Bell palsy


00:00 / 00:00



Bell palsy

Nervous system

Central nervous system disorders

Spina bifida

Chiari malformation

Dandy-Walker malformation


Tethered spinal cord syndrome

Aqueductal stenosis

Septo-optic dysplasia

Cerebral palsy

Spinocerebellar ataxia (NORD)

Transient ischemic attack

Ischemic stroke

Intracerebral hemorrhage

Epidural hematoma

Subdural hematoma

Subarachnoid hemorrhage

Saccular aneurysm

Arteriovenous malformation

Broca aphasia

Wernicke aphasia

Wernicke-Korsakoff syndrome

Kluver-Bucy syndrome

Concussion and traumatic brain injury

Shaken baby syndrome


Febrile seizure

Early infantile epileptic encephalopathy (NORD)

Tension headache

Cluster headache


Idiopathic intracranial hypertension

Trigeminal neuralgia

Cavernous sinus thrombosis

Alzheimer disease

Vascular dementia

Frontotemporal dementia

Lewy body dementia

Creutzfeldt-Jakob disease

Normal pressure hydrocephalus


Essential tremor

Restless legs syndrome

Parkinson disease

Huntington disease

Opsoclonus myoclonus syndrome (NORD)

Multiple sclerosis

Central pontine myelinolysis

Acute disseminated encephalomyelitis

Transverse myelitis

JC virus (Progressive multifocal leukoencephalopathy)

Adult brain tumors

Acoustic neuroma (schwannoma)

Pituitary adenoma

Pediatric brain tumors

Brain herniation

Brown-Sequard Syndrome

Cauda equina syndrome

Treponema pallidum (Syphilis)

Vitamin B12 deficiency


Friedreich ataxia

Neurogenic bladder


Neonatal meningitis


Brain abscess

Epidural abscess

Cavernous sinus thrombosis

Creutzfeldt-Jakob disease

Central and peripheral nervous system disorders

Sturge-Weber syndrome

Tuberous sclerosis


von Hippel-Lindau disease

Amyotrophic lateral sclerosis

Peripheral nervous system disorders

Spinal muscular atrophy


Guillain-Barre syndrome

Charcot-Marie-Tooth disease

Trigeminal neuralgia

Bell palsy

Winged scapula

Thoracic outlet syndrome

Carpal tunnel syndrome

Ulnar claw

Erb-Duchenne palsy

Klumpke paralysis


Myasthenia gravis

Lambert-Eaton myasthenic syndrome

Autonomic nervous system disorders

Orthostatic hypotension

Horner syndrome

Nervous system pathology review

Congenital neurological disorders: Pathology review

Headaches: Pathology review

Seizures: Pathology review

Cerebral vascular disease: Pathology review

Traumatic brain injury: Pathology review

Spinal cord disorders: Pathology review

Dementia: Pathology review

Central nervous system infections: Pathology review

Movement disorders: Pathology review

Neuromuscular junction disorders: Pathology review

Demyelinating disorders: Pathology review

Adult brain tumors: Pathology review

Pediatric brain tumors: Pathology review

Neurocutaneous disorders: Pathology review


Bell palsy


0 / 10 complete

USMLE® Step 2 questions

0 / 2 complete

High Yield Notes

3 pages


Bell palsy

of complete


USMLE® Step 2 style questions USMLE

of complete

A 45-year-old man comes to the office to evaluate right-sided facial heaviness for the past 10 hours. He also reports decreased tear production on the right side and the inability to tolerate loud sounds that started simultaneously. Medical history is remarkable for a right-sided parotid gland adenoma which was surgically resected one month ago. The patient has no hearing loss, ringing sensation in the ears, or difficulty walking. Vitals are within normal limits. Physical examination findings are shown in the image below.


Examination of the right auditory canal and auricle is noncontributory. Which of the following is the most likely cause of the findings seen in this patient?

External References

First Aid








Bell palsy

sarcoidosis and p. 701



Sam Gillespie, BSc

Tanner Marshall, MS

Bell’s palsy, named after the surgeon Charles Bell who first described it, is when there’s weakness or paralysis of the muscles on one side of the face, caused by damage to the seventh cranial nerve, which is the facial nerve.

The underlying cause of cranial nerve damage is idiopathic which means it’s unknown, so when there’s facial nerve a paralysis from a known cause like a stroke, a tumor, or trauma, it’s not considered a Bell’s palsy.

George Clooney had this disorder for nine months when he was a teenager.

Broadly speaking, the nervous system has two parts: the central nervous system, which consists of the brain, brainstem, and spinal cord, and the peripheral nervous system, which consists of all of the nerves that fan out from the central nervous system.

Peripheral nerves that emerge from the brain and brainstem are called cranial nerves, and there are a total of 12 pairs of cranial nerves.

The seventh cranial nerve, the facial nerve, emerges from the brainstem, and then enters the temporal bone where it travels through a narrow, Z-shaped canal, called the facial canal.

The facial nerve exits the skull through a tiny hole called the stylomastoid foramen.

From there, the facial nerve branches off to different facial muscles that help with facial expression, like the ones you use while whistling to your favorite song.

Ultimately, control of each side of the face comes from a region of the brain called the motor cortex.

For example, let’s start with the lower half of the right side of the face. An upper motor neuron extends down from the left motor cortex, goes across the midline in the brainstem to the right side, and then meets with a right lower motor neuron which hitches a ride on the right facial nerve.


  1. "Clinical Practice Guideline" Otolaryngology–Head and Neck Surgery (2013)
  2. "Modern management of facial palsy: a review of current literature" British Journal of General Practice (2013)
  3. "The neurologist’s dilemma: A comprehensive clinical review of Bell’s palsy, with emphasis on current management trends" Medical Science Monitor (2014)
  4. "Bell Palsy and Herpes Simplex Virus: Identification of Viral DNA in Endoneurial Fluid and Muscle" Annals of Internal Medicine (1996)
  5. "Robbins Basic Pathology" Elsevier (2017)
  6. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  7. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  8. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)

Copyright © 2023 Elsevier, except certain content provided by third parties

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.