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Tibia

The tibia, commonly known as the shin bone, is the larger and medial bone of the leg, extending from the knee to the ankle. It is the second largest bone in the human body after the femur. The tibia bears most of the body’s weight and forms key articulations at the knee joint proximally and ankle joint distally. Its broad proximal end articulates with the femoral condyles, while its distal end forms the medial malleolus and articulates with the talus.

The tibia plays a crucial role in locomotion, weight transmission, and stability. Because of its subcutaneous location along the anterior border (“shin”), it is prone to trauma and fractures.

Synonyms

  • Shin bone

  • Medial long bone of the leg

  • Tibial shaft (body of tibia)

Muscular Attachments

  • Proximal tibia:

    • Quadriceps femoris (via patellar ligament to tibial tuberosity)

    • Semimembranosus (posteromedial condyle)

    • Pes anserinus tendons: Sartorius, Gracilis, Semitendinosus (anteromedial surface below tibial tuberosity)

  • Shaft of tibia:

    • Tibialis anterior (lateral surface of upper shaft)

    • Soleus (posterior surface via soleal line)

    • Flexor digitorum longus (posterior surface, medial part)

    • Tibialis posterior (posterior shaft, below soleal line)

  • Distal tibia:

    • No direct muscular attachment, but fibrous connections near ankle capsule and ligaments

Relations

  • Anteriorly: Subcutaneous tissue and skin (hence prone to trauma)

  • Posteriorly: Popliteus (upper tibia), tibialis posterior, flexor digitorum longus, soleus

  • Medially: Subcutaneous surface (no major muscles; palpable along shin)

  • Laterally: Fibula (connected via interosseous membrane) and muscles of anterior/lateral compartments of leg

Nerve Supply

  • The tibia itself is not innervated; periosteum receives sensory innervation from branches of the tibial nerve and saphenous nerve

Arterial Supply

  • Nutrient artery (branch of posterior tibial artery) — supplies medullary cavity

  • Periosteal arteries from anterior tibial and posterior tibial arteries

  • Anastomotic vessels around knee and ankle joints

Venous Drainage

  • Tibial veins (anterior and posterior) accompanying arteries

  • Drain into popliteal vein → femoral vein

Function

  • Primary weight-bearing bone of the leg

  • Provides leverage and support for locomotion

  • Forms major joints: knee (superiorly) and ankle (inferiorly)

  • Protects neurovascular structures posteriorly through muscular coverage

MRI Appearance

T1-weighted images:

  • Bone cortex: uniformly dark

  • Marrow: intermediate to bright signal (due to fat content)

  • Abnormal marrow (tumor, infection, edema): appears darker

T2-weighted images:

  • Bone cortex: uniformly dark

  • Marrow: intermediate to bright signal

  • Pathology (edema, tumor, infection): hyperintense compared to normal marrow

STIR (Short Tau Inversion Recovery):

  • Normal marrow: low signal (fat suppressed)

  • Edema, tumor, infection: bright hyperintensity

Proton Density (PD):

  • Marrow: intermediate to bright signal

  • Cortex: dark

  • Useful for trabecular bone detail

Proton Density Fat-Saturated (PD FS):

  • Normal marrow: low signal (fat suppressed)

  • Pathology: bright hyperintense foci or diffuse infiltration

T1 Fat-Sat Post-Contrast:

  • Normal marrow: mild uniform enhancement

  • Pathology: abnormal focal, diffuse, or rim enhancement (e.g., infection, neoplasm)

CT Appearance

Non-Contrast CT:

  • Cortical bone: dense hyperattenuating

  • Cancellous bone: trabecular pattern with mixed density

  • Marrow fat: hypodense compared to bone

  • Fractures, sclerosis, lytic lesions well visualized

Post-Contrast CT:

  • Cortical bone: no enhancement

  • Marrow: mild uniform enhancement possible

  • Pathology (infection, neoplasm): focal or diffuse enhancement, soft tissue extension, or periosteal reaction

MRI image

tibia coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

tibia sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT image

Tibia ct sag image

CT VRT image

Tibia 3d