Peripheral Nervous System (PNS) Flashcards
This are three connective tissue layers that surround the brain and spinal cord.
Meninges
The meninges is composed of three meningeal membrane or layer. What are these?
- Dura mater
- Arachnoid mater
- Pia mater
REMEMBER THE ACRONYM DAP
This is the outermost (most superficial) meningeal layer. This is also the toughest of all the meninges.
Dura mater
The dura mater forms how many layers around the brain and around the spinal cord?
- Two layers around the brain.
- One layer around the spinal cord.
The second meningeal membrane is the very thin, wispy _________________.
The term “wispy” is an adjective used to describe something that is thin, delicate, or fragile in appearance.
Arachnoid mater
What is the space between the dura mater and the arachnoid mater?
This is normally only a potential space containing a very small amount of serous fluid.
Subdural space
What is the space between the arachnoid mater and the pia mater?
Cerebrospinal fluid (CSF) and blood vessels are found in this space.
Subarachnoid space
What is the difference between subdural space and subarachnoid space?
Subdural space: Located between the dura mater and the arachnoid mater. It’s typically a “potential space,” meaning that it doesn’t usually exist under normal conditions unless blood or fluid accumulates, such as in a subdural hematoma.
Subarachnoid space: Located between the arachnoid mater and the pia mater. This is an actual space that always exists and is filled with cerebrospinal fluid (CSF).
What is the third meningeal membrane? This is very tightly bound to the surface of the brain and spinal cord.
Pia mater
The CNS contains fluid-filled cavities called ___________.
Ventricles
Are two large, C-shaped cavities located in each cerebral hemisphere of the brain. They are part of the brain’s ventricular system, which produces and circulates cerebrospinal fluid (CSF).
Lateral ventricle
This is a smaller, midline cavity located in the center of the diencephalon between the two halves of the thalamus and connected by foramina (holes) to the lateral ventricles.
Third ventricle
This located at the base of the cerebellum and connected to the third ventricle by a narrow canal, called the cerebral aqueduct.
It is continuous with the central canal of the spinal cord.
It also opens into the subarachnoid space through foramina in its walls and roof.
Fourth ventricle
Are two small channels that connect the lateral ventricles of the brain to the third ventricle.
These allow cerebrospinal fluid (CSF) to flow from the lateral ventricles into the third ventricle, continuing the pathway of CSF circulation through the brain’s ventricular system.
The foramina of Monro (also called interventricular foramina)
It is a narrow channel in the midbrain that connects the third ventricle to the fourth ventricle.
The cerebral aqueduct (also known as the aqueduct of Sylvius)
The horns of the lateral ventricles are extensions or projections of the lateral ventricles into different lobes of the brain. These horns are named based on their location within the brain and each has a specific function and anatomical relationship to nearby structures.
What are the horns of lateral ventricles?
- Lateral ventricle (anterior horn) - Extends into the frontal lobe of the brain.
- Lateral ventricle (posterior horn) - Extends into the occipital lobe, which is at the back of the brain.
- Lateral ventricle (inferior horn) - Extends into the temporal lobe of the brain.
It is a clear, colorless fluid that bathes the brain and spinal cord, providing a protective cushion around the CNS.
It fills the brain ventricles, the central canal of the spinal cord, and the subarachnoid space.
Cerebrospinal Fluid (CSF)
Cerebrospinal fluid (CSF) is primarily produced by what?
Ependymal cells located in the choroid plexuses of the ventricles
What is the flow of CSF?
Choroid plexuses (ependymal cells)
↓
Lateral Ventricle
↓
Foramina of Monro
↓
Third ventricle
↓
Cerebral aqueduct
↓
Fourth ventricle
[The CSF exits the fourth ventricle through small openings in its walls and roof and enters the subarachnoid space]
- Masses of arachnoid tissue.
- Penetrate the superior sagittal sinus, a dural venous sinus in the longitudinal fissure, and CSF passes from the subarachnoid space into the blood through these granulations.
- Regulated the amount of CSF in the brain.
Arachnoid granulations
The total volume of cerebrospinal fluid in the human body at any given time is about __________.
