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Sympathetic Pupillary Pathway
Key Anatomy
- Sympathetic circuitry begins within the hypothalamus.
- Descends via the posterolateral hypothalamospinal tract.
- Innervates the ciliospinal center of Budge at C8 – T2.
- Innervates the superior cervical ganglion, which sends fibers that ascend the carotid artery to innervate the head and neck.
Horner's syndrome, manifests with, amongst other pathologic signs:
- Ptosis, which is eyelid droop; we can detect it if we compare the palpebral fissure size of the normal eye to the abnormal eye; here it will be more narrow because of the eyelid droop, from loss of superior tarsal muscle tone.
- Miosis, pupil constriction, from a loss of innervation to the dilator muscles.
- Anhidrosis, loss of sweating, from loss of sympathetic innervation to sweat glands to the face.
The acronym "PAM" is used to remember this triad.