MOTOR EXAMINATION is a topic covered in the Harrison's Manual of Medicine.

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  • The bare minimum: Look for muscle atrophy and check extremity tone. Assess upper limb strength by checking for pronator drift and strength of wrist or finger extensors. Test for lower limb strength by asking pt to walk normally and on heels and toes and testing power of the toe extensors.

Power should be systematically tested for major movements at each joint (Table 180-1). Strength should be recorded using a reproducible scale (e.g., 0 = no movement, 1 = flicker or trace of contraction with no associated movement at a joint, 2 = movement present but cannot be sustained against gravity, 3 = movement against gravity but not against applied resistance, 4 = movement against some degree of resistance, and 5 = full power; 4 values can be supplemented with + and – signs to provide additional gradations). Speed of movement, ability to relax contractions promptly, and fatigue with repetition should all be noted. Loss in bulk and size of muscle (atrophy) should be noted, as well as the presence of irregular involuntary contraction (twitching) of groups of muscle fibers (fasciculations). Any involuntary movements should be noted at rest, during maintained posture, and with voluntary action.

 MuscleNerveSegmental InnervationFunction
ShoulderSupraspinatusSuprascapular n.C5,6Abduction of upper arm
 DeltoidAxillary n.C5,6Abduction of upper arm
ForearmBicepsMusculocutaneous n.C5,6Flexion of the supinated forearm
 BrachioradialisRadial n.C5,6Forearm flexion with arm between pronation and supination
 TricepsRadial n.C6,7,8Extension of forearm
 Ext. carpi radialisRadial n.C5,6Extension and abduction of hand at the wrist
 Ext. carpi ulnarisP. interosseous n.C7,8Extension and adduction of hand at the wrist
 Ext. digitorumP. interosseous n.C7,8Extension of fingers at the MCP joints
 SupinatorP. interosseous n.C6,7Supination of the extended forearm
 Flex. carpi radialisMedian n.C6,7Flexion and abduction of hand at the wrist
 Flex. carpi ulnarisUlnar n.C7,8,T1Flexion and adduction of hand at the wrist
 Pronator teresMedian n.C6,7Pronation of the forearm
WristExt. carpi ulnarisUlnar n.C7,8,T1Extension/adduction at the wrist
 Flex. carpi radialisMedian n.C6,7Flexion/abduction at the wrist
HandLumbricalsMedian + ulnar n.C8,T1Extension of fingers at PIP joint with the MCP joint extended and fixed
 InterosseiUlnar n.C8,T1Abduction/adduction of the fingers
 Flex. digitorumMedian + A. interosseous n.C7,C8,T1Flexion of the fingers
ThumbOpponens pollicisMedian n.C8,T1Touching the base of the 5th finger with thumb
 Ext. pollicisP. interosseous n.C7,8Extension of the thumb
 Add. pollicisUlnar n.C8,T1Adduction of the thumb
 Abd. pollicisMedian n.C8,T1Abduction of the thumb
 Flex. pollicis br.Ulnar n.C8,T1Flexion of the thumb
ThighIliopsoasFemoral n.L1,2,3Flexion of the thigh
 GluteiSup. + inf. gluteal n.L4,L5,S1,S2Abduction, extension, and internal rotation of the leg
 QuadricepsFemoral n.L2,3,4Extension of the leg at the knee
 AdductorsObturator n.L2,3,4Adduction of the leg
 HamstringsSciatic n.L5,S1,S2Flexion of the leg at the knee
FootGastrocnemiusTibial n.S1,S2Plantar flexion of the foot
 Tibialis ant.Deep peroneal n.L4,5Dorsiflexion of the foot
 PeroneiDeep peroneal n.L5,S1Eversion of the foot
 Tibialis post.Tibial n.L4,5Inversion of the foot
ToesExt. hallucis l.Deep peroneal n.L5,S1Dorsiflexion of the great toe
Abbreviation: MCP, metacarpophalangeal; PIP, proximal interphalangeal.

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