Unit Three: The Meninges Flashcards
What are the three connective tissue layers surrounding the brain?
- Dura. 2. Arachnoid. 3. Pia.
What are the functions of the cranial meninges? (4)
- Cover and protect brain. 2. Enclose and protect blood vessels. 3. Stabilize the brain in the skull. 4. Contain cerebralspinal fluid.
How do the meninges cover and protect the brain? (2)
- Protect against foreign substances and trauma. 2. Separate the soft tissue of the brain from the bones of the skull.
Are the meninges anchored to the skull? What is the brain suspended in?
Yes. The meninges.
What is the outer, thickest layers of the meninges?
The dura mater.
What are the two layers of the dura mater?
- Periosteal. 2. Meningeal.
Which layer of dura mater is fused to the periosteum on the inner aspect of the skull?
The periosteal layer.
What does space between the periosteal and meningeal dura form?
Large collecting veins. Where veins of the brain empty into the sinuses.
What are cranial dural reflections?
Where the meningeal layer of dura extends deep into the cranial cavity between sections of the brain.
What are the functions of the cranial dural reflections? (3)
- Subdivide cranial cavity. 2. Support brain. 3. Limit movement of the brain.
Where is the falx cerebri?
Within the longitudinal fissure between the hemispheres.
What does the falx cerebri contain? (2)
- Inferior sagittal sinus. 2. Superior sagittal sinus.
Where is the tentorium cerebelli located?
Between the occipital lobes of the cerebrum and the cerebellum.
What is the thin, avascular, semitransparent membrane covering the brain?
Arachnoid mater.
What is contained within the arachnoid mater?
Arachnoid granulations.
What is the function of arachnoid granulations?
Send CSF from the subarachnoid space into the blood within the superior sagittal sinus.
What is the thin, delicate connective tissue tightly attached to the brain?
The pia mater.
Where does the pia mater follow?
All contours of the sulci and gyri.
What does the pia mater do?
Supports large cerebral blood vessels.
Where is the subarachnoid space?
Between the arachnoid and pia mater.
Where are arachnoid trabeculae found and what are they?
In the subarachnoid space. They are web like threads
extending across the subarachnoid space from arachnoid mater to pia mater.
What does the subarachnoid space contain? (2)
- Cerebrospinal fluid. 2. Blood vessels.
What is cerebrospinal fluid?
Colorless fluid that circulates in the ventricles and
subarachnoid space.
What produces cerebrospinal fluid?
Choroid plexus found within all ventricles of the brain.
What do choroid plexes contain?
Specialized ependymal cells and highly permeable capillaries.
Is cerebrospinal fluid always being produced?
Yes.
What is another function of choroid plexes?
Removes waste from CSF and alters its composition if needed.
How does CSF move through the brain? (3)
- Movement of cilia on the ependymal cells. 2. Movements of the vertebral column moving it around the spinal cord. 3. Pressure from the constant production forcing it out through the arachnoid granulations.
What are 4 functions of CSF?
- Buoyancy. 2. Protection. 3. Environmental stability. 4. Transports hormones, waste, nutrients, and chemicals.
What is the function of the blood brain barrier?
Tightly regulates what can leave the blood vessels and enter the space surrounding the brain tissue.
What kind of capillaries are found in the blood brain barrier?
Continuous.
What prevents materials from diffusing between epithelial cells in the blood brain barrier?
Extensive tight junctions.
What surrounds the capillaries of the blood brain barrier?
Astrocyte perivascular feet.
What restricts the permeability of the capillary epithelial cells in the blood brain barrier?
Astrocytes.
Where is there increased permeability in the blood brain barrier and why? (3)
- By the hypothalamus and pituitary glands in order to allow for hormone diffusion. 2. By the pineal gland. 3. Choroid plexes.
Where are the lateral ventricles? What are they separated by?
In each hemisphere. They are separated by the midline septum pellucidum.
Where is the 3rd ventricle?
Midline, between the right thalamus and left thalamus.
Where is the 4th ventricle?
Between the pons and cerebellum, extending into the superior portion of the medulla oblongata.
What connects the lateral ventricle to the 3rd ventricle?
Interventricular foramen.
What connects the 3rd ventricle to the 4th ventricle?
The cerebral aqueduct.
How can CSF leave the 4th ventricle? (3)
- Lateral aperture. 2. Median aperture. 3. Central canal of the spinal cord.
Describe the first step of the longest possible path that CSF can take. (3)
- Lateral ventricles. 2. Interventricular foramen of
Monro. 3. 3rd ventricle
Describe the second step of the longest possible path that CSF can take. (3)
- 3rd ventricle. 2. cerebral aqueduct. 3. 4th ventricle
Describe the third step of the longest possible path that CSF can take. (2)
- 4th ventricle. 2. One of these routes into the
subarachnoid space: Paired lateral apertures, midline median aperture, central canal of the spinal cord.
Describe the fourth step of the longest possible path that CSF can take.
CSF enters the arachnoid space.
Describe the fifth step of the longest possible path that CSF can take.
CSF flows into arachnoid granulations, which
transport it into the dural venous sinuses.
What are the major dural venous sinuses? (5)
- Superior sagittal sinus. 2. Inferior sagittal sinus. 3. Transverse sinus. 4. Straight sinus. 5. Confluence of sinuses.
