SCID 243 - Quiz 2 - Scalp, Cranial Cavity & Meninges

1. A sixty-four-year old man was diagnosed with an acoustic neuroma (tumor of the 8th cranial nerve) where it entered the temporal bone. What other cranial nerve might also be affected since this nerve uses the same foramen as the 8th in its course?

Abducens

Facial

Glossopharyngeal

Trigeminal

Vagus

The facial nerve enters the temporal bone with the vestibulocochlear nerve--both cross into the internal acoustic meatus.

Explanation

The facial nerve enters the temporal bone with the vestibulocochlear nerve--both cross into the internal acoustic meatus.

2. Infections may spread from the nasal cavity to the meninges along the olfactory nerves, as its fibers pass from the mucosa of the nasal cavity to the olfactory bulb via the: _______

Superior orbital fissure

Foramen caecum

Crista galli

Cribriform plate of the ethmoid

The olfactory nerve exits the skull through the cribriform plate of the ethmoid bone--an infection in the nasal cavity may be carried to the olfactory bulb by the nerves that are passing through the cribriform plate. The crista galli is a ridge on the ethmoid bone between the two sides of the cribriform plate; it provides an anchor for the falx cerebri. Foramen cecum is a small hole in the frontal bone near the anterior end of the crista galli--it transmits an emissary vein.

Explanation

The olfactory nerve exits the skull through the cribriform plate of the ethmoid bone--an infection in the nasal cavity may be carried to the olfactory bulb by the nerves that are passing through the cribriform plate. The crista galli is a ridge on the ethmoid bone between the two sides of the cribriform plate; it provides an anchor for the falx cerebri. Foramen cecum is a small hole in the frontal bone near the anterior end of the crista galli--it transmits an emissary vein.

3. A patient who has sustained a fracture to the middle cranial fossa following a fall from a height, might have any of these nerves injured EXCEPT: _____

Trigeminal

Oculomotor

Abducens

Trochlear

Hypoglossal

Several cranial nerves enter foramina in the middle cranial fossa; all of these nerves might have been damaged in the fall.

Explanation

Several cranial nerves enter foramina in the middle cranial fossa; all of these nerves might have been damaged in the fall.

4. After head trauma, the scan shows a skull fracture and an accumulation of blood between the dura and the cranial bone on the side of his head, compressing his cerebrum. After a few hours, he regains consciousness and has an uneventful recovery. The hemorrhage from the trauma would be described as: ______

Epidural

Intracerebral

Subaponeurotic

Subarachnoid

Subdural

An epidural hemorrhage is a hemorrhage of blood into the space between the dura and the skull. These hemorrhages are usually caused by rupturing the middle meningeal artery, which supplies blood to the dura and the bones of the cranial vault.

Explanation

An epidural hemorrhage is a hemorrhage of blood into the space between the dura and the skull. These hemorrhages are usually caused by rupturing the middle meningeal artery, which supplies blood to the dura and the bones of the cranial vault.

5. The most likely source of blood in a patient with an epidural hemorrhage is: ________

Vertebral artery

Middle cerebral artery

Superior cerebral veins

Anterior cerebral artery

Middle meningeal artery

The middle meningeal artery supplies most of the dura mater and the bones of the cranial vault. It is this artery or vein that is usually ruptured in an epidural hemorrhage.

Explanation

The middle meningeal artery supplies most of the dura mater and the bones of the cranial vault. It is this artery or vein that is usually ruptured in an epidural hemorrhage.

6. You have been asked to assess the neurological deficit that might exist in a patient diagnosed with cavernous sinus thrombosis. You will focus your examination on cranial nerves related to the sinus that includes all the following EXCEPT: ____

Abducens

Facial

Oculomotor

Ophthalmic division of the trigeminal nerve

Trochlear

The cavernous sinus is a venous sinus of the brain, lateral to the body of the sphenoid bone. All of the cranial nerves and vessels that pass out of the skull at the superior orbital fissure pass through the cavernous sinus. This includes the oculomotor nerve, the trochlear nerve, the ophthalmic division of the trigeminal nerve, and the abducens nerve.

Explanation

The cavernous sinus is a venous sinus of the brain, lateral to the body of the sphenoid bone. All of the cranial nerves and vessels that pass out of the skull at the superior orbital fissure pass through the cavernous sinus. This includes the oculomotor nerve, the trochlear nerve, the ophthalmic division of the trigeminal nerve, and the abducens nerve.

7. The "danger zone" of the scalp is recognized as which of the following layers?

Galea aponeurotica

Loose connective tissue

Pericranium

Skin

Subcutaneous connective tissue

The scalp is comprised of the following layers, from superficial to deep: Skin, Connective tissue, Aponeurosis, Loose connective tissue, and Pericranium. If you take the first letter of each, it spells SCALP. So, now that you know the order of the layers, you need to figure out which one is the danger zone--the place where infections can spread very quickly. And that layer is layer 4, the loose connective tissue. Pus or blood can spread easily in this layer, and infections in this layer can pass into the cranial cavity through emissary veins.

Explanation

The scalp is comprised of the following layers, from superficial to deep: Skin, Connective tissue, Aponeurosis, Loose connective tissue, and Pericranium. If you take the first letter of each, it spells SCALP. So, now that you know the order of the layers, you need to figure out which one is the danger zone--the place where infections can spread very quickly. And that layer is layer 4, the loose connective tissue. Pus or blood can spread easily in this layer, and infections in this layer can pass into the cranial cavity through emissary veins.

8. During childbirth, an excessive anteroposterior compression of the head may tear the anterior attachment of the falx cerebri from the tentorium cerebelli. The bleeding that follows is likely to be from which of the following venous sinuses?

Occipital sinus

Sigmoid sinus

Straight sinus

Superior sagittal sinus

Transverse sinus

The straight sinus drains the deep cerebrum--it lies within the junction of the falx cerebri and tentorium cerebelli. This is exactly the location that was damaged in birth, so this is the correct answer.

Explanation

The straight sinus drains the deep cerebrum--it lies within the junction of the falx cerebri and tentorium cerebelli. This is exactly the location that was damaged in birth, so this is the correct answer.