Head and Neck: Arterial and Venous Supply of the Brain

Where is the Superior Sagittal Sinus located?

Upper fixed border of the Falx cerebri

Where is the Inferior Sagittal Sinus located?

Lower free border of the Falx cerebri

Where is the Straight Sinus located?

Junction of Falx cerebri with Tentorium cerebelli

Which two veins unite to form the Straight Sinus?

Inferior Sagittal sinus and Great Cerebral vein (Vein of Galen)

Where does the Right Transverse Sinus receive blood from?

Superior Sagittal sinus

Where does the Left Transverse Sinus receive blood from?

Straight sinus

What sinus does the Transverse Sinus continue as, and what does it drain into?

Continues as the Sigmoid sinus, which drains into the Internal Jugular vein

Which arteries are connected by the Anterior Communicating Artery?

Left and right Anterior cerebral arteries

Which arteries are connected by the Posterior Communicating Artery?

Internal carotid artery and Posterior cerebral artery

What are the distal terminal branches of the Basilar Artery?

Left and right Posterior cerebral arteries

What are the main branches of the Basilar Artery from proximal to distal?

Pontine arteries, Superior cerebellar artery, and Posterior cerebral artery

What are the key cerebral branches of the Internal Carotid Artery?

Ophthalmic artery, Anterior choroidal artery, Middle cerebral artery, Anterior cerebral artery, and Posterior communicating artery

Which artery passes directly inside the Cavernous Sinus?

Internal Carotid artery

Which cranial nerve passes directly inside the Cavernous Sinus alongside the internal carotid artery?

Abducens nerve (CN VI)

Which structures lie in the lateral wall of the Cavernous Sinus from superior to inferior?

Oculomotor nerve (CN III), Trochlear nerve (CN IV), Ophthalmic division of trigeminal nerve (CN V1), and Maxillary division of trigeminal nerve (CN V2)

What is the Cavernous Sinus, and where is it located?

A venous dural sinus lying on the lateral side of the body of the Sphenoid bone

Which veins drain anteriorly into the Cavernous Sinus?

Superior Ophthalmic vein and central vein of the retina

How does the Cavernous Sinus drain posteriorly into the Transverse Sinus?

Via the Superior petrosal sinus

How does the Cavernous Sinus drain posteriorly into the Sigmoid Sinus?

Via the Inferior petrosal sinus

What is the anterior boundary of the Cavernous Sinus?

Extends into the medial end of the superior orbital fissure

What is the posterior boundary of the Cavernous Sinus?

Extends up to the apex of the petrous temporal bone

What is the medial boundary of the Cavernous Sinus?

Pituitary gland above and sphenoid bone below

What is the lateral boundary of the Cavernous Sinus?

Temporal lobe and uncus

What is the superior boundary of the Cavernous Sinus?

Optic chiasm

What is the inferior boundary of the Cavernous Sinus?

Endosteal dura mater and greater wing of sphenoid

Which internal structures pass directly through the center of the Cavernous Sinus?

Internal Carotid artery and Abducens nerve (CN VI)

Which cranial nerves are embedded in the lateral wall of the Cavernous Sinus?

CN III (Oculomotor), CN IV (Trochlear), CN V1 (Ophthalmic), and CN V2 (Maxillary)

What neighboring anatomical structures surround the Cavernous Sinus?

Pituitary gland (medially), facial veins (anteriorly), and superior/inferior petrosal sinuses (posteriorly)

What are the common primary sources of infection leading to Cavernous Sinus Thrombosis?

Infections in the orbit, nasal sinuses, and superior part of the face

What are the boundaries of the "Danger Area of the Face"?

Triangular area with APEX opposite medial angles of eyes/nose and BASE formed by upper lip

Which vein drains the Danger Area of the Face?

Facial vein

How does infection from the facial vein reach the cavernous sinus?

Facial veins connect with the cavernous sinus via the superior ophthalmic veins

Which nerves and vessels are vulnerable in Cavernous Sinus Thrombosis?

CN III, CN IV, CN VI, CN V1, CN V2, and the Internal carotid artery

What are the clinical features of Cavernous Sinus Thrombosis?

