Chapter 11 - Skull Flashcards
How many bones are in the skull
8 cranial
14 facial
What bones make up the skull cap
Frontal
Right Parietal
Left Parietal
Occipital
What bones make up the skull floor
Right Temporal
Left Temporal
Sphenoid
Ethmoid
What part of the frontal bone forms the forehead
Squamous or vertical portion
What is the smooth raised prominence between the eyebrows and above the bridge of the nose
Glabella
What is the slight depression above reach eyebrow
Supraorbital Groove
What is directly below each eyebrow
Supercilliary arch
What is the superior rim of each orbit
Supraorbital margin
What is the small foramen in the supraorbital margin
Supraorbital notch
What goes through the superorbital notch
An artery and a nerve
What are large prominences of the squamous portion of the frontal bone
Frontal tuberosity
The orbital or horizontal portion of the frontal bone can be better viewed from the ________ aspect
Inferior
What forms the superior part of the orbit
Orbital plate
What lies below the orbital plate
Facial bones
What is above the orbital plate
Anterior part of the floor of the brain case
Each orbital plate is separated by the ________ _____
Ethmoid notch
What makes up the lateral walls and roof of the cranium
Parietal bones
What makes up the widest portion of the skull
Parietal tubercles
What is the inferopostior portion of the calvarium
Occipital bone
What is the external surface of the occiptial bone
Squamous portion
The squamous portion of the occipital bone is superior to the ________ _____________
Occipital protuberance
Occipital protuberance is also known as the
Inion
Inferior to the inion is the _______ _______
Foramen magnum
What does foramen magnum mean
Great hole
What passes through the foramen magnum
Spinal cord
Two part articulation between the skull and the cervical spine is called the ______-______ joint
Atlantoccipital joint
What are the 3 primary parts of the temporal bones
Squamous, mastoid, and petrous portion
Temporal bones house complex structures of ___________ and ________
Hearing and balance
What starts from the temporal bone and extends anteriorly to one of the facial bones
Zygomatic process
What is the EAM
External Auditory Meatus
Where is the TMJ located
Inferior to the zygomatic process
Anterior to EAM
What is the slender bone projection between the mandible and EAM
Styloid process
What portion of the temporal bone is thin and very vulnerable to fracture
Squamous portion
What portion of the temportal bone is posterior to the EAM
Mastoid portion
What makes up the upper portion of the petrous pyramid
Petrous ridge
What is the thickest, most dense bone in the cranium
Petrous pyramid
Petrous pyramids house organs of _________
Hearing and equilibrium
Level of the petrous pyramids are at the level of the _____
TEA (top of ear attachment)
What are the two foramen called of the petrous pyramid
Jugular foramen
What is the opening superior to the jugular foramen
Internal acoustic meatus
Internal acoustic meatus tranmits the nerves of ______ and ______
Hearing and equilibrium
What bones forms the anchor for all 8 cranial bones
Sphenoid
What is the central depression of the body of the sphenoid bone
Sella Turcica
What gland does the sella turcica partially surround and protect
Pituitary gland or hypophysis cerebri
What is seen in the back of the sella turcica in a lateral view
Dorsum sallae
The clivus forms the base of support for the ____ portion of the brain and the _____ artery
Pons
Basilar
The lesser wings of the sphenoid bone end ______ and forms the _______
Medially
Anterior clinoid process
Between the lesser wings and the anterior bodies are groove like canals which begin the:
Optic groove
Where does the optical groove end
Optic foramen
What view are optic foramen seen
PA obliques of the orbits
What extends from the sides of the sphenoid body and forms a portion of the cranium floor
Greater wings
What are the 3 foramen located on the greater wings
Foramen rotundum
Foramen ovale
Foramen spinosum
Where does the ethmoid bone lie
Mostly beneath the floor of the cranium
The ethmoid bone sits in the ____ ____ of the frontal bone
Ethmoid notch
What is the small horiztonal portion of the ethmoid
Cribiform plate
The cribiform plate contains many small openings for:
Olfactory nerves
What is the small projection from the cribiform plate tht is similar to a roosters comb
Crista galli
Projecting downwards in the midline of the ethmoid is the:
Perpendicular plate
What does the perpendicular plate of the ethmoid help form
Nasal septum
