Exam 2 Flashcards
Spinal Cord: Length: (cm and in.) Max Diameter (and where it occurs): Weight: Superior Boundary: Inferior Boundary:
40 - 45 cm (16 - 18 in) Long 1.3 cm Max Dia. - C5-C6 27 - 35 grams Foramen Magnum Disc between L1-L2
Bell-Magendi Law
Dorsal roots contain sensory (afferent) fibers
Ventral roots are motor (efferent) fibers
C1 exits…
C4 exits…
C8 exits…
C1 - between Occiput and Atlas
C4 - IVF between C3 and C4
C8 - IVF between C7 and T1
T1 exits…
T6 exits…
T12 exits…
T1 - IVF between T1 and T2
T6 - IVF between T6 and T7
T12 - IVF between T12 and L1
L1 exits…
L5 exits…
L1 - IVF between L1 and L2
L5 - IVF between L5 and S1
S1 thru S4 exit…
S5 exits…
S1-S4 - Dorsal and Ventral Sacral Foramina
S5 - Sacral Hiatus
Coccygeal Nerve: (2)
Co1 exits the Sacral Hiatus
May be missing
Cord and vertebral column are approximately the same length during what period of development?
First 3 months of embryonic development
At birth, the Co1 cord level is typically at the same level as…
L1-L3 Vertebra
Tapering end of the cord is called…
Conus Medullaris
_______, ________ and ________ nerves run for an extended distance, below the cord, down through the _______ ______.
This formation is called the ______ ______ because it resembles a horse’s tail.
Lumbar, Sacral and Coccygeal run through the LUMBAR CISTERN.
Cauda Equina
Quadriplegic = Injury to... Paraplegic = Injury to...
Quadriplegic = C1 - C8 Paraplegic = T1 or below
Central Canal (of the spinal cord):
- Cranially, it is continuous with the central canal of the… (2)
- Inferiorly, it expands in the ______ ______ as a _______ _______
- continuous with the central canal of the MEDULLA OBLONGATA and the 4TH VENTRICLE.
- expands in the CONUS MEDULLARIS as a TERMINAL VENTRICLE
Terminal Ventricle vs. Lumbar Cistern
Terminal Ventricle = Within Cord
Lumbar Cistern = Outside Cord
Microanatomy of Gray Matter:
Composition: (4)
Neuron Cell Bodies
Thick Dendritic Mats
Support Glial Cells
Capillary Beds
Groups of cell bodies form ______
Nuclei
Lamina I
Thin Cap over Dorsal Horn
Gray Matter Gross Structure Horn Functions: Dorsal Horns - Lateral Horns - Ventral Horns -
Dorsal Horns - Sensory Info
Lateral Horns - T1-L2 and S2-S4; Autonomic/Preganglionic
Ventral Horn - Motor Info
Gray Matter Gross Structure: (1)
White Matter Gross Structure: (1)
Substantia Grisea
Substantia Alba
Funiculus:
Fasciculi:
Funiculus: A longitudinal bundle of white matter fibers
Fasciculi: Bundles of functionally related axons within a funiculus
Lamina II (3)
Substantia Gelatinosa
Sensory
Pain
Lamina III and IV (2)
Nucleus Proprius
Sensory of touch/pressure
Lamina V (2)
Reticular formation in cervical area only
Send axons to contralateral spinothalamic tracts
Lamina VI
Missing at some cord levels
Lamina VII (nucleus one + 2 points) (nucleus two + 3 points)
Nucleus Dorsalis C8 - L3
- Most axons to the Posterior Spinocerebellar Tract
- Sensory info to maintain balance, muscle tone, etc.
Intermediolateral Nucleus T1-T12, L1, L2, S2-S4
- Autonomic Motor Neurons
- Preganglionic Sympathetic (T1 - L2)
- Postganglionic Parasympathetic (S2 - S4)
Lamina VIII
Medial aspect of anterior horn
Lamina IX (3)
- Somatic Motor Horn
- Motor innervates most skeletal muscle
- Class A alpha motor neurons - longest, fastest conducting motor neurons
Lamina X (2)
- Surrounds Central Canal
- Gray Commissures - nonmyelinated, connects equivalent structures on opposite sides
__________ ____________ form _______ and give white matter its white appearance
Interfascicular Oligiodendrocytes for Myelin
Diameter of axons in white matter?
Myelinated?
