Comprehensive Test Bank: CT
Basics Module 9 –
Cross-Sectional Anatomy of
Major Body Cavities
Section 1: The Cranial Cavity
Question 1 On an axial CT scan of the head, the anatomical space that accommodates the
cerebellum and brainstem is known as which of the following? A. Anterior cranial fossa B.
Middle cranial fossa C. Posterior cranial fossa D. Suprasellar cistern
Answer: C. Posterior cranial fossa
Rationale: The cranial cavity is divided into three distinct compartments, or fossae, which form
the "floor" of the skull upon which the brain rests.
● A. Anterior cranial fossa: This is incorrect. The anterior cranial fossa is the most
superior of the three and is formed primarily by the frontal bone, ethmoid bone, and lesser
wings of the sphenoid bone. It accommodates the anterior parts of the frontal lobes of the
cerebrum.
● B. Middle cranial fossa: This is incorrect. The middle cranial fossa is located posterior
and inferior to the anterior fossa. It is formed by the sphenoid and temporal bones and
accommodates the temporal lobes of the cerebrum.
● C. Posterior cranial fossa: This is correct. The posterior cranial fossa is the most inferior
and posterior of the fossae. It is formed by the occipital bone and petrous portions of the
temporal bones. It is separated from the middle fossa by the petrous ridges and the
dorsum sellae. This fossa houses the cerebellum and the components of the brainstem
(pons and medulla).
● D. Suprasellar cistern: This is incorrect. The suprasellar cistern is a cerebrospinal fluid
(CSF)-filled space located within the middle cranial fossa, superior to the sella turcica,
and is not a fossa itself.
Question 2 A trauma patient presents with a fracture at the pterion, the region where the
frontal, parietal, sphenoid, and temporal bones join. This location is clinically critical due to its
close relationship with which of the following vascular structures? A. Basilar artery B. Middle
meningeal artery C. Internal carotid artery D. Superior sagittal sinus
Answer: B. Middle meningeal artery
Rationale:
● A. Basilar artery: This is incorrect. The basilar artery is located deep within the posterior
cranial fossa, in the prepontine cistern, anterior to the pons. It is far removed from the
lateral aspect of the skull at the pterion.
● B. Middle meningeal artery: This is correct. The pterion is a known weak point of the
skull. The anterior branch of the middle meningeal artery runs in a groove on the inner
surface of the skull directly at this junction. A fracture here can sever this artery, leading to
, an epidural (extradural) hematoma, which is a neurosurgical emergency.
● C. Internal carotid artery: This is incorrect. The internal carotid artery (ICA) enters the
skull base through the carotid canal and travels through the cavernous sinus before
emerging in the suprasellar cistern. It is not located near the pterion.
● D. Superior sagittal sinus: This is incorrect. The superior sagittal sinus is a dural venous
sinus located in the superior margin of the falx cerebri, running along the midline of the
calvarium from anterior to posterior. It is not associated with the lateral pterion.
Question 3 Which cerebrospinal fluid (CSF)-filled space directly connects the paired lateral
ventricles to the third ventricle? A. Cerebral aqueduct (of Sylvius) B. Foramen of Monro C.
Foramen of Luschka D. Quadrigeminal cistern
Answer: B. Foramen of Monro
Rationale: The ventricular system is a network of communicating cavities that produce,
circulate, and resorb CSF. Understanding this pathway is essential for diagnosing
hydrocephalus.
● A. Cerebral aqueduct (of Sylvius): This is incorrect. The cerebral aqueduct is a narrow
channel that connects the third ventricle to the fourth ventricle. Stenosis of this aqueduct
is a common cause of obstructive hydrocephalus.
● B. Foramen of Monro: This is correct. The interventricular foramen, or foramen of Monro,
is the bilateral channel that connects each of the lateral ventricles to the single, midline
third ventricle.
● C. Foramen of Luschka: This is incorrect. The foramina of Luschka (plural) are two lateral
apertures that allow CSF to exit the fourth ventricle and enter the subarachnoid space,
specifically the cerebellopontine angle cisterns.
● D. Quadrigeminal cistern: This is incorrect. This is a subarachnoid cistern, not a
component of the ventricular system itself. It is located posterior to the midbrain and
inferior to the splenium of the corpus callosum.
Question 4 On an axial CT of the head, which structure forms the floor of the fourth ventricle?
A. Cerebellar vermis B. Pons and medulla C. Midbrain (tectum) D. Splenium of the corpus
callosum
Answer: B. Pons and medulla
Rationale: The fourth ventricle is a diamond-shaped CSF-filled structure located in the posterior
fossa. Its relational anatomy is critical for identifying posterior fossa pathology.
