Chapter 14 - Brain & Cranial Nerves Flashcards
What are the 4 major parts of the brain?
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum
What does the brain stem consist of?
Medulla Oblongata
Pons
Midbrain
- continuous with the spinal cord
What does the diencephalon consist of?
Thalamus
Hypothalamus
Epithalamus
- superior to the brain stem
What does the cerebellum do?
Coordinates and regulates muscular activity
- located at the back of the skull
What does the cerebrum do?
Integration of complex sensory and neural functions
Initiation and coordination of voluntary activities
- the principal and most anterior part of the brain
What are the cranial meninges?
Protective layer of the brain
- consists of three layer
(Dura mater, arachnoid mater & pia mater)
- continuous with spinal meninges
What are the names of the three craninal meninges?
outer layer to inner layer
- Dura Mater
- Arachnoid Mater
- Pia Mater
What two things protect the brain?
- Cranial bones
2. Cranial meninges
How is the cranial dura mater different from the spinal cord dura mater?
Cranial has two layers instead of one
What are the two layers of the cranial dura mater called?
- Periosteal layer (external)
2. Meningeal layer (internal)
What separates the two hemispheres of the cerebrum?
Falx cerebri
What separates the two hemispheres of the cerebellum?
Falx cerebelli
What separates the cerebrum from the cerebellum?
Tentorium cerebelli
What does the blood-brain barrier consist of?
Mainly of tight junctions that seal together the endothelial cells of brain blood capillaries and a thick basement membrane that surrounds the capillaries
What substances can and cannot cross the BBB?
Yes - glucose - active transport
Yes - oxygen, carbon dioxide, alcohol - cross easily
Yes - urea, most ions - diffuse very slowly
No - proteins, antibiotics
What is cerebrospinal fluid? (CSF)
Clear, colourless liquid composed primarily of water
- protects the brain and spinal cord from chemical and physical injuries
Where is cerebrospinal fluid in the body?
Circulates continuously in cavities in the brain & spinal cord and in the sub-arachnoid space
What does the cerebrospinal fluid contain?
Small amounts of glucose, proteins, lactic acid, urea, cations (K+, Na+, Ca+2, Mg+2) and anion (Cl- and HCO3-)
- some white blood cells
What is the sub-arachnoid space?
Space between arachnoid and pia mater
What is the name for cavities in the brain that are filled with cerebrospinal fluid?
Ventricles
How many ventricles are in the brain?
Four
- Lateral ventricle - right hemisphere of cerebrum
- Lateral ventricle - left hemisphere of cerebrum
- Third ventricle - between the right and left halves of the thalamus
- Fourth ventricle - between brain stem and the cerebellum
What are the functions of cerebrospinal fluid?
- Mechanical protection - shock absorption
- Homeostatic function - pH of CSF affects pulmonary ventilation and cerebral blood flow
- Circulation - medium for minor exchange of nutrients & waste products
What is the choroid plexuses?
What does it do?
Networks of blood capillaries in the walls of the ventricles
- production of cerebrospinal fluid
What does the blood-cerebrospinal fluid barrier do?
Permits certain substances to enter the CSF but excludes others
- protects the brain & spinal cord from harmful substances