0.2 - 30 microns
Myelinated >2 microns
Molecules that keep fasciculi together
NCAM’s - Nerve Cell Adhesion Molecules
Descending Tracts: (p.68)
Tectospinal Anterior Cortacospinal Medial Reticulospinal Lateral Reticulospinal Vestibulospinal Rubrospinal Lateral Corticospinal
Ascending Tracts: (p. 68)
Gracilis Cuneatus Posterior Spinocerebellar Anterior Spinocerebellar Lateral Spinothalamic Anterior Spinothalamic
Gracilis
Location:
Synapse:
Fiber Type:
Dorsal Funiculus of ALL cord levels.
Synapse in NUCLEUS GRACILIS of M.O.
Afferent
Cuneatus
Location:
Synapse:
Fiber Type:
- Dorsal Funiculus of T5/T6 and above
- Synapse in NUCLEUS CUNEATUS of M.O.
- Afferent
Functions of Gracilis and Cuneatus: (2)
- 2pt touch discrimination and vibratory sensation
- Kinesthetic sensation - conscious perception of position and movement of body parts (i.e. knowing where your big tow is without looking
Most frequently misinterpreted test for gracilis/cuneatus damage:
Romberg’s Test: Stand with eyes closed - losing balance indicated problem.
Gracilis signal path (primary, secondary, tertiary neurons):
Gracilis:
- Primary: Enters at any cord level, skips gray matter, travels up to M.O. where it synapses with Nucleus Gracilis
- Secondary: Internal Arcuate Fibers immediately cross over and go thru the Medial Lemniscus up to the Thalamus where it synapses again.
- Tertiary: Thalamus to Cortex on opposite side of signal origin
Cuneatus signal path (primary, secondary, tertiary neurons):
Cuneatus:
- Primary: Enters at T6 or above, skips gray matter, travels up to M.O. where it synapses with Nucleus Cuneatus
- Secondary: Internal Arcuate Fibers immediately cross over and go thru the Medial Lemniscus up to the Thalamus where it synapses again.
- Tertiary: Thalamus to Cortex on opposite side of signal origin
Lateral Spinothalamic
Location:
Function:
Part of signal path that differs from Anterior Spinothalamic:
- Lateral Funiculus of ALL cord levels
- Pain/Temperature
- Crosses quickly
Anterior Spinothalamic
Location:
Function:
Part of signal path that differs from Lateral Spinothalamic:
- Anterior Funiculus of ALL cord levels
- Light Touch/Pressure
- Crosses gradually
Lateral Spinothalamic signal path (primary, secondary, tertiary neurons)
- Primary: Pain/Temp. info enters at any cord level and immediately synapses in gray matter
- Secondary: Immediately crosses over and goes straight up to the Thalamus
- Tertiary: Thalamus to Cortex on opposite side of signal origin
Anterior Spinothalamic signal path (primary, secondary, tertiary neurons)
- Primary: Touch/Pressure info enters at any cord level and immediately synapses in gray matter
- Secondary: GRADUALLY crosses over and goes straight up to the Thalamus
- Tertiary: Thalamus to Cortex on opposite side of signal origin
Lesions to Spinothalamic tracts lead to ________ (defeinition) and ___________ (definition) on _______ side of the body.
Analgesia - loss of pain sensation
Thermoanaesthesia - loss of temp sensation
OPPOSITE side of body from lesion.
Lesion of Gracilis/Cuneatus tracts would lead to…
Loss of 2pt TOUCH DISCRIMINATION and KINESTHETIC info from SAME side as lesion.
The lateral and anterior spinothalamic tracts make up a large part of the __________ system when considered together.
Anterolateral System
Anterior Spinocerebellar Tract
Location:
Function:
- Lateral Funiculus of Lumbosacral
- Send input on general state of gross movements of lower body and what is about to happen from MOTOR neurons in that part of the cord
Anterior Spinocerebellar Tract signal path:
- Primary neuron enters lumbosacral and synapses in gray laminae
- Secondary neuron immediately crosses over, travels up, and crosses back over thru the superior cerebellar peduncle (terminates in cerebellum)
Posterior Spinocerebellar Tract
Location:
Function:
- Lateral Funiculus of C8 - L3 - Nucleus Dorsalis
- Proprioceptive input of Fine Movements from what just happened
Posterior Spinocerebellar Tract signal path:
- Primary neuron enters C8 - L3 and synapses with Nucleus Dorsalis
- Secondary neuron (does NOT cross) travels straight up and thru Inferior Cerebellar Peduncle (terminates in cerebellum)
Proprioceptive input above C8 uses which tract?
