Anatomy-Scalp & Meninges Flashcards
A 34 year old man went skiing and bumped his head. At first he was fine, but after a few hours he had a seizure and when he got to the hospital he was non coherent with a non-reactive pupil. Imaging reveals and epidural hematoma. What blood vessel was most likely ruptured in this patient when he hit his head?
Middle Meningeal Artery
What are the 5 layers of the scalp?
Skin, CT, Aponeurosis, Loose areolar tissue and Pericranium
You are operating on a forward medical team and a soldier comes to your tent with a laceration in his scalp. Why might you consider stapling this wound instead of simply applying pressure?
The blood vessels of the scalp are in the connective tissue. The collagen in the CT keeps the blood vessels open and may result in profuse bleeding if not closed.
What cranial nerve is responsible for innervation of the muscles indicated below?
Cranial nerve VII (facial nerve) innervated the frontalis and occipitalis muscles
Why do you see a gaping scalp wound in this patient?
The laceration was so deep that it cut the aponeurosis. The occipitalis and frontalis muscles pull on the lacerated aponeurosis and cause the wound to open wider.
What layer of the scalp is considered the danger layer?
The loos areolar layer. The looseness of the tissue allows for infection to spread from the emissary veins that pass through the layer and into the cerebral sinuses.
What causes the cephalohematoma seen below?
The pericranium adhered tightly to the sutures of the skull. When there is blood leakage from the skull, the pericranium contains the hemorrhage to that region of the skull (parietal in this image)
Where do the arteries that supply the scalp come from?
Anterior arteries come from the internal carotid. The posterior arteries come from the external carotid.
What nerves innervate the scalp?
The trigeminal innervates the scalp & forehead (opthalmic V1), cheeks (maxillary V2) and temple & jaw (mandibular V3). The areas innervated by the great auricular, greater occipital and lesser occipital nerves are shown below.
What is the significance of the structure indicated below?
This is the pterion. It is the junction of the frontal, temporal, parietal and greater wing of sphenoid all come together. Deep to the pterion lies the anterior branch of the middle meningeal artery. The pterion is thin, so if you break it and rupture the middle meningeal artery you will also get an epidural hematoma.
Where are the cranial fossae located?
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What 5 bones make up the cranial fossa?
Frontal, ethmoid, sphenoid, temporal and occipital bone.
What are the different regions of the sphenoid bone?
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What are the three bony parts of the temporal bone?
Squamous part, petrous part and the mastoid part
What bone structure supports the ventral aspect of the brainstem?
Clivus
What structures go through the cranial fossa indicated below?
A) CN I goes through the Cribriform plate B) CN II and Opthalmic Artery go through the Optic Canal C) CN III, IV, V1, VI and the opthalmic vein go through the Superior Orbital Fissure D) CN V2 goes through the Foramen Rotundum E) CN V3 goes through the Foramen Ovale F) CN V3 meningeal branch and middle meningeal artery goes through the Foramen Spinosusm G) The internal carotid travels right ontop of the Foramen Lacerum
What structures go through the cranial fossa indicated below?
A) Brain stem, spinal cord and CN XI pass through the Foramen Magnum B) CN VII & VIII pass through the internal acoustic meatus C) CN IX, X, XI, the inferior petrosal sinus and jugular bulb pass through the Jugular Foramen D) CN XII passes through the Hypoglossal Canal
A patient comes to see you after a car accident and presents with the lesions seen below. Where are likely locations of fractures in this patient?
This patient has basilar skull fractures that cause blood or CSF accumulation in the regions below the skull. His fractures are most likely in the frontal bone causing Raccoon Eyes/bloody nose and a temporal bone fracture.
What are the two layers of dura matter in the skull?
Periosteal and meningeal layers.
What meningeal layers create potential spaces and what layers create real spaces?
Potential Spaces: epidural space (between the dura and the skull bone) and the subdural space (between the meningeal dura and arachnoid mater). Real space: subarachnoid space (between arachnoid and pia mater)
Rupture of what structures are likely to cause a subdural hematomas?
Bridging veins that come from cerebral veins that cross the arachnoid mater to get to the dural venous sinuses.
A patient comes to see you with the worst headache they’ve ever had in their life. MRI of his brain reveals blood coursing through and outlining the gyri and sulci of the brain. What structures may have ruptured to cause his condition?
Cerebral artery or vein in the subarachnoid space.
In what locations does the meningeal dura peel away from the periosteal border?
The meningeal dura peels away from the periosteal dura to form the double layered falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae
Through what meningeal opening does the brain stem pass as it move from the infratentorial space to the supratentorial space?
Tentorial notch/hiatus
What are the three types of brain herniation?
Transtentorial (uncus herniated from supratentorial to infratentorial compartment), Subfalcine (cingulate girus herniates through the falx cerebri) and Tonsillar (cerebellar tonsil herniates through the foramen magnum)
What are the main dural venous sinuses in the skull?
Superior sagittal sinus in the fixed border of the falx cerebri, inferior sagittal sinus in the free border of the falx cerebri, Straight sinus draining the superior & inferior sagittal sinuses, occipital sinus, paired transverse sinuses, cavernous sinus, superior petrosal sinus, inferior petrosal sinus and the right sigmoid sinus draining into the jugular bulb.
What makes the cavernous sinus so important?
CN III, IV, V1, V2, VI, the internal carotid artery and the pituitary gland all sit in this sinus.
