Source directory

We research scientific publications and established specialist institutions. Each article links its sources and explains which claims they support. Uncertainty remains visible: a plausible explanation is not automatically proven.

1. NIH: What goosebumps are for (opens a new tab)

   Explains arrector pili muscles and sympathetic control.

2. Kawchuk et al.: Real-Time Visualization of Joint Cavitation (opens a new tab)

   Shows cavity formation during knuckle cracking on real-time MRI.

3. Chandran Suja & Barakat: A Mathematical Model for the Sounds Produced by Knuckle Cracking (2018) (opens a new tab)

   A mathematical model supports partial bubble collapse as a possible source of the sound; the exact origin remains debated.

4. Illusory perceptions of space and time preserve cross-saccadic perceptual continuity (opens a new tab)

   The first interval after a saccade appears prolonged; the study examines temporal backdating of perception.

5. Hiccups: a common problem with some unusual causes and cures (opens a new tab)

   Hiccups involve involuntary inspiratory contractions and glottis closure; longer-lasting episodes require evaluation of their cause.

6. Floaters — National Eye Institute (opens a new tab)

   Vitreous opacities cause moving shadows; sudden new floaters and accompanying warning signs need an eye examination.

7. Involuntary musical imagery as a component of ordinary music cognition: A review of empirical evidence (opens a new tab)

   Earworms are involuntary musical imagery; the review examines triggers and the memory processes involved.

8. Wilder-Smith und Chow: Water-immersion wrinkling is due to vasoconstriction (opens a new tab)

   Examines vasoconstriction as the cause of water-induced wrinkling.

9. EEG-Studie zu den neuronalen Grundlagen des Lichtniesens (opens a new tab)

   The study describes cortical differences, but does not establish a single reflex mechanism.

10. Diagnostic Criteria, Differential Diagnosis, and Treatment of Minor Motor Activity and Less Well-Known Movement Disorders of Sleep (opens a new tab)

    Hypnic jerks are common physiological sleep movements; more severe forms can cause sleep problems.

11. DermNet: Dermographism (opens a new tab)

    Describes short-lived linear wheals, histamine, and the incompletely understood trigger.

12. Kimura und Kitagawa: Embryological development of human palmar, plantar, and digital flexion creases (opens a new tab)

    Prenatal formation in a study of 160 fetuses.

13. American Academy of Ophthalmology: Heterochromia (opens a new tab)

    Describes forms of different-colored irises and acquired causes.

14. Darwin's Tubercle: Review of a Unique Congenital Anomaly (opens a new tab)

    Anatomical location and definition.

15. Sebastin et al.: Does the absence of the palmaris longus affect grip and pinch strength? (opens a new tab)

    Examines grip and pinch strength in congenital absence of the muscle.

16. Hypermobility spectrum disorders: A review (opens a new tab)

    Symptoms, causes, and assessment.

17. Cleveland Clinic: Bulging Veins (opens a new tab)

    Explains the influence of subcutaneous fat, age, and exercise, as well as warning signs.

18. Morton und Callister: Exercise-Related Transient Abdominal Pain (opens a new tab)

    Review of side stitch; explicitly assesses mechanisms as not conclusively established.

19. Change blindness: past, present, and future (opens a new tab)

    Major changes can go unnoticed; the review explains limits of attention and of conclusions about memory.

20. Touching a Rubber Hand: Feeling of Body Ownership Is Associated with Activity in Multisensory Brain Areas (opens a new tab)

    An experimental hand illusion links body ownership with multisensory processing and premotor and parietal areas.

21. Multisensory Integration Dominates Hypnotisability and Expectations in the Rubber Hand Illusion (opens a new tab)

    Examines the contributions of multisensory integration, expectations, and suggestibility to the rubber-hand illusion.

22. Gustatorische Rhinitis: nahrungsbedingter Nasenfluss (Raphael et al.) (opens a new tab)

    The study establishes a nerve-mediated secretory reflex after spicy food.

