22 - Central Nervous System Flashcards
What organs does the central nervous system contain?
The brain and spinal cord
What are the directional terms unique to the CNS?
- Rostral – toward the nose (anterior)
- Caudal – toward the back (posterior)
- Dorsal – superior
- Ventral – inferior
What plane divides the brain into right and left sides?
Sagittal plane
Where does the brain lie?
Within the cranial cavity in the skull
Where is the spinal cord placed?
It continues from the brain and rests within the vertebral canal in the vertebral column
What structures protect the brain and spinal cord?
Bone, fluid, and meninges
What are meninges?
Three layers located between the bone and the soft tissues of the nervous system, protecting the brain and spinal cord
What is the largest part/divison of the brain?
Cerebrum
What does the diencephalon consist of?
The thalamus and the hypothalamus
T or F: the diencephalon is not part of the cerebrum
True
The brain stem is continuous with what? And what does it consist of?
It is continuous with the spinal cord and consists of medulla oblongata, pons, and midbrain
Describe the position of the cerebellum relative to the brain stem?
The cerebellum is posterior to the brain stem
How is the cerebrum divided?
Into two hemispheres, which are also divided into four lobes.
What connects the different divisions of the brain?
Corpus callosum
What is the cerebral cortex?
The outermost layer of gray matter making up the superficial aspect of the cerebrum
What are the four lobes of the brain? Describe their positions
- Frontal lobe – located deep to the frontal bone of the skull
- Parietal lobe – located deep to the parietal bone of the skull
- Occipital lobe – located deep to the occipital bones of the skull
- Temporal lobes – located on the sides of the brain, deep to the temporal bones of the skull
What are the features of the cerebrum?
Gyri, sulci, and fissures
What are gyri?
Elevated ridges winding around the brain
What separates the frontal lobe from the parietal lobe?
Central sulcus
What are sulci?
Small groves dividing the gyri
What are fissures?
Deep grooves that generally divide large regions/lobes of the brain
What are the different fissures? Describe them
- Longitudinal fissure – divides the two cerebral hemispheres (along sagittal plane)
- Transverse fissure – separates cerebrum from cerebellum
- Sylvian/lateral fissure – divides temporal lobe from parietal and frontal lobes
Where is the diencephalon located?
Between the cerebral hemispheres and above brain stem
Describe the positions of the thalamus and hypothalamus.
- Thalamus: bulges into 3rd ventricle
* Hypothalamus: form the lower walls and floor of the 3rd ventricle
Where is the midbrain located?
Between the cerebrum and pons below
Describe the pons
Rounded bulge in front of the cerebellum
Where is the pons located?
Below the midbrain and above the medulla oblongata
Where is the medulla oblongata located?
It extends from the pons above and continues with the spinal cord below
What does the cerebellum consist of?
Two hemispheres
What separates the two hemispheres in the cerebellum?
A layer of dura mater
What connects the two hemispheres in the cerebellum?
Vermis
What is vermis composed of?
White matter
What surrounds the white matter in the cerebellum?
A thin cortex of gray matter
Describe the elongation and the termination of the spinal cord
It begins as a continuation of the medulla oblongata and terminates near the intervertebral disk that separates the first and second lumbar vertebrae in an adult
What does the spinal cord contain?
Cervical and lumbar enlargements that serve as points of origin for nerves to the extremities
Describe the structure of the spinal cord
Each structure has a hole through it, which line up to form the spinal canal. There is a large bundle of nerves that run through the spinal canal, called the spinal cord
How many pairs of spinal nerves do we have?
31
How many pairs of cervical nerves do we have?
8
How many pairs of thoracic nerves do we have?
12
How many pairs of lumbar nerves do we have?
5
How many pairs of sacral nerves do we have?
5
How many pairs of coccygeal nerves do we have?
Just one
What are the paths of communication between the spinal cord and the rest of the body?
Spinal nerves
How many cervical bones do we have?
7, but one spinal nerve goes above the first bone, so we have a total of 8 cervical nerves
What do we call the nerves after L2?
Horsetail nerves – cauda equina
What clefts partially separate left and right halves of the spinal cord?
- Anterior median fissure
* Posterior median sulcus
What is gray matter?
Neuron cell bodies, dendrites, neuroglia, nonmyelinated axons
What is gray matter divided into? Explain
3 Horns:
- Posterior (dorsal) horn
- Anterior (ventral) horn
- Lateral horn
What is white matter?
Myelinated axons
What is white matter divided into?
3 Columns/funiculi: 1. Ventral 2. Dorsal 3. Lateral Each of which is divided into sensory or motor tracts
What set of structures protect the CNS?
- Cranium and spinal cord vertebrae
- Meninges
- Cerebrospinal fluid
- Blood brain barrier
Describe the layers of the meninges
- Outermost layer: dura mater
- Middle layer: arachnoid
- Innermost meninx: pia mater
What is the pia mater?
A thin, transparent connective tissue layer that adheres to the surface of the spinal cord and brain
What separates the dura and the arachnoid?
Subdural space
What separates the arachnoid and the pia?
Subarachnoid space
Which space contains cerebrospinal fluid?
Subarachnoid space
What part of the meninges is attached to the brain or spinal cord?
Pia mater