Long head of biceps tendon

Function

Where the tendon starts

The biceps brachii is the two-headed muscle on the front of the upper arm, and this tendon belongs to its long head^1,2. The tendon starts at the top of the shoulder socket¹. There it attaches to the supraglenoid tubercle, a bump of bone, and to the upper labrum, the rim of tough tissue around the socket¹.

The exact starting point varies from person to person⁶. In about half of people it starts mainly from the back part of the labrum⁶. In about 20% it starts straight from the bony tubercle, and in about 30% from both⁶. The tendon is widest at this starting point⁶.

How it runs down the arm

The tendon averages about 9 cm long⁶. In 207 shoulders measured during arthroscopy (keyhole surgery inside a joint), it averaged 6.0 mm wide, with a range of 3 to 10 mm⁷. It runs inside the shoulder joint but outside the joint’s synovial lining, the thin inner layer of the joint⁶. It narrows as it runs at a slant toward a groove in the humerus⁶.

That groove, the intertubercular or bicipital groove, runs between two bumps on the humerus called the greater and lesser tubercles². Where the tendon leaves the top of the groove, it turns 30 to 40 degrees toward its start point⁶. For that reason, the soft tissues at this bend are described as critical to keeping it in place⁶.

Its shape changes along the way⁸. In seven fresh-frozen tendons, it was flatter where it passed over the humeral head (the ball at the top of the humerus)⁸. It was more triangular inside the groove⁸.

What holds it in the groove

At the groove, a sling of soft tissue holds the tendon, known as the biceps pulley¹. It is made of these parts¹:

• part of the subscapularis, a rotator cuff muscle on the front of the shoulder blade¹;
• part of the supraspinatus, a rotator cuff muscle along the top of the shoulder blade¹;
• the coracohumeral ligament, a tough band of tissue that holds bones together¹;
• the superior glenohumeral ligament, a ligament at the top of the main shoulder joint¹.

A scoping review reports growing agreement that this pulley is the main thing keeping the tendon in its groove³.

What the biceps does

The biceps crosses both the shoulder and the elbow². It bends the elbow, helps supinate the forearm (turn the palm up), and helps raise the arm forward at the shoulder². With the elbow straight it bends the elbow, but with the elbow bent it becomes the forearm’s strongest supinator⁹. Abduction means lifting the arm out to the side. One reference text states that, with the arm turned outward, the biceps supplies about 10% of the total power for abduction¹.

What studies disagree on at the shoulder

Studies disagree on whether the long head works at a healthy shoulder³. A scoping review found six studies showing long head activity as the arm was raised, and four finding no significant activity³. Two studies with the elbow braced show the split^10,11:

Study	What it found
11 healthy men, sensors on the skin	Both biceps heads were active in every arm-raising task tested, and more so as the arm rose10
Ten shoulders, fine wires in the long head	No electrical activity during shoulder movement, even with a 5-pound weight11

The same review found 13 studies of intact shoulders in cadavers, bodies donated for study³. It found six more that simulated injuries such as rotator cuff tears³. Ten showed a role in steadying the shoulder, and six a role in holding the humeral head down³. Across 214 articles, the review concluded that the long head does little to raise or steady a healthy shoulder³. It found a larger role when the rotator cuff has failed or the tendon is missing³.

How strong it is and where its blood comes from

In pull tests of seven fresh-frozen tendons, the tendon failed at 32.5 megapascals (a unit of force per area)⁸. Its modulus, a measure of how stiff the material is in itself, was 421 megapascals⁸. Every one of the seven failed in its middle part⁸.

The tendon’s blood comes from an artery called the anterior humeral circumflex artery¹. Studies have found two areas with little blood supply¹. One is on its deep underside in the groove, and one is near its start at the top of the socket¹.

Breakdown

The kinds of problem

A scoping review lists the common long head problems³:

• instability of the tendon, where it partly or fully slips out of its groove^3,7;
• tendinopathy, including tears and ruptures³;
• pulley lesions³;
• abnormal grooves³;
• superior labral (SLAP) lesions, at the upper labrum³;
• a missing tendon³.

A scoping review found anatomical variations in 36 studies, most often unusual starting points, extra heads and a missing long head tendon³. In 229 shoulders seen during arthroscopy, the tendon was missing in 21, or 9.2%⁷.