● A. Cerebellar vermis: This is incorrect. The cerebellar vermis forms the roof (posterior
border) of the fourth ventricle.
● B. Pons and medulla: This is correct. The floor (anterior border) of the fourth ventricle is
formed by the posterior surfaces of the pons (superiorly) and the medulla oblongata
(inferiorly).
● C. Midbrain (tectum): This is incorrect. The midbrain, which contains the cerebral
aqueduct, is located superior to the fourth ventricle.
● D. Splenium of the corpus callosum: This is incorrect. This structure is located
significantly superior to the posterior fossa, forming the posterior aspect of the corpus
callosum.
Question 5 The suprasellar cistern, a critical intracranial space, is located superior to the sella
turcica. Which of the following major anatomical structures is contained within this cistern? A.
Cerebral aqueduct B. Pineal gland C. Circle of Willis D. Medulla oblongata
Answer: C. Circle of Willis
Rationale: Subarachnoid cisterns are widenings of the subarachnoid space. The suprasellar
cistern is a "star-shaped" cistern at the base of the brain, and its contents are among the most
, critical in neurology.
● A. Cerebral aqueduct: This is incorrect. The cerebral aqueduct is a narrow channel
within the midbrain, posterior to the suprasellar cistern.
● B. Pineal gland: This is incorrect. The pineal gland is located more posteriorly, within the
quadrigeminal plate cistern.
● C. Circle of Willis: This is correct. The suprasellar cistern contains the arterial polygon
known as the Circle of Willis, as well as the optic chiasm and the pituitary infundibulum
(stalk). Effacement of this cistern is a key sign of uncal herniation or subarachnoid
hemorrhage.
● D. Medulla oblongata: This is incorrect. The medulla oblongata is a component of the
brainstem located in the posterior fossa, inferior to the suprasellar cistern.
Question 6 Which group of deep gray matter nuclei, typically isodense to cortex on
non-contrast CT, is composed of the putamen and the globus pallidus? A. Caudate nucleus B.
Thalamus C. Lentiform nucleus D. Corpus callosum
Answer: C. Lentiform nucleus
Rationale: The basal ganglia are a group of subcortical nuclei involved in motor control,
cognition, and emotion.
● A. Caudate nucleus: This is incorrect. The caudate nucleus (specifically its head) forms
the lateral wall of the lateral ventricle and is a component of the basal ganglia, but it is
anatomically distinct from the putamen and globus pallidus.
● B. Thalamus: This is incorrect. The thalamus is a large mass of gray matter in the dorsal
part of the diencephalon; it is located medial to the lentiform nucleus, separated from it by
the internal capsule.
● C. Lentiform nucleus: This is correct. The lentiform nucleus (or lenticular nucleus) is the
anatomical term for the lens-shaped structure that combines the more lateral putamen
and the more medial globus pallidus.
● D. Corpus callosum: This is incorrect. The corpus callosum is the largest white matter
tract in the brain, connecting the left and right cerebral hemispheres. It is not gray matter.
Question 7 On a superior axial CT slice at the level of the basal ganglia, a V-shaped white
matter tract is seen separating the caudate nucleus and thalamus from the lentiform nucleus.
What is this structure? A. External capsule B. Corpus callosum (genu) C. Internal capsule D.
Sylvian fissure
Answer: C. Internal capsule
Rationale: This question tests the critical relational anatomy of the deep gray matter.
● A. External capsule: This is incorrect. The external capsule is a thin white matter tract
located lateral to the lentiform nucleus (putamen), separating it from the insular cortex.
● B. Corpus callosum (genu): This is incorrect. The genu is the anterior, U-shaped portion
of the corpus callosum, which is superior to the basal ganglia and forms the roof of the
frontal horns of the lateral ventricles.
● C. Internal capsule: This is correct. The internal capsule is a V-shaped (on axial view)
white matter structure. Its anterior limb separates the head of the caudate nucleus from
the lentiform nucleus. Its posterior limb separates the thalamus from the lentiform
nucleus.
● D. Sylvian fissure: This is incorrect. The Sylvian fissure (or lateral sulcus) is a large
cistern that separates the temporal lobe from the frontal and parietal lobes.
