Radiological anatomy of the thigh and leg.

Dr/ ABD ALLAH NAZEER. MD.

RADIOLOGICAL IMAGING: Plain Radiography. Computed Tomography (CT). Magnetic Resonance Imaging(MRI).

Lower limb bones.

Thigh muscles: cross sectional anatomy.

Mid Leg

Level.

Arrows, Red=semitendinosus, Gold=combined hamstring tendonsYellow=semimembranosus, Green=biceps femoris - long headMagenta - semimembranosus and biceps femoris - long headText. GM=Gluteus Maximus.

Arrows, Red=semitendinosus, Gold=combined hamstring tendonsYellow=semimembranosus, Green=biceps femoris - long headMagenta - semimembranosus and biceps femoris - long headText. GM=Gluteus Maximus. AM=Adductor Magnus

Arrows Red=semitendinosus, Yellow=semimembranosus, Green=biceps femoris -long head Purple=biceps femoris - short head . Text: AM=Adductor Magnus

Arrows, Red=semitendinosus, Yellow=semimembranosusGreen=biceps femoris - long head, Purple=biceps femoris - short head

Normal MR Imaging.Anatomy of the Thigh and Leg

The thigh is best described in terms of compartmental anatomy, and

is composed of anterior, posterior, and medial (adductor) compartments. In terms of spread of pathologic processes, such as tumor and infection, other delineated compartments include the skin and subcutaneous fat, bone bounded by periosteum and cortex, and parosteal space (between the bone and overlying soft tissues).3 The thigh extends from the superior margin of the subtrochanteric region through the distal femoral metadiaphysis. Each compartment is composed of muscles, neurovascular structures, and intermuscular fascia. Muscles are of intermediate signal intensity to fat on T1W and T2W FSE sequences.1 Peripheral nerves are round or oval and have a fascicular appearance, best depicted on T2W sequences. They are isointense to muscle on T1W sequences with intermixed increased signal intensity similar to fat. On T2W sequences, they are isointense to slightly hyperintense relative to muscles.

The leg extends from the proximal tibial metaphysis through the distal

metaphysis. The soft tissues are similarly organized in a compartmental fashion, and are supported by the tibia and fibula. The lower leg is composed of 4 compartments: anterior, superficial posterior, deep posterior, and lateral. The interosseous membrane separates the anterior and deep posterior compartments. The transverse septum separates the superficial and deep posterior compartments. The anterior compartment contains the tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles, and the anterior neurovascular bundle, including the anterior tibial artery and vein, and deep peroneal nerve. The tibialis anterior muscle originates from the lateral surface of the tibia and neighboring interosseous membrane in the upper leg, and extends distally over the anterior tibia to insert upon the dorsal aspect of the first metatarsal. The extensor digitorum longus muscle originates from the anterior surface of the interosseous membrane and fibula, courses inferiorly along the anterior tibia, and gives rise to tendons that insert upon the distal phalanges of the second through fifth toes. The peroneus tertius muscle, when variably present, is closely associated with the extensor digitorum longus muscle, coursing in the same synovial sheath; however, its tendon attaches to the dorsal aspect of the base of the fifth metatarsal.

Axial T1W images. Compartmental muscle anatomy. (A) Mid thigh. Compartmental boundaries are delineated by solid black lines. (B) Mid leg. Compartmental boundaries are delineated by solid black lines.

MRI showing cross sectional view of lower leg musculature along with the position of the 15 electrodes along the circumference of the lower leg. Muscle activity levels were measured for FDL (flexor digitorum longus), SOL (soleus), PR (peroneus group) and AC (anterior compartment group.

Axial T1W image. Upper thigh. Compartmental muscle anatomy. Add., Adductor; a., artery; Glut Max., gluteus maximus; m., muscle; n., nerve; Obt. Ext./Int., obturator externus/internus; Smb, semimembranosus; t., tendon; Tens., tensor; v., vein; V., vastus.

Axial T1W image. Upper thigh. Compartmental muscle anatomy. Add., Adductor; a., artery; BF LH, biceps femoris long head; Interm., intermedius; Long., longus; m., muscle; n., nerve; Smb, semimembranosus; Smt, semitendinosus; t., tendon; v., vein; V., vastus.

Axial T1W image. Mid thigh. Compartmental muscle anatomy. Add., Adductor; a., artery; BF LH, biceps femoris long head; Lat. Intmsclr. Sptm., lateral intermuscular septum; m., muscle; n., nerve; Smb, semimembranosus; Smt, semitendinosus; t., tendon; v., vein; V., vastus.