How it goes with rotator cuff problems

Long head problems and rotator cuff problems tend to be found together^4,12. In 406 shoulder MRI reports from adults with shoulder pain, any cuff problem was linked to a long head problem⁴. The odds ratio, how many times higher the odds are in one group, was 6.9⁴. When the long head showed tendinopathy, only 5% of supraspinatus tendons were normal⁴. When the supraspinatus showed tendinopathy, about half of long head tendons were normal⁴.

A systematic review sums up the research on a question in a set, checkable way. One such review of five studies found long head lesions in 22% to 78.5% of people with long-term supraspinatus problems¹². The smaller studies reported the higher rates¹². A scoping review found that the two often occur together, but whether one causes the other has not been shown³.

A scoping review found that the two often occur together, but whether one causes the other has not been shown.

Impingement is pinching of tissue in the space beneath the acromion, the bony point at the top of the shoulder. In 200 shoulders having surgery for impingement, 40% showed visible wear of the long head tendon¹³. Of those shoulders, 91% also had rotator cuff tears¹³.

How it changes with age

In the 406 MRI reports, long head tendinopathy grew more common with age, by about 4% per year⁴. Among the adults imaged for shoulder pain, everyone aged 85 or older had both long head and rotator cuff tendinopathy⁴.

When the pulley tears and the tendon slips

In one group of shoulders seen during arthroscopy, 67 of 207, or 32.4%, had a torn biceps pulley⁷. People with pulley tears were older, 57 years against 44 on average⁷. Pulley tears were linked to the tendon partly or fully slipping out of its groove⁷. The pulley was torn in all 27 shoulders where the tendon had fully slipped out⁷. Pulley tears were also linked to rotator cuff injury⁷.

A scoping review found a strong link between an unstable tendon and rotator cuff problems in twelve articles³. Eight of them involved subscapularis tears³.

When the tendon ruptures

One study followed 27 people with a sudden long head rupture who had MRI scans¹⁴. Of these, 74% were men, and their average age was 61¹⁴. In 85% the injury was low-energy, and 41% had shoulder pain beforehand¹⁴. The scans showed rotator cuff disease in 93%, including 13 full-thickness tears, tears right through the tendon¹⁴. A case report, which covers a single patient, describes a young, active man who ruptured the tendon during 25-pound biceps curls¹⁵.

Recovery

After a rupture, with and without repair

One study compared people whose ruptures were repaired by surgery with people managed without surgery¹⁶. Lasting arm pain was uncommon¹⁶. Elbow weakness was self-reported by 20 of 30 people without surgery, against 4 of 27 repaired shoulders¹⁶. The group without surgery went back to work sooner¹⁶. But 11 of them could not return to full work capacity, against 2 in the surgery group¹⁶.

In the same study, 13 people without surgery had their strength tested¹⁶. On average they had lost 21% of their supination strength and 8% of their elbow-bending strength¹⁶. They had no loss in grip, in turning the palm down, or in straightening the elbow¹⁶.

Cutting versus reattaching the tendon

Tenotomy means cutting the long head tendon, and tenodesis means reattaching it⁵. Reviews and randomised trials, which assign people to groups by chance, report these results^5,17,18,19. They include Popeye deformity, a bulge of the biceps low in the upper arm^17,19:

Study	Pain and function	Popeye deformity or arm shape
Meta-analysis of 8 studies, 615 people	No difference in long-term pain or a shoulder function score5	More common after cutting, odds ratio 4.705
Meta-analysis of 11 randomised trials, 860 people	Similar reported function and pain17	Less common after reattaching, odds ratio 0.2917
Review of 5 randomised trials, 468 people, mean age about 60	Only one of the trials that tested strength found a difference: better supination after reattaching18	Cosmetic deformity in 23.3% after cutting and 6.8% after reattaching18
One randomised trial, followed to 24 months	Younger people with a deformity were less satisfied with it, though the study found no difference in function at 24 months19	33% after cutting and 9.5% after reattaching19

Returning to sport and duty after reattaching

Two systematic reviews looked at return to sport after tenodesis^20,21. One covered 17 studies with 374 cases, and found that 217 of 269 cases, or 80.7%, returned to sport²⁰. Of 59 cases, 43, or 72.9%, returned to the same level²⁰. The average time to return was 5.4 months²⁰. In the same review, 79.6% of overhead athletes returned to play, and 82.4% of military personnel returned to duty²⁰.

