The Skull and Cranial Fossae Practice Questions

Question 1

A nine-year-old boy was playing soccer when he took a blow to the side of the head. He was immediately taken to the hospital where CT scans reveal a lens shaped hematoma around the area where the frontal, parietal, temporal, and greater wing of the sphenoid join. The artery likely damaged, passes through which foramen to gain access to the cranial vault?

A. Foramen magnum

B. Foramen spinosum

C. Foramen ovale

D. Superior orbital fissure

E. Stylomastoid foramen

F. Internal acoustic meatus

G. Jugular foramen

Answer 1

B

The point where the frontal, parietal, temporal, and greater wing of the sphenoid join is known as the pterion. Passing behind the pterion is the middle meningeal artery, which passes through foramen spinosum to access the cranial vault.

Question 2

The three branches of the trigeminal nerve (CN V) exit the skull through which of the following, respectively?

A. Superior orbital fissure, internal acoustic meatus, jugular foramen.

B. Superior orbital fissure, foramen rotundum, foramen ovale.

C. Foramen rotundum, stylomastoid foramen, internal acoustic meatus.

D. Internal acoustic meatus, foramen ovale, superior orbital fissure.

E. Foramen rotundum, foramen ovale, jugular foramen.

Answer 2

B

The ophthalmic division of the trigeminal nerve (CN V1) passes through the superior orbital fissure, the maxillary division (CN V2) through the foramen rotundum, and the mandibular division (CN V3) through foramen ovale.

Question 3

You are doing rounds with your attending when you get a patient with a suspected skull fracture. After taking a patient history, you suspect that the fracture is somewhere within the viscerocranium. Which of the following bones is NOT a part of the viscerocranium?

A. Palatine

B. Frontal

C. Lacrimal

D. Ethmoid

E. Zygomatic

Answer 3

B

The viscerocranium can be thought of as the bones that form the face, while the neurocranium is comprised of bones that house the brain.

Question 4

A patient was diagnosed with a tumor of the vestibulocochlear nerve (CN VIII) where it enters the petrous temporal bone. Which other nerve could potentially be affected as well since it enters the bone through the same foramen?

A. Mandibular branch of the trigeminal nerve

B. Spinal accessory nerve

C. Facial nerve

D. Hypoglossal nerve

E. Vagus nerve

Answer 4

C

Both CN VII and CN VIII enter the temporal bone through the internal acoustic meatus.

Question 5

A 4-month-old girl presents to the Emergency Department with what the physician suspects to be a form of meningitis. During the physical exam he palpates a clinically relevant area on top of the skull known as the anterior fontanelle to examine for an increase in intracranial pressure. This fontanelle closes at approximately what age, post-partum?

A. 18 months

B. 2 years

C. 2 -3 months

D. 16 months

E. 6- 9 months

Answer 5

A.

At around 18 months, the coronal, sagittal, and frontal sutures fuse to form what is known as the bregma. The anterior fontanelle is no longer palpable.

Question 6

Following a car accident, a patient presents with signs of increased intracranial pressure. Radiologic studies reveal a crescent-shaped hematoma near the junction of the parietal and frontal lobes, which does not cross the midline. Which structure impedes the collection of blood from crossing the midline?

A. Falx cerebelli

B. Superior sagittal sinus

C. Tentorium cerebelli

D. Falx cerebri

E. Cavernous sinus

Answer 6

D

This is an example of a subdural hematoma, which is usually caused by ruptured veins that bleed into the space between the dura and arachnoid mater. The falx cerebri is an extension of the dura mater and since this hematoma is deep to the dura, it is blocked from crossing the midline by this structure. The superior sagittal sinus is contained within the falx cerebri but is not the structure directly preventing the hematoma from spreading.

Question 7

The cranial fossa is divided into three sections: anterior, middle, and posterior. Within each section there are various foramina for the cranial nerves to exit the skull. In the middle cranial fossa, there is an important foramen that provides the exit for CN III, CN IV, and CN V1, and CN VI. This aperture is also known as:

A. Foramen spinosum

B. Foramen rotundum

C. Foramen ovale

D. Superior orbital fissure

E. Foramen lacerum

Answer 7

D

CN III, CN IV, CNV₁ and CN VI all exit the cranial vault through the superior orbital fissure.

Question 8

The posterior 1⁄4 of the roof of the mouth is formed by which bone(s) of the skull?

A. Maxilla

B. Ethmoid

C. Mandible

D. Palatine

E. Sphenoid

F. Temporal

Answer 8

D

The anterior roof of the mouth is formed by the maxilla, while the posterior 1⁄4 is formed by the palatine bones.

