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Anatomy > Spinal Cord > Flashcards

Spinal Cord Flashcards

0
Q

Location of spinal cord

A
  • Continuation of medulla oblongata
  • Projects through the vertebral canal
  • Extends from foramen magnum to lower border of L1 (adults), L3 (children)
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1
Q

Spinal cord enclosed by meninges

A

Spinal dura sac terminates at S2.
Dural root sleeve covers nerve rootlets and becomes continuous with the epineurium of spinal nerves.
Filum terminale projection of pia mater covered in dura mater anchors spinal cord to the coccyx.

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2
Q

Termination of spinal cord

A

Terminates caudally as conus medullaris

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3
Q

Enlargements

A

Enlargements from C5 –T1 and from L1-S2 due to increased numbers of motor neurons and interneurons going to upper and lower extremities.

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4
Q

Blood supply of spinal cord

A

Spinal arteries:
• 1 x anterior
• 2 x posterior
• Subclavian => vertebral => spinal arteries.
• Reinforced by segmental medullary arteries.

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5
Q

Attachments of spinal cord

A
  1. Denticulate ligaments
  2. Filum terminale
  3. Spinal nerve roots
    Suspend and anchor cord within the dural sac
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6
Q

Gray matter

A

Posterior horn contains sensory interneurons
Lateral horn contains preganglionic sympathetic neurons T1-12
Anterior horn contains cell bodies of large motor neurons that supply skeletal muscle

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7
Q

Funiculi

A

Divisions of spinal cord white matter containing fasciculi

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8
Q

Dorsal column

A

Fasiculus gracilis “Slender”

Fasciculus cuneatus “Wedge”

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9
Q

Dorsal fasciculi

A

Mainly ASCENDING primary afferent fibres from mechanoreceptors of body to CNS.
Dorsal column fibres synapse in nucleus gracilis or nucleus cuneatus in the caudal medulla.

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10
Q

Medial lemniscus pathway (dorsal/sensory)

A
  • 2nd order fibres arise from dorsal column nuclei and form the medial lemniscus which projects through the brainstem and terminates in the thalamus.
  • 3rd order fibres arise in thalamus (ventral posterolateral nucleus) and ascend to synapse in postcentral gyrus (primary somatosensory cortex).
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11
Q

Fasciculus cuneatus

A

Sensory axons from upper extremity
• Carries fibres conveying conscious PROPRIOCEPTION and FINE CUTANEOUS TOUCH from the UPPER LIMB.
• Only present in spinal cord segments C5-T1.

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12
Q

Fasciculus gracilis

A

Sensory axons from lower extremity

• Carries fibres conveying conscious PROPRIOCEPTION and FINE CUTANEOUS TOUCH from the LOWER LIMB.

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13
Q

Ascending tracts

A
  1. Anterior spinothalamic tract
  2. Lateral spinothalamic tract
  3. Anterior spinocerebellar tract
  4. Posterior spinocerebellar tract
  5. Fasciculus cuneatus
  6. Fasciculus gracilis
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14
Q

Anterior spinothalamic tract

A

Conveys light touch sensation

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15
Q

Lateral spinothalamic tract

A

Conveys itch, pain & temperature
• 1st order neuron sense pain/temperature and end in posterior horn.
• 2nd order neurons cross the midline and form the spinothalamic tract that ascends to the VPL nucleus of the thalamus.
• 3rd order neurons project to somatosensory cortex (postcentral gyrus)

16
Q

Spinocerebellar tracts

A
  • Unconscious co-ordination of motor activities.
  • Convey afferent impulses from muscles/tendons/joints to the CEREBELLUM.
  • VENTRAL spinocerebellar tract fibres ascend CONTRA- & IPSILATERALLY to enter cerebellum through SUPERIOR CEREBELLAR PEDUNCLE.
  • DORSAL spinocerebellar tract fibres ascend IPSILATERALLY and enter cerebellum through INFERIOR CEREBELLAR PEDUNCLE.
17
Q

Summary of sensory pathways

A
  • Proprioception, vibration, light touch ascend through dorsal column.
  • Pain and temperature information ascend through anterolateral pathways.
  • Decussate before passing through brainstem in medial lemniscus then on to thalamus and terminate in primary somatosensory cortex.
18
Q

Descending tracts

A
  1. Anterior corticospinal tract
  2. Lateral corticospinal tract
  3. Rubrospinal tract
  4. Reticulospinal tract
  5. Vestibulospinal tract
  6. Tectospinal tract
19
Q

Corticospinal tract

A

• Collection of fibres that descend from cell bodies
in the motor areas of the cerebral cortex and
terminate in the spinal cord.

  • Corticospinal axons decussate (cross the midline).
  • Damage to one cerebral hemisphere will results in somatosensory deficit and weakness in the contralateral arm and leg.
  • Myelination of corticospinal tracts not complete until end of 2nd year of postnatal life.
20
Q

Lateral corticospinal tract “Pyramidal tract”

A
  • Concerned with volitional skilled motor activity (primarily of digits and upper limb).
  • Originates from the premotor, precentral motor and postcentral sensory cortex.
  • Terminates via interneurons on ventral horn motor neurons and sensory neurons of dorsal horn.
21
Q

Anterior corticospinal tract

A
  • Formed by descending fibres that don’t decussate at the pyramids.
  • Concerned with control of axial muscles.
  • Synapses with lower motor neurons in anterior horn of spinal cord grey matter.
22
Q

Rubrospinal tract

A
  • Arises in contralateral red nucleus of the midbrain.
  • Plays a role in control of flexor tone.
  • Anterior to lateral corticospinal tract.
23
Q

Vestibulospinal tract

A
  • Originates in vestibular nucleus.
  • Found at all spinal cord levels.
  • Plays role in control of extensor tone.
  • Located in ventral funiculus.
24
Q

Control movement of limbs:

A

Lateral corticospinal

Rubrospinal

25
Q

Control movement of trunk (posture & balance), head & neck orientation:

A

Anterior corticospinal
Vestibulospinal
Reticulospinal
Tectospinal

26
Q

Dermatome

A
  • Area of skin supplied by a SINGLE spinal nerve (coming from single spinal cord segment).
  • Somites = sclerotome (bone), myotome (muscle), dermatome (skin).
  • Each spinal nerve retains it relationship with its somite during development.
27
Q

Important dermatomes

A
  • Upper arm (lateral surface): C5
  • Thumb: C6
  • Middle finger: C7
  • Little finger: C8
  • Nipple: T4
  • Umbilicus: T10
  • Big toe: L5
  • Heel: S1
  • Back of thigh: S2
28
Q

Lesions of spinal cord and peripheral nerves

A
  • Dorsal root lesions will lead to sensory disturbances in dermatomes.
  • Ventral root lesions will lead to motor disturbances = weakness (paresis) because muscles usually receive innervation from several segments
29
Q

Reticulospinal tract

A
  • Extra-pyramidal tract.
  • Fibres to all spinal levels.
  • Medial reticulospinal tract facilitates voluntary movements.
  • Lateral reticulospinal tract inhibits voluntary movements.
30
Q

Tectospinal tract

A
  • Originates in tectum (specifically: superior colliculus) of midbrain.
  • Reflexive movement of head toward sounds or visual moving objects.
  • Supplies cervical levels of spinal cord.

Anatomy (15 decks)

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