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Sympathetic Nervous System, Part 1

Sympathetic Nervous System, Part 1

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Sympathetic nervous system (Part 1)

Summary..

Overview

  • The sympathetic nervous system brings is active in states of action; it produces the so-called fight or flight response.
  • It originates in the spinal cord from the intermediolateral cell column from T1 to L2.
  • It relays in paravertebral and prevertebral ganglia.
  • It innervates:
    • Endocrine and exocrine glands.
    • Nonglandular body organs.
    • Blood vessels and skin.

the origins of the sympathetic nervous system

  • The intermediolateral cell column lies from T1 to L2, which houses the origins of the sympathetic nervous system.
  • The paravertebral chain (aka sympathetic chain) as a series of beads on a string.

Paravertebral Chain

24 Ganglia

  • On average, it comprises 24 total ganglia:
    • 3 cervical
    • 10 thoracic
    • 3 – 5 lumbar
    • 3 – 5 sacral
    • And the ganglion impar (which is the most caudal paravertebral ganglion); it neighbors the coccyx.

Cervical & Upper Thoracic Ganglia

  • Superior cervical ganglion
  • Middle cervical ganglion
  • Inferior cervical ganglion
  • First thoracic ganglion.
  • Stellate ganglion refers to the combined inferior cervical and first thoracic ganglia.

Prevertebral Ganglia

Show that they overlie the descending aorta from superior to inferior as the:

  • Celiac
  • Aorticorenal
  • Superior mesenteric
  • Inferior mesenteric

Clinical Correlation - Paraganglioma

Sympatheitc Innervation

Now, we're ready to walk through the sympathetic innervation of the body.

  • Demarcate the ciliospinal center of Budge at C8 – T2.
  • Show that it innervates the Head and Neck.
  • Divide the intermediolateral cell column into:
    • T1 to T5, which produce cardiopulmonary splanchnic nerves that innervate the thorax. These nerves originate from the paravertebral chain, which we'll illustrate in part 2 of the tutorial.
    • T5 to L2, which produce abdominopelvic splanchnic nerves that innervate the abdomen and pelvis. These nerves bypass the paravertebral ganglia; they synapse in prevertebral ganglia (which we'll illustrate in part 2 of the tutorial).
  • The ciliospinal center of Budge is innervated via the posterolateral hypothalamospinal tract. It innervates the superior cervical ganglion.
  • Postganglionic superior cervical ganglion fibers ascend the carotid artery to innervate the head and neck.

Horner's Syndrome

See: Horner's syndrome*

Full-Length Text

  • Here, we will draw the motor division of the sympathetic nervous system.
    • This is part 1 of a 2 part tutorial.
  • Denote that the sympathetic nervous system brings is active in states of action; it produces the so-called fight or flight response.
  • Denote that it originates in the spinal cord from the intermediolateral cell column from T1 to L2.
  • It relays in paravertebral and prevertebral ganglia.
  • It innervates:
    • Endocrine and exocrine glands.
    • Nonglandular body organs.
    • Blood vessels and skin.

To begin, let's draw the origins of the sympathetic nervous system.

  • Draw an outline of the brain and the spinal cord.
  • Demarcate the intermediolateral cell column from T1 to L2, which houses the origins of the sympathetic nervous system.
  • Then, draw the paravertebral chain (aka sympathetic chain) as a series of beads on a string.
  • Indicate that, on average, it comprises 24 total ganglia.
  • Now, section the ganglia into:
    • 3 cervical
    • 10 thoracic
    • 3 – 5 lumbar
    • 3 – 5 sacral
    • And the ganglion impar, which is the most caudal paravertebral ganglion; it neighbors the coccyx.
  • Next label 3 ganglia beneath the superior cervical ganglion as the:
    • Middle cervical ganglion
    • Inferior cervical ganglion
    • First thoracic ganglion.
  • Show that the stellate ganglion refers to the combined inferior cervical and first thoracic ganglia.

Next, let's draw the 4 prevertebral ganglia.

  • Show that they overlie the descending aorta from superior to inferior as the:
    • Celiac
    • Aorticorenal
    • Superior mesenteric
    • Inferior mesenteric

Now, we're ready to walk through the sympathetic innervation of the body.

  • Demarcate the ciliospinal center of Budge at C8 – T2.
  • Show that it innervates the Head and Neck.

Next, divide the intermediolateral cell column into:

  • T1 to T5, which produce cardiopulmonary splanchnic nerves that innervate the Thorax.
    • Write that these nerves originate from the paravertebral chain, which we'll illustrate in part 2 of the tutorial.
  • T5 to L2, which produce abdominopelvic splanchnic nerves that innervate the Abdomen and Pelvis.
    -Write that these nerves bypass the paravertebral ganglia.
    • And that they synapse in prevertebral ganglia, which we'll illustrate in part 2 of the tutorial.
  • As shown, overlap exists at T5.
  • Separate these organ regions at the diaphragm.

Now, let's get into specifics of these innervation patterns.

  • Deep within the center of the brain, for anatomical reference, draw the:
    • Thalami
    • Lateral ventricles
    • 3rd ventricle
  • Then, square off the hypothalamus, which surrounds the 3rd ventricle.
  • Indicate that it innervates the ciliospinal center of Budge via the posterolateral hypothalamospinal tract.
  • Next, show that the ciliospinal center of Budge innervates the superior cervical ganglion.
  • Then, draw the carotid artery.
  • Show that postganglionic superior cervical ganglion fibers ascend the carotid artery to innervate the head and neck.
  • As a clinical correlation, show that injury to this pathway results in Horner's syndrome, which presents with exam findings of:
    • Ptosis
    • Miosis, and
    • Anhidrosis.
  • Indicate that Horner's syndrome occurs from injury along the pathway, most commonly from:
    • Medullary brainstem strokes,
    • Paravertebral masses (such as Pancoast tumor (a form of apical lung tumor)
    • Carotid dissection.