{"id":19956,"date":"2013-11-14T06:06:48","date_gmt":"2013-11-14T13:06:48","guid":{"rendered":"http:\/\/www.featheredphotography.com\/blog\/?p=19956"},"modified":"2013-11-14T12:31:06","modified_gmt":"2013-11-14T19:31:06","slug":"the-supracoracoideus-an-ingenious-adaptation-for-flight","status":"publish","type":"post","link":"https:\/\/featheredphotography.com\/blog\/2013\/11\/14\/the-supracoracoideus-an-ingenious-adaptation-for-flight\/","title":{"rendered":"The Supracoracoideus – An Ingenious Adaptation For Flight"},"content":{"rendered":"

When I was teaching high school zoology I was fascinated by the many adaptations of birds for flight.\u00a0 Still am.\u00a0\u00a0One of them is a unique muscle arrangement that allows the return stroke of the wing while maintaining aerodynamic stability.\u00a0 I hope you’ll allow me a little change in direction with today’s post as I attempt to explain and illustrate one of the anatomical adaptations of birds for flight.<\/p>\n

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\"bald<\/a><\/p>\n

The body of a bird basically hangs down\u00a0from the wings during flight.\u00a0 The wings attach high on the body and the\u00a0huge breast muscle (pectoralis) lies below that attachment.\u00a0 This arrangement provides a low center of gravity and aerodynamic stability.\u00a0 The pectoralis muscle attaches to the keel of the sternum and the humerus of the wing so when that muscle contracts it provides the\u00a0powered down-stroke of the wing.<\/p>\n

But one of the dilemmas of bird flight is how to design a muscle arrangement\u00a0that will power the upstroke of the wing and still maintain that low center of gravity.\u00a0 Muscles can only contract under power so it seems logical that the\u00a0muscle that would provide\u00a0the upstroke would be along the back.\u00a0 But such an arrangement would place a relatively large muscle mass high on the body, raise the center of gravity and compromise aerodynamic stability.\u00a0\u00a0Anyone who has ever eaten a chicken back knows that there is very little meat (muscle) there and that particular\u00a0placement of the muscle\u00a0along the back is not the solution that\u00a0nature came up with.<\/p>\n

So how was the problem solved?…<\/p>\n

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\"supracoracoideus\"<\/a><\/p>\n

By L. Shyamal [CC-BY-SA-2.5 (http:\/\/creativecommons.org\/licenses\/by-sa\/2.5<\/a>)], via Wikimedia Commons<\/strong><\/em><\/p>\n

The solution is truly ingenious.<\/p>\n

In this graphic you can see how the contraction of the pectoralis would power the wing down.\u00a0 But beneath and lying next to the pectoralis is another muscle – the supracoracoideus (the word is a mouthful, I know.\u00a0 It means “above the coracoid” bone).\u00a0 The supracoracoideus is antagonistic to the pectoralis and provides the upstroke.\u00a0 It is attached to the upper <\/em>side <\/em>of the humerus by a unique “rope and pulley” arrangement of a tendon that travels up and over a notch in the scapula before attaching to the humerus.\u00a0 So even though the muscle is below the humerus, the direction of pull is from slightly above so that\u00a0when it contracts it raises the wings and aerodynamic stability is maintained.<\/p>\n

Most folks are very familiar with the supracoracoideus, they just don’t know the formal name.\u00a0 Chicken “tenders” are the supracoracoideus muscle of that domestic fowl.\u00a0 When we eat a chicken breast the supracoracoideus is the shiny, more tender piece of meat lying between the larger mass of the breast (pectoralis muscle) and the bone.\u00a0 If you’ve ever deboned a chicken breast you’ve likely noticed (and removed) the tendon coming off the “tender”.\u00a0 That tendon is the one that attaches to the humerus and provides uplift to the wing.<\/p>\n

The graphic above is misleading in a couple of ways (it’s the only appropriate Creative Commons graphic I could find).\u00a0 The graphic shows a large space between the pectoralis and the\u00a0supracoracoideus, a space that does not exist.\u00a0 The two muscles actually\u00a0lie atop one another and are separated only by a very thin membrane.\u00a0 The graphic also shows the\u00a0tendon to be as large in diameter as the muscle itself\u00a0when in reality the tendon is something like a narrow string coming out of the much larger\u00a0muscle.<\/p>\n

I realize this post won’t be everyone’s cup of tea but I’m also aware that some\u00a0folks (me included)\u00a0like to know everything they can about their beloved birds.\u00a0 This post is for you…<\/p>\n

Tomorrow I’ll get back to more standard fare.<\/p>\n

Ron<\/p>\n

Many thanks to L. Shyamal for providing the graphic to Creative Commons.\u00a0 <\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

When I was teaching high school zoology I was fascinated by the many adaptations of birds for flight. Still am. One of them is a unique muscle arrangement that allows the return stroke of the wing while maintaining aerodynamic stability. I hope you’ll allow me a little change in direction with today’s post as I attempt to explain and illustrate one of the anatomical adaptations of birds for flight.<\/p>\n

Continue reading<\/span><\/i><\/a> <\/p>\n","protected":false},"author":2,"featured_media":19957,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[355,334],"tags":[1743,1744,43,1748,127,1187,1745,1747,1746],"class_list":["post-19956","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bald-eagles","category-birds","tag-adaptations-for-flight","tag-aerodynamic-stability","tag-bald-eagle","tag-chicken-tender","tag-evolution","tag-humerus","tag-pectoralis","tag-sternum","tag-supracoracoideus"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/featheredphotography.com\/blog\/wp-content\/uploads\/2013\/11\/bald-eagle-8330-ron-dudley.jpg","jetpack_shortlink":"https:\/\/wp.me\/p1zzJh-5bS","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/posts\/19956","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/comments?post=19956"}],"version-history":[{"count":0,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/posts\/19956\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/media\/19957"}],"wp:attachment":[{"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/media?parent=19956"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/categories?post=19956"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/featheredphotography.com\/blog\/wp-json\/wp\/v2\/tags?post=19956"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}