Back: Spinal Cord Flashcards

1
Q

Spinal Cord

A
  • Part of the central nervous system
  • Located in the vertebral canal
  • Spans from the foramen magnum to L2
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2
Q

Cervical Enlargement

A
  • C4-T1 segments of cord
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3
Q

Lumbar Enlargement

A
  • L1-S3 segments of cord
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4
Q

Conus Medullaris

A
  • End of the spinal cord located at L2
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5
Q

Thoracic Spine

A
  • Gives rise to the nerves that innervate the upper extremity
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6
Q

Lumbar Spine

A
  • Nerves that innervate the lower extremities
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7
Q

Embryology

A
  • Differential growth between cord and vertebral column/dura mater
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8
Q

Embryo/Fetus Prior to 8 Weeks

A
  • Cord extends length of vertebral canal
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9
Q

Embryo/Fetus 6 Months Onward

A
  • Tip of cord is at vertebral level S1
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10
Q

Spinal Cord Segment

A
  • Gives rise to rootlets at a particular level
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11
Q

Anterior (Ventral) Rootlets

A
  • Contain efferent (motor) nerve fibers
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12
Q

Posterior (Dorsal) Rootlets

A
  • Contain afferent (sensory) nerve fibers
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13
Q

Dorsal Root Ganglion

A
  • Cell bodies of pseudounipolar sensory neurons
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14
Q

Anterior and Posterior Root

A
  • Unite to form spinal nerve
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15
Q

Spinal Nerve

A
  • Mixed nerve (motor and sensory)
  • Representative of spinal cord segment
  • Exits out intervertebral foramen
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16
Q

Cauda Equina

A
  • spinal nerve roots from the lumbosacral enlargement and conus medullaris
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17
Q

Posterior and Anterior Rami

A
  • Spinal nerves branch into these
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18
Q

Posterior Ramus

A
  • Facet joints of vertebral column
  • Deep back muscles
  • Skin over the back
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19
Q

Anterior Ramus

A
  • Supply almost everything else
  • Anterior and lateral trunk/abdomen (intercostal nerves)
  • Upper and lower extremity (brachial & lumbosacral plexuses)
  • Neck (cervical plexus)
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20
Q

Meningeal Branches of Spinal Nerves

A
  • Recurrent meningeal nerve

- Branch off the spinal nerve of anterior ramus

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21
Q

Supplied by Recurrent Meningeal Nerve

A
  • Periosteum of portion of the vertebra
  • Outer annulus fibrosis
  • Dura mater
  • PLL
  • Blood vessels
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22
Q

Recurrent Meningeal Nerve

A
  • Loops back/passes through the IVF
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23
Q

Posterior Ramus

A
  • Provides motor to deep back muscles and branches that supply the skin, facet joints, zygapophyseal joints
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24
Q