Cuneocerebellar Tract
Cuneocerebellar Tract
Location:
Function:
- From Accessory Cuneate Nucleus of M.O. to Cerbellum
- Proprioceptive input of Fine Movements above C8 - Pecotral Girdle and Extremity
How does proprioception of fine movements BELOW L3 get to the cerebellum?
Hitches a ride on Gracilis and synapses with Nucleus Dorsalis in L2-L3 region, and then continues on Posterior Spinocrebellar Tract (like all other signals like it)
6 other ascending tracts not covered in class:
Spinoreticular - Pain Spinocortical - terminates in cerebral cortex Spinoolivary - Proprioception Spinovestibular - Postural Reflexes Spinopontine - Cerebellum Spinotectal - Spino-Visual Reflex
Anterior Corticospinal Tract % of corticospinal fibers: Location: Function: Signal Path:
- 5-15% of corticospinal fibers
- Anterior Funiculus down to Thoracic Cord Level
- Unclear - Seem to influence axial musculature of neck and shoulders
- Cerebral Cortex, down same side no lower than T6, neuron crosses outside of tract
Lateral Corticospinal Tract % of corticospinal fibers: Location: Function: Signal Path:
- 85-95% of cortico spinal fibers
- Lateral Funiculus OPPOSITE of origin in cerbral cortex (entire cord)
- Initiating and Accomplishing Precise Skilled Voluntary Movements
- Cerebral Cortex, crosses in Pyramids of M.O., terminates throughout entire spinal cord
Lower Motor Neurons:
Upper Motor Neurons:
Lower - Originate in Spinal Cord or Brainstem, extend into PNS, and innervate Somatic Musculature
Upper - Originate high (Cortex or Brainstem) and influence Lower Motor Neurons (i.e. Corticospinal Tract Fibers + others)
UMN Lesions vs LMN Lesions
Both: Reduction or absence of voluntary movement
UMN: Hyperreflexia, Increased muscle tone, Clonus, Babinski sign (Cerebral Palsy)
LMN: Hyporeflexia/Areflexia, Decreased muscle tone and atrophy, Muscle Fibrillations/Fasciculations (Polio)
Pyramidal Neurons:
Upper Motor Neurons involved with Initiation of Skilled Voluntary Movements
Extrapyramidal Neurons: (2)
- A COMPLEX of UMNs which originate in the brainstem and extend down the cord.
- Influence Posture, Muscle Tone, Enhance Reflexes and thus allow Voluntary Movements to be SMOOTH and EFFECTIVE
Three tracts that are good examples of extrapyramidal neurons
Tectospinal
Rubrospinal
Vestibulospinal
Tectospinal Tract Origin: Path: Termination: Function:
Origin: Superior Colliculus of Midbrain’s Tectum
Path: Crosses as it descends
Termiantion: In Upper Four Cervical Cord Levels
Function: Postural Reflex adjustments to the Traps and Steinocleidomastoid when dealing with Sight and Auditory stimuli
Rubrospinal Tract Origin: Path: Termination: Function: Strongly influenced by...
Origin: Red Nucleus of midbrain’s Tegmentum
Path: Cross in Midbrain as they descend
Termination: Reach all cord levels
Function: Predominately influence CONTRALATERAL HAND and FOOT FLEXOR musculature.
Strongly influenced by CEREBELLUM and CEREBRAL CORTEX
Vestibulospinal Tract Origin: Path: Termination: Function:
Origin: Vestibular Nucleus (lateral part) in M.O.
Path: Fibers do NOT cross
Termination: Runs entire length of cord along the ANTERIOR-LATERAL FUNICULAR JUNCTION
Function: Muscle Tone and Postural Adjustments primarily in Ipsilateral EXTENSORS while Inhibiting Flexors.
Maintains proper orientation when falling.
Medial Reticulospinal Tract Funiculus: Origin: Path: Termination:
- Anterior Funiculus
- Origin: Pons Tegmentum
- Path: Does NOT cross
- Termination: All cord levels
Lateral Reticulospinal Tract Funiculus: Origin: Path: Termination:
- Lateral Funiculus
- Origin: M.O.
