7 - Spinal Cord Anatomy Flashcards

1
Q

basic definitions of spinal cord anatomy

A
  • Spinal Column, Spine or Vertebral Column is the collection of bones that form the backbone.
  • Vertebrae: bones of the spinal column.
  • Spinal Cord: the portion of the central nervous system enclosed by the spine that connects the brain to all parts of the body.
  • Spinal Nerve: one of the 31 pairs of nerves that arise from the spinal cord that carry motor, sensory, and autonomic fibers.
  • “Myelo-”: pertaining to the spinal cord
    – e.g.myelopathy is a disease of the spinal cord
  • “Radiculo-”: pertaining to an individual
    spinal nerve
    – e.g.radiculopathy is a disease of a spinal nerve
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2
Q

Vertebral Column

A
  • Protective container for spinal cord
  • 33 bones (vertebrae) comprise the spine or
    vertebral column
  • Vertebrae components include the vertebral
    body, pedicles, laminae, transverse and spinous processes.
  • Openings include the spinal canal and the
    neural foramen
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3
Q

Vertebral Components

A
  • Body: major weight-bearing component
  • Laminae: posterior bones of vertebrae that make up foramen
  • Transverse Process: bilateral projections from vertebrae
  • Pedicles: connects the vertebral body to the spinous and transverse processes
  • Spinous Process: posterior prominence on vertebrae
  • Pars interarticularis: the segment of bone between facets
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4
Q

Superior openings of the spinal canal

A
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5
Q

Inferior openings of the spinal canal

A
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6
Q

openings in the spine

A
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7
Q

Cervical Spine

A
  • 7 cervical vertebrae
  • 8 cervical spinal nerves
  • C-1 (Atlas) - securely affixed to the occiput
  • C-2 (Axis) - odontoid process (dens)
  • C-7 - prominent spinous process
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8
Q

Thoracic Spine

A
  • Larger and stronger than cervical spine
  • 12 thoracic vertebrae
  • 1 st rib articulates with T-1
  • Next nine ribs attach to the inferior and superior portion of adjacent vertebral bodies
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9
Q

Lumbar Spine

A
  • 5 vertebrae
  • Largest and thickest vertebral bodies and intervertebral disks
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10
Q

Sacral Spine

A
  • 5 fused vertebrae
  • Form posterior plate of pelvis
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11
Q

spinal nerve organization

A

31 pairs of
Spinal Nerves

8 Cervical (C1-C8)
12 Thoracic (T1-T12)
5 Lumbar (L1-L5)
5 Sacral (S1-S5)
1 Coccygeal (Co1)

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12
Q

distal end of the spinal cord

A
  • Conus Medularis: distal tapering of spinal cord
  • Filum Terminale a fibrous band that extends from the conus medullaris to the periosteum of the coccyx
  • Cauda Equina: (aka – horse
    tail) extension of ventral and dorsal roots
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13
Q

tethered cord

A
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14
Q

Spinal Meninges

A
  • Dura Mater
  • Arachnoid
  • Pia Mater
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15
Q

Denticulate
ligaments

A
  • lateral projections of the pia mater
    forming triangular-shaped ligament
  • There are usually 21 denticulate ligament pairs, with the uppermost pair occurring just below the foramen magnum, and the lowest pair occurring between spinal nerve roots of T12 and L1
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16
Q

Spinal Cord development, Dural sac, lumbar puncture

A

Spinal Cord
* Adults: the foramen magnum to L1
* Infants: ends at L3 and moves up as they grow older

Dural Sac
* Adults: extend to S2
* Infants: often ends at S3 in children

Lumbar puncture
* Adult: below L1
* Children: below L3

17
Q

Lumbar puncture technique

A

Palpate the L4 spinous process (should be at the level of iliac crests)

Identify the L2-3, L3-4 and L4-5 interspaces

18
Q

organization/general function of the spinal cord (gray/white, afferent/efferent, dorsal/ventral, somatic/autonomic/sensory) (diagrams)

A

Posterior gray horns:
Somatic and Visceral Sensory nuclei.

Anterior gray horns:
Somatic Motor control.

Lateral gray horns:
Visceral Motor neurons.

Gray commissures
Axons of interneurons crossing and unmyelinated axons.

19
Q

Dermatomes & Myotomes

A
  • Dermatome – an area of skin innervated by a single posterior root
  • Myotome – a group of muscles innervated by a single anterior root
20
Q

The Vertebral Arteries

A

Branches of the vertebral arteries are-the posterior spinal artery, the anterior spinal artery, and the posterior inferior cerebellar arter.

