Biceps Brachii
Musculus biceps brachii
Overview
The biceps brachii is a powerful pennate muscle that originates from the supraglenoid tubercle via a short, largely fibrocartilaginous tendon that runs in the intertubercular groove (protected by the intertubercular bursa). An internal tendon runs through the muscle belly and continues as the insertion on the radial tuberosity and medial collateral ligament; the lacertus fibrosus leaves the muscle to join the extensor carpi radialis tendon. It extends the shoulder, flexes the elbow, and forms a critical passive component of the forelimb stay apparatus via the lacertus fibrosus. Its architecture allows elastic energy storage and rapid release (catapult mechanism) for fast limb protraction at speed. Clinically, inflammation of the intertubercular (bicipital) bursa causes shoulder-region lameness that can be localized by diagnostic anesthesia or ultrasound. Injury to the tendon of origin or muscle belly is less common but occurs with trauma.
Anatomical Details
Origin: Supraglenoid tubercle of the scapula
Insertion: Radial tuberosity and medial collateral ligament of the elbow; lacertus fibrosus to extensor carpi radialis
Action: Extends the shoulder; flexes the elbow; key component of the stay apparatus
Innervation: Musculocutaneous nerve (C6-C7)
Clinical Significance
Bicipital bursitis is diagnosed by ultrasound, synovial fluid analysis, or diagnostic anesthesia of the bursa. Treatment includes rest, anti-inflammatories, and sometimes intrabursal medication. The lacertus fibrosus is a key stay-apparatus structure.
Common Conditions & Injuries
Bicipital bursitis
## Overview Bicipital bursitis is inflammation of the bursa that lies between the biceps brachii tendon and the humerus at the point of the shoulder. The bursa allows the tendon to glide smoothly. In
Biceps tendon strain
## Overview Biceps tendon strain (bicipital tendinitis or tenosynovitis) involves the tendon of the biceps brachii muscle as it runs through the bicipital groove of the humerus and its associated bur
What Horse Owners Should Know
Shoulder lameness that improves with rest or appears after work, especially with a shortened cranial phase, warrants veterinary evaluation. Avoid forcing the limb into full extension if the horse resists.
Frequently Asked Questions
What is Bicipital bursitis in horses?
## Overview Bicipital bursitis is inflammation of the bursa that lies between the biceps brachii tendon and the humerus at the point of the shoulder. The bursa allows the tendon to glide smoothly. Inflammation may be aseptic (from trauma or overuse) or septic (from penetrating wounds or, rarely, blood-borne infection). Because little soft tissue covers the area, the bursa is vulnerable to external trauma. ## Causes Direct trauma, kicks, or falls are the most common triggers. Penetrating wounds introduce bacteria and produce septic bursitis. Overuse and concurrent biceps tendon injury can cause aseptic inflammation. Brucella species have historically been implicated in some cases. ## Diagnosis Forelimb lameness with a shortened cranial stride, heat, swelling, and pain at the point of the shoulder are typical. Ultrasound-guided synoviocentesis confirms sepsis when present. Radiographs and ultrasound evaluate concurrent bone or tendon damage. ## Treatment Aseptic cases are managed with rest, anti-inflammatories, and sometimes intrabursal medication. Septic bursitis requires aggressive lavage (bursoscopy or through-and-through needle lavage) plus systemic antibiotics. Prognosis is fair with prompt treatment. ## Recovery and Prognosis Many horses become serviceably sound. Return to high-level athletics is less certain, especially after septic disease or significant tendon involvement. Chronic cases may leave residual mechanical limitation. ## Prevention Prompt wound care after shoulder trauma and avoidance of repeated contusion reduce risk. Signs include: forelimb lameness; swelling and heat at the point of the shoulder; pain on palpation; shortened cranial phase of the stride
What is Biceps tendon strain in horses?
## Overview Biceps tendon strain (bicipital tendinitis or tenosynovitis) involves the tendon of the biceps brachii muscle as it runs through the bicipital groove of the humerus and its associated bursa. The tendon stabilizes the shoulder and helps flex the elbow and advance the limb. Injury produces a characteristic shortened cranial phase of the stride and forelimb lameness that can be difficult to localize. ## Causes Repetitive overload from work that loads the forehand, poor foot balance, or compensatory stress from lower-limb or neck problems are common. Acute trauma from forceful backward extension of the limb can also tear the tendon. Conformation and fatigue contribute. ## Diagnosis Shortened stride, reluctance to extend the shoulder, and pain on palpation or flexion of the shoulder are suggestive. Diagnostic analgesia of the bicipital bursa or tendon sheath often improves the lameness. Ultrasound evaluates tendon fiber pattern and bursal effusion; radiographs rule out associated bone injury. ## Treatment Rest, anti-inflammatory medication, and controlled exercise form the core of management. Intrabursal medication may help aseptic inflammation. Severe tears or concurrent septic bursitis may require bursoscopy or more aggressive intervention. ## Recovery and Prognosis Mild cases often return to work in one to three months. More severe tendinopathy can require longer rehabilitation and carries a guarded prognosis for high-level athletic use. Recurrence is possible if underlying biomechanical issues are not addressed. ## Prevention Balanced shoeing, progressive conditioning, and attention to saddle fit and rider balance reduce chronic overload. Signs include: forelimb lameness with shortened cranial stride; pain on shoulder flexion or palpation; reluctance to extend the limb fully; occasional swelling at the point of the shoulder
What are the clinical concerns for the Biceps Brachii?
Bicipital bursitis is diagnosed by ultrasound, synovial fluid analysis, or diagnostic anesthesia of the bursa. Treatment includes rest, anti-inflammatories, and sometimes intrabursal medication. The lacertus fibrosus is a key stay-apparatus structure.
What should horse owners know about the Biceps Brachii?
Shoulder lameness that improves with rest or appears after work, especially with a shortened cranial phase, warrants veterinary evaluation. Avoid forcing the limb into full extension if the horse resists.
Explore This Structure in 3D
See the Biceps Brachii on our interactive 3D horse model. Open 3D Model