Chapter 12 - Nervous System Flashcards
How far does the spinal cord extend? What are its segments?
From the foramen magnum in the skull to the lumbar vertebra.
- Cervical, Thoracic, Lumbar, Sacral
- What is the Cervical enlargement?
- What is the Lumbar enlargement?
- Cervical enlargement: supplies upper limbs
- Lumbar enlargement: supplies lower limbs
- What is the Conus medullaris?
- What is the Cauda equina?
- Conus medullaris: tapered inferior end
- Cauda equina: origins of spinal nerves extending inferiorly from the lumbosacral enlargement and conus medullaris.
What’s the Dura Mater?
Connective tissue membrane surrounding the spinal cord and brain.
- Most superior / Thickest layer
- Forms a sac-like structure that extends from the foramen magnum to the level of 2nd sacral vertebrae
What’s the Arachnoid Mater?
Connective tissue membrane surrounding the spinal cord and brain.
- Second layer / Thin and wispy
- Follows Dura Mater through spinal cord
What’s the Pia Mater?
Connective tissue membrane surrounding the spinal cord and brain.
- Most deep layer
- Bound tightly to surface of brain and spinal cord
- Forms the filum terminale which anchors spinal cord to coccyx
- Forms denticulate ligaments that attach the spinal cord to the dura mater.
What is the Epidural? What does it contain?
- A space within the spinal cord between the periosteum of the bone and the dura mater.
- Contains roots of the spinal nerves, blood vessels, areolar connective tissue, and fat.
- Epidural anesthesia is injected in this space.
What is the Subdural? What does it contain?
- A space within the spinal cord between the dura mater and the arachnoid mater.
- Contains a small amount of serous fluid.
- It’s very small.
What is the Subarachnoid? What does it contain?
- A space within the spinal cord between the arachnoid mater and the pia mater.
- Contains cerebrospinal fluid and blood vessels within web-like strands of arachnoid tissue.
- Lumbar puncture is done here.
What is the Anterior median fissure and posterior median sulcus?
Cross sections of the spinal cord
- Deep clefts partially separating left and right halves of the spinal cord.
Describe the White matter.
- Located peripherally
- Made of myelinated axons that form nerve tracts
- Three columns (tracts) of white matter: ventral, dorsal, lateral
- These columns carry information to or from the CNS
Describe the Gray matter.
- Centrally located
- Made of neuron cell bodies
- Organized into Horns: posterior (dorsal), anterior (ventral), lateral
Describe Commissures. What are the 2 types?
- They are connections between left and right halves of the spinal cord.
- Two types:
Gray Commissure: Connects the right and left sides of the horns. Contains the central canal.
White Commissure: Connects the right and left sides of the white matter.
Describe Roots.
- Multiple rootless combine to form roots
- Two types: Dorsal & Ventral
- The two types of roots merge laterally to form a spinal nerve. (also called a mixed nerve)
Describe Dorsal Roots.
Dorsal:
- Contains axons of sensory neurons
- Has Dorsal Root Ganglions which are collections of cell bodies of sensory neurons
Describe Ventral Roots
Ventral:
- Contains axons of motor neurons
- Cell bodies located in spinal cord gray matter, anterior or lateral horns
- Two types: somatic neurons in the anterior horn, autonomic neurons in the lateral horn.
What do spinal nerves consist of?
- Axon bundles
- Schwann cells
- Connective tissue: Endoneurium, Perineurium, Epineurium
What is Endoneurium?
Connective tissue of spinal nerves that surrounds individual neurons and Schwann cell sheath.
What is Perineurium?
Connective tissue of spinal nerves that surrounds axon groups to form fascicles.
What is Epineurium?
Connective tissue of spinal nerves that surrounds the entire nerve.
How many pairs of spinal nerves are there? How many of each type are there? (cervical, thoracic, lumbar, sacral, coccygeal)
31 pair total
- 8 Cervical
- 12 Thoracic
- 5 Lumbar
- 5 Sacral
- 1 Coccygeal
Describe the Dorsal Ramus.
Provides motor innervation to deep muscles of the trunk, responsible for the movement of the vertebral column and the connective tissue & skin near the midline of the back.
Describe the Ventral Ramus.
It is distributed in 2 ways, depending on which part of the spinal cord is considered.
- Thoracic region: form intercostal nerves that innervate the intercostal muscles and the skin over the thorax
- Remaining spinal nerves ventral rami form 5 plexus (intermingling of nerves): Cervical, Brachial, Lumbar, Sacral, Coccygeal
What are Cervical Plexus? What are the nerve branches within it?
Originate from ventral rami of C1-C4
Innervates:
- Superficial neck structures and the skin of the neck & posterior head.
Phrenic nerve
What is the Phrenic nerve?
Nerve within the Cervical Plexus
Originates from ventral rami of C3-C5
- Innervates: the diaphragm (helps us breathe)
What are Brachial Plexus? What are the nerve branches within it? Explain.
Originated from ventral rami of C5-T1
- Axillary
- Radial
- Musculocutaneous
- Ulnar
- Median
Explain the Axillary nerve.