Question 8 Which component of the ventricular system is typically seen as a small, round,
fluid-filled structure within the midbrain on axial CT images? A. Third ventricle B. Cerebral
aqueduct C. Temporal horn of the lateral ventricle D. Fourth ventricle
Basics Module 9 –
Cross-Sectional Anatomy of
Major Body Cavities
Section 1: The Cranial Cavity
Question 1 On an axial CT scan of the head, the anatomical space that accommodates the
cerebellum and brainstem is known as which of the following? A. Anterior cranial fossa B.
Middle cranial fossa C. Posterior cranial fossa D. Suprasellar cistern
Answer: C. Posterior cranial fossa
Rationale: The cranial cavity is divided into three distinct compartments, or fossae, which form
the "floor" of the skull upon which the brain rests.
● A. Anterior cranial fossa: This is incorrect. The anterior cranial fossa is the most
superior of the three and is formed primarily by the frontal bone, ethmoid bone, and lesser
wings of the sphenoid bone. It accommodates the anterior parts of the frontal lobes of the
cerebrum.
● B. Middle cranial fossa: This is incorrect. The middle cranial fossa is located posterior
and inferior to the anterior fossa. It is formed by the sphenoid and temporal bones and
accommodates the temporal lobes of the cerebrum.
● C. Posterior cranial fossa: This is correct. The posterior cranial fossa is the most inferior
and posterior of the fossae. It is formed by the occipital bone and petrous portions of the
temporal bones. It is separated from the middle fossa by the petrous ridges and the
dorsum sellae. This fossa houses the cerebellum and the components of the brainstem
(pons and medulla).
● D. Suprasellar cistern: This is incorrect. The suprasellar cistern is a cerebrospinal fluid
(CSF)-filled space located within the middle cranial fossa, superior to the sella turcica,
and is not a fossa itself.
Question 2 A trauma patient presents with a fracture at the pterion, the region where the
frontal, parietal, sphenoid, and temporal bones join. This location is clinically critical due to its
close relationship with which of the following vascular structures? A. Basilar artery B. Middle
meningeal artery C. Internal carotid artery D. Superior sagittal sinus
Answer: B. Middle meningeal artery
Rationale:
● A. Basilar artery: This is incorrect. The basilar artery is located deep within the posterior
cranial fossa, in the prepontine cistern, anterior to the pons. It is far removed from the
lateral aspect of the skull at the pterion.
● B. Middle meningeal artery: This is correct. The pterion is a known weak point of the
skull. The anterior branch of the middle meningeal artery runs in a groove on the inner
surface of the skull directly at this junction. A fracture here can sever this artery, leading to
, an epidural (extradural) hematoma, which is a neurosurgical emergency.
● C. Internal carotid artery: This is incorrect. The internal carotid artery (ICA) enters the
skull base through the carotid canal and travels through the cavernous sinus before
emerging in the suprasellar cistern. It is not located near the pterion.
● D. Superior sagittal sinus: This is incorrect. The superior sagittal sinus is a dural venous
sinus located in the superior margin of the falx cerebri, running along the midline of the
calvarium from anterior to posterior. It is not associated with the lateral pterion.
Question 3 Which cerebrospinal fluid (CSF)-filled space directly connects the paired lateral
ventricles to the third ventricle? A. Cerebral aqueduct (of Sylvius) B. Foramen of Monro C.
Foramen of Luschka D. Quadrigeminal cistern
Answer: B. Foramen of Monro
Rationale: The ventricular system is a network of communicating cavities that produce,
circulate, and resorb CSF. Understanding this pathway is essential for diagnosing
hydrocephalus.
● A. Cerebral aqueduct (of Sylvius): This is incorrect. The cerebral aqueduct is a narrow
channel that connects the third ventricle to the fourth ventricle. Stenosis of this aqueduct
is a common cause of obstructive hydrocephalus.
● B. Foramen of Monro: This is correct. The interventricular foramen, or foramen of Monro,
is the bilateral channel that connects each of the lateral ventricles to the single, midline
third ventricle.
● C. Foramen of Luschka: This is incorrect. The foramina of Luschka (plural) are two lateral
apertures that allow CSF to exit the fourth ventricle and enter the subarachnoid space,
specifically the cerebellopontine angle cisterns.
● D. Quadrigeminal cistern: This is incorrect. This is a subarachnoid cistern, not a
component of the ventricular system itself. It is located posterior to the midbrain and
inferior to the splenium of the corpus callosum.
Question 4 On an axial CT of the head, which structure forms the floor of the fourth ventricle?
A. Cerebellar vermis B. Pons and medulla C. Midbrain (tectum) D. Splenium of the corpus
callosum
Answer: B. Pons and medulla
Rationale: The fourth ventricle is a diamond-shaped CSF-filled structure located in the posterior
fossa. Its relational anatomy is critical for identifying posterior fossa pathology.
