View source for Biceps

{{Short description|Muscle on the front of the upper arm}}
{{About|a muscle}}
{{distinguish|Biceps femoris}}
{{Redirect|Bicep}}
{{Use mdy dates|date=September 2011}}
{{Infobox muscle
| Name        = Biceps brachii
| Latin       = musculus biceps brachii
| Greek       =
| Image       = 1120 Muscles that Move the Forearm Humerus Flex Sin.png
| Caption     = The biceps is a two-headed muscle and is one of the chief flexors of the forearm. Here is the left side, seen from the front.
| Origin      = '''Short head:''' [[coracoid process]] of the [[scapula]].<br />'''Long head:''' [[supraglenoid tubercle]]
| Insertion   = [[Radial tuberosity]] and [[bicipital aponeurosis]] into deep fascia on medial part of forearm
| Blood       = [[Brachial artery]]
| Nerve       = [[Musculocutaneous nerve]] ([[Lateral cord|C5–C7]])<ref name=Bogart2007 />
| Action      = 
* [[Flexion|Flexes]] [[Elbow-joint|elbow]]<ref name=Bogart2007 />
* [[Flexion|flexes]] and [[Abduction (kinesiology)|abducts]] [[shoulder]]<ref name=Bogart2007 />
* [[supinates]] [[Proximal radioulnar articulation|radioulnar joint]] in the [[forearm]]<ref name=Bogart2007 />
| Antagonist  = [[Triceps brachii muscle]]
| pronunciation = {{IPAc-en|ˈ|b|aɪ|s|ɛ|p|s|_|ˈ|b|r|eɪ|k|i|aɪ}}
}}
The '''biceps''' or '''biceps brachii''' ({{langx|la|musculus biceps brachii}}, "two-headed muscle of the arm") is a large [[muscle]] that lies on the front of the upper arm between the shoulder and the [[elbow]]. Both [[Muscle head|heads of the muscle]] arise on the [[scapula]] and join to form a single [[muscle belly]] which is attached to the upper forearm. While the long head of the biceps crosses both the [[shoulder]] and elbow joints, its main function is at the elbow where it flexes and [[supination|supinates]] the forearm.<!-- ref for entire intro --><ref name="Lippert">{{cite book | last = Lippert | first = Lynn S. | name-list-style = vanc | title = Clinical kinesiology and anatomy | url = https://archive.org/details/clinicalkinesiol00lipp_357 | url-access = limited | edition = 4th | publisher = F. A. Davis Company | location = Philadelphia | isbn = 978-0-8036-1243-3 | year = 2006 | pages = [https://archive.org/details/clinicalkinesiol00lipp_357/page/n140 126]–7 }}</ref>

== Structure ==
[[Image:Biceps brachii muscle06.png|thumb|right|Location of biceps. Two different colors represent two different bundles which compose biceps. {{legend|#009900|Short head}}{{legend|#FF0000|Long head}}]]
[[File:Braus 1921 194.png|thumb|Attachment to the radial tuberosity and Bursa bicipitoradialis.]]

The biceps is one of three muscles in the [[Fascial compartments of arm#Anterior compartment|anterior compartment of the upper arm]], along with the [[brachialis muscle]] and the [[coracobrachialis muscle]], with whom the biceps shares a nerve supply.<ref name="Bogart2007">{{cite book | title = Elsevier's integrated anatomy and embryology | first1 = Bruce Ian | last1 = Bogart | first2 = Victoria H | last2 = Ort | name-list-style = vanc |date=2007|publisher=Elsevier Saunders|isbn=978-1-4160-3165-9|location=Philadelphia, Pa.|pages=262–267}}</ref> The biceps muscle has two heads, the short head and the long head, distinguished according to their origin at the coracoid process and supraglenoid tubercle of the scapula, respectively.<ref name=Bogart2007 /> From its origin on the glenoid, the long head remains tendinous as it passes through the shoulder joint and through the [[intertubercular groove]] of the [[humerus]].<ref name="Lippert" /> Extending from its origin on the coracoid, the tendon of the short head runs adjacent to the tendon of the [[coracobrachialis]]. Unlike the other muscles in the anterior compartment of the arm, the long head of the biceps muscle crosses two joints, the shoulder joint and the elbow joint.