Anterior Ramus

A
  • Larger component of the spinal nerve that innervates everything else
  • Forms a plexus (network of nerves)
  • T1 and sometimes T2, the lumbar and sacral region nerves connect with each other to for plexus
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25
PLL
- Supplies dura mater
26
Cervical Spinal Nerves
- Exit vertebral canal above same number vertebrae
27
Cervical
- 8 spinal nerves
28
Thoracic
- 12 spinal nerves
29
Lumbar
- 5 spinal nerves
30
Thoracic and Lumbar Spinal Nerves
- Exit vertebral canal below same number vertebrae
31
Sacral
- 5 spinal nerves
32
Spinal Nerve S5
- Exits through sacral hiatus
33
S1-S4
- Anterior/posterior rami exit through anterior/posterior sacral foramina
34
Coccygeal
- Nerves exit through sacral hiatus
35
Anterior Rami
- Give rise to the intercostal nerves in the thoracic region | - Form plexuses in the cervical and lumbosacral regions
36
Plexuses
- Give rise to multi-segmental peripheral nerves
37
Peripheral Nerve
- Nerves that come together from different regions to form a new name nerve
38
Somatic Nervous System
- Sensory and motor to everything except viscera, smooth muscle, glands
39
Somatic Nerve Fibers
- Sensation from the body, typically reaches consciousness - Pain, temperature, touch, pressure - Proprioceptive (mostly subconscious)
40
Afferent
- General sensory
41
Efferent
- Somatic motor
42
Somatic Motor (Efferent) Nerves
- Skeletal muscle (voluntary) | - Single neuron from spinal cord to muscle
43
Dermatome
- Area of skin supplied by a spinal segment and spinal nerve | - Usually there is overlap between them
44
Peripheral Nerve Distribution
- Area of skin supplied by peripheral nerve
45
Myotome
- Group of muscles innervated by a spinal nerve - Most muscle groups of the extremity are innervated by multiple spinal nerves (formed by multiple of these) - One or two are more strongly associated with each muscle groups
46
Peripheral Nerve Innervation
- Can innervate one or muscle groups
47
Visceral Innervation
- Cardiac and smooth muscle, glands
48
Visceral Sensory
- Normally not perceived, subconscious reflexes - Not sensitive to touch, vibration - Sensitive to chemical irritation, ischemia - Large amounts of distension, contraction - Referred pain
49
Visceral Motor
- Autonomic nervous system
50
Visceral Motor (Autonomic Nervous System)
- Involuntary muscle (cardiac and smooth muscles) | - Glandular tissue
51
Autonomic Nervous System
- Efferent to cardiac and smooth muscle, glands
52
Autonomic Nervous System
- Sympathetic (thoracolumbar) division | - Parasympathetic (craniosacral) division
53
Autonomic Nervous System
- 2 neuron chain - Presynaptic and postsynaptic neuron - Pre-synaptic neuron synapses on the postsynaptic in an autonomic ganglia
54
Presynaptic Neurons (Sympathetic ANS)
- Originate in the intermediolateral cell columns (IML) - Lateral horn of T1-L2(3) gray matter - Leave through the ventral root - Enter sympathetic trunk via white rami communicantes
55
White Rami
- Enter sympathetic trunk via these communicantes | - Only found at T1-L2(3) spinal cord segments
56
Upon Entering Sympathetic Trunk
- Synapse at same level - Ascend or descend to synapse in paravertebral ganglia at another level (above T1 or below L3) - Pass through w/o synapsing
57
Gray Rami Communicantes
- 1 & 2 exit sympathetic trunk exit through this
58
Postsynaptic Neurons
- Reach destination via spinal/peripheral nerves and periarterial plexus
59
Parasympathetic Division of ANS (Craniosacral)
- Innervates head, viscera, erectile tissue | - Not found in the limbs or body wall
60
Presynaptic Fibers Originate
- Brainstem - Follows cranial nerves III, VII, IX, X - S2-4 segments of spinal cord - Pelvic splanchnic nerves
61
Parasympathetic Ganglia
- 4 associated with the head (later)
62
GI Tract and Heart
- Have their own network of neural tissue that governs their function - Modulated by sympathetic and parasympathetic
63
Spinal Meninges
- Connective tissue membranes - Support the cord and nerve roots - Contain the CSF
64
Dura Mater
- Tough outermost fibrous sheath | - Continuous with cranial dura
65
Arachnoid Mater
- Deep to dura (stays in contact with dura) - ** trabeculae connect with pia mater - Encloses CSF filled subarachnoid space - Ends at S2 - Forms spinal dural sac (dural sheath)
66
Dural Sac
- Ends at S2
67
Pia Mater
- Covers spinal cord and nerve roots | - Thin and delicate
68
Leptomeninges
- Arachnoid & pia
69
Filum Terminale
- End of the conus medullaris
70
Filum Terminale Internum
- Pia mater (L2 – S2)
71
Filum Terminale Externum
- Coccygeal ligament: pia and dura | - Attaches to coccyx (S2-coccyx)
72
Denticulate Ligaments
- 20 – 22 pairs of sawtooth fibrous extensions of pia mater - Attach to inner dural sac - Pass between dorsal and ventral roots
73
Epidural Space
- Between bony wall of vertebral canal and dura mater - Fat - Internal vertebral venous plexus - Spinal nerves - Blood vessels
74
Dural Root Sleeve
- Extension of dural sheath around roots and dorsal root ganglia
75
Subarachnoid Space
- Between arachnoid and pia mater | - Continuous with cranial **
