Lecture 5

Question 1

What are Meninges?

Answer 1

Fibrous membranes on the external surface of the brain and spinal cord

Question 2

What is the main function of Meninges?

Answer 2

To support and protect the brain

Question 3

What are the 3 layers of Meninges?

Answer 3

1) Pia mater
2) Arachnoid mater
3) Dura mater

Question 4

What are the layers of the Scalp?

Answer 4

• Skin
• Connective tissue (Dense)
• Aponeurosis
• Loose connective tissue
• Pericranium

Question 5

What are the spaces in between the Meninges?

Answer 5

1) Epidural
2) Subdural
3) Subarachnoid spaces

Question 6

What are the characteristics of Dura Matter?

Answer 6

• 2 layers
• THICK, TOUGH & FIBROUS

Question 7

What does the inner layer of the Dura Matter have?

Answer 7

Meningeal layer has folds within it

Question 8

What are the Dural folds of the brain?

Answer 8

1) Falx Cerebri
2) Falx Cerebelli
3) Tentorium Cerebelli

Question 9

Where is the Flax Cerebri?

Answer 9

• Between the 2 cerebral hemispheres
• Attached to the crista galli

Question 10

Where is the Flax Cerebelli?

Answer 10

Between the 2 cerebellar hemispheres

Question 11

Where is the Tentorium Cerebelli?

Answer 11

• Between cerebellum and cerebrum
• Attached anteriorly to the petrous part of temporal bone

Question 12

What are the 2 sinuses that don’t lie between inner and outer layer of the dura?

Answer 12

• Inferior sagittal sinus
• Straight sinus

Question 13

What are the 6 sinuses in the dura?

Answer 13

1) Superior sagittal sinus
2) Inferior sagittal sinus
3) Straight sinus
4) Transverse sinus
5) Sigmoid sinus
6) Cavernous sinus

Question 14

Where is the Superior sagittal sinus located?

Answer 14

In the upper border of the Falx cerebri

Question 15

What is the function of the Superior sagittal sinus?

Answer 15

• Receives deoxygenated blood from upper & posterior parts of both medial & lateral surfaces of both hemispheres
• Receives CSF

Question 16

Where does the Superior sagittal sinus go posteriorly?

Answer 16

It usually turns to the right to become the Rt Transverse sinus

Question 17

Where is the Inferior sagittal sinus located?

Answer 17

In the lower border of falx cerebri

Question 18

Where does the Inferior sagittal sinus go posteriorly?

Answer 18

It flows into the straight sinus

Question 19

Where is the Straight sinus located?

Answer 19

At junction of falx cerebri & tentorium cerebelli

Question 20

What is the function of the Straight sinus?

Answer 20

Receives the great cerebral vein, blood from occipital lobes & from upper surface of cerebellum

Question 21

Where does the Straight sinus go posteriorly?

Answer 21

It usually turns to the left and becomes the Left Transverse sinus

Question 22

Where is the Transverse sinus located?

Answer 22

Within the outer border of the tentorium cerebelli- grooves the occipital bone

Question 23

Where does the Sigmoid sinus drain into?

Answer 23

Each one drains into jugular foramen where it becomes the IJV

Question 24

What is the function of the Sigmoid sinus?

Answer 24

Receives blood from superior petrosal sinus

Question 25

What is the function of the Cavernous sinus?

Answer 25

Receives blood from **cerebral veins, ophthalmic veins, pterygoid plexus of veins**

Question 26

Where does the Cavernous sinus drain into?

Answer 26

Each drains by **superior and inferior petrosal** into the **sigmoid** and **IJV** respectively

Question 27

What is the brain supplied by?

Answer 27

- 2 internal carotid arteries - 2 vertebral arteries

Question 28

What is the course of the Internal Carotid Artery?

Answer 28

**Ascends** in the **neck** and then through the **carotid canal** into the **middle cranial fossa**

Question 29

What are the 4 branches of the ICA?

Answer 29

1) Ophthalmic Artery 2) Posterior Communicating Artery 3) Anterior Cerebral Artery 4) Middle Cerebral Artery

Question 30

Describe the Posterior Communicating Artery

Answer 30

Joins the middle to the posterior cerebral artery

Question 31

Describe the Middle Cerebral Artery

Answer 31

- Lateral surface of each cerebral hemisphere (motor & sensory cortex, auditory & speech) - Largest & most direct branch of the ICA- thus high risk of embolism

Question 32

What is the Circle of Willis?

Answer 32

Circle of vessels that sit around the pituitary gland - Provides crucial redundant circulation to ensure uninterrupted blood supply to the brain

Question 33

What is the significance of the Circle of Willis?

Answer 33

The communicating arteries allow another route for blood supply to all of the brain in disease condition - (Acts as a backup system)

Question 34

What are the 3 arteries involved in the Circle of Willis?

Answer 34

1) Anterior Cerebral Artery 2) Middle Cerebral Artery 3) Posterior Cerebral Artery

Question 35

What is the function of the ACA?

Answer 35

**Supplies** the **medial aspect** of the **cerebral hemispheres** in the **anterior 2/3** of the **cerebrum**

Question 36

What is the function of the MCA?

Answer 36

Supplies virtually 100% of the lateral surface of the cerebral hemisphere - Small bit posteriorly is supplied by PCA

Question 37

What is the function of the PCA?

Answer 37

Supplies the **posterior 1/3** of the **medial aspect** of the **cerebral hemispheres** - Occipital lobe, inferior temporal lobe, superior brainstem