Question 9

At the level of the internal occipital protuberance, lies the confluence of sinuses. Which dural venous sinuses make up the confluence of sinuses?

A. Superior sagittal, straight, inferior sagittal

B. Sigmoid, superior sagittal, inferior petrosal

C. Transverse, superior sagittal, straight

D. Transverse, occipital, superior petrosal

Answer 9

C

Transverse, superior sagittal, and straight sinuses form the confluence with contributions from the occipital sinus.

Question 10

The optic nerve (CN II) exits the cranial cavity by passing through which foramen and in which cranial fossa?

A. Cribriform plate; anterior cranial fossa

B. Optic canal; anterior cranial fossa

C. Optic canal; middle cranial fossa

D. Optic canal; posterior cranial fossa

E. Superior orbital fissure; middle cranial fossa

Answer 10

C

CN II exits the skull through the optic canal, which is located in the middle cranial fossa.

Question 11

Structures that pass thru the

Superior Orbital Fissure

Answer 11

A fissure between the greater and lesser sphenoid wings, connecting the middlecranial fossa and orbit.

Structures passing through include:

• Trochlear nerve (CN IV)
• Ophthalmic division of the trigeminal nerve (CN V1): lacrimal, frontal and nasociliary branches
• Abducent nerve (CN VI)
• Superior and inferior ophthalmic veins

Question 12

Structures that pass thru the

Inferior Orbital Fissure

Answer 12

A fissure between the sphenoid bone (greater wing) and the maxilla, connecting the infratemporal fossa and orbit.

Connects the infratemporal fossa and orbit.

Structures passing through include:

• Inferior ophthalmic vein

Question 13

Structures that pass thru the

Optic Canal

Answer 13

Canal that runs through the lesser wing of the sphenoid bone, connecting the anterior cranial fossa and orbit.

Structures:

Optic Nerve [CN II]

Ophthalmic artery

Question 14

Pterion

Answer 14

where the sphenoid, temporal, frontal, and parietal bones meet

an extremely thin region of the skull.

Weakest part of the skull. The anterior division of the middle meningeal artery runs underneath the pterion. Consequently, a traumatic blow to the pterion may rupture the middle meningeal artery causing an epidural haematoma.

Question 15

The temporomandibular joint (TMJ) is formed by the articulation of _____________

Answer 15

the mandible with the temporal bone of the cranium.

Question 16

Clivus

Answer 16

the region of the occipital bone anterior to the foramen magnum

Question 17

Bones that form the nasal cavity include ______.

Answer 17

frontal, ethmoid, sphenoid, palatine, lacrimal, vomer, nasal*, inferior nasal concha*, and maxilla.

Question 18

Structures going thru the

Incisive canal

Answer 18

nasopalatine nerve and sphenopalatine artery

Question 19

Enclosures and bones of

The neurocranium

Answer 19

Encloses: the brain, meninges, vessels, proximal parts of cranial nerves, and internal ear.

Composed of 8 bones: frontal, ethmoid, sphenoid, occipital, temporal*, and parietal*.

Question 20

Enclosures and bones of

The viscerocranium

Answer 20

Includes: the inferior orbit, nasal cavity, and oral cavity.

Composed of 15 bones: mandible, ethmoid, vomer, maxilla*, inferior nasal concha*, zygomatic*, palatine*, nasal*, and lacrimal*.

Question 21

Two outer surface of the calvaria has a number of important landmarks:

Answer 21

Bregma: where the parietal bones meet the frontal bone.

Lambda: where the parietal bones meet the occipital bone.

Question 22

Closures of 4 Fontanelles

(membrane covered areas in immature skulls between two bones, where a suture will form later.)

Answer 22

Mastoid fontanelle: closes ~12 months.

Anterior fontanelle: closes ~18 months.

Posterior fontanelle: closes ~2-3 months.

Sphenoid fontanelle: closes ~2-3 months.

Question 23

Structures passing thru

Superior orbital fissure

Answer 23

Ophthalmic veins

Optic nerve (CN V1)

CN III

CN IV

CN VI

Sympathetic fibres.

Question 24

Structures passing thru

Foramen rotundum

Answer 24

Maxillary nerve (CN V₂)

Question 25

Structures passing thru **_Foramen ovale_**

Answer 25

Mandibular nerve (CN V₃) Accessory meningeal artery.

