Normal anatomical variants

A gallery of normal anatomical variants for trainees revising for the First FRCR Anatomy exam


A normal variant is an atypical finding that is seen in a percentage of the population, which generally has no clinical significance, and is considered within the spectrum of normal findings.  Scroll down to view images of normal anatomical variants.  Click on an image to see a full larger version with arrows.  Please note that this list is still incomplete.  If you have any examples you would like to add to this page then please feel free to contribute!

 

Chest


  • Aberrant right subclavian artery as seen on an axial CT (normal variant)
    Aberrant right subclavian artery

    Axial CT

  • Aberrant right subclavian artery as seen on an axial CT (normal variant)
    Aberrant right subclavian artery

    Sagittal CT

  • Aberrant left pulmonary artery as seen on an axial CT (normal variant)
    Aberrant left pulmonary artery

    Axial CT

  • Aberrant left pulmonary artery as seen on a sagittal CT (normal variant)
    Aberrant left pulmonary artery

    Sagittal CT

  • Hemiazygos continuation of the inferior vena cava (IVC) as seen on an axial CT (normal variant)
    Hemiazygos continuation of the IVC

    Axial CT

  • Azygos fissure as seen on a PA chest radiograph (normal variant)
    Azygos fissure

    PA chest radiograph

  • Azygos fissure as seen on a PA chest radiograph (normal variant)
    Azygos fissure

    PA chest radiograph

  • Azygos fissure as seen on an axial CT (normal variant)
    Azygos fissure

    Axial CT

  • Dextrocardia as seen on a PA chest radiograph (normal variant)
    Dextrocardia

    PA chest radiograph

  • Pectus excavatum as seen on a PA chest radiograph (normal variant)
    Pectus excavatum

    PA chest radiograph

  • Pectus excavatum as seen on a PA chest radiograph (normal variant)
    Pectus excavatum

    PA chest radiograph

  • Pectus excavatum as seen on a lateral chest radiograph (normal variant)
    Pectus excavatum

    Lateral chest radiograph

 

Abdomen and pelvis


  • Riedel's lobe of the liver as seen on an abdominal radiograph (normal variant)
    Riedel's lobe

    Abdominal radiograph

  • Horseshoe kidney as seen on an axial CT (normal variant)
    Horseshoe kidney

    Axial CT

  • Horseshoe kidney as seen on ultrasound (normal variant)
    Horseshoe kidney

    Ultrasound

  • Pelvic kidney (right) as seen on axial CT (normal variant)
    Pelvic kidney

    Axial CT

  • Pelvic kidney (right) as seen on axial CT (normal variant)
    Pelvic kidney

    Axial CT

  • Double ureter (right) as seen on an axial CT (normal variant)
    Double ureter (right)

    Axial CT

  • Double ureter (right) as seen on a coronal CT (normal variant)
    Double ureter (right)

    Coronal CT

  • Double ureter (right) as seen on an axial CT (normal variant)
    Double ureter (right)

    Axial CT

  • Bicornuate uterus as seen on a coronal MRI (normal variant)
    Bicornuate uterus

    Coronal MRI

  • Aortic origin of the common hepatic artery as seen on 3D reconstruction (normal variant)
    Aortic origin of the common hepatic artery

    3D reconstruction

  • Superior mesenteric artery (SMA) origin of the right hepatic artery as seen on angiography (normal variant)
    SMA origin of the right hepatic artery

    Angiogram

  • Retroaortic left renal vein as seen on an axial MRI (normal variant)
    Retroaortic left renal vein

    Axial MRI

  • Retroaortic left renal vein as seen on an axial CT (normal variant)
    Retroaortic left renal vein

    Axial CT

  • Left sided inferior vena cava (IVC) as seen on an axial CT (normal variant)
    Left sided IVC

    Axial CT

  • Absent inferior vena cava (IVC) as seen on an axial CT (normal variant)
    Absent IVC

    Axial CT

  • Absent inferior vena cava (IVC) as seen on an axial CT (normal variant)
    Absent IVC

    Axial CT

 

Musculoskeletal


  • Luno-triquetral coalition as seen on a wrist radiograph (normal variant)
    Luno-triquetral coalition

    Wrist radiograph

  • Luno-triquetral coalition as seen on an AP wrist radiograph (normal variant)
    Luno-triquetral coalition

    AP wrist radiograph

  • Os acromilae as seen on a shoulder radiograph (normal variant)
    Os acromiale

    Shoulder radiograph

  • Calcaneonavicular coalition as seen on an ankle radiograph (normal variant)
    Calcaneonavicular coalition

    Ankle radiograph

  • Cervical rib (right) as seen on a PA chest radiograph (normal variant)
    Cervical rib (right)

    PA chest radiograph

  • Bipartite patella as seen on an AP knee radiograph (normal variant)
    Bipartite patella

    AP knee radiograph

  • Bipartite patella as seen on a lateral knee radiograph (normal variant)
    Bipartite patella

    Lateral knee radiograph

 

Head and neck


  • Concha bullosa as seen on a coronal CT (normal variant)
    Concha bullosa

    Coronal CT

  • Accessory sinus in the clivus as seen on an axial CT (normal variant)
    Accessory sinus in the clivus

    Axial CT

  • Cavum septum pellucidum as seen on an axial CT (normal variant)
    Cavum septum pellucidum

    Axial CT

  • Cavum vergae as seen on an axial CT (normal variant)
    Cavum vergae

    Axial CT

  • Fetal origin of the posterior cerebral artery as seen on 3D reconstruction (normal variant)
    Fetal origin of the PCA

    3D reconstruction

  • Persistent metopic suture as seen on axial CT (normal variant)
    Persistent metopic suture

    Axial CT

  • Trifurcation of the anterior cerebral artery as seen on 3D reconstruction (normal variant)
    Trifurcation of the anterior cerebral artery

    3D reconstruction

 


Contributors

Christopher Clarke
Lara Sammut
Karthik
Alan Naz
Laura Smith
Chloe Yang
(would you like to see your name here?  See below...)

 


Add to this collection of normal variants!

If you have any examples of normal anatomical variants not shown on this page (or shown with a different modality), then contribute using the form below!  We review every submission and reply to every message.  If your image is used and you decide to tell us your name, we will also give you credit on this site!

 

Upload a normal anatomical variant

 

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