- Path: Does NOT cross
- Termination: All cord levels
Functions of Medial and Lateral Reticulospinal Tracts
- Heart, Blood Pressure and Respiratory Rates and Rhythms
- Alternative paths is Corticospinal tract fibers are destroyed
Two tracts that both ascend and descend
Fasciculus Proprius
Dorsolateral Tract of Lissauer
Fasciculus Proprius
Location:
Function:
- Originate and terminate within the cord
- Coordination for Spinal Reflexes
Dorsolateral Tract of Lissauer
Location:
Originate between Rexed Lamina I and Posterior Lateral Sulcus, and terminate in gray horns (all within the cord)
Cause of CNS lesions: (4)
STROKE
Trauma
Tumors
Disease/Infection
UMN vs. LMN - Which would cause quadriplegic and which would cause paraplegic
UMN - Quadriplegic
LMN - Paraplegic
Dorsal Root vs. Ventral Root - Which would inhibit PNS and which would inhibit CNS
Dorsal Root - CNS - Sensory coming into CNS would be inhibited
Ventral Root - PNS - Motor going out would be inhibited
2 common sites for sever spinal injury
C5/C6
T12/L1
Total loss of either the right or left side of the spinal cord
Brown-Sequard Syndrome
______ _______: Bacterial tertiary syphilis resulting in wasting away of the dorsal funiculus.
The actual attack is on the dorsal root ganglia - primarily those contributing to _________ ________ (which tract)
Tabes Dorsalis
Fasciculus Gracilis
________ ________: Resulting in destruction of CNS myelin.
- More common in ________ with onset most commonly between ages ____ and ____.
Multiple Sclerosis
- more common in FEMALES… onset between 20 and 40 years of age
Amyotrophic Lateral Sclerosis: Results in destruction of… (2)… principally in the _______ _________ tracts.
- More common in _______ with onset after age ____
destruction of UMNs and LMNs principally in the LATERAL CORTICOSPINAL tracts
- MALES after age 45
Hexachlorophene (germicide) is an example of a toxin causing injury through _______ alteration.
Myelin
\_\_\_\_\_\_\_ \_\_\_\_\_\_\_ ("Combined Systems Disease")
- Deficiency of...Pernicious Anemia
B12 Deficiency
___________: A rare condition where the cord’s central canal or adjacent areas begin to hollow out (erode).
Syringomyelia
Poliomyelitis: A virus that alters the ________ of the neurons’ cell body until death of cell occurs.
Cytoplasm
- Approximately ___-___% of the CNS tumors develop in the spinal cord tissue
- Most common cord tumor is __________ and usually occurs in the _______ ________.
- Most common tumors in the vertebral canal are ___________.
- 10-15% of CNS tumors develop in spina cord tissue
- Most common CORD tumor is EPENDYMOMA and it occurs in the CONUS MEDULLARIS
- Most common VERTEBRAL CANAL tumor is MENINGIOMA
- ___-___% of CNS tumors are within the cranial vault.
- Most common primary brain tumor is ______
- Most malignant tumor known to man is _________ _________
- 85-90% of CNS tumors are within the cranial vault
- GLIOMA is most common
- GLIOBLASTOMA MULTIFORMA is most malignant
Rhombencephalon includes which gross parts of the brain?
Myelencephalon - Medulla Oblongata
Metencephalon - Pons and Cerebellum
Gross parts of brainstem from superior to inferior?
Midbrain
Pons
Medulla Oblongata
Apparent Origin:
Nucleus of Origin:
Nucleus of Termination:
Apparent Origin: Where C.N. appears to attach
Nucleus of Origin: Contribute motor fibers to C.N.s
Nucleus of Termination: Receive incoming afferent input from C.N.