What is suspended from the undersurface of the cribiform plate
2 lateral labyrinths (masses)
The ethmoid lateral masses contain:
Ethmoid air cells
What do the ethmoid lateral masses help to form
Medial orbital walls
Lateral walls of the nasal cavity
What extends from each labyrinth
Superior and middle nasal conchae
What does the coronal suture separate
Frontal and two parietals
What does the Sagittal suture separate
Two parietals from midline
What does the Lambdoidal suture separate
Two parietals from occipital
What does the Squamosal suture separate
Inferior junction of each parietal bone with their respective temporal bone
Anterior end of the sagittal suture
Bregma
Posterior end of the sagittal suture
Lambda
Points at the junctions between the sphenoid, temporals, and parietals
Pterions
Posterior to the ear where the squamosal and lamboidal sutures meet
Asterions
What makes up the external ear
Aurical
EAM
The Aurical channels ________ ________ to the EAM
Sounds waves
Where does the EAM end
Tympanic membrane (eardrum)
The actual tube like portion of the EAM is called the
Acoustic canal
Middle ear contains:
Air
Where is the middle ear located
Between the eardrum and the inner ear
What are the 3 small bones called of the middle ear
Auditory ossicles
Function of auditory ossicles
Trasmit sound interactions from eardrum to the oval window of the internal ear
What are the 3 bones of the auditory ossicles
Malleus
Incus
Stapes
Which auditory ossicle is slightly anterior and the most lateral
Malleus
What auditory ossicle is located in the middle of the malleus and the stapes
Incus
What auditory ossicle is the most medial
Stapes
What auditory osscile connects to the oval window of the cochlea
Stapes
The tympanic cavity is located in what part of the ear?
Middle
What is the superior portion of the tympanic cavity
Epitympanic attic
The tympanic cavity proper communicates with which part of the pharynx through the auditory tube
Nasopharynx
How long is the eustation tube
4 cm
Function of the eustation tube
Equalizes pressure between the middle ear and outside pressure
What part of the ear do ear infections occur
Eustation tube
What part of the ear is attached to the drumcrest
Tympanic membrane
What separates the EAM from the epitympanic recess
Drum crest
The second communication to the middle ear occurs posteriorly to the mastoid air cells
Mastoids
Opening between the mastoid air cells and epitympanic recess
Aditus
The Aditus connects directly to the:
Antrum
What is the large chamber before the air cells
Antrum
What causes encephalitis
Infection crosses from the middle ear to the mastoid area
What is the small bone separating the mastoid air cells from the brain
Tegmen tympani
What makes up the osseous bony labyrinth of the inner ear
Cochlea, vestibule, and semicircular canals
Internal ear contrains both sensory apparatus for _______ and _______
Hearing and equilibrium
What part of the inner ear houses a long tubelike duct of the membranous labyrinth
Cochlea
What part of the inner ear is the most anterior
Cochlea
What part of the inner ear has a round window at the base of it
Cochlea
What part of the inner ear is related to hearing
Cochlea
What part of the inner ear is the central portion which contains the oval window
Vestibule
What part of the inner ear is related to sense of equilibrium and direction
Semicircular canals
How are the semicircular canals named
According to position - superior, posterior and lateral
Each semicircular canal is located at what type of angle to each other
Right angle
Frontal bone articulations
Right parietal
Left parietal
Sphenoid
Ethmoid
Parietal bone articulations
Frontal
Occipital
Temporal
Sphenoid
Opposite parietal bones
Occipital bone articulations
Two parietals
Two temporals
Sphenoid
Atlas
Temporal bone articulations
Parietal
Occipital
Sphenoid
Sphenoid bone articulations
All seven cranial bones
Ethmoid bone articulations
Frontal
Sphenoid
What are the soft spots in an infant
Anterior and posterior fontanels
How big is the anterior fontanel and when does it close
1” wide
1.5” long
18 months
What does the anterior fontanel turn into
Bregma
What does the posterior fontanel turn into
Lambda
What does the right sphenoid fontanel turn into
Right pterion
What does the left sphenoid fontanel turn into
Left pterion
What does the right mastoid fontanel turn into
Right asterion
What does the left mastoid fontanel turn into
Left asterion
What is perp to the IR in a Townes 30 degree position
OML
What is seen in a Townes 30 degree position?