● A. Cerebellar vermis: This is incorrect. The cerebellar vermis forms the roof (posterior
border) of the fourth ventricle.
● B. Pons and medulla: This is correct. The floor (anterior border) of the fourth ventricle is
formed by the posterior surfaces of the pons (superiorly) and the medulla oblongata
(inferiorly).
● C. Midbrain (tectum): This is incorrect. The midbrain, which contains the cerebral
aqueduct, is located superior to the fourth ventricle.
● D. Splenium of the corpus callosum: This is incorrect. This structure is located
significantly superior to the posterior fossa, forming the posterior aspect of the corpus
callosum.
Question 5 The suprasellar cistern, a critical intracranial space, is located superior to the sella
turcica. Which of the following major anatomical structures is contained within this cistern? A.
Cerebral aqueduct B. Pineal gland C. Circle of Willis D. Medulla oblongata
Answer: C. Circle of Willis
Rationale: Subarachnoid cisterns are widenings of the subarachnoid space. The suprasellar
cistern is a "star-shaped" cistern at the base of the brain, and its contents are among the most
, critical in neurology.
● A. Cerebral aqueduct: This is incorrect. The cerebral aqueduct is a narrow channel
within the midbrain, posterior to the suprasellar cistern.
● B. Pineal gland: This is incorrect. The pineal gland is located more posteriorly, within the
quadrigeminal plate cistern.
● C. Circle of Willis: This is correct. The suprasellar cistern contains the arterial polygon
known as the Circle of Willis, as well as the optic chiasm and the pituitary infundibulum
(stalk). Effacement of this cistern is a key sign of uncal herniation or subarachnoid
hemorrhage.
● D. Medulla oblongata: This is incorrect. The medulla oblongata is a component of the
brainstem located in the posterior fossa, inferior to the suprasellar cistern.
Question 6 Which group of deep gray matter nuclei, typically isodense to cortex on
non-contrast CT, is composed of the putamen and the globus pallidus? A. Caudate nucleus B.
Thalamus C. Lentiform nucleus D. Corpus callosum
Answer: C. Lentiform nucleus
Rationale: The basal ganglia are a group of subcortical nuclei involved in motor control,
cognition, and emotion.
● A. Caudate nucleus: This is incorrect. The caudate nucleus (specifically its head) forms
the lateral wall of the lateral ventricle and is a component of the basal ganglia, but it is
anatomically distinct from the putamen and globus pallidus.
● B. Thalamus: This is incorrect. The thalamus is a large mass of gray matter in the dorsal
part of the diencephalon; it is located medial to the lentiform nucleus, separated from it by
the internal capsule.
● C. Lentiform nucleus: This is correct. The lentiform nucleus (or lenticular nucleus) is the
anatomical term for the lens-shaped structure that combines the more lateral putamen
and the more medial globus pallidus.
● D. Corpus callosum: This is incorrect. The corpus callosum is the largest white matter
tract in the brain, connecting the left and right cerebral hemispheres. It is not gray matter.
Question 7 On a superior axial CT slice at the level of the basal ganglia, a V-shaped white
matter tract is seen separating the caudate nucleus and thalamus from the lentiform nucleus.
What is this structure? A. External capsule B. Corpus callosum (genu) C. Internal capsule D.
Sylvian fissure
Answer: C. Internal capsule
Rationale: This question tests the critical relational anatomy of the deep gray matter.
● A. External capsule: This is incorrect. The external capsule is a thin white matter tract
located lateral to the lentiform nucleus (putamen), separating it from the insular cortex.
● B. Corpus callosum (genu): This is incorrect. The genu is the anterior, U-shaped portion
of the corpus callosum, which is superior to the basal ganglia and forms the roof of the
frontal horns of the lateral ventricles.
● C. Internal capsule: This is correct. The internal capsule is a V-shaped (on axial view)
white matter structure. Its anterior limb separates the head of the caudate nucleus from
the lentiform nucleus. Its posterior limb separates the thalamus from the lentiform
nucleus.
● D. Sylvian fissure: This is incorrect. The Sylvian fissure (or lateral sulcus) is a large
cistern that separates the temporal lobe from the frontal and parietal lobes.
Question 8 Which component of the ventricular system is typically seen as a small, round,
fluid-filled structure within the midbrain on axial CT images? A. Third ventricle B. Cerebral
aqueduct C. Temporal horn of the lateral ventricle D. Fourth ventricle
