cranium, facial bones, paranasal sinuses

the skull rest on the __ of the vertebral column

superior end

two main sets of skull bones and how many

1. cranial bones (8)

2. facial bones (14)

cranial bones can be divided into what two things

1. calvaria (skull cap)

2. floor

bones in the cranial bone calvaria

4 bones

1. frontal

2. right parietal

3. left parietal

4. occipital

bones of the cranial bone floor

4 bones

1. right temporal

2. left temporal

3. sphenoid

4. ethmoid

some cranial bones articulate with how many facial bones

14

most readily visible cranium bone

frontal

what cranium bone contributes to the formation of the forehead and superior part of each orbit

frontal

two main parts of frontal bone

1. squamous or vertical portion (forehead)

2. orbital or horizontal portion (superior portion of orbits)

what is the glabella

the smooth, raised prominence between the eyebrows above the bridge of the nose

what does the squamous portion consist of

• glabella

• supraorbital groove (SOG)

• supraorbital notch

• frontal tuberosity

what is the supraorbital groove (SOG)

a slight depression just above each eyebrow

• above is a prominence called frontal tuberosity

why is the supraorbital groove an important landmark

• corresponds to the floor of the anterior fossa of the cranial vault

• the highest level of facial bone mass at the level of orbital plate

what is the superior rim

supraorbital margin (SOM)

• small opening on SOM is supraorbital notch, allows supraorbital nerve and artery to pass

what can be seen on the orbital portion inferior view

glabella, superciliary ridges (eyebrows), and frontal tuberosities

what forms the superior part of each orbit

orbital plate on each side

each orbital plate is separated from the other by the

ethmoidal notch

the frontal bone articulations of cranial bones (4)

1. right parietal

2. left parietal

3. sphenoid

4. ethmoid

the parietal bone forms what two things

1. lateral walls of cranium

2. part of the roof of cranium

surface and shape of the parietal bones

concave internal surface and square shaped

widest portion of skull is located

between the parietal tubercles of two parietal bones

what is anterior, posterior, inferior, and infero-anterior of parietal bones

anterior: frontal bone

posterior: occipital

inferior: temporal

infero-anterior: greater wings of the sphenoid bone

parietal bone articulations of cranial bones (5)

1. frontal

2. occipital

3. temporal

4. sphenoid

5. parietal bone of other side

the occipital forms what part of skull cap

the infero-posterior portion of skull cap

what’s the external surface of the occipital bone

a rounded part called squamous portion

• forms most of the back of the head

what is the inion of the occipital bone

• aka external occipital protuberance

• prominent bump at infero-posterior portion of skull

the occipital bone contains a large opening at its base called the

foramen magnum -  where spinal cord passes as it leaves brain

what is the occipital condyles

• two lateral condylar portions

• oval processes

• convex surfaces on each side of foramen magnum

what does the occipital condyles artiulate with

the atlas of the C spine

atlantoocipital joint is formed by the artiulcations of

• skull

• c spine joint

occipital bone articulates with how many CRANIAL BONES AND IN GENERAL

cranial bones: 5

in general: 6

1. atlas

2. sphenoid

3. right temporal bone

4. left temporal bone

5. right parietal bone

6. left parietal bone

temporal bones house the organs of

hearing and balance

an important extension from temporal bone is called the

zygomatic process

anterior portion from squamous portion

zygomatic process

what creates the zygomatic arch (cheekbonee)

zyogmatic proccess articulates with temporal process of zygoma

inferior of zyogmatic process AND anterior to EAM (temporal bone lateral view)

temporomandibular fossa

what forms the temporomandibular joint (TMJ)

mandible articulates with TM fossa

posterior to mandible AND anterior to the eam is a bony projection called

styloid process

temporal bone is divided into three primary portions

1. squamous

2. mastoid

3. petrous

most vulnerable bone to fracture in skull

temporal bone - squamous portion

most thickest and dense bone in cranium

petrous pyramid of temporal bone

petrous pyramid projects

anterior and toward midline from area of EAM

topographic landmarks: petrous ridge corresponds to the level of 

top of the ear (TEA)

temporal bone articulates with 3 other cranial bone

1. sphenoid (anteriorly)

2. occipital (posteriorly)

3. parietal (superior and posterior)

sphenoid bone shape

bat shaped

sphenoid bone is located and forms

• centrally and lies in midline of the floor of the cranium

• forms anchor of 7 other cranial bones

central portion of sphenoid is the and contains

• body

• contains sphenoid sinus

central depression body of sphenoid

sella trecica

• looks like a saddle from lateral view

• two anterior clinoid processes and two posterior clinoid processes

• surrounds pituitary gland

posterior to sella turcica is the back of the saddle called

dorsum sellae

posteroinferior aspect of dorsum sellae is

a clivus

• small shallow depression

• extends posterior to foramen magnum at base of occipital bone

what extends laterally from sphenoid bone

greater and lesser wings

• lesser wings are triangle and end medially in two anterior clinoid processes

• greater wings extend lateral from sides of body and form portion floor/side of cranium

three pairs of openings (foramina) present in greater wings

1. foramen rotundum (maxillary nerve)

