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MENA 
- Maximal inspiratory pressure
- Maximal oxygen uptake
- Maximization
- Maximum Residue Limit
- Maximum androgen blockade
- Maximum intercuspation
- Maximum life span
- Maximum parsimony
- Maximum permissible dose
- Maximum tolerated dose
- Maxon
- May-Hegglin anomaly
- Mayer waves
- Maytenus
- Mazindol
- Mazzotti reaction
- McArdle's disease
- McBurney's point
- McCarthy Scales of Children's Abilities
- McDonald criteria
- McFarland standards
- McGurk effect
- McKenzie Method
- McKusick-Kaufman syndrome
- McNemar test
- McRoberts maneuver
- Mdm2
- Me-too drug
- Meal replacement
- Mean airway pressure
- Mean arterial pressure
- Mean corpuscular hemoglobin
- Mean free path
- Mean residence time
- Meaning
- Meaning-making
- Measles
- Measles vaccine
- Measles virus
- Meat products
- Meat spoilage
- Meatal stenosis
- Meatotomy
- Meatus
- Mebendazole
- Mebeverine
- Mebrofenin
- Mecamylamine
- Mecasermin
- Mechanical index
- Mechanical ventilation
- Mechanism of action
- Mechanism of autism
- Mechanobiology
- Mechanochemistry
- Mechanomyogram
- Mechanoreceptors
- Mechanosensation
- Mechanosensitive ion channels
- Mechanostat
- Mechanotaxis
- Mechanotherapy
- Mechanotransduction
- Mecillinam
- Meckel syndrome
- Meckel's cartilage
- Meckel's cave
- Meckel's diverticulum
- Meckel-Gruber syndrome
- Meclizine
- Meclofenamic acid
- Meclofenoxate
- Meclozine
- Mecobalamin
- Meconium
- Meconium aspiration syndrome
- Meconium ileus
- Meconium peritonitis
- Mecoprop
- MedCalc
- MedWatch
- Medetomidine
- Media panic
- Medial
- Medial circumflex femoral artery
- Medial collateral ligament
- Medial condyle
- Medial cord
- Medial cutaneous nerve of arm
- Medial dorsal cutaneous nerve
- Medial dorsal nucleus
- Medial eminence
- Medial epicondyle
- Medial epicondyle of the femur
- Medial epicondyle of the humerus
- Medial epicondylitis
- Medial forebrain bundle
- Medial frontal
- Medial frontal gyrus
- Medial geniculate body
- Medial geniculate nucleus
- Medial intermuscular septum
- Medial lemniscus
- Medial longitudinal fasciculus
- Medial malleolus
- Medial meniscus
- Medial nasal prominence
- Medial palpebral ligament
- Medial patellofemoral ligament
- Medial pectoral nerve
- Medial plantar artery
- Medial plantar nerve
- Medial pontine reticular formation
- Medial prefrontal cortex
- Medial preoptic area
- Medial pterygoid muscle
- Medial pterygoid plate
- Medial rectus muscle
- Medial sural cutaneous nerve
- Medial temporal lobe
- Medial umbilical fold
- Medial umbilical ligament
- Medial vestibular nucleus
- Medial vestibulospinal tract
- Median aerodynamic diameter
- Median antebrachial vein
- Median aperture
- Median arcuate ligament
- Median arcuate ligament syndrome
- Median artery
- Median cubital vein
- Median eminence
- Median follow-up
- Median nerve
- Median plane
- Median preoptic nucleus
- Median raphe nucleus
- Median sacral artery
- Median sacral vein
- Median sternotomy
- Median test
- Median umbilical ligament
- Mediastinal
- Mediastinal fibrosis
- Mediastinal germ cell tumor
- Mediastinal lymphadenopathy
- Mediastinal mass
- Mediastinal shift
- Mediastinal tumors
- Mediastinitis