The second review covered nine studies of 161 people aged 35 or younger, with a mean age of 25²¹. Across those studies, return-to-sport rates ranged widely, from 35% to 100%²¹.

When the rotator cuff is torn too

In 291 people with full-thickness rotator cuff tears that could not be repaired, the long head tendon was cut³. Afterwards, the humeral head moved significantly upward³. A scoping review also looked at people whose long head tendon was healthy³. Adding tenotomy or tenodesis to a cuff repair gave no extra improvement over the cuff repair alone³.

Connections

The rest of the biceps

Below the groove, the long head joins the short head in the middle third of the upper arm¹. The muscle then crosses the elbow and attaches to the radial tuberosity, a bump on the forearm bone¹. It also attaches to the forearm’s fascia, a sheet of tough tissue that wraps or joins muscles¹. The distal biceps tendon is the tendon at that elbow end²².

What studies of the biceps curl show

Related exercise pages: biceps curl^15,23. One study used shear wave elastography, an ultrasound method, to estimate tension in this tendon in 13 healthy women²³. With the elbow bent to 90 degrees, tension was lower with the palm up than palm down during a contraction without weight²³. When holding a weight, tension did not differ significantly between the two forearm positions²³.

The rotator cuff

The rotator cuff is formed by the tendons of four muscles that join the shoulder blade to the humerus². Two of those muscles, the subscapularis and supraspinatus, form part of the sling that holds this tendon in its groove¹. A scoping review found early and excess long head activity in people with unstable shoulders or rotator cuff tears that cause symptoms³. This came from studies using electromyography (EMG), measuring a muscle’s activity by picking up its electrical signals³. The authors suggest the long head may be compensating in these injured shoulders³.