23. Ein Modell der Aromawahrnehmung: Geschmack, Berührung und Geruch (opens a new tab)

    The chapter explains retronasal transport and the multisensory composition of flavor perception.

24. Bauchgeräusche – MedlinePlus (opens a new tab)

    The patient information explains bowel sounds as movement of intestinal contents and names accompanying warning signs.

25. Orthostatische Hypotonie – StatPearls (opens a new tab)

    The overview describes position-related blood-pressure drops, compensatory circulatory responses, and visual disturbances.

26. Drummond und Lance: Facial flushing and sweating mediated by the sympathetic nervous system (opens a new tab)

    Examines the contribution of sympathetic nerves to facial blood flow.

27. Children’s Hospital of Philadelphia: Clinodactyly (opens a new tab)

    Sideways finger curvature, possible overlap, and clinical assessment.

28. Singh: Distichiasis – An update on etiology, treatment and outcomes (opens a new tab)

    Overview of extra eyelashes at Meibomian gland openings and corneal irritation.

29. NIH: Elements of Morphology – Anatomy of the Ear (opens a new tab)

    Describes the structure and forms of the outer ear, including the earlobe.

30. StatPearls: Anatomy, Head and Neck, Ear (opens a new tab)

    Describes the cartilage-free earlobe made of skin, fat, and connective tissue.

31. The Plantaris Muscle Is Not Vestigial: Developmental, Comparative, and Functional Evidence for Its Sensorimotor Role (opens a new tab)

    Anatomy, function, and variability of the plantaris.

32. AAOS: Snapping Hip (opens a new tab)

    Explains tendon and connective-tissue gliding as a cause of snapping hip.

33. Gorillas in Our Midst: Sustained Inattentional Blindness for Dynamic Events (opens a new tab)

    In a focused visual task, participants miss unexpected, clearly visible events.

34. Sleep Paralysis — StatPearls (opens a new tab)

    Sleep paralysis combines wakeful awareness with persistent REM muscle inhibition and may involve dream-like perceptions.

35. Messung und Charakterisierung des menschlichen Nasenzyklus (opens a new tab)

    Side sleeping is associated with greater airflow through the opposite nasal side.

36. Frey-Syndrom: Ursachen, Beschwerden und Behandlung (opens a new tab)

    The clinical overview describes gustatory sweating after nerve injury and misdirected regeneration.

37. Gas im Verdauungstrakt – NIDDK (opens a new tab)

    Swallowed air is a normal source of digestive gas; belching releases gas through the mouth.

38. Sinusarrhythmie – StatPearls (opens a new tab)

    The source describes the usually harmless breathing-related change in sinus rhythm.

39. DermNet: Ephelis (opens a new tab)

    Explains ephelides, pigmentation, and dependence on sunlight.

40. Xiang et al.: Accessory navicular in children (opens a new tab)

    Developmental variation of the ossification center and clinical symptoms.

41. Hospital for Sick Children: Accessory navicular (opens a new tab)

    Location, tendon relation, usually absent symptoms, and irritation from load.

42. Blind Spot — Exploratorium (opens a new tab)

    The optic disc has no light receptors; a paper experiment demonstrates the blind spot and perceptual completion.

43. DermNet: Red ear syndrome (opens a new tab)

    Describes painful redness attacks and their uncertain cause.

44. Cleveland Clinic: Delayed Onset Muscle Soreness (opens a new tab)

    Explains delayed exercise soreness and distinguishes it from acute injury.

45. Merck Manual: Joint Noises (opens a new tab)

    Places joint sounds in context with and without other symptoms.

46. Independence of perceptual and sensorimotor predictions in the size-weight illusion (opens a new tab)

    The weight illusion persists although lifting forces adapt to the actual mass.

47. REM Sleep at its Core – Circuits, Neurotransmitters, and Pathophysiology (opens a new tab)

    Brainstem and spinal networks produce normal REM muscle inhibition; individual muscle groups are affected differently.

48. Laryngopharyngealer Reflux – StatPearls (opens a new tab)

    This source supports the description and physiological context of this entry.