21
Q

Vascular supply - arterial

A
  • One anterior spinal artery ventral cord
  • Two posterior spinal artery dorsal cord
22
Q

Vascular supply - arterial

A

Six to ten segmental arteries (radicular arteries) unite with the anterior and posterior spinal arteries to form the spinal arterial plexus

23
Q

Vascular supply - arterial

A
  • Prominent artery of Ademkiewicz –direct branch of the aorta into the spinal arterial plexus
  • Can see occlusion or transections
24
Q

Nerve Root Anatomy

A
25
Q

SCI Neurological classification

A
  • Neurological levels
  • American Spinal Injury Association (ASIA) impairment scale (A through E)
  • Clinical syndromes (incomplete injuries only)
  • Examples:
    – T4 ASIA A
    – C4 ASIA D central cord
26
Q

Neurological levels

A
  • Broadly divided into cervical (C), thoracic (T), lumbar (L) and sacral (S).
  • Neurologic level is the most caudal level with normal motor and sensory function
  • Determined by key dermatomes (sensation) and myotomes (motor)
27
Q

Dermatomes (diagram)

A
28
Q

Myotomes

A
29
Q

Monitor Neurologic Status

A

Neurologic examination at 72 hours is
the most accurate predictor of functional
outcome.

  • Incomplete - based on detection of sacral
    sparing, either motor or sensory.
  • Complete - if no sacral sparing.
  • Neurologic level of injury (NLI) - needs to be monitored acutely to ensure a progressive neurologic loss is not missed.
30
Q

ASIA Impairment Classification

A
  • A. Complete – No sacral sensory or motor
  • B. Sensory but no motor below NLI
  • C. More than half of Key muscles below
    NLI have muscle grade <3
  • D. At least half of key muscles below NLI
    have muscle grade > or = to 3
  • E. Sensory and Motor normal.
31
Q

Neurological recovery with the zone of injury

A
  • Some (30%) initial Grade 0 muscles will develop some motor power but will likely be nonfunctional
  • Most (90%) initial Grade 1-2 muscles will develop functional motor power (>3/5).
  • Most (70-80%) quadriplegic patients will “descend” a full neurological level.
  • Most recovery within the first 9 months of injury
32
Q

Neurological recovery below the level of injury

A
  • ASIA A rarely develop significant recovery (<3%)
  • Some ASIA B will convert to ASIA C and D (more common if pinprick is preserved) – on average 50% will attain functional ambulation
  • Most younger (< 50 yrs) ASIA C will attain functional ambulation
  • Nearly all ASIA D will attain functional ambulation
33
Q

Functional outcome by level

A
  • C3-5: ventilator dependency
  • C5: hand to face approximation
    power mobility
  • C6: short distance manual wheelchair
  • C7: transfers could achieve independence at wheelchair level
  • C8/T1: fine hand control
  • T2-T10: complete independence at WC level
  • L2: short distance ambulation with bracing
  • L3: community ambulation with bracing
34
Q

Central cord syndrome

A
  • Incomplete (ASIA C or D) cervical spinal cord syndrome
  • Arm weakness greater than leg weakness
  • Neuropathology controversial
  • Mechanism controversial
35
Q

Brown-Sequard syndrome

A
  • Incomplete spinal cord syndrome
  • Ipsilateral weakness and contralateral pain and temperature loss
  • Neuropathology: hemisection of spinal cord
  • Mechanism: penetrating trauma
36
Q

Anterior cord syndrome

A
  • Incomplete spinal cord syndrome
  • Absent pain sensation and motor function with sparing of light touch, temperature, and proprioception
  • Neuropathology: lesion of anterior 2/3 of spinal cord
  • Mechanism: ischemia of anterior spinal artery
37
Q

Posterior cord syndrome

A
  • Incomplete spinal cord syndrome
  • Rarest of spinal cord syndromes
  • Varying degrees of motor preservation with
    loss of some sensory modalities
  • Neuropathology: lesion of posterior 1/3 of
    spinal cord
  • Mechanism: ischemia of posterior spinal
    arteries
38
Q

Autonomic Dysreflexia

A
  • Alteration of sympathetic control caused by noxious stimuli below the level of spinal lesion.
  • Occurs in cervical and upper thoracic injuries
  • Signs/Symptoms: dramatic hypertension, bradycardia, headache, sweating
  • Treatment: removal of inciting cause
39
Q

Sympathetic Trunk

A

Lies just lateral to the vertebral
bodies from T1 to L2/3lt