphenoid are four processes that correspond to the legs of the "imaginary bat;" the more lateral, flat extensions are called the

lateral pterygoid processes (plates)

There are 3 pairs of small openings, or foramina, that exist in the greater wings of the sphenoid for passage of certain cranial nerves. ___________ that can cause erosion of these foramina can be detected radiographically.

lesions

When do cranial sutures ossify completely?

mid-to-late 20's, with some not closing until the 5th decade of life

The inferoposterior portion of the calvarium (skullcap) is formed by the

occipital bone

Between the anterior body and the lesser wings on each side are groove-like canals through which the ________ nerve and certain arteries pass into the orbital cavity.

optic

A portion of the frontal bone, which forms the superior part of the orbit.

orbital or horizontal portion

The _________________, which can be found on each side of the inferior aspect of the frontal bone, forms the superior part of each orbit.

orbital plate

The widest portion of the entire skull is located between the _____________________ of the 2 parietal bones.

parietal tubercles (eminences) [2]

Projecting downward in the midline of the ethmoid is the ____________________, which helps to form the bony nasal septum.

perpendicular plate

The petrous portion of the temporal bones is sometimes also called the _____________________ because it includes the mastoid portion.

petromastoid portion

The upper border or ridge of the petrous pyramids in the temporal bones is commonly called the

petrous ridge, or petrous apex

What are the processes that extend superiorly from the dorsum sellae, and are best seen laterally?

posterior clinoid processes

The right and left _______________ are points at the junction of the frontal, parietals, temporals, and the greater wings of the sphenoid. The points are at the posterior end of the sphenoparietal suture.

pterions

Separating the 2 parietal bones in the midline is the __________ suture.

sagittal

Central depression of the body of the sphenoid is called the _______________, which looks like a saddle from the side, and derives its name from words meaning "Turkish saddle."

sella turcica

The _________, or bony skeleton of the head, rests on the superior end of the vertebral column and is divided into 2 main sets of bones - cranial and facial.

skull

The centrally located __________________ forms the anchor for the other 7 cranial bones. This bone is compared with a bat.

sphenoid bone

The _______________ sutures are formed by the inferior junctions of the 2 parietal bones with their respective temporal bones.

squamosal

A portion of the frontal bone, which forms the forehead.

squamous or vertical portion

The first of the temporal sections is the thin upper portion that forms part of the wall of the skull, called the

squamous portion

The external surface of the occipital bone presents a rounded part called the

squamous portion (4)

Projecting inferior to the mandible and anterior to the EAM is a slender bony projection of the temporal bone called the

styloid process

Extending medially and downward from the medial wall of each lateral labyrinth are thin, scroll-shaped projections of bone called ________________________, which are best shown on facial bone drawings.

superior and middle nasal conchae (turbinates)

Slightly lateral and posterior to the optic foramina on each side are irregularly shaped openings, which are best seen on the oblique view, and are called the ______________________. These openings provide additional communication with the orbits for numerous cranial nerves and blood vessels.

superior orbital fissures

The _________________ is the slight depression above each eyebrow.

supraorbital groove (SOG)

The superior rim of each orbit is the ____________________.

supraorbital margin (SOM)

The __________________ is a small hole or opening within the SOM slightly medial to its midpoint. The supraorbital nerve and artery pass through this opening.

supraorbital notch (foramen)

In an adult, sutures are immovable and therefore are ______________-type joints.

synarthrodial

Which of the clinoid processes is larger and more spread apart than the other?

the anterior processes

What part of the skull changes from a baby to an adult?

the cranial bones fuse together in an adult to form a protective enclosure for the brain

What do the pterygoid processes or plates form part of?

the lateral walls of the nasal cavities

Because the ossification of the cranial bones is incomplete at birth, the spaces between the bones cannot remain open, so what happens after birth?

they become membrane-covered spaces

The zygomatic process meets the temporal process of the zygomatic bone (one of the facial bones) to form the easily palpated

zygomatic arch

Extending anteriorly from the squamous portion of the temporal bone is an arch of bone termed the

zygomatic process

The __________ is a shallow depression that begins on the posteroinferior aspect of the dorsum sellae of the sphenoid bone and extends posteriorly to the foramen magnum at the base of the occipital bone. This forms a base of support for the pons and basilar artery.

clivus

The 2 lateral _____________________, located on the occipital bone, are oval processes with convex surfaces, with one on each side of the foramen magnum.

condylar portions (occipital condyles) [1]

The ____________ suture separates the frontal bone from the 2 parietal bones.

coronal

The small upper horizontal plate of the ethmoid bone that contains many small openings or foramina through which branches of the olfactory nerves (smell) pass is termed:

cribriform plate

Projecting superiorly from the cribriform plate of the ethmoid is the "rooster's comb" also called the

crista galli

Posterior to the sella turcica, is the back of the saddle, the

dorsum sellae

In the sagittal view of the cranium, the ___________ bone is anterior to the sphenoid bone.

ethmoid

This last, single cranial bone lies primarily below the floor of the cranium; only the top of this bone can be seen on a superior view.

ethmoid

Each orbital plate is separated from the other by the __________________, in which a bone of the same name fits into this notch.

ethmoidal notch (C)

The squamous portion forms most of the back of the head and is the part of the occipital bone that is superior to the ________________________, which is the prominent bump or protuberance at the inferoposterior portion of the skull.

external occipital protuberance (inion)

The occipital condyles articulate with depressions on the

first cervical vertebra, atlas

The petrous ridge of these temporal bone pyramids (petrous) corresponds to the level of an important external landmark, the _______.

TEA (top of ear attachment)

The mastoid portion of the temporal bones contains many

air cells

How many cranial bones does the sphenoid bone articulate with and what are they?

all other 7 bones - frontal, 2 parietals, 2 temporals, occipital, and ethmoid

In early life, the bregma and lambda are not bony, but are membrane-covered openings or "soft spots," termed the _____________ and _________________, respectively.

anterior and posterior fontanels

The lesser wings end in these two processes that project laterally from the superoanterior portion of the body of the sphenoid and extend to the middle of each orbit.

anterior clinoid processes

The right and left __________ are points posterior to the ear where the squamosal and lambdoidal sutures meet.

asterions

The two-part articulation between the skull and the cervical spine is called the

atlantoccipital joint

Where does the major portion of the ethmoid bone lie?

beneath the floor of the cranium

Each end of the sagittal suture is identified as a point or area. The anterior end of the sagittal suture is termed the ___________, and the posterior end is called the __________.

bregma lambda

The 8 bones of the cranium are divided into the _______________ and the _______; with each area primarily consisting of 4 bones.

calvarium (skullcap) floor