Nerve within the Brachial Plexus
Supply the shoulder
-Motor Innervation: Deltoid, Teres minor
- Sensory Innervation: Inferior lateral shoulder
Explain the Radial nerve.
Nerve within the Brachial Plexus
Supply the posterior arm, forearm, and hand
- Motor Innervation: All extensor muscles of the upper limb
- Sensory Innervation: Posterior upper limb & lateral dorsum of hand
Explain the Musculocutaneous nerve.
Nerve within the Brachial Plexus
Supply the anterior arm
- Motor Innervation: Anterior muscles of the arm
- Sensory Innervation: Lateral forearm
Explain the Median nerve.
Nerve within the Brachial Plexus
Supply the anterior arm and hand
- Motor Innervation: All flexor muscles of the forearm & thumb muscles
- Sensory Innervation: Lateral palm of hand & the fingers
Explain the Ulnar nerve.
Nerve within the Brachial Plexus
Supply the anterior arm and hand
- Motor Innervation: Flexor carpi ulnaris & flexor digitorum, Hand muscles
- Sensory Innervation: Medial part of hand, ring finger, little finger
What are Lumbar and Sacral Plexus? What are the nerve branches within it?
- Lumbar originates from ventral rami of L1-L4
- Sacral originates from ventral rami of L4-S4
(Lumbosacral Plexus L1-S4) - Obturator
- Femoral
- Tibial
- Common fibular
Explain the Obturator nerve.
Nerve within the Lumbosacral Plexus
Supply the medial thigh
- Motor Innervation: Thigh adductors
- Sensory Innervation: Medial side of thigh
Explain the Femoral nerve.
Nerve within the Lumbosacral Plexus
Supply the anterior thigh
- Motor Innervation: Iliopsoas, Sartorius, Quadriceps femoris
- Sensory Innervation: Anterior and lateral thigh & medial leg and foot
Explain the Tibial nerve.
Nerve within the Lumbosacral Plexus
Supply the posterior leg and foot
- Motor Innervation: Posterior thigh and leg muscles
- Sensory Innervation: the foot
Explain the Common Fibular nerve.
Nerve within the Lumbosacral Plexus
Supply the lateral & anterior leg and foot
- Motor Innervation: Biceps femoris
- Sensory Innervation: lateral surface of knee, 2nd toe, dorsum of foot
What are the 4 major portions of the brain?
- Cerebrum
- Cerebellum
- Diencephalon
- Brainstem
Explain the Brainstem portion of the brain.
Connects the spinal cord to the cerebrum
- Acts as a pathway for nerve tracks & is in control of many autonomic reflexes
Consist of the:
1. Medulla Oblongata
2. Pons
3. Midbrain
Explain the Medulla Oblongata.
A portion in the Brainstem
Its discrete nuclei in internal gray matter that either relay impulses to higher brain centers or control some vital reflexes.
- Has: Respiratory Center, Cardiac Center, Vasomotor Center. (swallowing, vomiting, hiccupping, coughing, sneezing)
- Nuclei of cranial nerves 5, 9-12
- Contains pyramids & olives.
Explain what pyramids are.
A portion of the Medulla Oblongata
- Descending motor nerve tracts that carry motor information from higher brain centers to the body. They inferiorly decussate (cross).
(the right side of the brain controls the left side of the body)
Explain what olives are.
A portion of the Medulla Oblongata
- Nuclei that help regulate balance, coordination, modulation of sound from inner ear
Explain the Pons.
A portion in the Brainstem
- Has a specific nuclei called the pontine that helps with voluntary movement
- Nuclei of cranial nerves 5-9
- Nuclei that makes up the sleep center: initiates REM sleep
- Has a respiratory center that coordinates with the medulla oblongata (backup)
Explain the Midbrain.
A portion in the Brainstem
- Contains tracts that connect lower parts of the brain stem and the spinal cord with higher parts of the brain
- Nuclei of cranial nerves 3,4,5
- Contains the Corpora Quadrigemina
What is the Corpora Quadrigemina? Explain.
Bulging area consisting of 4 areas of gray matter, each separate part is a colliculus.
Two superior colliculi:
- Receive incoming sensory input from visual, auditory, and tactile senses.
- Involved in reflex movements of head, eyes, body
Two inferior colliculi:
- Involved in hearing
- Neurons in the inner ear synapse here and then auditory sensory information is routed to higher brain centers.
Explain the Cerebellum portion of the brain.
Attached to brainstem posterior to pons
- Communicates with other areas of the CNS through 3 tracts: Superior, Middle, and Inferior Peduncles
Functions:
- Balance and posture
- Coordinating voluntary movements
- Works with frontal lobe in learning complex movements
Explain the Diencephalon portion of the brain.
Located between the brainstem and cerebrum
- Function as a relay center for sensory information and autonomic control
Components:
- Thalamus
- Hypothalamus
- Epithalamus
- Subthalamus
What is the Thalamus? Explain.
