Middle Cervical Ganglion

Horner's Syndrome

Lesions of the sympathetic pathway to the head produce abnormalities that are easily detectable on physical examination. The deficits of function occur ipsilateral to the lesion and include:

• Partial constriction of the pupil as a result of loss of sympathetic pupillodilator action

• Drooping of the eyelid, termed ptosis, as a result of loss of sympathetic activation of Muller's muscle of the eyelid

• Dryness of the face as a result of the lack of sympathetic activation of the facial sweat glands.

A pattern of historical or physical examination findings that is consistent from patient to patient is often termed a syndrome. Johann Horner, a 19th century Swiss ophthal mologist, described this pattern of eye and facial abnormalities in patients, and these are referred to as Horner's syndrome. Etiologies for Horner's syndrome include:

• Brainstem lesions, such as produced by strokes, which interrupt the tracts that descend to the sympathetic neurons in the spinal cord

• Upper thoracic nerve root lesions, such as those produced by excessive traction on the arm or from infiltration of the nerve roots by cancer spreading from the lung

• Cervical paravertebral ganglia lesions from accidental or surgical trauma, or metastatic cancer

• Arterial injury in the neck, from neck hyperextension, or direct trauma, which interrupt the postganglionic axons traveling in the carotid periarterial plexus.

Sympathetic Division

Parasympathetic Division

Paravertebral ganglia A = Superior cervical ganglion B = Middle cervical ganglion C = Inferior cervical ganglion

Cervical

Sympathetic Division

Parasympathetic Division

Paravertebral ganglia A = Superior cervical ganglion B = Middle cervical ganglion C = Inferior cervical ganglion

Cervical Ganglion Function

Cervical

Midbrain

Medulla

Thoracic

Lumbar

Sacral

Prevertebral ganglia

1 = Celiac ganglion

2 = Superior mesenteric ganglion

3 = Inferior mesenteric ganglion

The organ-specific arrangement of the ANS. Preganglionic axons are indicated by solid lines, postganglionic axons by dashed lines. Sympathetic ax-

ons destined for the skin and musculoskeletal system are shown on the left side of the spinal cord. Note the named paravertebral and prevertebral ganglia.

Midbrain

Medulla

Thoracic

Lumbar

Sacral

Prevertebral ganglia

1 = Celiac ganglion

2 = Superior mesenteric ganglion

3 = Inferior mesenteric ganglion

The organ-specific arrangement of the ANS. Preganglionic axons are indicated by solid lines, postganglionic axons by dashed lines. Sympathetic ax-

ons destined for the skin and musculoskeletal system are shown on the left side of the spinal cord. Note the named paravertebral and prevertebral ganglia.

Chromaffin Cells Epinephrine

^HNGUREni^fe Sympathetic innervation of the adrenal ^■■■■■■Vmedulla. Preganglionic sympathetic axons terminate on the chromaffin cells. When stimulated, the chromaffin cells release epinephrine into the circulation.

superior mesenteric ganglion innervates the small and large intestines. Preganglionic axons originate primarily in T10 to T12. The inferior mesenteric ganglion innervates the lower colon and rectum, urinary bladder, and reproductive organs. Preganglionic axons originate in L1 to L3.

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