Question 26

Structures passing thru **_Foramen spinosum_**

Answer 26

Middle meningeal artery and vein Meningeal branch of CN V₃

Question 27

Structures of the **_Foramen lacerum_**

Answer 27

Deep petrosal nerve

Question 28

Structures of the **_Groove of hiatus of greater petrosal nerve_**

Answer 28

Greater petrosal nerve

Question 29

Structures passing thru the **_Jugular foramen_**

Answer 29

CN IX CN X CN XI Superior bulb of the internal jugular vein Inferior petrosal Sigmoid sinuses

Question 30

Which nerves passes thru the Hypoglossal canal

Answer 30

Hypoglossal nerve (CN XII)

Question 31

Major dural in-foldings: ## Footnote **Falx cerebri**

Answer 31

Divides the two cerebral hemispheres. Attaches anteriorly to the frontal crest and crista galli. Posteriorly it inserts onto the superior surface of the tentorium cerebelli.

Question 32

Major dural in-foldings: **_Tentorium cerebelli_**

Answer 32

Separates the cerebrum from the cerebellum. Attaches posteriorly to the occipital bone and laterally to the superior aspect of the petrous temporal bone. Anteriorly it is attached to the anterior clinoid processes. The tentorial notch is formed by the anterior free edge of the tentorium cerebelli.

Question 33

Major dural in-foldings: **_Falx cerebelli_**

Answer 33

Separates the two hemispheres of the cerebellum. Originates on the occipital bone and inserts superiorly into the tentorium cerebelli.

Question 34

The middle meningeal artery

Answer 34

Is a branch of the **maxillary artery**. Supplies the **dura mater** on its external surface. The anterior branch of the middle meningeal artery runs deep to the **pterion**.

Question 35

The internal carotid artery

Answer 35

Arises from the **common carotid** artery in the neck. Arises around the level of the **fourth cervical vertebra**.

Question 36

The vertebral artery

Answer 36

Originate from the **subclavian artery** in the neck. Pass through the **transverse foramina** of the upper six cervical vertebrae. Upon exiting the transverse foramen of C1, the arteries cross the posterior arch of C1, through the sub-occipital triangle, before entering foramen magnum. • In the skull, the arteries contribute to the **Circle of Willis**.

Question 37

The external carotid artery has eight branches (8)

Answer 37

* Superior thyroid artery * Ascending pharyngeal artery * Lingual artery * Facial artery * Occipital artery * Posterior auricular artery * Maxillary artery * Superficial temporal artery Some Anatomists Like Freaking Out Poor Medical Students.

Question 38

the four cranial nerves that are located in the lateral wall of the cavernous sinus.

Answer 38

CN III CN IV CNV₁ CN V₂

Question 39

Basilar Skull Fractures: Signs and Symptoms

Answer 39

CSF otorrhea/ rhinorrhea Anosmia: lack of sense of smell Retroauricular/Mastoid ecchymosis (Battlesign): develops when the fracture line communicates with mastoid air cells, resulting in an accumulation of blood in cutaneous tissues. Periorbital ecchymosis (Racoon eyes): results from bleeding at a fracture site in the anterior portion of the skull base; may also be caused by facial fractures. Hemotympanum vertigo: presence of blood in the middle ear, leading to vertigo. Decreased hearing or deafness. Facial Nerve (CN VII) palsy

Question 40

Basilar Skull Fractures bones affected may include **If cribriform plate or sphenoid are suspected, DO NOT use a nasopharyngeal airway device when trying to manage your patient’s airway!**

Answer 40

petrous and squamous portions of temporal bones (most common) – **typically tears dura mater, leading to otorrhea & rhinorrhea.**

Question 41

**_Clinical Correlates_** Subdural hematoma

Answer 41

Is the accumulation of blood between the **dura mater** and **arachnoid mater.** Cresent-shaped and often blood will fill the entire hemisphere. Usually caused by the rupturing of bridging veins that connect superficial cerebral veins to the dural venous sinuses. As the blood accumulates, it places pressure on the brain and if this pressure becomes great enough, it can lead to unconsciousness and death. **Typical presentation: blow to the head (e.g. car accident, fall, or assault) --\> headache (precipitating trauma may be considered insignificant).**

Question 42

**_Clinical Correlates_** Epidural hematoma

Answer 42

Is the most serious complication of a head injury and develops when bleeding occurs between the dura mater and the skull. Arterial bleed- meningeal arteries e.g. middle meningeal artery as it runs over the pterion is especially vulnerable. Often involves a loss of consciousness, vomiting, headache, confusion, and sometimes includes seizures. Disc or lens-shaped because their development is limited by the sutures where the dura mater is tightly attached to the skull. **Typical presentation: blow to the head (usually a sporting injury) --\> sometimes brief concussion --\> constant headache --\> lucid intervals of some hours --\> drowsiness and coma.** • Diagnosed using a CT scan or MRI.