Extensor expansion
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| Extensor expansion | |
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| Tendons of forefinger and vincula tendina. (Extensor expansion not labeled, but region is visible.) |
An extensor expansion (dorsal expansion, dorsal hood) is an anatomical term that refers to the flattened tendons (aponeurosis) of extensor muscles that run into the back of the hand. At the distal end of the metacarpal, the extensor tendon will expand to form a hood, which covers the back and sides of the head of the metacarpal and the proximal phalanx.
The expansion soon divides into three bands:
- Two lateral bands pass on either side of the proximal phalanx and stretch all the way to the distal phalanx. The lumbricals of the hand, the dorsal interossei of the hand, and the palmar interossei insert on these bands.
- A single median band passes down the middle of the finger along the back of the proximal phalanx, ending at the base of the middle phalanx.
A band known as the retinacular ligament runs obliquely along the middle phalanx, and connects the fibrous digital sheath on the anterior side of the phalanges to the extensor expansion.
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General anatomy of upper limbs | |
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| Arm | Axilla • Axillary sheath • axillary folds (Anterior, Posterior)
spaces (Quadrangular space, Triangular space, Triangular interval) • Clavipectoral triangle compartment of arm (Posterior, Anterior) fascia (Axillary, Brachial) - intermuscular septa (Lateral, Medial) |
| Forearm | Cubital fossa (Bicipital aponeurosis) • Cubital tunnel • common tendons (Extensor, Flexor) • Interosseous membrane of the forearm
compartment of forearm (Posterior, Anterior) fascia (Antebrachial fascia) |
| Hand | posterior: Extensor retinaculum • Extensor expansion • Vincula tendina • Anatomical snuff box
anterior: Flexor retinaculum • Carpal tunnel • Palmar aponeurosis • Ulnar canal • Synovial sheath (Common synovial sheath for the flexor tendons]) Finger |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
