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3D Skeletal System: Function of the Sphenoid

The sphenoid. Aside from having the most sci-fi name in all existence, it's pretty much theSphenoid skull bone coolest-looking bone in the body. Best yet? It's in your skull. Bet you never thought you've been walking around all this time with a bat-shaped bone in your head.

The sphenoid is an interesting bone in that while it doesn't actively protect the brain like the bones of the calvaria, it does have a multitude of functions, particularly in creating tunnels through which various nerves pass.

 

IMPORTANCE OF THE SPHENOID

There are 22 bones that make up the skull, and the sphenoid (don't you just love saying it?) is one of the 8 bones of the neurocranium. It is situated at the base of the skull, acting as the keystone. A keystone in architecture is the piece at the apex of an arch; it locks all the other pieces together and bears the weight. And just like a keystone holds everything together in an archway, so does the sphenoid in the skull.

Sphenoid bone articulation

The sphenoid articulates with 12 bones:
  • frontal
  • occipital
  • parietals
  • temporals
  • zygomatics
  • ethmoid
  • vomer
  • palatines

Of these 12 bones, 10 belong to the neurocranium. In my previous post, I discussed the neurocranium's role in protecting the brain. While it is part of the neurocranium, the sphenoid does little in the way of protection. It serves more as a base for the skull.

 

SPHENOID LANDMARKS

Our bat-shaped sphenoid is divided into a median body, two greater wings, two lesser wings, and two pterygoid plates.

Think of the body of the sphenoid as the body of the bat it's shaped like: it is from theSphenoid bone body body that the wings and processes project. It is cubical in shape. It also has two hollowed-out, air-filled cavities—the sphenoidal sinuses. There are four pairs of sinuses, and like the others the sphenoidal sinuses have two jobs: to help lighten the weight of the skull, and to give each person's voice individual character.

There is also a deep depression in the superior surface of the bone called the sella turcica, or "Turkish saddle." It is so named because of its resemblance to the saddles Turks used to use, with supports in the front and back. It is in this depression that the pituitary gland sits.

The greater and lesser wings are processes of bone that extend outward. The greater wings are perforated by various foramen, the most obvious being the large superior orbital fissures, which are formed by both sets of wings. Various structures pass through the fissures, including the oculomotor nerve (III); the trochlear nerve (IV); the lacrimal, frontal, and nasocillary branches of the ophthalmic nerve (V); and divisions of the ophthalmic vein. The greater wings also serve as the attachment site for the temporalis muscles.

The lesser wings and the body of the sphenoid form the optic canal. It is through this canal that the optic nerve (II) passes from the brain to the eyes.

The lateral and medial processes project downward from the body of the bone, like legs. It is to the lateral processes that the lateral and medial pterygoid muscles attach. The sphenoidal processes of the palatine and the ala of the vomer articulate with the medial processes.

 

Sphenoid sinuses

PATHOLOGIES OF THE SPHENOID

The thing about the sphenoid is that it's located in such a place that injuries to it are not as common as injuries to bones at the forefront of the skull. That said, you can definitely injure it. Fracturing the bone following severe bumps, impacts, and whiplash can affect vision or cause nerve damage.

One of the more common pathologies is sphenoid sinusitis. Sinusitis is an inflammation of the mucous membranes of sinus cavities. Symptoms include headache, facial pain, and infected nasal drainage, as well as nerve irritation.

Sometimes, sinusitis can become very severe and complications, such as recesses (small cavities), can arise, or other issues can form in the sinuses (such as a tumor), prompting the need for a sphenoidotomy. A sphenoidotomy is, quite simply, the surgical procedure of cutting into the sphenoid sinus, with the most common approaches through the nasal cavity or nasal septum. A sphenoidectomy is when part of the sphenoid is removed, usually in instances involving tumors.

Hard to believe so much is associated with your bat bone, huh? The sphenoid, like all bones in the body, is a wellspring of information and serves a slew of purposes. Regardless of its importance, it is still—without a doubt—the coolest-looking bone you have.

 

Want to review more about the sphenoid? Check out our mini ebook!  It includes dozens of images from our upcoming app that includes a comprehensive human anatomy skeleton model with tons of content on bony landmarks, joints, bone tissue, and common bone pathologies.



Sources:

Rimal, D., Hashmi, S., & Prinsley, P. (2006). An unusual presentation of sphenoid sinusitis with septicaemia in a healthy young adult. Emergency Medicine Journal23(36), doi: 10.1136/emj.2005.033340

Schaefer, MD, S. (2012). Sphenoidotomy. In Retrieved from http://www.nyee.edu/ent_rss_sts_sphenoid01.html

 

Comments

buenas imagenes ,exelentes pero solo pediria que tambien hubiera en español los textos para poder leerlos gracias.
Posted @ Friday, October 19, 2012 7:29 PM by cesar
This is very informative and well-written! I also love the bits of humor thrown in there; it makes the writing feel fresh and alive. Great job! Thank you!
Posted @ Wednesday, October 24, 2012 11:43 AM by Amy
There is much more to the shenoid than mentioneed here and the ebook. The Dura Mater origionates from the sphenoid and plays a vital role in the respiratory CSF mechanism. On inspiration the sphenoid lifts and lowers on expiration. To check this simply put your fingers on the greater wing of the sphenoid and breathe. If this mechanism is interfered with it can cause increased occular pressure taht can be confused with glacauma. Now imagine what effect this can have on the rest of the nervous system when CSF circulation is insufficienct and the pituatry gland gets affected. This is one area that c8nventional medicine doesnt even consider, let alone how to investigate it. One area where Cranial Therapy and SOT in Chiropractic is light years ahead. 
Posted @ Thursday, January 03, 2013 4:55 PM by Jan Jones
Just a thank you here. I have been using your software for a while now and it is great to be able to show patients what we are dealing with.It is great to show them how everything is related. 
Posted @ Thursday, January 03, 2013 5:10 PM by Jan Jones
Thanks so much, Jan Jones, for highlighting the role of the Sphenoid in breathing - my head feels lighter, more spacious,freer - and at the same time - more connected to the torso as a result. *
Posted @ Tuesday, September 10, 2013 5:01 AM by Cheryl Yonker
i faced ghost dream when i sleep touch sphenoid condition....what problem i have....any reasons about touch SPHENOID
Posted @ Sunday, April 27, 2014 5:43 PM by suresh
3D images and videos are really more attractive than 2D images and videos. These days, 3D technology also use in various studies and experiments as well. From this article, We can easily confirm about the usability of 3D images and snaps. We can easily explain about skeletal system of a human body by using 3D pictures. 3D Photography is simply awesome. 3D Photography Software
Posted @ Wednesday, August 06, 2014 5:48 AM by Lenish Richard
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