{{Short description|Fluid-filled sacs which cushion the bones and muscles around joints}} {{redirect|Bursae|other uses|Bursa (disambiguation)}} {{More citations needed|date=September 2012}} {{Infobox anatomy | Name = Synovial bursa | Latin = bursa synovialis | Image = Joint.svg | Caption = Typical joint | Image2 = Knee bursae.svg | Caption2 = Within the knee joint: bursae visible top right, middle right and bottom right | Precursor = | System = | Artery = | Vein = | Nerve = | Lymph = }}
A '''synovial bursa''', usually simply '''bursa''' ({{plural form}}: '''bursae''' or '''bursas'''), is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of viscous synovial fluid (similar in consistency to that of a raw egg white). It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement. Bursae are found around most major joints of the body.
==Structure== Based on location, there are three types of bursa: subcutaneous, submuscular and subtendinous. A subcutaneous bursa is located between the skin and an underlying bone. It allows skin to move smoothly over the bone. Examples include the prepatellar bursa located over the kneecap and the olecranon bursa at the tip of the elbow. A submuscular bursa is found between a muscle and an underlying bone, or between adjacent muscles. These prevent rubbing of the muscle during movements. A large submuscular bursa, the trochanteric bursa, is found at the lateral hip, between the greater trochanter of the femur and the overlying gluteus maximus muscle. A subtendinous bursa is found between a tendon and a bone. Examples include the subacromial bursa that protects the tendon of shoulder muscle as it passes under the acromion of the scapula, and the suprapatellar bursa that separates the tendon of the large anterior thigh muscle from the distal femur just above the knee.<ref name="ana&physio">{{cite book |last1=Betts |first1=J. Gordon |title=Anatomy & physiology |date=2013 |publisher=OpenStax |location=Houston, Texas |chapter=9.4 Synovial joints |isbn=978-1-947172-04-3 |url=https://openstax.org/books/anatomy-and-physiology/pages/9-4-synovial-joints |access-date=14 May 2023}}</ref>
An adventitious bursa is a non-native bursa. When any surface of the body is subjected to repeated stress, an adventitious bursa develops under it. Examples are student's elbow and bunion.
==Clinical significance== Infection or irritation of a bursa leads to bursitis (inflammation of a bursa). The general term for disease of bursae is "bursopathy".
==Etymology== {{lang|la|Bursa}} is Medieval Latin for "purse", so named for the bag-like function of an anatomical bursa. ''Bursae'' or ''bursas'' is its plural form.
== See also == *Bursa of Fabricius (a lymphatic organ in birds) *Bursectomy *Knee bursae *Shoulder joint#Bursae
==References== {{reflist}}
==External links== {{Commons category|Synovial bursae}} *{{cite journal |last1=Hirji |first1=Zameer |last2=Hunjun |first2=Jaspal S |last3=Choudur |first3=Hema N |title=Imaging of the Bursae |journal=Journal of Clinical Imaging Science |date=2 May 2011 |volume=1 |pages=22 |doi=10.4103/2156-7514.80374 |pmid=21966619 |pmc=3177464 |doi-access=free }} * [https://web.archive.org/web/20060318193646/http://www.allaboutarthritis.com/image/stock_image/elbow_bursitis_anatomy01_MMG.jpg Diagram of elbow with olecranon bursa]
==Source text== {{Free-content attribution| | title = Anatomy and Physiology | author = J. Gordon Betts ''et al'' | publisher = [https://openstax.org/ Openstax] | source= <!-- The source of the work if not from the publisher or the author --> | documentURL = https://openstax.org/details/books/anatomy-and-physiology | License statement URL = <!-- The URL of the license statement of the work if not included within the document --> | license = CC BY 4.0 |howto = }}
{{Joints}} {{Bursae}} {{Authority control}}
Category:Synovial bursae Category:Soft tissue Category:Musculoskeletal system