Axial T1W image. Mid thigh. Compartmental muscle anatomy. Add., Adductor; a., artery; BF LH, biceps femoris long head; Lat. Intmsclr. Sptm., lateral intermuscular septum; m., muscle; n., nerve; Smb., semimembranosus; Smt., semitendinosus; v., vein; V., vastus.

Axial T1W image. Lower thigh. Compartmental muscle anatomy. Add., Adductor; a., artery; BF SH, LH, biceps femoris short head, long head; m., muscle; n., nerve; Smb, semimembranosus; Smt, semitendinosus; v., vein; V., vastus.

Axial T1W image. Lower thigh. Compartmental muscle anatomy. BF SH, LH, biceps femoris short head, long head; Comm. Peron., common peroneal; F, femur; Fem., femoris; Interm., intermedius; m., muscle; n., nerve; Smb, semimembranosus; Smt, semitendinosus; t., tendon; V., vastus.

Axial T1W image. Upper leg. Compartmental muscle anatomy. a., artery; Ant. Tib., anterior tibial; Ext. Dig. Long, extensor digitorum longus; Memb., membrane; M.H./L.H. Gastroc., gastrocnemius, medial and lateral heads; m., muscle; Peron. Longus, peroneus longus; Peron., peroneal; Post. Tib, posterior tibialis; Tib. Ant., tibialis anterior; Tib. Post., tibialis posterior.

Axial T1W image. Upper leg. Compartmental muscle anatomy. a., artery; Ant. Tib., anterior tibial; DPN, deep peroneal nerve; Ext. Dig. Long., extensor digitorum longus; Ext. Hal. Long., extensor hallucis longus; Flex. Dig. Long, flexor digitorum longus; M.H./L.H. Gastroc., gastrocnemius, medial and lateral heads; m., muscle; n., nerve; Peron. Longus., Brv., peroneus longus, brevis; Peron., peroneal; Post. Tib, posterior tibialis; Tib. Ant., tibialis anterior; Tib. Post., tibialis posterior; Tib., tibial.

Axial T1W image. Mid leg. Compartmental muscle anatomy. a., artery; Ant. Tib., anterior tibial; DPN, deep peroneal nerve; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FDL, flexor digitorum longus; FHL, flexor hallucis longus; Gastroc. M.H./L.H., gastrocnemius, medial and lateral heads; m., muscle; n., nerve; Peron. L., Br., peroneus longus, brevis; Peron., peroneal; Post. tib., posterior tibialis; Tib. Ant., tibialis anterior; Tib. Post.,tibialis posterior; Tib., tibial.

Axial T1W image. Mid leg. Compartmental muscle anatomy. a., artery; Ant. Tib., anterior tibial; DPN, deep peroneal nerve; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FDL, flexor digitorum longus; FHL, flexor hallucis longus; M.H. Gastroc., gastrocnemius, medial head; m., muscle; n., nerve; Peron. Lg., Brv., peroneus longus, brevis; Peron., peroneal; Post Tib, posterior tibialis; SPN, superficial peroneal nerve; Tib. Ant., tibialis anterior; Tib. Post., tibialis posterior; Tib., tibial.

Axial T1W image. Lower leg. Compartmental muscle anatomy. a., artery; Ant Tib., anterior tibial; DPN, deep peroneal nerve; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FDL, flexor digitorum longus; FHL, flexor hallucis longus; Gastroc., gastrocnemius; m., muscle; n., nerve; Peron. L., Br., peroneus longus, brevis; Peron., peroneal; Post Tib, posterior tibialis; SPN, superficial peroneal nerve; t., tendon; Tib. Ant., tibialis anterior; Tib. Post., tibialis posterior; Tib., tibial.

Axial T1W image. Lower leg. Compartmental muscle anatomy. a., artery; Ant Tib., anterior tibial; DPN, deep peroneal nerve; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FDL, flexor digitorum longus; FHL, flexor hallucis longus; Gastroc., gastrocnemius; m., muscle; n., nerve; Peron. Lg., Br., peroneus longus, brevis; Peron., peroneal; Post Tib, posterior tibialis; SPN, superficial peroneal nerve; t., tendon; Tib. Ant., tibialis anterior; Tib. Post., tibialis posterior; Tib., tibial.