Both heads of the biceps join in the middle upper arm to form a single muscle mass, usually near the insertion of the [[Deltoid muscle|deltoid]], to form a common muscle belly;<ref>{{Cite web |title=Google Scholar |url=https://scholar.google.com/scholar_lookup?title=Clinical+Oriented+Anatomy&author=K.+L.+Moore&author=A.+F.+Dalley&publication_year=1999& |access-date=2024-08-21 |website=scholar.google.com}}</ref> although several anatomic studies have demonstrated that the muscle bellies remain distinct structures without confluent fibers.<ref name="Athwal_2007">{{cite journal | vauthors = Athwal GS, Steinmann SP, Rispoli DM | title = The distal biceps tendon: footprint and relevant clinical anatomy | journal = The Journal of Hand Surgery | volume = 32 | issue = 8 | pages = 1225–9 | date = October 2007 | pmid = 17923307 | doi = 10.1016/j.jhsa.2007.05.027 }}</ref><ref name="Eames_2007">{{cite journal | vauthors = Eames MH, Bain GI, Fogg QA, van Riet RP | title = Distal biceps tendon anatomy: a cadaveric study | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 89 | issue = 5 | pages = 1044–9 | date = May 2007 | pmid = 17473142 | doi = 10.2106/JBJS.D.02992 }}</ref> As the muscle extends [[Anatomical terms of location#Proximal and distal|distally]], the two heads rotate 90 degrees externally before inserting onto the radial tuberosity. The short head inserts distally on the tuberosity while the long head inserts proximally closer to the apex of the tuberosity.<ref name="Athwal_2007" /> The [[bicipital aponeurosis]], also called the lacertus fibrosus, is a thick fascial band that organizes close to the [[musculotendinous junction]] of the biceps and radiates over and inserts onto the ulnar part of the [[antebrachial fascia]].<ref name="Platzer-154">{{cite book | last = Platzer | first = Werner | name-list-style = vanc | title = Color Atlas of Human Anatomy | volume = 1: Locomotor System | page = 154 | publisher = Thieme | isbn = 978-1-58890-159-0 | year = 2004 | edition = 5th }}</ref>

The tendon that attaches to the radial tuberosity is partially or completely surrounded by a [[Synovial bursa|bursa]], the [[bicipitoradial bursa]], which ensures frictionless motion between the biceps tendon and the proximal radius during [[pronation]] and [[supination]] of the forearm.<ref name=Kegels>{{cite journal | vauthors = Kegels L, Van Oyen J, Siemons W, Verdonk R | title = Bicipitoradial bursitis. A case report | journal = Acta Orthopaedica Belgica | volume = 72 | issue = 3 | pages = 362–5 | date = June 2006 | pmid = 16889153 | url = http://actaorthopaedica.be/assets/1288/19-Kegels.pdf}}</ref>

Two muscles lie underneath the biceps brachii. These are the [[coracobrachialis muscle]], which like the biceps originates from the coracoid process of the scapula, and the [[brachialis muscle]] which connects to the [[ulna]] and along the mid-shaft of the [[humerus]]. Besides those, the [[brachioradialis muscle]] is adjacent to the biceps and also inserts on the radius bone, though more distally.

<gallery mode="nolines">
File:Flexión del brazo.png|Biceps and [[Triceps brachii muscle|triceps]].
File:Animation triceps biceps.gif|Movement of biceps and triceps when arm is flexing
File:Kelly Lynn bicep flex 2.jpg|The split line between the long and short heads
</gallery>

===Variation===
Traditionally described as a two-headed muscle, biceps brachii is one of the most [[anatomical variation|variable]] muscles of the human body and has a third head arising from the [[humerus]] in 10% of cases (normal variation)—most commonly originating near the insertion of the coracobrachialis and joining the short head—but four, five, and even seven [[Supernumerary body part|supernumerary]] heads have been reported in rare cases.<ref>{{cite journal | vauthors = Poudel PP, Bhattarai C | s2cid = 9963394 | title = Study on the supernumerary heads of biceps brachii muscle in Nepalese | journal = Nepal Medical College Journal | volume = 11 | issue = 2 | pages = 96–8 | date = June 2009 | pmid = 19968147 }}</ref>

One study found a higher than expected number of female cadavers with a third head of biceps brachii, equal incidence between sides of the body, and uniform innervation by musculocutaneous nerve.<ref>{{Cite journal|last1=Schwerdtfeger|first1=Luke A.|last2=Pascoe|first2=Michael A.|last3=Clapp|first3=Tod|date=September 2018|title=High incidence of a third head of biceps brachii in females|journal=Translational Research in Anatomy|volume=12|pages=25–27|doi=10.1016/j.tria.2018.08.001|doi-access=free}}</ref>