Component of the Diencephalon
- Is a relay station for sensory information heading to the brain.
- All sensory information (except smell) from the spinal cord synapses here before being sent to the cerebrum. This allows the sensory information to be sent to the correct area of the cerebrum for interpretation.
- Different areas of the thalamus relay different types of information: Medial Geniculate nucleus, Lateral Geniculate nucleus, and Ventral Posterior nucleus.
What is the Hypothalamus? Explain.
Component of the Diencephalon
(president of the autonomic N.S.)
- Contains several small nuclei and tracts. Receives sensory information from many parts of the body and sends out motor/efferent commands
- Efferent fibers lead to the brainstem, spinal cord, pituitary gland, and some cranial nerves.
- Has autonomic functions
Explain the Cerebrum portion of the brain.
Composed of right and left hemispheres each of which has lobes:
- Frontal, Parietal, Temporal, Occipital, Insula
Composed of sulci and fissures:
- Longitudinal fissure, Lateral fissure, Central sulcus
Explain the different lobes of the Cerebrum.
- Frontal lobe: voluntary motor function, personality, decision-making
- Parietal lobe: Sensory information (except smell, hearing, and vision)
- Occipital lobe: reception and integration of visual input
- Temporal lobe: reception and evaluation for smell and hearing (insula is within - receives and evaluates taste)
Explain the different sulci and fissures of the Cerebrum.
Longitudinal fissure:
- Separates the right and left hemispheres of the cerebrum
Lateral fissure:
- Separates the temporal lobe from the frontal and parietal lobes
Central sulcus:
- Separates frontal and parietal lobes, located between the precentral gyrus (voluntary motor function starts here - primary motor complex) and postcentral gyrus (all general sensory info is routed here - primary somatic sensory cortex)
What are Ventricles?
Ventricles are a cavity system that produces and circulates cerebrospinal fluid.
(4 Ventricles total)
- 2 Lateral ventricles
- Third ventricle
- Fourth ventricle
What is Cerebrospinal fluid (CSF)?
Froms a protective cushion around the brain and spinal cord (protects from shock of rapid head movements
- Choroid plexuses: produce CSF which fills ventricles and other parts of the brain and spinal cord (composed of ependymal cells)
Explain Cranial nerves. What are the 3 functions that they can have?
They are indicated by Roman numerals 1-12 from anterior to posterior.
May have one or more of three functions
1. Sensory: special or general
2. Somatic motor: control of skeletal muscles
3. Parasympathetic: regulation of glands, smooth muscle, cardiac muscle
Explain the Cranial Nerve - Olfactory
Cranial Nerve (I) #1
- Sensory function: smell
Explain the Cranial Nerve - Optic
Cranial Nerve (II) #2
- Sensory function: vision
Explain the Cranial Nerve - Oculomotor
Cranial Nerve (III) #3
- Motor function: muscles of eye movement
- Parasympathetic function: control pupil size
Explain the Cranial Nerve - Trochlear
Cranial Nerve (IV) #4
- Motor function: muscles of eye movement
Explain the Cranial Nerve - Trigeminal
Cranial Nerve (V) #5
- Sensory function: scalp, forehead, nose, cheeks, chin, eyelids, teeth
- Motor function: muscles of mastication, throat, ears
Explain the Cranial Nerve - Abducens
Cranial Nerve (V1) #6
- Motor function: muscles of eye movement
Explain the Cranial Nerve - Facial
Cranial Nerve (VII) #7
- Sensory function: taste on anterior tongue
- Motor function: muscles of facial expressions
- Parasympathetic function: salivary glands
Explain the Cranial Nerve - Vestibulocochlear
Cranial Nerve (VIII) #8
- Sensory function: hearing and balance
Explain the Cranial Nerve - Glossopharyngeal
Cranial Nerve (IX) #9
- Sensory function: taste on posterior tongue, carotid arteries
- Motor function: pharyngeal muscles
- Parasympathetic function: salivary glands
Explain the Cranial Nerve - Vagus
Cranial Nerve (X) #10
- Sensory function: pharynx, larynx, abdominal organs
- Motor function: pharynx and muscles of voice
- Parasympathetic function: thoracic and abdominal viscera
Explain the Cranial Nerve - Accessory
Cranial Nerve (XI) #11
- Motor function: trapezius and sternocleidomastoid muscles
Explain the Cranial Nerve - Hypoglossal
Cranial Nerve (XII) #12
- Motor function: tongue muscles
Where is the Dura mater located?
Where is the Arachnoid mater located?
Where is the Pia mater located?
Where is the Epidural space located?
Where is the Subdural space located?
Where is the Subarachnoid space located?
Where is the White and Gray matter located?
Where are Ventral and Dorsal roots located?
Identify
Brainstem
Identify
Midbrain
Identify
Pons
Identify
Medulla Oblongata
Identify
Thalamus
Identify
Hypothalamus
Identify
Occipital lobe
Identify
Parietal lobe
Identify
Postcentral and Precentral gyrus
Identify
Frontal lobe
Identify
Temporal lobe
