Page 584 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

540 SecTioN iii Neurology aNd Special SeNSeS ` neurology—oPhthAlmology Neurology aNd Special SeNSeS ` neurology—oPhthAlmology

Horner syndrome Sympathetic denervation of face Ž: PAM is horny (Horner).
ƒ Ptosis (slight drooping of eyelid: superior
tarsal muscle) Hypothalamus Ophthalmic division
of trigeminal nerve
ƒ Anhidrosis (absence of sweating) and Long ciliary nerve
flushing of affected side of face To sweat glands
ƒ Miosis (pupil constriction) of forehead
Associated with lesions along the sympathetic To smooth muscle of eyelid
chain: Internal To pupillary dilator
To sweat glands of face
ƒ 1st neuron: pontine hemorrhage, lateral carotid External carotid artery
artery
medullary syndrome, spinal cord lesion C2 Third neuron
above T1 (eg, Brown-Séquard syndrome, First neuron Superior cervical ganglion
late-stage syringomyelia)
Synapse in
ƒ 2nd neuron: stellate ganglion compression lateral horn T1
by Pancoast tumor Second neuron
ƒ 3rd neuron: carotid dissection (painful) Spinal cord

Ocular motility
Superior Superior Superior Superior CN VI innervates the Lateral Rectus.
rectus oblique rectus oblique CN IV innervates the Superior Oblique.
muscle muscle muscle muscle CN III innervates the Rest.
Trochlea Medial
rectus The “chemical formula” LR SO R .
muscle 6 4 3
Lateral Medial
rectus rectus
muscle muscle

Lateral
Inferior Inferior rectus
oblique rectus muscle
muscle muscle
Inferior Inferior
rectus oblique
muscle muscle
Obliques go Opposite (left SO and IO tested
with patient looking right).
IOU: IO tested looking Up.

FAS1_2019_12-Neurol.indd 540 11/8/19 7:39 AM