Sources

1. Varacallo MA, Mair SD (2023). Proximal Biceps Tendinitis and Tendinopathy.. StatPearls. PMID 30422594
2. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, Korol O, Johnson JE, Womble M, DeSaix P (2022). Anatomy and Physiology 2e. OpenStax. Link
3. Diplock B, Hing W, Marks D (2023). The long head of biceps at the shoulder: a scoping review.. BMC Musculoskeletal Disorders. doi:10.1186/s12891-023-06346-5 PMID 36978047
4. Canavan K, Zai Q, Bruni D, Alexander J, Oude Nijhuis KD, Ring D (2025). Long Head of Biceps Tendinopathy Is Associated With Age and Cuff Tendinopathy on MRI Obtained for Evaluation of Shoulder Pain.. Clinical Orthopaedics and Related Research. doi:10.1097/CORR.0000000000003342 PMID 39679662
5. Pozzetti Daou J, Nagaya DY, Matsunaga FT, Sugawara Tamaoki MJ (2021). Does Biceps Tenotomy or Tenodesis Have Better Results After Surgery? A Systematic Review and Meta-analysis.. Clinical Orthopaedics and Related Research. doi:10.1097/CORR.0000000000001672 PMID 33617158
6. Varacallo MA, Mair SD (2023). Biceps Tendon Dislocation and Instability.. StatPearls. PMID 30475566
7. Braun S, Horan MP, Elser F, Millett PJ (2011). Lesions of the biceps pulley.. The American Journal of Sports Medicine. doi:10.1177/0363546510393942 PMID 21335355
8. McGough RL, Debski RE, Taskiran E, Fu FH, Woo SL (1996). Mechanical properties of the long head of the biceps tendon.. Knee Surgery, Sports Traumatology, Arthroscopy. doi:10.1007/BF01466622 PMID 8739718
9. Tiwana MS, Charlick M, Varacallo MA (2024). Anatomy, Shoulder and Upper Limb, Biceps Muscle.. StatPearls. PMID 30137823
10. Sakurai G, Ozaki J, Tomita Y, Nishimoto K, Tamai S (1998). Electromyographic analysis of shoulder joint function of the biceps brachii muscle during isometric contraction.. Clinical Orthopaedics and Related Research. doi:10.1097/00003086-199809000-00015 PMID 9755771
11. Levy AS, Kelly BT, Lintner SA, Osbahr DC, Speer KP (2001). Function of the long head of the biceps at the shoulder: electromyographic analysis.. Journal of Shoulder and Elbow Surgery. doi:10.1067/mse.2001.113087 PMID 11408907
12. Redondo-Alonso L, Chamorro-Moriana G, Jiménez-Rejano JJ, López-Tarrida P, Ridao-Fernández C (2014). Relationship between chronic pathologies of the supraspinatus tendon and the long head of the biceps tendon: systematic review.. BMC Musculoskeletal Disorders. doi:10.1186/1471-2474-15-377 PMID 25408141
13. Murthi AM, Vosburgh CL, Neviaser TJ (2000). The incidence of pathologic changes of the long head of the biceps tendon.. Journal of Shoulder and Elbow Surgery. doi:10.1067/mse.2000.108386 PMID 11075320
14. Vestermark GL, Van Doren BA, Connor PM, Fleischli JE, Piasecki DP, Hamid N (2018). The prevalence of rotator cuff pathology in the setting of acute proximal biceps tendon rupture.. Journal of Shoulder and Elbow Surgery. doi:10.1016/j.jse.2018.01.006 PMID 29478942
15. Miller KE, Solomon DJ (2008). Paralabral rupture of the proximal biceps tendon from light weightlifting.. Military Medicine. doi:10.7205/milmed.173.12.1238 PMID 19149346
16. Mariani EM, Cofield RH, Askew LJ, Li GP, Chao EY (1988). Rupture of the tendon of the long head of the biceps brachii. Surgical versus nonsurgical treatment.. Clinical Orthopaedics and Related Research. PMID 3342572
17. Hartland AW, Islam R, Teoh KH, Rashid MS (2022). Clinical effectiveness of tenotomy versus tenodesis for long head of biceps pathology: a systematic review and meta-analysis.. BMJ Open. doi:10.1136/bmjopen-2022-061954 PMID 36220319
18. Belk JW, Kraeutler MJ, Houck DA, Chrisman AN, Scillia AJ, McCarty EC (2021). Biceps tenodesis versus tenotomy: a systematic review and meta-analysis of level I randomized controlled trials.. Journal of Shoulder and Elbow Surgery. doi:10.1016/j.jse.2020.11.012 PMID 33373685
19. Woodmass JM, McRae SMB, Lapner PL, Sasyniuk T, Old J, Stranges G, Dubberly J, Verhulst FV, MacDonald PB (2021). Effect of age, gender, and body mass index on incidence and satisfaction of a Popeye deformity following biceps tenotomy or tenodesis: secondary analysis of a randomized clinical trial.. Journal of Shoulder and Elbow Surgery. doi:10.1016/j.jse.2021.05.003 PMID 34022365
20. Cassidy JT, Hurley ET, Moore D, Pauzenberger L, Mullett H (2021). The majority of patients return to athletic activity following biceps tenodesis.. Knee Surgery, Sports Traumatology, Arthroscopy. doi:10.1007/s00167-020-05930-9 PMID 32185452
21. Jackson GR, Tuthill T, Allahabadi S, Brusalis CM, Kaplan DJ, Rea P, Sugrañes J, Obioha O, Knapik DM, Chahla J, Verma NN (2023). Biceps Tenodesis in Patients Age 35 Years and Younger Yields Favorable Clinical Outcomes With Variable Rates of Return to Sport and Complications: A Systematic Review.. Arthroscopy. doi:10.1016/j.arthro.2022.12.009 PMID 36528216
22. Hsu D, Anand P, Mabrouk A, Chang KV (2023). Biceps Tendon Rupture.. StatPearls. PMID 30020607
23. Pederson Z, Giambini H (2026). In Vivo Long Head of the Biceps Tendon Stiffness Varies with Forearm Position During Active Contraction: Implications for Personalized Rehabilitation After SLAP Lesions.. Journal of Personalized Medicine. doi:10.3390/jpm16040194 PMID 42042560

Every source the library cites

Changes

• September 29, 2026 Tidy pass: minor review findings fixed, glosses aligned with the reviewed glossary.
• September 29, 2026 First published.