The distal biceps tendons are completely separated in 40% and [[wikt:bifurcation|bifurcated]] in 25% of cases.
<ref>{{cite journal | vauthors = Dirim B, Brouha SS, Pretterklieber ML, Wolff KS, Frank A, Pathria MN, Chung CB | title = Terminal bifurcation of the biceps brachii muscle and tendon: anatomic considerations and clinical implications | journal = AJR. American Journal of Roentgenology | volume = 191 | issue = 6 | pages = W248-55 | date = December 2008 | pmid = 19020211 | doi = 10.2214/AJR.08.1048 | author5 = Frank, Andreas | author6 = Pathria, Mini N | author7 = Chung, Christine B }}</ref><ref name="Eames_2007" />

===Nerve supply===
{{See also|Biceps reflex}}
The biceps shares its nerve supply with the other two muscles of the anterior compartment. The muscles are supplied by the  [[musculocutaneous nerve]]. Fibers of the fifth, sixth and seventh [[cervical nerves]] make up the components of the musculocutaneous nerve which supply the biceps.<ref name=Bogart2007 />

=== Blood supply ===
The blood supply of the biceps is the [[brachial artery]]. The distal tendon of the biceps can be useful for palpating the brachial pulse, as the artery runs medial to the tendon in the [[cubital fossa]].

== Function ==
{{multiple image
| align = right
| image1 = Arm flex pronate.jpg
| width1 = 150
| alt1 = 
| caption1 = 
| image2 = Arm flex supinate.jpg
| width2 = 150
| alt2 = 
| caption2 = 
| footer = Flexed arm in the '''pronated''' position (left); with the biceps partially contracted and in a '''supinated''' position with the biceps more fully contracted, approaching minimum length (right.)
}}
The biceps works across three joints.<ref>{{cite web | title = Biceps Brachii | url = http://www.exrx.net/Muscles/BicepsBrachii.html | publisher=ExRx.net | access-date = 16 January 2017}}</ref>  The most important of these functions is to supinate the forearm and flex the elbow. Besides, the long head of biceps prevents the upward displacement of the head of the humerus.<ref name="BD Chaurasia">{{cite book|last1=Krishna|first1=Garg| name-list-style = vanc |title=BD Chaurasia's Human Anatomy (Regional and Applied Dissection and Clinical) Volume 1 - Upper limb and thorax|date=2010|publisher=CBS Publishers and Distributors Pvt Ltd|location=India|isbn=978-81-239-1863-1|page=88|edition=Fifth|chapter=8 - Arm}}</ref> In more detail, the actions are, by joint:<ref>{{cite book | title = Travell & Simons' Myofascial Pain and Dysfunction | url = https://archive.org/details/myofascialpaindy00simo | url-access = limited | chapter = 30: Biceps Brachii Muscle | last1 = Simons | first1 = David G. | last2 = Travell | first2 = Janet G. | last3 = Simons | first3 = Lois S. | name-list-style = vanc | publisher = Williams and Wilkins | year = 1999 | editor = Eric Johnson | edition = 2nd | location = Baltimore, Maryland | isbn = 978-0-683-08363-7 | pages = [https://archive.org/details/myofascialpaindy00simo/page/n663 648]–659 }}</ref>