80 - 150 mL
Arachnoid granulations are very important as it regulates or control the amount of CSF in our brain which is 80-150 mL.
What is the medical condition characterized by an accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain, leading to increased intracranial pressure.
This condition can occur due to various factors, including obstruction of CSF flow, overproduction of CSF, or impaired absorption.
Hydrocephalus
Cranial nerves are a set of twelve pairs of nerves that emerge directly from the brain, primarily the brainstem.
What are the 12 pair of cranial nerves?
- Oh - Olfactory
- Oh - Optic
- Oh - Occulomotor
- To - Trochlear
- Touch - Trigeminal
- And - Abducens
- Feel - Facial
- Very - Vestibulocochlear
- Good - Glossopharyngeal
- Velvet - Vagus
- Ahh - Accessory
- Heaven - Hypoglossal
Cranial nerves are named by using what?
Roman numerals
Cranial nerves has 2 categories of functions. What are these?
Sensory and motor
Cranial nerves can be Sensory and Motor.
Use an acronym to know the categories of function of each cranial nerve.
- Some - Olfactory (Sensory)
- Say - Optic (Sensory)
- Marry - Occulomotor (Motor)
- Money - Trochlear (Motor)
- But - Trigeminal (Both)
- My - Abducens (Motor)
- Brother - Facial (Both)
- Says - Vestibulocochlear (Sensory)
- Big - Glossopharyngeal (Both)
- Brain - Vagus (Both)
- Matter - Accessory (Motor)
- Most - Hypoglossal (Motor)
It is a pure sensory nerve for smell.
Cranial Nerve I (Olfactory)
It is a pure sensory nerve for vision.
Cranial Nerve II (Optic)
It is a pure motor nerve for eye movement.
Cranial Nerve III (Occulomotor)
It is a pure motor nerve for vertical eye movement (movement of eye downward and outward).
Cranial Nerve IV (Trochlear)
It is both a motor and sensory nerve. It is sensory for pain, touch, and temperature for the eye and lower and upper jaws. It is motor for muscles of chewing.
Cranial Nerve V (Trigeminal)
It is a pure motor nerve for lateral eye movement (movement of eye outward, left and right, sides).
Cranial Nerve VI (Abducens)
It is both a sensory and motor nerve. It is sensory for taste and motor for facial expression.
Cranial Nerve VII (Facial)
It is a pure sensory nerve for hearing and equilibrium.
Cranial Nerve VIII (Vestibulocochlear)
It is both a motor and sensory nerve. It is sensory for taste and motor for swallowing.
Cranial Nerve IX (Glossopharyngeal)
It is both a motor and sensory nerve. It is sensory and motor for organs in the thoracic and abdominal cavities.
Cranial Nerve X (Vagus)
It is a pure motor nerve for the trapezius, sternocleidomastoid, and muscles of the larynx.
Cranial Nerve XI (Accessory)
It is a pure motor nerve for the tongue.
Cranial Nerve XII (Hypoglossal)
It refers to difficulty or discomfort in swallowing. It can occur at any stage of the swallowing process, which includes moving food or liquids from the mouth, through the throat, and down the esophagus to the stomach.
Cranial Nerve IX (Glossopharyngeal) is the one responsible for swallowing.
Dysphagia
It refers to the activation of the vagus nerve, which is the tenth cranial nerve (cranial nerve X). The vagus nerve is involved in controlling various autonomic functions, including heart rate, digestion, and respiratory rate, and plays a key role in regulating the parasympathetic nervous system, often referred to as the “rest and digest” system.
Vagal stimulation
It is an automatic response that occurs when the back of the throat is stimulated. It serves as a protective mechanism to prevent choking or aspiration of foreign objects into the airway.
The glossopharyngeal nerve (cranial nerve IX) detects touch or other stimuli in the back of the throat, especially the soft palate, the base of the tongue, and the tonsillar area.
The gag reflex (also known as the pharyngeal reflex)
The Spinal Cord extends from (a)__________ to (b)___________.
It is protected by vertebral column.
- (a) foramen magnum
- (b) 2nd lumbar vertebra