49. Physiologie des gastro-kolischen Reflexes – StatPearls (opens a new tab)

    The reflex increases colonic motility after food intake.

50. Herzklopfen: Symptome, Ursachen und Behandlung (opens a new tab)

    The source distinguishes common triggers from possible heart disease and names warning signs.

51. National Cancer Institute: Common Moles, Dysplastic Nevi, and Risk of Melanoma (opens a new tab)

    Explains clusters of pigment cells and changes that should be assessed.

52. Seattle Children’s: Syndactyly (opens a new tab)

    Development, simple and complex forms, and different implications in hands and feet.

53. Neural Locus of Color Afterimages (opens a new tab)

    Colored afterimages can also arise through adaptation of downstream retinal cells, not only from bleaching of photopigments.

54. Variability and stability in the McGurk effect: contributions of participants, stimuli, time, and response type (opens a new tab)

    Audiovisual sound fusion varies greatly across people, stimuli, and response formats.

55. NINDS: Tremor (opens a new tab)

    Distinguishes physiological tremor, amplifying factors, and disease-related forms.

56. Cleveland Clinic: Hitchhiker’s Thumb (opens a new tab)

    Describes the usually symptom-free hyperextension of the thumb end joint.

57. Rapid and dynamic processing of face pareidolia in the human brain (opens a new tab)

    Face-like objects trigger early face-related processing before their object properties are represented more strongly.

58. REM sleep behavior disorder: update on diagnosis and management (opens a new tab)

    REM sleep behavior disorder involves loss of normal muscle inhibition and acting out dreams; sleep diagnosis and injury prevention are important.

59. Geruchsadaptation: Ableitungen vom menschlichen Riechepithel (opens a new tab)

    The human study investigates peripheral and perceptual adaptation to repeated odor stimulation.

60. Ausscheidung und Wahrnehmung des charakteristischen Uringeruchs nach Spargel (opens a new tab)

    The human study distinguishes odor production from the ability to perceive the odor.

61. Vasovagale Episode – StatPearls (opens a new tab)

    The overview describes triggers, blood-pressure drop, and possible slowing of heart rate in reflex syncope.

62. Luo et al.: GWASs Identify Genetic Loci Associated with Human Scalp Hair Whorl Direction (opens a new tab)

    Genome-wide study of multiple genetic regions associated with scalp hair-whorl direction.

63. Phosphenes: What They Are & Common Causes (opens a new tab)

    Phosphenes are light sensations without a corresponding external light source and can have different ocular or neurological causes.

64. The Ventriloquist Illusion as a Tool to Study Multisensory Processing: An Update (opens a new tab)

    Visual information can shift the perceived position of a sound; spatial and temporal matching affect integration.

65. StatPearls: Eyelid Myokymia (opens a new tab)

    Describes fine contractions of the orbicularis oculi and typical triggers.

66. NHS: Rheumatoid arthritis – Symptoms (opens a new tab)

    Compares morning stiffness in osteoarthritis and inflammatory arthritis.

67. Déjà vu experiences in healthy subjects are unrelated to laboratory tests of recollection and familiarity for word stimuli (opens a new tab)

    The study discusses a discrepancy between erroneous memory signals and memory monitoring; it does not establish a single conclusive mechanism.

68. Yawning in neurology: a review (opens a new tab)

    Yawning is a coordinated neurological process; several functional hypotheses are discussed without a definitive explanation.

69. Autosomal-dominantes Niesen bei Magenfülle: der Snatiation-Reflex (opens a new tab)

    The family report documents sneezing triggered by stomach fullness; it does not establish a confirmed mechanism.

70. Landkartenzunge: Ursachen, Symptome und Behandlung (opens a new tab)

    The overview describes migrating smooth areas, loss of papillae, and the benign course.

71. Beeturie – StatPearls (opens a new tab)

    The overview describes betacyanins as the cause of urine discoloration and how to distinguish it from blood in the urine.

