Singh 3 Flashcards
The Spinal Cord:
Length?
Extent (both organ and skeletal)
Define the “conus medullaris”
The Spinal Cord:
Length: 43-45 cm
Extent: from base of medulla to the conus medullaris (end of spinal chord)
OR from a skeletal view from the foramen magnum to the interspace between L1-L2 vertebrae in the adult
Conus Medullaris: located at the caudal tip of the spinal cord, located in L3 in kids and L1 in adults
The Spinal Cord
- Define the following terms:
Filum terminale
Cauda Equina
Central Canal
Spinal Cord:
Filum Terminale: extends from the tip of the conus and attaches to the distal dural sac (consists of pia and glial fibers and often contains a vein)
Cauda Equina: the dorsal and ventral spinal rootlets of the lumbar and sacral spinal nerves
Central Canal: lined with ependymal cells and filled with CSF
The spinal roots:
Dorsal roots carry ________ fibers with cell bodies in ____
Ventral roots carry ________ fibers with cell bodies in _______
The spinal roots:
Dorsal roots carry afferent fibers with cell bodies in DRG
Ventral roots carry efferent fibers with cell bodies in ventral gray matter
Remember for the spinal cord
DORSAL means ____
Ventral means _____
DORSAL for the spinal cord is posterior (SENSORY)
Ventral means anterior/in front (MOTOR)
Pattern of Spinal Nerve Emergence:
In the cervical cord, nerve roots exit _____
In the lower cord, nerve roots exit ______
Pattern of Spinal Nerve Emergence:
In the cervical cord, nerve roots exit above vertebrae
In the lower cord, nerve roots exit below vertebrae
Functions of the spinal cord:
1.
2.
3.
4.
Functions of the Spinal Cord:
- Conduit for the transmission of crucial nerve impulses (information) connecting the brain with most of the body
- Segmental reflexes
- Control of motor activity
- Modulation of sensory phenomena, especially pain transmission, and proprioception
Basic Structure of the Spinal Cord:
Gray Matter includes the:
1.
2.
3.
White matter includes:
1.
2.
3
Gray matter (contains cell bodies, is middle of chord)
- ventral horn
- dorsal horn
- intermediolateral gray column (ANS)
White Matter: myelinated fibers, axons
- Dorsal columns
- Lateral columns
- Anterior/ventral columns
Explain the following terms and show where they are in the image below:
Posterior Lateral Sulcus
Anterior lateral Sulcus
Anterior/ventral median fissure
Posterior Lateral Sulcus: dorsal root entry zone
Anterior Lateral Sulcus: ventral root exit zone
Anterior/ventral median fissure: contains the sulcal branch of the anterior spinal artery (aka the cord’s intrinsic arterial blood supply)
Define the following terms:
Posterior/dorsal median sulcus
Posterior/dorsal intermediate sulcus
Posterior/dorsal median sulcus: seperates the right and left dorsal funiculi
Posterior/dorsal intermediate sulcus: present only in segments above T6
Explain the differences in the gray and white matter in the spinal cord cross sections (differences between cervical, thoracic, and lumbar)
Notable, the gray matter is the smallest in the thoracic region
The white matter is the largest in the cervical region
and the gray matter is the biggest in the lumbar region
A key point here is that the dorsal/ventral horn appears larger in segments of the spinal cord that serve extremities
Gray Matter of the Cord:
Organization: related to degree of _______
Where are the enlargements?
Where does the sympathetic neurons lie?
Gray matter of the cord:
Organization: related to degree of innervation supplied by the segment
C4-T1: cervical enlargement:
- Brachial plexus
- Large posterior and ventral gray horns
L1-S2 lumbar enlargement:
- Lumbrosacral plexus
- Large posterior and ventral gray horns
Sympathetic neurons: Intermediolateral cell column
White Matter Organization:
Expplain the Posterior/Dorsal Column
List important functions of the dorsal column
Posterior (dorsal) column:
Sensory pathways only
Fasc. gracilis and fasc. cuneatus (aka the dorsal columns that dorm the DCML sensory pathway)
Proprioception, epicritic sensation (two point discriminative touch and vibratory sensation) are carried by pathways of the posterior columns
White Matter Organization:
Explain the lateral columns
White Matter Organization:
Lateral Column (or funiculus):
- SENSORY (lateral spinothalamic tract)
and MOTOR (lateral corticospinal tract)
White Matter Organization:
Explain the Anterior/Ventral Column or funiculus
Anterior/Ventral Column
MOTOR pathways primarily (ventral corticospinal)
Explain what the following ascending pathways are related to:
Fasiculus Gracilis (DCML)
Faciculus Cunneatus (DCML)
Lateral and ventral spinothalamic tracts
Fasiculus Gracilis (think graceful legs…. LEGS)
Faciculus Cunneatus…. arms
Lateral and ventral spinothalamic tract: pain and temperature sensation
Explain the following spinal cord tracts:
Ascending:
Faciculus Gracilis & Faciculus Cuneatus
Remember, the fasiculus gracilis and fasciculus cuneatus make up the DCML pathways
THINK concious proprioception
Leg nerve enters fasiculus gracilis (arm enters cuneatus)
The axons of these neurons ascend uncrossed in the posterior finiculi to the nucleuses located in the medulla oblongata
they then cross over to the primary somatosensory cortex in the brain
Explain the lateral spinothalamic tract
Lateral Spinothalamic: think pain and temperature
these neurons cross the middle region (region of decussation) within the spinal cord
Explain the anterior spinothalamic tract
Anterior spinothalamic tract: think touch and pressure
What is an important function of Lissauer’s tract (aka posterolateral tract)?
Lissauer’s Tract (aka the posterior lateral tract) carries information related to location, intensity, and quality of pain
Explain looking at a cross-section of the spinal cord, where the following areas that are in charge of these functions lie:
Voluntary Motion
Proprioception, Pain, Temp, Pressure
Proprioception, deep touch, vibration
Explain the corticospinal tract
What is the babinski sign?
Presence of a babinski sign is evidence of what?
Normally, when you graze an object down your foot you are supposed to curl your toes and point downward
The babinski sign is when you extend your feet upward
It is a sign of an issue with your corticospinal tract
Infants have this because their corticospinal tract (which is also in charge of fine motor control) is not fully developed
What are some signs of upper motor neuron defecits?
1.
2.
3.
4.
5.
Upper motor neuron defecits:
Spastic paralysis
hyper-reflexia
little to no muscle atrophy
no fasiculations
presence of babinski sign
What are some signs of lower motor neuron defecits?
1.
2.
3.
4.
5.
Lower motor neuron defecits:
Flaccid paralysis
Hypo-reflexia
significant muscle atropy
fasiculations present
no babinski sign
