ANATOMY

Upper Extremities

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Axillary nerve injury results in -?-deltoid paralysis with total inability to abduct the arm and severe impairment of flexion & extension at the glenohumeral joint.
Mid hemeral fracture may involve the deep brachial artery and the radial nerve as they wind about the -?-posterior aspect of the humerus. Arterial injury produces -?-ischemic contracture; nerve injury paralyzes the -?-wrist extensors and extrinsic extensors of the hand.
Except on the ulnar side, the forearm -?-flexor compartment is innervated by the median nerve.
Scaphoid fracture is most common because it transmits forces from the abducted hand directly to the -?-radius. Since the blood supply enters distally, the scaphoid is especially prone to -?-avascular necrosis.
Lunate dislocation is most common in falls on the out-stretched hand, compressing the -?-median nerve within the carpal tunnel and producing carpal tunnel syndrome.
Extension of the proximal phalanges is accomplished by the extensor digitorium in the forearm, innervated by the -?-radial nerve. Digital extension at the interphalangeal joints is primarily by dorsal and ventral interossei, both innervated by the -?-ulnar nerve.
Proximal phalangeal flexion is by the -?-interossei and lumbricales (median and ulnar nerves); middle phalangeal flexion is by the -?-extensor digitorum superficialis (median nerve); distal phalangeal flexion is by the -?-flexor.
Digital abduction is a function of the -?-dorsal interossei; digital adduction is a function of -?-palmar interossei.
The ulnar artery is the principal supply to the superficial palmar -?-arch in the hand.
Lymphaatic drainage from the palmar hand and digits is toward the dorsal subcutaneous space of the hand, explaining the extreme -?-swelling of this region that accompanies infections of the digits or volar surface.
Radial sensory function is tested in the -?-web space of the thumb; ulnar sensory function is tested along the -?-fifth digit. The digital brances of the median and ulnar nerves lie along the sides of the fingers where they may be -?-anesthetized.
Nerve function, tests, and dysfunctions
Nerve Muscle Group Reflex Test Sign or Functional Deficit
Long thoracic Serratus anterior -- -?-Wing scapula
Suprascapular -?-supraspinatus
-?-infraspinatus
-- Difficulty initiating arm abduction
Axillary deltoid -- Inability to fully abduct arm
Musculocutaneous Flexors of arm, forearm -?-Triceps & wrist extension reflexes Weak arm flexion, weak forearm flexion, weak forearm supination
Median -?-Wrist & hand flexors Wrist flexion reflex Paralysis of flexor, pronator, and thenar muscles; inability to fully flex the index & middle fingers (sign of benediction)
-?-Ulnar Wrist and hand flexors, phalangeal extensors -- Inability to extend the distal & middle phalanges (clawhand); loss of thumb adduction
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