MRI DISTAL BICEPS TENDON: LONG vs SHORT HEAD PATHOLOGY — WHAT TO LOOK FOR

The distal biceps tendon has two heads — and one can tear while the other stays normal

The distal biceps tendon is made up of two separate tendons — the Long Head and the Short Head of Biceps — that fuse together before inserting onto the radial (bicipital) tuberosity.
Tendonosis, tears, or rupture can affect the tendon of one head only, with the other head spared.
Diagnosing these abnormalities starts with knowing the normal anatomy of the distal biceps tendon.
The MRI appearance of tendonosis, tears, and rupture in this tendon follows the same general appearance as tendon pathology elsewhere in the body.

▾ Long Head vs Short Head – Axial Anatomy

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The tendon of the Long Head of Biceps lies on the radial side of the combined tendon, with a proximal insertion on the radial (bicipital) tuberosity.
The tendon of the Short Head of Biceps lies on the ulnar side of the combined tendon, with a distal insertion on the radial (bicipital) tuberosity.
On axial scans, the Long Head (purple arrows), Short Head (blue arrows), and combined tendon (yellow arrows) can be identified as separate structures.

▾ Insertion Level – Coronal Anatomy

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On the coronal image, the Long Head inserts more superiorly (purple region) than the Short Head (blue region).

▾ Tendonosis of the Long Head

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Tendonosis predominantly involves the Long Head, with the Short Head less involved.
On axial imaging, a difference in signal is seen between the Long and Short Heads at their respective levels.

▾ Tear of the Short Head

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Severe tendonosis and tear of the Short Head of Biceps can occur with sparing of the Long Head.

▾ Rupture of the Short Head

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When the Short Head ruptures and retracts, only a single tendon is seen on axial images where two tendons should normally be present.
The Long Head can remain attached to the radial tuberosity even when the Short Head has ruptured.

The distal biceps tendon is formed by two separate tendons — the Long Head (radial side, proximal insertion) and the Short Head (ulnar side, distal insertion) — that fuse before inserting on the radial tuberosity.
Tendonosis, tears, and rupture can selectively affect one head while sparing the other, so assess the Long and Short Heads independently.
On axial images, look for asymmetric signal between the two heads, or a missing tendon, to identify one-head-only pathology.
A ruptured and retracted head may leave only a single tendon visible on axial images, while the unaffected head remains normally attached.

▾ Can the Long Head and Short Head of the distal biceps tendon be affected independently?

Yes. Tendonosis, tears, or rupture can affect the tendon of one head only, with the other head spared.

▾ Where does the Long Head tendon lie, and where does it insert?

The Long Head lies on the radial side of the combined tendon and has a proximal insertion on the radial (bicipital) tuberosity.

▾ Where does the Short Head tendon lie, and where does it insert?

The Short Head lies on the ulnar side of the combined tendon and has a distal insertion on the radial (bicipital) tuberosity.

▾ On coronal imaging, which head inserts more superiorly?

The Long Head inserts more superiorly than the Short Head.

▾ What does a ruptured and retracted Short Head look like on axial MRI?

Only a single tendon is seen on axial images where two tendons should normally be present, while the Long Head may remain attached to the radial tuberosity.