* '''[[Proximal radioulnar joint]]''' of the elbow – The biceps brachii functions as a powerful supinator of the forearm, i.e. it turns the palm upwards. This action, which is aided by the [[supinator]] muscle, requires the [[humeroulnar joint]] of the elbow to be at least partially flexed. If the  humeroulnar joint is fully extended, supination is then primarily carried out by the supinator muscle. The biceps is a particularly powerful supinator of the forearm due to the distal attachment of the muscle at the radial tuberosity, on the opposite side of the bone from the supinator muscle. When flexed, the biceps effectively pulls the radius back into its neutral supinated position in concert with the supinator muscle.<ref name="Saladin_2015">{{Cite book|title=Anatomy and Physiology: The Unity of Form and Function |last=Saladin |first=Kenneth| name-list-style = vanc |year=2015 |isbn=978-0-07-340371-7 | publisher =McGraw-Hill Education | location = New York, NY }}</ref>{{rp|346–347}}
* '''[[Humeroulnar joint]]''' of the elbow – The biceps brachii also functions as an important flexor of the forearm, particularly when the forearm is supinated.<ref name=Bogart2007 /> Functionally, this action is performed when lifting an object, such as a bag of groceries or when performing a [[biceps curl]]. When the forearm is in [[pronation]] (the palm faces the ground), the brachialis, [[brachioradialis]], and supinator function to flex the forearm, with minimal contribution from the biceps brachii. Regardless of forearm position, (supinated, pronated, or neutral) the force exerted by the biceps brachii remains the same; however, the brachioradialis has a much greater change in exertion depending on position than the biceps during concentric contractions. That is, the biceps can only exert so much force, and as forearm position changes, other muscles must compensate.<ref>{{cite journal | vauthors = Kleiber T, Kunz L, Disselhorst-Klug C | title = Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position | journal = Frontiers in Physiology | volume = 6 | pages = 215 | date = 2015-01-01 | pmid = 26300781 | pmc = 4526813 | doi = 10.3389/fphys.2015.00215 | doi-access = free }}</ref>
* '''[[Glenohumeral joint]]''' (shoulder joint) – Several weaker functions occur at the glenohumeral joint. The biceps brachii weakly assists in forward flexion of the shoulder joint (bringing the arm forward and upwards). It may also contribute to [[abduction (kinesiology)|abduction]] (bringing the arm out to the side) when the arm is externally (or laterally) rotated. The short head of the biceps brachii also assists with horizontal [[adduction]] (bringing the arm across the body) when the arm is internally (or medially) rotated. Finally, the short head of the biceps brachii, due to its attachment to the [[scapula]] (or shoulder blade), assists with stabilization of the shoulder joint when a heavy weight is carried in the arm. The tendon of the long head of the biceps also assists in holding the head of the humerus in the glenoid cavity and prevents an impingement of the supraspinatus tendon.<ref name=":12">[[Hermann Braus]], [[Curt Elze]]: ''Musculus biceps brachii.'' In: ''Anatomie des Menschen. Ein Lehrbuch für Studierende und Ärzte. Erster Band. Bewegungsapparat''. 3. Auflage. Julius Springer, Berlin 1954. [https://digi.ub.uni-heidelberg.de/diglit/braus1921bd1 Digitalisat der Universität Heidelberg.] S. 298-301.</ref><ref name="Saladin_2015" />{{rp|295}}
{{clear}}

[[Motor unit]]s in the lateral portion of the long head of the biceps are preferentially activated during elbow flexion, while motor units in the medial portion{{Clarify|reason=of the long head or short head?|date=April 2021}} are preferentially activated during forearm supination.<ref>{{Cite journal|last1=ter Haar Romeny|first1=B.M.|last2=Denier van der Gon|first2=J.J.|last3=Gielen|first3=C.C.A.M.|date=September 1984|title=Relation between location of a motor unit in the human biceps brachii and its critical firing levels for different tasks|journal=Experimental Neurology|volume=85|issue=3|pages=631–650|doi=10.1016/0014-4886(84)90036-0|pmid=6468581|hdl=1874/23877|s2cid=36705348 |issn=0014-4886|hdl-access=free}}</ref>

The biceps are usually attributed as representative of strength within a variety of worldwide cultures.{{citation needed|date=May 2019}}

==Clinical significance==
[[File:PreacherBenchBicepsCurl.JPG|thumb|right|The Preacher curl, also known as the Scott Curl, is a popular exercise for biceps]]

The proximal tendons of the biceps brachii are commonly involved in pathological processes and are a frequent cause of anterior shoulder pain.<ref>{{cite journal | vauthors = Frost A, Zafar MS, Maffulli N | title = Tenotomy versus tenodesis in the management of pathologic lesions of the tendon of the long head of the biceps brachii | journal = The American Journal of Sports Medicine | volume = 37 | issue = 4 | pages = 828–33 | date = April 2009 | pmid = 18762669 | doi = 10.1177/0363546508322179 | s2cid = 35918574 }}</ref> Disorders of the distal biceps brachii tendon include insertional tendonitis and partial or complete tears of the tendon. Partial tears are usually characterized by pain and enlargement and abnormal contour of the tendon.<ref>{{cite journal | vauthors = Chew ML, Giuffrè BM | title = Disorders of the distal biceps brachii tendon | journal = Radiographics | volume = 25 | issue = 5 | pages = 1227–37 | year = 2005 | pmid = 16160108 | doi = 10.1148/rg.255045160 }}</ref> Complete tears occur as [[avulsion fracture|avulsion]] of the tendinous portion of the biceps away from its insertion on the tuberosity of the radius, and is often accompanied by a palpable, audible "pop" and immediate pain and soft tissue swelling.<ref name="Miller_2015">{{cite book | title = DeLee & Drez's orthopaedic sports medicine : principles and practice. | first1 = Mark D | last1 = Miller | first2 = Stephen R | last2 = Thompson | first3 = Jesse | last3 = DeLee | first4 = David | last4 = Drez | name-list-style = vanc  | isbn = 978-1-4557-4376-6 |edition=Fourth | date = 2015 |location=Philadelphia, PA |oclc=880421005 }}</ref>

