Page 554 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

510 SecTioN iii Neurology aNd Special SeNSeS ` neurology—AnAtomy And Physiology Neurology aNd Special SeNSeS ` neurology—PAthology

Clinical reflexes Reflexes count up in order (main nerve root in Additional reflexes:
bold): Cremasteric reflex = L1, L2 (“testicles move”)
Achilles reflex = S1, S2 (“buckle my shoe”) Anal wink reflex = S3, S4 (“winks galore”)
C5, 6 Patellar reflex = L2-L4 (“kick the door”)
C6, 7, 8 Biceps and brachioradialis reflexes = C5, C6
(“pick up sticks”)
L2, 3, 4 Triceps reflex = C6, C7, C8 (“lay them
straight”)
S1, 2

Primitive reflexes CNS reflexes that are present in a healthy infant, but are absent in a neurologically intact adult.
Normally disappear within 1st year of life. These primitive reflexes are inhibited by a mature/
developing frontal lobe. They may reemerge in adults following frontal lobe lesions Ž loss of
inhibition of these reflexes.
Moro reflex “Hang on for life” reflex—abduct/extend arms when startled, and then draw together
Rooting reflex Movement of head toward one side if cheek or mouth is stroked (nipple seeking)
Sucking reflex Sucking response when roof of mouth is touched
Palmar reflex Curling of fingers if palm is stroked
Plantar reflex Dorsiflexion of large toe and fanning of other toes with plantar stimulation
Babinski sign—presence of this reflex in an adult, which may signify a UMN lesion
Galant reflex Stroking along one side of the spine while newborn is in ventral suspension (face down) causes
lateral flexion of lower body toward stimulated side

Landmark dermatomes
dermAtome ChArACteristiCs
C2 Posterior half of skull
V1 C2
C3 High turtleneck shirt C3
V2 C2 C4
Diaphragm and gallbladder pain referred V3 C3 C5 C6
to the right shoulder via phrenic nerve C4 C5 C7 C8 T1
T1 T2 T3
C3, 4, 5 keeps the diaphragm alive T2 T3 T4 T5
T4 T6 T7
C4 Low-collar shirt T5 T6 C6 T8 T9
T7 C6 C8 T10
T11
T8 C7 T12
C6 Includes thumbs T10 T9 C5 L1 L2 L3
Thumbs up sign on left hand looks like a 6 T11 L4 L5
T12 L1 S1
S2 S3
T4 At the nipple L2 C6 C7 S4 S5
S2 S3 C8 C8
T4 at the teat pore L3 L5 S1 S2
T7 At the xiphoid process L4 L1
7 letters in xiphoid L2
T10 At the umbilicus (belly butten) L3
Point of referred pain in early appendicitis L5 S1 S2

L1 At the Inguinal Ligament S1 L4 S1
L4 Includes the kneecaps L4 L5
Down on ALL 4’s L5 L4
S2, S3, S4 Sensation of penile and anal zones
S2, 3, 4 keep the penis off the floor

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