Severe headache around the eye, swelling/bulging of the eye, facial/eye pain or numbness, double vision, and inability to move the eye

A depressed fracture at the anterior inferior angle of the parietal bone causing an extradural hematoma involves tearing of which vessel?

Middle meningeal artery

Which sinus does the Great Cerebral Vein of Galen drain into?

Straight sinus

Why are lacrimal gland secretions unaffected in a cavernous sinus thrombosis?

Lacrimal parasympathetic fibers travel via CN VII (Facial nerve), which does not pass through the cavernous sinus

Is the Mandibular division of the Trigeminal nerve (CN V3) affected in septic cavernous sinus thrombosis?

No, CN V3 does not travel in or through the cavernous sinus

Where is the Dangerous Area of the Face located?

Root of the nose and two angles of the mouth

What is the common etiology of an Extradural (Epidural) Hemorrhage?

Injuries to the middle meningeal artery at the pterion

What are the clinical features of an Extradural Hemorrhage?

Intracranial pressure rises; blood clot exerts pressure on the motor area in the precentral gyrus

Where is an Extradural Hemorrhage located?

Between the skull bone and dura mater

What is the classic CT scan appearance of an Extradural Hemorrhage?

Convex (biconvex / lens-shaped)

What is the etiology of a Subdural Hemorrhage?

Tearing of the superior cerebral veins (bridging veins) at their point of entrance into the superior sagittal sinus

What mechanism typically causes a Subdural Hemorrhage?

A sudden minor blow to the front or back of the head causing antero-posterior displacement of the brain

Where is a Subdural Hemorrhage located?

Between dura and arachnoid mater

What is the classic CT scan appearance of a Subdural Hemorrhage?

Concave crescent-shaped

What is the most common cause of a Subarachnoid Hemorrhage?

Leakage or rupture of a congenital aneurysm (saccular/berry) on the Circle of Willis

How is a diagnosis of Subarachnoid Hemorrhage confirmed on lumbar puncture?

By withdrawing blood-stained CSF (xanthochromia)

Where is a Subarachnoid Hemorrhage located?

Between arachnoid and pia mater

What is the classic CT scan appearance of a Subarachnoid Hemorrhage?

Hyper-attenuation around the Circle of Willis and basal cisterns

What is the etiology of a Cerebral (Intracerebral) Hemorrhage?

Rupture of lenticulostriate arteries branching off the middle cerebral artery (hemorrhagic stroke)

What motor pathways and deficits are produced in a cerebral hemorrhage?

Involves corticobulbar and corticospinal tracts, producing contralateral hemiplegia

Where is a Cerebral Hemorrhage located?

Within the brain parenchyma

What is the CT scan appearance of a Cerebral Hemorrhage?

Hyper-attenuation in the brain parenchyma

Which cranial nerve exits through the cribriform plate of the ethmoid in the anterior cranial fossa?

CN I (Olfactory nerve)

What clinical signs result from a fracture of the Anterior Cranial Fossa?

Loss of smell (anosmia), periorbital bruising (raccoon eyes), and CSF leakage from the nose (rhinorrhea)

What important structures pass through or are housed within the Petrous Temporal Bone?

Houses vestibulocochlear organ; transmits CN 7, 8, 9, 10, 11, internal carotid artery, petrosal and sigmoid sinuses

What clinical signs result from a fracture of the Petrous Temporal Bone?

Blood or CSF escaping from the ear (otorrhea), hearing loss, and Facial nerve damage

What is the general presentation of Maxillofacial Fractures?

Extensive facial swelling, malocclusion of teeth, possible CSF leakage (ethmoid fracture), and diplopia (orbital wall damage)

What is a Le Fort I fracture?

Horizontal fracture superior to the maxillary alveolar process

What is a Le Fort II fracture?

Fracture through posterolateral parts of maxillary sinuses; central part of the face separated from cranium

What is a Le Fort III fracture?

Horizontal fracture passing through superior orbital fissures, ethmoid, and nasal bones extending to greater wing of sphenoid; maxillae and zygomatic bones separated from cranium

Which scalp layer is directly responsible for a gaping scalp wound when lacerated?

Galea aponeurotica (due to epicranial aponeurosis tension)