76
Content of Subarachnoid Space
- CSF - Arteries and veins - Arachnoid trabeculae - Cauda equina - Filum terminale
77
Vertebral Column From Outside Inward
1. Bone 2. Epidural space (extradural space) 3. Dura mater 4. Subdural space (potential space) 5. Arachnoid mater 6. Subarachnoid space 7. Pia mater 8. Spinal cord
78
Lumbar Cistern
- Enlargement of subarachnoid space in the dural sac - Caudal to conus medullaris (L2 – S2) - Site of lumbar puncture
79
Lumbar Puncture
- Performed midline between L3/4 or L4/5 - Patient position in a flexed position - Gain access to subarachnoid space (anesthesia or CSF sample)
80
Lumbar Puncture Entry Order
1. Skin 2. Superficial fascia 3. Supraspinous ligament 4. Interspinous ligament 5. Ligamentum flavum 6. Epidural space 7. Dura mater 8. Arachnoid mater 9. Subarachnoid space
81
Spinal Anesthesia
- Anesthesia introduced into subarachnoid space
82
Epidural Anesthesia (Blocks)
- Similar to lumbar puncture | - Between lamina or through sacral hiatus (caudal)
83
Spina Bifida
- Developmental neural tube defect that is the result in nonunion of the neural arches. - Caused by disruption of neurulation in the embryo
84
Spinal Bifida Occulta
- Neural tissue IS NOT involved
85
Spina Bifida Manifesta (Cystica)
- Neural tissue and/or meninges ARE involved
86
Meningocele (SB Manifesta)
- Meninges protrude through the defect
87
Meningomyelocele (SB Manifesta)
- Meninges and cord/nerve roots protrude through the defect
88
Blood Supply of Vertebral Column and Spinal Cord
- Anterior and Posterior Spinal Arteries
89
Spinal Branches that Pass through the IVF
- Vertebral - Ascending cervical - Segmental arteries - Posterior Intercostal - Subcostal - Lumbar - Lateral sacral
90
Anterior Spinal Artery
- Branch of vertebral artery - Runs in anterior median sulcus - Gives off sulcal arteries - Supply anterior 2/3 cross-sectional area
91
Posterior Spinal Arteries
- Branch of posterior inferior cerebellar (most common) or vertebral artery
92
A/P Radicular Arteries
- Supply the nerve roots
93
A/P Segmental Medullary Arteries
- Supplement blood supply to spinal cord | - Not present at every level
94
Great Anterior Segmental Medullary Artery
- Artery of Adamkiewicz
95
Artery of Adamkiewicz
- Largest segmental medullary artery - Origin varies: usually left side from lower intercostal or upper lumbar artery - Blockage can result in caudal cord ischemia
96
Bastons plexus (Venous Drainage)
- Network of paraspinal veins
97
Vertebral Column
- Internal/external vertebral venous plexus (epidural venous plexus) - Basivertebral veins - Intervertebral vein
98
Internal/External Vertebral Venous Plexus (Epidural Venous Plexus)
- Communicate with each other through IVF
99
Basivertebral Veins
- Drain the vertebral bodies | - Communicates with internal & external plexuses
100
Intervertebral Vein
- Drain cord & column drain into segmental veins
101
Ant/Post Spinal Veins
- Communicate with internal and external venous plexuses
102
Vertebal Veinous Plexuses
- Communicate with the dural venous sinuses and deep pelvic veins - Route of metastasis - Valveless
103
Content/Boundaries of IVF
- Spinal nerve - DRG - Recurrent meningeal nerve - Spinal branches of segmental arteries - Intervertebral veins - Adipose
104
Flexion
- Increases IVF size
105
Extension
- Decreases IVF size
106
L5
- Has the thickest spinal nerve but smallest IVF (of the lumbar region)
107
Anatomical Sources of Lower Back Pain
- IVD - Spinal nerve - Zygapophyseal joints - Subchondral bone - Ligaments - Muscles - Viscera (kidneys) - Sacroiliac joint
108
Viscera (Kidneys)
- Refer pain to the lower back
109
Spondylosis
- More generic, broad term that refers to any type of degenerative changes to the spine
110
Narrowing of IVF
- Osteophytes (bone spurs) on the facet joint | - Osteophytes on uncovertebral processes in the cervical spine
111
Herniation
- Can decrease the size of the IVF
112
Herniated Discs
- Can also compress cauda equina and impinge on nerves
113
Narrowing of Vertebral Canal Causes
- Ligament hypertrophy - Osteophyte formation - Disc herniation - Congenital
114
Ligament Hypertrophy
- Repeated injuring and healing with additional scar tissue to the point where they become larger - Can result in narrowing of vertebral canal
115
Laminectomy
- Removes the lamina of vertebrae (both sides is complete **and one side is partial/hemi**)
116
Laminotomy
- Does not remove the lamina, but burrows an opening and removes a portion that is encroaching on cauda equina, nerve roots, etc.
117
Foraminotomy
- Opens up IVF if it gets narrowed
118
Discectomy
- Removes pieces if IVF gets narrowed
119
Herniated Nucleus Pulposus
- Can cause spinal and foraminal stenosis | - Can put pressure on the nerve roots and/or spinal cord
120
Posterolateral Herniation
- L4/5 and L5/S1 are the most common in lumbar spine | - Typically affects the nerve root below the level of the herniated disc
121
L4/5 Disc Herniation
- Affects L5 nerve
122
L5/S1 Disc Herniation
- Affects S1 nerve
123
Radiculopathy
- Abnormal nerve root sensation depending on what is compressed