Flashcards in Chapter 7 (Pgs. 167 - 178) Deck (43):
Nervous system is divided into two parts:
- Central Nervous System
- Peripheral Nervous System
Anterior vs. Posterior
- Anterior (Rostral): The direction pointint towards the head.
- Posterior (Caudal) The direction pointing towards the rear.
Dorsal vs. Ventral
- Dorsal: Direction pointing up.
- Ventral: The direction pointing down.
The right and left sides are mirror images of each other.
The invisible line running down the middle of the nervous system.
- Medial: Close to the midline.
- Lateral: Farther from the midline.
Ipsilateral vs. Contralateral
- Ipsilateral: Two structures that are on the same side.
- Contralateral: Two structures that are on opposite side.
A slice of something.
Anatomical planes of section
- Midsagittal plane: Split into equal right and left halves.
- Sagittal plane: Sections parallel to the midsagittal plane.
- Horizontal plane - parallel to ground (dorsal and ventral).
- Coronal plane: Perpendicular to the ground (anterior and posterior).
The Central Nervous System
- Consists of parts of the nervous system that are encased in bone (brain and spinal cord).
Describe the cerebrum.
- The rostral most and largest part of the brain.
- Split down the middle into two cerebral hemispheres, separated by the deep sagittal fissure.
- Right hemisphere receives sensations from and controls movements of the left side of the body.
- Left hemisphere controls right.
Describe the cerebellum.
- Behind the cerebrum.
- Dwarfed by the cerebrum, but contains as many neurons as both cerebral hemispheres combined.
- Primarily a movement control center that has extensive connections with cerebrum and spinal cord.
- Left side concerned with movements of the left side of the body.
- Right side concerned with right.
Describe the brain stem.
- Forms the stalk from which the cerebral hemisphers and the cerebellum sprout.
- Complex nexus of fibers and cells that in part serve to relay info from the cerebrum to the spinal cord and cerebellum, and vice versa.
- Also the site where vital functions are regulated (breathing, consciousness, and control of body temp).
Describe the spinal cord.
- Encased in the bony vertebral column and attached to the brain stem.
- Major conduit of info from skin, joints, and muscles of the body to the brain, and vice versa.
Transection of spinal cords results in...
...anesthesia (lack of feeling) in skin and paralysis of muscles in parts of the body caudal to the cut.
- NOTE: Paralysis means the muscles cannot be controlled by the brain, not that the muscles cannot function.
The spinal cord communicates with the body via...
...the spinal nerves (part of the PNS).
- Spinal nerves exit spinal cord through notches between each vertebra of the vertebral column.
Each spinal nerve attaches to the spinal cord...
...by means of two branches, dorsal and ventral root.
Dorsal vs. Ventral root.
- Dorsal root contains axons that bring info into the spinal cord.
- The ventral root contains axons that carry info away from the spinal cord.
The Peripheral Nervous System
- Made up of all the parts of the nervous system other than the brain and spinal cord.
- Has two parts, the somatic PNS and the visceral PNS.
- All the spinal nerves that innervate the skin, the joints, and the muscles that are under voluntary control.
Somatic motor axons
- Command muscle contraction.
- Drive from motor neurons in the ventral spinal cord.
- NOTE: Cell bodies of motor neurons like within the CNS, but their axons are mostly in the PNS.
Somatic sensory axons
- Innervate and collect info from the skin, muscles, and joints.
- Enter the spinal cord via the dorsal roots.
- NOTE: Cell bodies of these neurons lie outside the spinal cord in clusters called "dorsal root ganglia" (there is a dorsal root ganglion for each spinal nerve).
The Visceral PNS
- The involuntary, vegetative, or autonomic nervous system (ANS) consists of neurons that innervate the internal organs, blood vessels, and glands.
Visceral sensory axons
- Bring info about visceral function to the CNS.
Visceral motor fibers
- Command the contraction and relaxation of muscles that form the walls of the intestines and the blood vessels (called smooth muscles), the rate of cardiac muscle contraction, and the secretory function of various glands.
Afferent and Efferent Axons.
- Afferent means "carry to", and efferent means "carry from".
- 12 pairs that arise from the brain stem and innervate (mostly) the head.
- Each has a name and number.
- Many contain a complex mixture of axons that perform different functions.
Are cranial nerves part of the CNS or PNS?
TRICK QUESTION BITCH: Some are part of the CNS, others are part of the somatic PNS, and others are the visceral PNS.
- Three membranes between the skull and the brain.
- Dura mater, arachnoid membrane, and the pia mater.
- Outermost covering
- Leatherlike consistency, tough inelastic bag sourrounding the brain and spinal cord.
- Just under the dura, looks like a spider web.
What can cause a subdural hematoma?
If blood vessels passing through the dura are ruptured, blood can collect here (forms a subdural hematoma). Usually there is no space between the dura and the arachnoid.
Buildup of fluid can disrupt brain function by...
...compressing parts of the CNS. it is treated by drilling a hole in the skull and draining the blood.
- Thin membrane that adheres closely to the surface of the brain.
- Many blood vessels run along the pia and ultimately dive into the substance underlying the brain.
What separates the pia mater and the arachnoid membrane?
- A fluid filled space. This subarachnoid space is filled with salty clear liquid called cerebrospinal fluid (CSF).
- Brain floats inside CSF.
What is the ventricular system?
- The fluid filled caverns and canals inside the brain.
- CSF is the fluid in this system.
How is CSF produced in the ventricular system?
- It is produced by a special tissue (choroid plexus) in the ventricles of the cerebra hemispheres.
After CSF is produced by the choroid plexus, where does it go?
- It flows from the paired ventricles of the cerebrum to a series of connected, unpaired cavities at the core of the brain stem.
- CSF exits the ventricular system and enters the subarachnoid space by way of small openings, or apertures, located near where the cerebellum attaches to the brain stem.
How does CSF actually get INTO the subarachnoid space?
It is absorbed by the blood vessels at special structures called arachnoid villi in the subarachnoid space.
Computed Tomography (CT)
- Generates an image of a slice of brain by rotating an X-ray source around the head within the plane of the desired cross section.
What did CT scans reveal for the first time?
Gross organization of gray and white matter, position of ventricles in the living brain.
How does magnetic resonance imaging work?
It uses info about how hydrogen atoms in the brain respond to perturbations of a strong magnetic field.
What is the advantage of functional brain imaging over CT and MRI? Give two techniques of it.
- CT and MRI deal with physical changes, and cannot see chemical and electrical activity in the brain.
Two techniques are Positron Emission Tomography (PET), and Functional Magnetic Resonance Imaging (fMRI).