Medulla Oblongata:
- Passive ________ _______
- Relay Nuclei: (3)
- C.N. Nuclei: (6) - Control centers for… (3)
Medulla Oblongata:
- Passive Fiber Conduction
- Relay Nuclei: Gracilis and Cuneatus, Inferior Olivary Nuclei
- C.N. Nuclei: V, VII-XII - Control centers for RESPIRATORY, SWALLOWING, C.V. FUNCTION
Medulla Oblongata is…
- Ventral to the _______
- Inferior to the _______
- Superior to the ________
- Inferior border is…
Medulla Oblongata is…
- Ventral to the CEREBELLUM
- Inferior to the PONS
- Superior to the SPINAL CORD
- Inferior border is the SUPERIOR MOST ANTERIOR ROOTLET of C1
Sulci of M.O. from midline - out
Dorsal Median Sulcus
Dorsal Intermediate Sulcus
Dorsal Lateral Sulcus
Origins of C.N.s of M.O.:
no C.N. V origin
VII, VII - Pontocerebellar Angle
IX, X, XI - near Ponterolateral Sulcus
XII - Ventrolateral Sulcus
Fibers come to the olive of the M.O. from the… (6)
Cord Red Nucleus Midbrain Cerebral Cortex Basal Ganglia Reticular Formation
The Reticular Formation is thought to control (as a complete unit) ________ _______
General Arousal
Fibers located in the pyramids
Descending Pyramidal Cortacospinal Fibers
Which fibers cross in the pyramids
Lateral Cortacospinal Tract
________ ___________: Ascending fibers throughout the M.O., Pons, Midbrain and terminate in the ________. These fibers will enlarge dramatically half-way up the M.O. as they receive about a million internal arcuate fibers from the OPPOSITE nucleus ________ and _________.
MEDIAL LEMNISCUS: Ascending fibers throughout the M.O., Pons, Midbrain and terminate in the THALAMUS. These fibers will enlarge dramatically half-way up the M.O. as they receive about a million internal arcuate fibers from the OPPOSITE nucleus GRACILIS and CUNEATUS.
Accessory Oculomotor Nucleus: _________ control of _______ and ________ constrictor smooth muscles of the eye - ___________
Parasympathetic
Ciliary and Pupillary
Preganglionic
Oculomotor Nuclei: ________ _______ muscle control for ___ of the 6 extraocular eye muscles and upper eyelid
Somatic Motor muscle control…
4 of the 6
Posterior Nucleus of Vagus:
Sensory and Motor (parasympathetic) for voice, heart, lung and instestine (C.N. X)
Nucleus Ambiguus:
C.N.s IX, X, XI share this nucleus in delivery of visceral efferent (motor) fibers to the pharynx
Nucleus Solitarius:
Sensory reception via VII, IX, X dealing with taste
Main and Spinal Nucleus of the Trigeminal Nerve:
Main sensory for face dealing with pain, thermal, discriminative tactile and proprioception
The spinal nucleus of the trigeminal nerve extends from the _______ down into the ____-___ cord levels
Pons - C1-C4 cord levels
Corticobulbar Fibers: (origin - termination)
Cerebral Cortex - M.O.
Additional tract similar to Fasciculus Proprius which assists with swallowing, chewing and moving eyes together.
Medial Longitudinal Fasciculus
_______ __________ Stroke Syndrome or “Wallenberg’s Stroke Syndrome”:
- Classic set of symptoms would include…
Lateral Medullary Stroke Syndrome
- Loss of pain/temp sensation on one side of face and opposite side of body
C.N. Nuclei of the Pons: (4)
V-VIII
Pons:
Ventral to the _______
Inferior to the _______
Superior to the _______
Ventral to Cerebellum
Inferior to Midbrain
Superior to M.O.
Two subdivisions of the Pons
Tegmentum - or Dorsal Division
Basilar - or Ventral Division
Basilar or Ventral division of Pons contains… (3)
Corticospinal tract fibers
Medial Lemniscus
Pontine Nuclei
Lateral Lemniscus of the Tegmentum of the Pons:
- ________ pathway
- Includes the anterior and posterior ________ nuclei and the ________ _______ nuclei
- This pathway ascends to the diencephalon’s ________ ________ body.
- The final interpretation of auditory input will occur in the _______ _______
Lateral Lemniscus of the Tegmentum of the Pons:
- AUDITORY pathway
- Includes the anterior and posterior COCHLEAR nuclei and the SUPERIOR OLIVARY nuclei
- This pathway ascends to the diencephalon’s MEDIAL GENICULATE body.
- The final interpretation of auditory input will occur in the TEMPORAL LOBE
Functions of the Cerebellum:
- Momentary status of… (4)
Muscle Contraction, Joint Tension, Visual and Auditory input on Equilibrium
Thee main attachments of the cerebellum
M.O. via Inferior Cerebellar Peduncle
Pons via Middle Cerebellar Peduncle
Midbrain Via Superior Cerebellar Peduncle
Another name for the Inferior Cerebellar Peduncle
Restiform
