Meninges, Dural Folds, and Venous Sinuses

Question 1

What are the Cranial Meninges?

Answer 1

Dura Mater (dense irregular CT)
Arachnoid Mater (Loose CT)
Pia Mater (loose CT with direct contact with brain)

Question 2

What are the Layers of the Dura Mater?

Answer 2

Periosteal Dura: inner periosteum of the cranial bones (cannot be separated from the bones)

Meningeal Dura: Forms Dural “Reflections” or “Folds” but also Dural Venous Sinuses

Question 3

What do dural venous sinuses do?

Answer 3

Carry venous blood and cerebrospinal fluid

Question 4

What is the pathway of sinus drainage?

Answer 4

Inferior Sagittal sinus drains into straight sinus to form confluence of sinus with the Superior sagittal sinus

Transverse sinuses drain the confluence into the sigmoid sinus before entering internal jugular veins

*cavernous sinus is also drains into this network via inferior/superior petrosal sinus

Question 5

How are Dural Venous Sinuses different than veins?

Answer 5

They do not have wall layers (only tunica intima) and no valves

Question 6

Where does the ophtalmic veins drain?

Answer 6

cavernous sinus

Question 7

What structures are found within the cavernous sinus?

Answer 7

Internal carotid a.
CN III, IV, V1, V2, VI

Question 8

What is cavernous sinus syndrome?

Answer 8

Inflammation of the cavernous sinus causing ophthalmoplegia (paralysis of eye muscles) and proptosis (protrusion of the eyes)

Trigeminal sensory loss

Question 9

Where does CSF flow?

Answer 9

Subarachnoid space

Question 10

What is the blood supply to the brain (percentages)?

Answer 10

Internal Carotid Artery: 75%
Vertebral Artery: 25%

Question 11

What are the embryological derivatives of the ventricles of the brain?

Answer 11

Telencephalon: Lateral Ventricle
Diencephalon: Third Ventricle
Mesencephalon: Cerebral Aqueduct
Metencephalon: Anterior part of the fourth ventricle
Myelencephalon: Posterior part of the fourth ventricle

Question 12

What are Choroid Plexus?

Answer 12

Structures that form CSF as blood filtrate

-found in walls of ventricles and supplied by cerebral arteries

Question 13

What is the pathway of CSF circulation?

Answer 13

Lateral Ventricles -> third ventricle -> Cerebral aqueduct -> fourth ventricle -> central canal or median/lateral apertures -> subarachnoid space -> arachnoid villi -> superior sagittal sinus

Question 14

Describe what an epidural hematoma is

Answer 14

Bleeding in the epidural space (convex)

Rupture of middle meningeal artery near the pterion is common cause

Question 15

Describe a Subdural hematoma

Answer 15

Bleeding in the subdural space. (concave)

Often caused by tearing of bridging veins

Question 16

What is a subarachnoid hemorrhage?

Answer 16

Artery of the circle of Willis ruptures

Question 17

Describe the pathway of Sympathetic Nerves of the head and neck

Answer 17

Preganglionic neurons bodies found in lateral horn of T1-T3

Synapse occurs at cervical sympathetic ganglia

Postganglionic fibers form plexuses around branches of carotid arteries

Question 18

What are the general patterns (levels) of sympathetic nerves of the head?

Answer 18

Superior cervical ganglion (levels C1 - C2)
Middle cervical ganglion (levels C6)
Inferior cervical ganglion (C7)

Question 19

What structures of the head get sympathetic innervation?

Answer 19

Dilator pupillae muscle: pupillary dilation
Superior tarsal muscle: elevation of upper eyelid
Blood vessels: vasoconstriction
Sweat glands: diaphoresis (sweating)

Question 20

What is Horner’s Syndrome?

Answer 20

Lesion of the sympathetic pathway to the head

-causes vasodilation, miosis, ptosis, anhidrosis

Question 21

Where does the oral cavity drain (lymph)?

Answer 21

Submandibular nodes

Question 22

What does the Anterior cervical nodes drain?

Answer 22

Larynx, tongue, oropharynx, and anterior neck

Question 23

Where structures drain into the supraclavicular nodes?

Answer 23

gastrointestinal tract, genitourinary tract, pulmonary

Question 24

What structures drain into the preauricular nodes?

Answer 24

Scalp and skin

Question 25

What structures drain into the posterior cervical nodes?

Answer 25

scalp, neck, upper thoracic skin