Updated: 9/26/2018

Upper Extremity Nerves

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Snapshot
  • A 12-year-old boy is brought to the emergency department by his mom because he has noticed that he is no longer able to fully extend the fingers of his right hand. Three weeks prior to presentation, he had suffered a right fibula fracture while riding his bike and was given a pair of crutches to use while his leg recovered. He says that he lost that set of crutches and therefore has been using his taller friend's crutches. Upon further questioning he reveals that the new crutches have been putting a lot of pressure on his axilla. On physical exam he is found to have a wrist drop and decreased sensation over his posterior forearm and dorsal hand. (Radial nerve palsy, also known as Saturday night palsy)


Overview
Axillary Nerve (C5 and C6)
  • Cause of injury
    • fractured surgical neck of humerus
    • dislocation of humeral head
  • Motor deficit
    • arm abduction at shoulder
  • Sensory deficit
    • over deltoid muscle
  • Sign
    • flattened deltoid
Radial Nerve (C5-T1)
  • Overview
    • also known as "great extensor nerve"
    • innervates "BEST"
      • Brachioradialis
      • Extensors of wrist, fingers
      • Supinator
      • Triceps
  • Cause of injury
    • fracture at midshaft of humerus
    • "Saturday night palsy"
      • extended compression of axilla by back of chair or crutches
  • Motor deficit
    • wrist extension
    • finger extension at MCP joints
    • supination
    • thumb extension and abduction
  • Sensory deficit
    • posterior arm
    • dorsal hand
    • dorsal thumb
  • Sign
    • wrist drop
Median Nerve (C6-C8 and T1)
  • Cause of injury
    • proximal lesion
      • fracture of supracondylar humerus
    • distal lesion
      • carpal tunnel syndrome
      • dislocated lunate
  • Motor deficit
    • proximal lesion
      • oppositon of thumb
      • lateral finger flexion
      • wrist flexion
    • distal lesion
      • wrist flexion
  • Sensory deficit
    • proximal lesion
      • palmar aspects of lateral 3 1/2 fingers
      • dorsal lateral 3 1/2 fingertips
      • thenar eminence
    • distal lesion
      • dorsal and palmar aspects of lateral 3 1/2 fingers
  • Sign
    • distal lesion
      • median claw hand (when asked to extend fingers)
      • due to loss of lateral lumbricals
    • proximal lesion
      • ulnar claw hand (when asked to flex fingers)
      • due to loss of long forearm flexors
      • "Pope's blessing / hand of benediction"
Ulnar Nerve (C8 and T1)
  • Cause of injury
    • proximal lesion
      • fracture of medial epicondyle of humerus
    • distal lesion
      • fracture of hook of hamate (falling onto outstretched hand)
  • Motor deficit
    • proximal lesion
      • medial finger flexion
      • wrist flexion
    • distal lesion
      • abduction and adduction of fingers (interossei)
      • adduction of thumb
      • extension of 4th and 5th fingers (lumbricals)
  • Sensory deficit
    • medial 1 1/2 fingers
    • hypothenar eminence
  • Sign
    • distal lesion 
      • ulnar claw hand (when asked to extend fingers)
      • due to loss of medial lumbricals
    • proximal lesion
      • median claw hand (when asked to flex fingers)
      • due to loss of long forearm flexors
Musculocutaneous Nerve (C5-C7)
  • Cause of injury
    • upper trunk of brachial plexus compression
  • Motor deficit
    • flexion of arm at elbow
  • Sensory deficit
    • lateral forearm
 

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Questions (1)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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