72. University of Delaware: Myths of Human Genetics – Widow’s Peak (opens a new tab)

    Reviews the insufficient evidence for a simple dominant inheritance pattern.

73. Investigation of the source of the blue field entoptic phenomenon (opens a new tab)

    The findings support the view that white blood cells in retinal capillaries create the bright moving dots.

74. Neuroanatomy, Vestibulo-ocular Reflex — StatPearls (opens a new tab)

    Vestibular signals generate compensatory eye movements to stabilize gaze.

75. Cleveland Clinic: Benign Fasciculation Syndrome (opens a new tab)

    Describes benign muscle twitches and the importance of accompanying muscle weakness.

76. Floyd et al.: Arthroscopic Excision of Bipartite Patella (opens a new tab)

    Arises from an additional ossification center, is often an incidental finding, and can cause pain.

77. The the the the induction of jamais vu in the laboratory: word alienation and semantic satiation (opens a new tab)

    Repeated writing of familiar words can induce a subjective feeling of unfamiliarity; the authors study this as jamais vu.

78. Corneal Reflex — StatPearls (opens a new tab)

    The corneal reflex has a trigeminal sensory limb and a facial motor limb, with closure of both eyelids.

79. Nasenbluten: Ursachen, Behandlung und Vorbeugung (opens a new tab)

    The patient information describes dry mucosa as a trigger as well as first measures and warning signs.

80. Furchenzunge: Ursachen und Umgang damit (opens a new tab)

    The source describes a benign surface variation and possible irritation from trapped food debris.

81. Evolution der Laktasepersistenz als Beispiel menschlicher Nischenkonstruktion (opens a new tab)

    The review describes genetically influenced maintenance of lactase activity and its relationship to dairying.

82. DermNet: Poliosis (opens a new tab)

    Definition, affected hairs, and possible associations.

83. Microsaccades restore the visibility of minute foveal targets (opens a new tab)

    Stationary stimuli can fade during fixation; small eye movements are associated with their becoming visible again.

84. Tinnitus — National Institute on Deafness and Other Communication Disorders (opens a new tab)

    Tinnitus has different causes and is often associated with hearing loss; auditory pathways and other brain networks are involved.

85. NHS: Leg cramps (opens a new tab)

    Triggers and usual self-help for leg cramps.

86. The Tip-of-the-Tongue Phenomenon: Cognitive, Neural, and Neurochemical Perspectives (opens a new tab)

    Temporary failure to retrieve a word can occur while its meaning is retained and there is a strong feeling that recall is close.

87. A Review on Various Topics on the Thermal Grill Illusion (opens a new tab)

    Interleaved mild warm and cold stimuli can produce burning or pain; several mechanistic models are discussed.

88. Resonanzstörungen – American Speech-Language-Hearing Association (opens a new tab)

    ASHA describes hyponasality as reduced nasal resonance, often caused by a blockage.

89. Torus palatinus: knöcherner Gaumenvorsprung (opens a new tab)

    The overview describes the location, benign nature, and possible mechanical symptoms.

90. Symptome und Ursachen der Laktoseintoleranz – NIDDK (opens a new tab)

    Lactase deficiency leads to malabsorption; bacterial breakdown and increased fluid explain the symptoms.

91. Pessa et al.: Double or bifid zygomaticus major muscle (opens a new tab)

    An anatomical study of a bifid zygomatic muscle as a possible explanation for dimples.

92. The motion after-effect reloaded (opens a new tab)

    Motion aftereffects are based on adaptation processes at several levels of visual motion processing.

93. “Doctor, I Hear Music”: A Brief Review About Musical Hallucinations (opens a new tab)

    Musical hallucinations can occur with hearing loss, medication effects, and neurological or psychiatric conditions.

94. StatPearls: Neuroanatomy, Spinal Cord Myotatic Reflex (opens a new tab)

    Explains muscle spindles and the wiring of the stretch reflex.

95. The hypnagogic state: A brief update (opens a new tab)

    Visual, auditory, and body-related perceptual impressions can occur in the transition between wakefulness and sleep.