Occipital bone, petrous ridges above orbits, and dorsum sallae/posterior clinoid processes visuaulized in foramen magnum
What causes dorsum sallae to be superior to foramen magnum in a 30 degree Townes position?
Underangulation/insufficient flexion
What causes superimposition of the posterior arch of C1 and dorsum sallae in a 30 degree Townes position?
Overangulation/excessive neck flexion
What is perp to the IR in a lateral skull position?
IPL and IOML
What is parallel to the IR in a lateral skull position?
GAL
What is in profile in a lateral skull position?
Sella turcica and dorsum sallae
What causes anterior/posterior separation of the mandibular ramis in lateral skull position
Rotation
What causes inferior/superior sepration of orbital plates and greater wings in lateral skull position
Tilt
What is perp to IR in PA Axial?
OML and MSP
What is seen in a PA Skull projection?
Occipital bone, petrous ridges fill orbits
Where are petrous ridges in a Caudwell 15 degree?
Bottom 1/3 of orbit
Where are petrous ridges in a Caudwell 30 degree?
Below orbit
What are the two main parts of the frontal bone
Squamous/vertical portion
Orbital/horizontal portion
What makes up the squamous portion of the frontal bone
Glabella
Supraorbital Groove
Supraorbital Margin
Superorbital Notch
Frontal Tuberosity
What makes up the horizontal portion of the frontal bone
Supraorbital margin
Supraciliary ridges
Glabella
Frontal tuberositites
Orbital plate
Where are the greater wings of the sphenoid bone compared to the parietal bones
Inferior and anterior
What type of joint is the atlantoccipital joint
Ellipsoidal
Where are the occipital condyles located?
On each side of the foramen magnum
Names of the petrous portion
Petrous pyramid
Pars petrosa
Petromastoid portion
What cranial nerves pass thorugh the jugular foramen
9, 10 and 11
The posterior clinoid processes extend superiorly from the:
Dorsum sallae
What are the four processes extending from the body of the sphenoid
Lateral pterygoid processes (plates)
Medial pterygoid processes
What is the small hooklike process extending from the medial pterygoid process
Pterygoid hamulus
What are the small irregular bones that develop in adult skull sutures
Sutural or wormian bones
Where are sutural/wormian bones most often found
Lambdoidal suture
What is the small liplike structure located anterior to the EAM and acts like a partial shield
Tragus
What is the size of the EAM and what is is made up of
1” long
Half bony structure, half cartilage
3 main parts of the middle ear
Tympanic membrane
Auditory ossicles
Tympanic cavity
What are the two parts of the tympanic cavity
Tympanic cavity proper
Epitympanic recess (attic)
What separates the EAM from the epitympanic recess
Drum crest
2 parts of the internal ear
Osseous/bony Labyrinth
Membranous labyrinth
What is the membranous labyrinth
A series of intercommunicating ducts and sacs
What is the endolymphatic duct?
A blind pouch or closed duct contained in a small, canal-like, bony structure
Function of the oval window
Receives vibrations from the external ear through the stapes and transmits these vibrations to the internal ear
Function of the round window
Allows movement of fluid within the closed duct system
The shape of the average head is termed:
Mesocephalic
What is the width to length percentage for mesocephalic
Width is 75-80% of length
What is the width to length percentage for brachycephalic
80% or greater than length
What is the width to length percentage for dolichocephalic
Less than 75% of the length
What is the average angle between the petrous pyramids and the MSP
47 degrees
What structures of the sphenoid bone help form part of the lateral walls of the nasal cavity
Medial and lateral pterygoid processes
What is perpendicular in Haas projection
OML
What angle is used for Haas projection
25 degree cephalic
Wahat is parallel to IR in SMV projection
IOML
Where does the CR exit in Haas projection?
1.5” above nasion
What bones make up pterions
Frontal, parietal, temporal, sphenoid
Where are pterions located
Posterior end of sphenoparietal suture
Asterions are located between what two sutures
Squamosal and lambdoidal
The frontal bone articulates with how many facial bones
8
The temporal bone articulates with how many facial bones
2
The sphenoid bone articulates with how many facial bones
5
The ethmoid bone articulates with how many facial bones
11