2. foramen ovale (mandibular nerve)

3. foramen spinosum (menningeal artery and spinous nerve)

sphenoid phone articulations cranium

1. frontal

2. left parietal bone

3. right parietal bone

4. occipital bone

5. right temporal bone

6. left temporal bone

7. ethmoid bone

ethmoid bone lies below the

floor of the cranium

small upper horizontal portion of ethmoid bone is called

cribiform plate

• contain small openings where branches of olfactory nerves passes

crista galli of ethmoid bone

• project superior from cribiform plate

major portion of ethmoid bone lies beneath

floor of cranium

projecting downard in midline of ethmoid bone is

perpendicular plate

• helps form. bony nasal septum

what is suspended from undersurface of cribiform plate on each side of perpendicular plate of ethmoid

two lateral labyrinths

what extends medially and downward from medial wall of each labyrinth

superior and middle nasal conchae

ethmoid bone articulates with CRANIAL AND FACIAL BONES

• cranial: 2 (frontal, sphenoid)

• 11 facial bones

how many facial bones are there, and how much are single bones

14 facial bones, 2 single bones

all facial bones

1. 2 maxillae (maxillary bones)

2. 2 zygomatic

3. 2 lacrimal

4. 2 nasal

5. 2 inferior nasal conchae

6. 2 palatine

7. 2 vomer

8. 1 mandible

largest immovable bone in face

2 maxillae

only facial bone larger than the maxilla

mandible

right and left maxillary bones are solidly united at midline just below the

nasal septum

maxilla assists formation of 3 cavities in face

1. mouth

2. nasal cavity

3. orbit

each maxilla consists of a body, and __ processes that project from body

4

4 process that project from body of maxilla

1. frontal: projects upward along lateral border of nose towards frontal bone

2. zygomatic: projects laterally and articulates with zygoma

3. alveolar process: inferior aspect of body of each maxillary bone

4. palatine: form anterior portion of roof called hard palate

the palatine process can only be demonstrated on which view of the maxilla

inferior

what is a cleft palate

• common congenital defect

• opening between palatine processess that is caused by incomplete joining of the two bones

maxillary bones unite at the

midline anteriorly

upper part of union is the

anterior nasal spine

superior aspect of the anterior nasal spine

acanthion (also used as a positioning landmark)

• midline point where nose and upper lip meet

maxilla articulations

2 cranial bones: frontal, ethmoid

7 facial bones

zygomatic bone can be found

laterally to the zygomatic process of each maxilla

zyomatic bones form

• prominence of cheeks

• lower outer portion of orbits

slender process that connects zygomatic process and temportal bone to form

zygomatic arch

what bone can be easily fractured by a blow to the cheek

zygomatic arch

zyomatic bone articulations

3 cranial bones: frontal, sphenoid, temporal

1 facial bone: maxilla

most fragile bone in the entire body

lacrimal and nasal bones, since theyre so thin

size of lacrimal bones

shape of a finger nail

the lacrimal bones lie

anteriorly on medial side of each orbit, posterior to the frontal process of maxilla

what does lacrimal mean and why is it important in the lacrimal bones

tear - bc closely associated with tear ducts

what do the nasal bones form

bridge of the nose and variable in size

point of junction of nasal bones with frontal bone (positioning landmark)

nasion

lacrimal bone articulates with two cranial bones and two facial bones

2 cranial: frontal, ethoid

2 facial bones: maxilla, inferior nasal conchae

nasal bones articulate with two cranial bones and two facial bones

2 cranial: frontal, ethmoid

2 facial: maxilla, adjacent nasal bone

what is the inferior nasal conchae

• in the nasal cavity, project from lateral walls on each side and extend medially

• two platelike, curved facial bones

• aka turbinates (cleanse and humidify air as it enters nose)

three pairs of nasal conchae

1. superior (part of ethmoid)

2. middle (part of ethmoid)

3. inferior (consist separate facial bones)

nasal conchae divides what into various compartments

nasal cavities

• break up flow of air coming into nasal cavities before it reaches lungs

• incoming air is warmed and cleaned as it comes in contact w/ mucous membrane that covers conchae

why are the two palatine bones difficult to visualize

they are located internally, not visible from outside

unique shape appearance of the palatine bone

L shape

• vertical portion extends upward btwn one maxilla and one pterygoid plate (sphenoid bone)

• horizontal portion makes up posterior portion of hard palate

inferior nasal concha articulations

1 cranial bone: ethmoid

3 facial bones: maxilla, lacrimal, palatine

palatine bone articulations

2 cranial bones: sphenoid, ethmoid

4 facial bones: maxilla, inferior nasal conchae, vomer, adjacent palatine

what is the vomer

• thin, triangle shaped

• forms inferoposterior part of nasal septum

• deviation occurs at junction between septal cartilage and vomer

vomer articulations

2 cranial: sphenoid, ethmoid

4 facial: maxillae, palatine bones

only movvable bone in the adult skull

mandible

largest facial bone in the skull

mandible

mandible in adult vs birth

• single bone in adult

• two separate bones at birth (join at 1)