00:00 / 00:00




Musculoskeletal system

Pediatric musculoskeletal conditions

Radial head subluxation (Nursemaid elbow)

Developmental dysplasia of the hip

Legg-Calve-Perthes disease

Slipped capital femoral epiphysis

Transient synovitis

Osgood-Schlatter disease (traction apophysitis)

Musculoskeletal injuries and trauma

Rotator cuff tear

Dislocated shoulder

Radial head subluxation (Nursemaid elbow)

Winged scapula

Thoracic outlet syndrome

Carpal tunnel syndrome

Ulnar claw

Erb-Duchenne palsy

Klumpke paralysis

Iliotibial band syndrome

Unhappy triad

Anterior cruciate ligament injury

Patellar tendon rupture

Meniscus tear

Patellofemoral pain syndrome

Sprained ankle

Achilles tendon rupture



Degenerative disc disease

Spinal disc herniation


Compartment syndrome


Bone disorders

Osteogenesis imperfecta


Pectus excavatum


Genu valgum

Genu varum

Pigeon toe

Flat feet

Club foot

Cleidocranial dysplasia



Bone tumors




Osteomalacia and rickets


Paget disease of bone


Lordosis, kyphosis, and scoliosis

Joint disorders



Spinal stenosis

Rheumatoid arthritis

Juvenile idiopathic arthritis


Calcium pyrophosphate deposition disease (pseudogout)

Psoriatic arthritis

Ankylosing spondylitis

Reactive arthritis


Septic arthritis


Baker cyst

Muscular disorders

Muscular dystrophy



Inclusion body myopathy

Polymyalgia rheumatica



Neuromuscular junction disorders

Myasthenia gravis

Lambert-Eaton myasthenic syndrome

Other autoimmune disorders

Sjogren syndrome

Systemic lupus erythematosus

Mixed connective tissue disease

Antiphospholipid syndrome

Raynaud phenomenon


Limited systemic sclerosis (CREST syndrome)

Musculoskeletal system pathology review

Back pain: Pathology review

Rheumatoid arthritis and osteoarthritis: Pathology review

Seronegative and septic arthritis: Pathology review

Gout and pseudogout: Pathology review

Systemic lupus erythematosus (SLE): Pathology review

Scleroderma: Pathology review

Sjogren syndrome: Pathology review

Bone disorders: Pathology review

Bone tumors: Pathology review

Myalgias and myositis: Pathology review

Neuromuscular junction disorders: Pathology review

Muscular dystrophies and mitochondrial myopathies: Pathology review




0 / 11 complete

USMLE® Step 1 questions

0 / 6 complete

USMLE® Step 2 questions

0 / 3 complete

High Yield Notes

10 pages



of complete


USMLE® Step 1 style questions USMLE

of complete

USMLE® Step 2 style questions USMLE

of complete

A 52-year-old man presents to the emergency department to evaluate low back pain. The patient was using the rowing machine at the gym when he felt a “pop” in his back followed by pain. He is otherwise healthy and does not take any medications daily. Vital signs are within normal limits. On physical examination, the patient has tenderness to palpation over the lumbar spine and diminished sensation over the anterior aspect of the left leg. The patient has 4/5 strength with hip flexion on the left compared to 5/5 strength on the right. Which of the following physical examination maneuvers is most likely to demonstrate a positive finding given this patient’s clinical presentation? 

External Links



Samantha McBundy, MFA, CMI

Stefan Stoisavljevic, MD

Evan Debevec-McKenney

Sciatica is a condition where there’s pain that starts in the lower back which then travels down the leg. Since the pain is associated with injury or compression of the sciatic nerve and follows the path of the sciatic nerve, it makes sense to name it sciatica.

The sciatic nerve is the longest and widest nerve in the body. It’s formed by the spinal nerves L4, L5, and S1-3, which leave the spinal canal through intervertebral foramen, an opening located between the vertebrae and behind the intervertebral discs. These nerves travel to the area in front of the sacrum, and join to make the sacral plexus.

All the nerves in the plexus, except S3 are split into two divisions: anterior and posterior. Anterior divisions of the L4, L5, S1, S2 and the entire S3 nerve create the tibial nerve, while posterior divisions of the L4, L5, S1 and S2 form the common fibular nerve. These two nerves are bound together by connective tissue and make up the sciatic nerve.

The sciatic nerve then passes beneath the piriformis muscle and through the greater sciatic foramen which is an opening formed by the pelvic bone, sacrospinous, and sacrotuberous ligaments.

It then travels down the back of the thigh to the back of the knee where it splits into the tibial and common fibular nerves. The sciatic nerve innervates the muscles in the back of the thigh. The Tibial nerve innervates the muscles of the posterior compartment of the leg and intrinsic flexors of the foot.

The Common fibular nerve is in charge of the muscles in the anterior and lateral compartments of the leg and intrinsic extensors of the foot. Now, each spinal nerve is in charge of the sensation of a specific area of the skin, called a dermatome.


Sciatica is a term used to describe symptoms of lower back pain, numbness, or tingling that originate in the lower back and travel down the sciatic nerve. It is often due to a spinal disc herniation pressing on one of the lumbar or sacral nerve roots. Other common causes are spinal stenosis, degenerative disc diseases. Treatment options include physical therapy, pain medication, exercise, and in some cases, surgery.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Sciatica" British Journal of Hospital Medicine (2016)
  6. "Late sciatic nerve entrapment following pelvic plate reconstruction in total hip arthroplasty" The Journal of Arthroplasty (1998)

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.