A soft-tissue mass is sometimes encountered in the anterior aspect of the arm, the so-called Reverse [[Popeye deformity]], which paradoxically leads to a decreased strength during flexion of the elbow and supination of the forearm.<ref>Arend CF. Ultrasound of the Shoulder. Master Medical Books, 2013. Free chapter on ultrasound evaluation of biceps tendon tears available at [http://www.shoulderus.com/ultrasound-of-the-shoulder/long-head-of-biceps-brachii-tendon-ultrasound-complete-tears/ ShoulderUS.com]</ref>

===Tendon rupture===
{{Main|Biceps tendon rupture}}
[[File:Panoramic ultrasonography of biceps tendon rupture - Annotated.jpg|thumb|[[Panoramic ultrasonography]] of a proximal biceps tendon rupture. Top image shows the contralateral normal side, and lower image shows a retracted muscle, with a [[hematoma]] filling out the proximal space.]]
Tears of the biceps brachii may occur during athletic activities, however avulsion injuries of the distal biceps tendon are frequently occupational in nature and sustained during forceful, eccentric contraction of the biceps muscle while lifting.<ref name="Miller_2015" />

Treatment of a biceps tear depends on the severity of the injury.  In most cases, the muscle will heal over time with no corrective surgery. Applying cold pressure and using anti-inflammatory medications will ease pain and reduce swelling. More severe injuries require surgery and post-op physical therapy to regain strength and functionality in the muscle. Corrective surgeries of this nature are typically reserved for elite athletes who rely on a complete recovery.<ref>{{cite web|title=Bicep tear - Muscular Injuries | url = http://www.nsmi.org.uk/articles/muscular-injuries/bicep-tear.html |publisher=Sports Medicine Information }}</ref>

===Training===
The biceps can be strengthened using [[weight training|weight]] and [[Strength training|resistance training]]. Examples of well known biceps exercises are the [[chin-up]] and [[biceps curl]]. The majority of weightlifters separate bicep exercises into two categories: exercises which focus on the short-head of the biceps brachii and those which work the long-head. Bicep curls, barbell curls, and concentration curls primarily focus on the short-head of the biceps brachii, while dumbbell waiter curls and close-grip barbell curls work the long-head of the biceps.<ref>{{Cite web |date=2018-01-28 |title=Peak Workout (Long Head Bicep Exercises) Size & Defenition |url=https://builtwithscience.com/workouts/bicep-peak-workout/ |access-date=2025-09-12 |language=en-US}}</ref> In addition to these, weightlifters include exercises for the brachialis muscle, such as hammer curls, to increase the size of the upper arm.

==Etymology and grammar==
The biceps brachii muscle is the one that gave all muscles their name: it comes from the [[Latin]] ''musculus'', "little mouse", because the appearance of the flexed biceps resembles the back of a mouse.  The same phenomenon occurred in [[Greek language|Greek]], in which μῦς, ''mȳs'', means both "mouse" and "muscle".{{citation needed|date=May 2019}}

The term ''biceps brachii'' is a Latin phrase meaning "two-headed [muscle] of the arm", in reference to the fact that the muscle consists of two bundles of muscle, each with its own origin, sharing a common insertion point near the elbow joint. The proper [[plural]] form of the [[Latin language|Latin]] [[adjective]] ''biceps'' is ''bicipites'',<ref>{{cite web |url=https://en.wiktionary.org/wiki/biceps#Declension |title=biceps |work=Latin Declension&nbsp;- Wiktionary |access-date=October 31, 2020}}</ref> a form not in general English use. Instead, ''biceps'' is used in both [[Grammatical number|singular]] and plural (i.e., when referring to both arms).