96. Sneezing reflex is mediated by a peptidergic pathway from nose to brainstem (opens a new tab)

    Investigates a sensory connection from nasal mucosa to brainstem networks; detailed circuit evidence comes substantially from mouse experiments.

97. Nasenklappenkollaps: Symptome, Ursachen und Untersuchung (opens a new tab)

    The source describes nasal-valve instability or narrowing as a cause of impaired nasal breathing.

98. Gespaltenes Zäpfchen: Ursachen und Symptome (opens a new tab)

    The clinical overview explains this developmental variation and its possible association with a submucous cleft palate.

99. Rolle von Stickstoffmonoxid bei der Magenakkommodation und der nahrungsbedingten Sättigung (opens a new tab)

    The human study examines the role of nitric oxide in reflexive relaxation of the stomach.

100. University of Delaware: Myths of Human Genetics – Cleft Chin (opens a new tab)

     Discusses variation in form and the limits of a simple Mendelian explanation.

101. The Perception of Depth — Webvision (opens a new tab)

     Stereopsis uses binocular image differences; additional depth cues are also available with one eye.

102. Middle Ear Myoclonus: Two Informative Cases and a Systematic Discussion of Myogenic Tinnitus (opens a new tab)

     Middle-ear muscle activity is a possible cause of clicking sounds; different muscular causes and diagnostic uncertainties must be considered.

103. University of Oregon: Spinal Reflexes (opens a new tab)

     Explains the wiring of the withdrawal reflex and reciprocal extension.

104. The cognitive neuroscience of lucid dreaming (opens a new tab)

     This source supports the description and physiological context of this entry.

105. Anatomy and neuro-pathophysiology of the cough reflex arc (opens a new tab)

     This source supports the description and physiological context of this entry.

106. Isolierte linguale Dystonie als Ausdruck eines durch Metoclopramid ausgelösten akuten extrapyramidalen Syndroms (opens a new tab)

     This source supports the description and physiological context of this entry.

107. Physiologie der Gallenblase – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

108. DermNet: Supernumerary nipple (opens a new tab)

     This source supports the description and physiological context of this entry.

109. Eyeing up the Future of the Pupillary Light Reflex in Neurodiagnostics (opens a new tab)

     This source supports the description and physiological context of this entry.

110. Neural mechanisms for illusory filling-in of degraded speech (opens a new tab)

     This source supports the description and physiological context of this entry.

111. StatPearls: Babinski Reflex (opens a new tab)

     This source supports the description and physiological context of this entry.

112. What Does the Sleeping Brain Say? Syntax and Semantics of Sleep Talking in Healthy Subjects and in Parasomnia Patients (opens a new tab)

     This source supports the description and physiological context of this entry.

113. Sleep talking: what happens in your brain? (opens a new tab)

     This source supports the description and physiological context of this entry.

114. Research Progress in the Study of Startle Reflex to Disease States (opens a new tab)

     This source supports the description and physiological context of this entry.

115. Physiologie der Speichelbildung – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

116. Der migrierende motorische Komplex: Steuerung und Funktion (opens a new tab)

     This source supports the description and physiological context of this entry.

117. DermNet: keratosis pilaris (opens a new tab)

     This source supports the description and physiological context of this entry.

118. Nervöse Regulation der Sekretion der Tränendrüse (opens a new tab)

     This source supports the description and physiological context of this entry.

119. Neural Correlates of Natural Human Echolocation in Early and Late Blind Echolocation Experts (opens a new tab)

     This source supports the description and physiological context of this entry.

120. Strauss et al.: Vestigial auriculomotor activity indicates the direction of auditory attention in humans (opens a new tab)

     This source supports the description and physiological context of this entry.

121. NonREM Disorders of Arousal and Related Parasomnias: an Updated Review (opens a new tab)

     This source supports the description and physiological context of this entry.

122. Relief of itch by scratching: state-dependent inhibition of primate spinothalamic tract neurons (opens a new tab)

     This source supports the description and physiological context of this entry.

