Cranial sutures and cranial bones

What are 3 ways to differentiate a skull fracture from a suture

1. A suture had symmetric borders while a fracture does not 2. A suture is windy, a fracture is usually linear 3. Normal sutures are normally located in specific areas

What are the 8 cranial bones

2 parietal bones, 1 frontal, 1 ethmoid, 1 sphenoid, 1 occipital, and 2 temporal bones

What is the crista galli

A bony projection that stems from the midline of the cribriform plate that serves as an attachment for the falx cerebri (connective tissue that anchors the brain to the anterior cranial fossa)

What is the sella turcica

A deep depression in the sphenoid bone that houses the pituitary gland (the hypophysis)

What is a metopic suture

A median frontal suture (usually goes away after birth or in infancy)

What is the cribriform plate

A portion of the ethmoid bone that contains many foramina for the passage of olfactory nerve fibers

What is located between the outer and inner layers of the skull

A spongy tissue called diploe

What is the mastoid antrum

An air filled cavity located on the anterosuperior of the mastoid process that communicates with the middle ear

What is the ethmoid notch

An area of the frontal bone between the orbital plates which receives the cribriform plate of the ethmoid bone

Where is the anterior fontanel located

At the junction of the frontal bone and the two parietal bones, also known as the bregma (usually closes after 2 years)

Where is the posterior fontanel located

At the junction of the two parietal bones and the occipital bone, also known as the lambda (usually closes after several months)

Why can't the adult skull be imaged using sonography and the neonate or young pediatric skull can

Because sonography can penetrate through fontanelles before they close

What are the 6 soft spots present on the skull at birth

Fontanels (they allow the skull to flex so it can pass through the birth canal)

What are the three paired foramen called on the greater wing of the sphenoid bone

Foramen rotundum (transmits the maxillary nerve), ovale, and spinosum

What are the 3 foramen on the sphenoid bone from posterior to anterior

Foramen rotundum, spinosum, and ovale

What are the parts of the ethmoid bone

Horiontal portion (the cribriform plate), vertical portion, and two lateral masses (it is a cube-shaped bone)

What is the shape of the sphenoid bone and where is it located

It is a butterfly shaped bone that extends completely across the floor of the middle cranial fossa

What is the parietal eminence and what is is important for

It is a central prominent bulge on each parietal bone and is used to determine the width of the skull

What is the hypoglossal canal

It is a foramen in the occipital bone just superior to the occipital condyles (where the hypoglossal nerve passes)

Where is the foramen rotundum found and what does it transmit

It is found on the greater wing of the sphenoid bone and it transmits the maxillary nerve (it is the largest foramen on the sphenoid bone)

What are synarthroses joints

Joints that have little to no movement

Where are the two mastoid fontanelles located

On either side of the skull at the junction of the occipital, temporal, and parietal bones

Where are the two sphenoidal fontanelles located

On either side of the skull at the junction of the sphenoid bone, the temporal bone, the frontal bone, and the parietal bone

Where is the optic canal located

On the lesser wing of the sphenoid bone

What holds synarthroses joints together

Sharpey fibers

What are the 4 primary sutures of the cranium

Squamous, lambdoidal, coronal, saggital

What is the atlantooccipital joint

The articulation between the atlas and the occipital bone

What are the 3 parts of the sphenoid bone

The body, the greater wing, and the lesser wing

What is the basilar portion of the occipital bone called

The clivus

What is the smallest of the cranial bones

The ethmoid bone

What separates the basilar portion of the occipital bone from the squamous portion

The external occipital protuberance (corresponds with the internal occipital protuberance)

What is located at the junction of the brainstem and spinal cord

The foramen magnum

What is the large oval aperture on the inferior portion of the occipital bone

The foramen magnum (this marks the junction of the brainstem and the spinal cord, also transmits the vertebral arteries)

What causes a brachycephalic head (short-headedness)

The frontal suture closing too soon

What cranial bones make up the frontal cranial fossa

The frontal, ethmoid, and sphenoid bones (which contain the frontal lobes of the brain)

What do the two temporal bones do

The help form the sides and base of the cranium (forming part of the middle cranial fossa along with the sphenoid bone)

What is the pterygoid process also called

The lateral pterygoid plate

What cranial bone completely houses the optic canal

The lesser wing of the sphenoid bone (houses the optic nerve and the ophthalmic artery)

What cranial bones make up the posterior cranial fossa

The occipital and temporal bones (contain the cerebellum and the brainstem)

What bone forms the posterior cranial fossa and the inferoposterior portion of the cranium

The occipital bone

What is the unicate process

The parts of the ethmoid bone that articulate with the inferior nasal conchae

What does the coronal suture connect

The posterior frontal bone with the anterior part of the parietal bone (it is best demonstrated on a lateral view)

What does the lambdoidal suture connect

The posterior parts of the two parietal bones with the superior border of the occipital bone

What causes a dolichocephalic head (long-headedness)

The saggital suture closing prematurely

What cranial bones make up the middle cranial fossa

The sphenoid and temporal bones (they house the pituitary gland, the hypothalamus, and the temporal lobes of the brain)

What is the only cranial bone that articulates with every other cranial bone

The sphenoid bone (it is known as the keystone cranial bone)

What are the 4 portions of the temporal bone

The squamous portion (the thinnest part that helps to form the sides of the cranium) The tympanic portion (forms the majority of the external auditory meatus) The mastoid portion (the mastoid portion which is mainly defined by the mastoid process) The petrous portion (this is pyramidal in shape and houses the opening to the internal auditory canal)

What does the squamousal suture connect

The superior temporal bone to the inferior parietal bone (it is best demonstrated on a lateral view)

What cranial bones contain the carotid canal

The temporal bones

What section of the cerebrum lies within the lowest portion of the middle cranial fossa

The temporal lobe

What is the most anterior and posterior part of the sella turcica called

The tuberculum sellae is the most anterior part and the dorsum sellae is the most posterior part (which give rise to the posterior clinoid processes)

What does the saggital suture connect

The two parietal bones (it is best viewed from looking down onto the cranium)

What is the highest point on the cranium

The vertex (the superior point between the two parietal bones)

What are the two portions of the frontal bone

The vertical (squamous) portion which forms the forehead and anterior vault of the cranium and contains the frontal sinus and the horizontal portion forms the roof over each orbit (called the orbital plate)

Why might a basilar skull fracture cause a patient to experience a salty taste

They can cause tears in the meninges which can cause CSF to leak into the nasopharynx and/or the nose (it can also manifest as bruising around the eyes or ears and loss of hearing, smell, and vision due to nerve damage)

What are the 4 parts of the occipital bone

Two lateral occipital condyles (both of which articulate with C1 or the atlas) , basilar portion (forms the anterior part of the foramen magnum and connects to the dorsum sella at the clivus), and squamous portion (forms the posterior part of the foramen magnum and articulates with the parietal and temporal bones)

What foramina is a jagged slit which allows the internal carotid artery to enter the cranium

foramen lacerum (located at the apex of the petrous portion of the temporal bone)

What is the clivus and why is it important

the part of the occipital bone that articulates with the dorsum sella of the sphenoid bone that supports the pons