The English form ''{{sic|bic|ep|hide=yes}}'', attested from 1939, is a [[back formation]] derived from misinterpreting the ''s'' of ''biceps'' as the [[English plural]] marker ''-s''.<ref>{{cite web |url=http://www.merriam-webster.com/dictionary/bicep |title=Bicep |work=Dictionary and Thesaurus&nbsp;— Merriam-Webster Online |access-date=December 22, 2010}}</ref><ref>{{cite web |url=http://languagelog.ldc.upenn.edu/nll/?p=369 |title=The dangers of satire | first = Arnold | last = Zwicky | name-list-style = vanc |author-link=Arnold Zwicky |date=July 30, 2008 |work=Language Log |access-date=December 22, 2010}}</ref>

[[Adriaan van den Spiegel]] called the biceps a ''Pisciculus'')<ref name=":1">[[Joseph Hyrtl]]: ''Muskeln. Anatomische Bedingung eines dreiköpfigen Biceps''. In: ''Handbuch der Topographischen Anatomie''. Band II. Braumüller, Wien 1865. S. 353–354.</ref> due to its fusiform shape, which is why in the Italian-language medical literature it is sometimes called ''il pescetto'', "the small fish".

==History==
{{Unreferenced section|date=May 2019}}
[[Leonardo da Vinci]] expressed the original idea of the biceps acting as a supinator in a series of annotated drawings made between 1505 and 1510; in which the principle of the biceps as a supinator, as well as its role as a flexor to the elbow were devised. However, this function remained undiscovered by the medical community as da Vinci was not regarded as a teacher of anatomy, nor were his results publicly released. It was not until 1713 that this movement was re-discovered by [[William Cheselden]] and subsequently recorded for the medical community. It was rewritten several times by different authors wishing to present information to different audiences. The most notable recent expansion upon Cheselden's recordings was written by [[Guillaume Duchenne]] in 1867, in a journal named ''Physiology of Motion''. It remains one of the major references on supination action of the biceps brachii. {{citation needed|date=December 2013}}

==Other species==

===Neanderthals===
{{See also|Neanderthal anatomy}}

In [[Neanderthal]]s, the radial bicipital tuberosities were larger than in [[Anatomically modern humans|modern humans]], which suggests they were probably able to use their biceps for supination over a wider range of pronation-supination.  It is possible that they relied more on their biceps for forceful supination without the assistance of the [[supinator muscle]] like in modern humans, and thus that they used a different movement when throwing.<ref>{{cite book | vauthors = Churchill SE, Rhodes JA | chapter = The Evolution of the Human Capacity for 'Killing at a Distance': The Human Fossil Evidence for the Evolution of Projectile Weaponry | title = The evolution of hominin diets: integrating approaches to the study of Palaeolithic subsistence | veditors = Hublin JJ, Richards MP | publisher = Springer Science + Business Media | year = 2009 | page = 208 | isbn = 978-1-4020-9698-3 | chapter-url = https://books.google.com/books?id=Xnz0_HSaDLoC&pg=PA208 }}</ref>

===Horses===
{{See also|Equine anatomy}}

In the horse, the biceps' function is to extend the shoulder and flex the elbow.  It is composed of two short-fibred heads separated longitudinally by a thick internal tendon which stretches from the origin on the supraglenoid tubercle to the insertion on the medial radial tuberosity.  This tendon can withstand very large forces when the biceps is stretched.  From this internal tendon a strip of tendon, the ''lacertus fibrosus'', connects the muscle with the [[extensor carpi radialis (disambiguation)|extensor carpi radialis]]&nbsp;-- an important feature in the horse's [[stay apparatus]] (through which the horse can rest and sleep whilst standing.)
<ref>{{cite journal | vauthors = Watson JC, Wilson AM | title = Muscle architecture of biceps brachii, triceps brachii and supraspinatus in the horse | journal = Journal of Anatomy | volume = 210 | issue = 1 | pages = 32–40 | date = January 2007 | pmid = 17229281 | pmc = 2100266 | doi = 10.1111/j.1469-7580.2006.00669.x }}</ref>

== References ==
{{Reflist}}

== External links ==
{{Commons category|Biceps brachii}}
{{Wiktionary|biceps}}
* {{SUNYAnatomyLabs|06|05|01|02}}

{{Muscles of upper limb}}
{{Authority control}}

[[Category:Elbow flexors]]
[[Category:Forearm supinators]]
[[Category:Muscles of the upper limb]]
[[Category:Shoulder flexors]]