Topics

Topic

design image
Infrapatellar branch of saphenous nerve

The infrapatellar branch of the saphenous nerve is a small but clinically important cutaneous branch of the saphenous nerve. It arises near the knee and provides sensation to the skin over the anterior and medial aspect of the knee joint, particularly the area below the patella. It is especially relevant in orthopedic surgery, knee arthroscopy, and nerve entrapment syndromes, as injury to this branch may result in anteromedial knee pain or numbness.

Synonyms

  • Infrapatellar nerve

  • Cutaneous branch of saphenous nerve (knee)

  • Anterior knee sensory branch

Origin, Course, Branches, and Termination

  • Origin:

    • Arises from the saphenous nerve (branch of the femoral nerve) in the distal thigh near the adductor canal.

  • Course:

    • Passes through or near the sartorius muscle or tendon, occasionally piercing it

    • Runs anteriorly and inferiorly across the knee joint region

    • Courses obliquely downward and medially, crossing the patellar tendon region

  • Branches:

    • Gives off small cutaneous branches that spread across the anterior and medial knee region

  • Termination:

    • Ends in the skin over the anterior and medial knee, especially the area inferior to the patella and anterior to the tibial tuberosity

Relations

  • Superiorly: Related to the sartorius muscle and adductor canal

  • Inferiorly: Related to the patellar tendon and tibial tuberosity

  • Anteriorly: Subcutaneous tissue and skin of anterior knee

  • Posteriorly: Femoral condyle and knee joint capsule

  • Laterally: Patella and patellar tendon

  • Medially: Continuity with the saphenous nerve and medial cutaneous nerves of the leg

Function

  • Provides cutaneous sensory innervation to:

    • Skin over the anterior and medial aspect of the knee

    • Skin below the patella

    • Area over the proximal tibia and patellar tendon

Clinical Significance

  • May be injured during knee surgery or arthroscopy (common cause of numbness after ACL reconstruction)

  • Entrapment in the sartorius tendon or at fascial openings may cause infrapatellar neuropathy

  • Source of anteromedial knee pain or neuropathic pain syndromes

  • Important landmark in nerve block techniques for knee pain management

MRI Appearance

T1-weighted images:

  • Nerve appears as a thin low-to-intermediate signal structure against surrounding bright fat

T2-weighted images:

  • Nerve appears with intermediate to mildly hyperintense signal compared to muscle

  • Pathology (neuropathy, entrapment) shows focal bright signal

STIR (Short Tau Inversion Recovery):

  • Normal nerve is low signal

  • Inflamed or damaged nerve is bright hyperintense

Proton Density Fat-Saturated (PD FS):

  • Normal nerve is low-to-intermediate signal

  • Neuropathy or injury shows bright signal after fat suppression

T1 Fat-Sat Post-Contrast:

  • Normal nerve enhances minimally

  • Pathology (neuritis, neuroma, entrapment) may show focal or nodular enhancement

CT Appearance

Non-Contrast CT:

  • Nerve not directly visualized; course inferred in subcutaneous fat anterior to knee

  • Fat planes help localize nerve pathway

Post-Contrast CT:

  • Nerve itself shows no significant enhancement

  • Pathological processes (neuroma, inflammation, scarring) may appear as enhancing soft tissue density along expected nerve course

MRI images

Infrapatellar branch of saphenous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

Infrapatellar branch of saphenous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000_00001

MRI images

Infrapatellar branch of saphenous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000_00002

MRI images

Infrapatellar branch of saphenous nerve coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000