123. Frontiers in pruritus research: scratching the brain for more effective itch therapy (opens a new tab)

     This source supports the description and physiological context of this entry.

124. Physiologie des Würgereflexes – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

125. Anatomie des Analkanals – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

126. Stuhlinkontinenz – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

127. DermNet: milia (opens a new tab)

     This source supports the description and physiological context of this entry.

128. Krokodilstränensyndrom – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

129. Exploding Head Syndrome — StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

130. Five Specific Tongue Movements in a Healthy Population (opens a new tab)

     This source supports the description and physiological context of this entry.

131. A Neural Basis for Contagious Yawning (opens a new tab)

     This source supports the description and physiological context of this entry.

132. Phantom Limb Pain: Mechanisms and Treatment Approaches (opens a new tab)

     This source supports the description and physiological context of this entry.

133. Mandelsteine: Symptome, Ursachen und Behandlung (opens a new tab)

     This source supports the description and physiological context of this entry.

134. Einfluss von Kaffee auf die Funktion des distalen Dickdarms (opens a new tab)

     This source supports the description and physiological context of this entry.

135. DermNet: cherry angioma (opens a new tab)

     This source supports the description and physiological context of this entry.

136. Physiologie der Ohrtrompetenfunktion – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

137. Synesthesia: an introduction (opens a new tab)

     This source supports the description and physiological context of this entry.

138. Pins and needles — NHS (opens a new tab)

     This source supports the description and physiological context of this entry.

139. Numbness and tingling — MedlinePlus Medical Encyclopedia (opens a new tab)

     This source supports the description and physiological context of this entry.

140. Morgenatem: warum er entsteht und was hilft (opens a new tab)

     This source supports the description and physiological context of this entry.

141. Nachtröpfeln bei Männern: Ursachen und Behandlung (opens a new tab)

     This source supports the description and physiological context of this entry.

142. Cleveland Clinic: Cold Hands (opens a new tab)

     This source supports the description and physiological context of this entry.

143. The Anatomy of Blindsight (opens a new tab)

     This source supports the description and physiological context of this entry.

144. Schwarze Haarzunge: Symptome, Ursachen und Behandlung (opens a new tab)

     This source supports the description and physiological context of this entry.

145. NHS: Blue or grey skin or lips (cyanosis) (opens a new tab)

     This source supports the description and physiological context of this entry.

146. Prosopagnosia: current perspectives (opens a new tab)

     This source supports the description and physiological context of this entry.

147. Eiskopfschmerz: Beschwerden und Umgang damit (opens a new tab)

     This source supports the description and physiological context of this entry.

148. Romero et al.: Palmar hyperhidrosis (opens a new tab)

     This source supports the description and physiological context of this entry.

149. Lives without imagery – Congenital aphantasia (opens a new tab)

     This source supports the description and physiological context of this entry.

150. Wirksamkeit von sechs Methoden zur Entfernung von Kehlkopfschleim (opens a new tab)

     This source supports the description and physiological context of this entry.

151. DermNet: Keloid and hypertrophic scar (opens a new tab)

     This source supports the description and physiological context of this entry.

152. Nächtliches Schlucken verstärkt Weckreaktionen und den dabei auftretenden Pulsanstieg (opens a new tab)

     This source supports the description and physiological context of this entry.

153. DermNet: White nail (opens a new tab)

     This source supports the description and physiological context of this entry.

154. Umgang mit Bruxismus – StatPearls (opens a new tab)

     This source supports the description and physiological context of this entry.

155. Messung von Allylmethylsulfid, Allylmethylsulfoxid und Allylmethylsulfon in Muttermilch und Urin nach gekochtem und geröstetem Knoblauch (opens a new tab)

     This source supports the description and physiological context of this entry.

156. Zahnabdrücke am Zungenrand: mögliche Ursachen (opens a new tab)

     This source supports the description and physiological context of this entry.

157. Übelkeit und Erbrechen – Clinical Methods (opens a new tab)

     This source supports the description and physiological context of this entry.