Glenoid cavity
| Bone: Glenoid cavity | |
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| Glenoid fossa of right side. | |
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| Left scapula. Lateral view. | |
| Latin | cavitas glenoidalis, fossa glenoidalis |
| Gray's | subject #50 207 |
The glenoid cavity (or glenoid fossa of scapula from Greek: gléne, "socket") is a shallow pyriform, articular surface, which is located on the lateral angle of the scapula. It is directed laterally and forward and articulates with the head of the humerus; it is broader below than above and its vertical diameter is the longest.
This cavity forms the glenohumeral joint along with the humerus. This type of joint is classified as a synovial, ball and socket joint.
The cavity surface is covered with cartilage in the fresh state; and its margins, slightly raised, give attachment to a fibrocartilaginous structure, the glenoid labrum, which deepens the cavity.
Compared to the acetabulum (hip-joint) the glenoid cavity is relatively shallow. This makes the shoulder joint prone to luxation. Strong ligaments and muscles prevents luxation in most cases.
By being so shallow the glenoid cavity allows the glenohumeral joint to have the greatest mobility of all joints in the body, allowing 120 degrees of unassisted flexion. This is also accomplished by the great mobility of the scapula (shoulder blade).
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[edit] Evolution
Interpretations of the fossil remains of Australopithecus africanus (STS 7) and A. afarensis (AL 288-1; a.k.a. Lucy) suggest that the glenoid fossa was oriented more cranially in these species than in modern humans. This reflects the importance of overhead limb postures and suggests a retention of arboreal adaptations in these hominoid primates, whereas the lateral orientation of the glenoid in modern humans reflects the typical lowered position of the arm. [1]
[edit] Additional images
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[edit] See also
[edit] Notes
- ^ Larson 2009, p. 65
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
[edit] References
- Larson, Susan G. (2009). "Evolution of the Hominin Shoulder: Early Homo". In Grine, Frederick E.; Fleagle, John G.; Leakey, Richard E.. The First Humans – Origin and Early Evolution of the Genus Homo. Springer. doi:10.1007/978-1-4020-9980-9. ISBN 978-1-4020-9979-3. http://www.springerlink.com/content/p22t46/#section=62942&page=1.
[edit] External links
- Diagram at cerrocoso.edu
- SUNY Figs 03:02-07
- Glenoid+fossa at eMedicine Dictionary
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