Shoulder Safety Part 2: bony shoulder anatomy

Anders Hendricks, Aurora Sports Medicine Institute

Anders is a licensed athletic traininer at the Aurora Sports Medicine Institute in Burlington and at Badger High School in Lake Geneva.

The shoulder (glenohumeral joint) is very complicated.  It is comprised of three bones, the shoulder blade (scapula), collar bone (clavicle) and upper arm bone (humerus).  It is classified as a ball and socket joint (similar to the hip), but lacks the bony stability featured in the hip and other joints.  In fact, the shoulder joint is often compared to a golf ball resting on a tee, with the ball representing the head of the humerus and the tee representing the shoulder blade.  This depiction accurately shows how the shoulder sacrifices bony stability for exceptional range of motion.

The clavicle provides the shoulder with the only bony attachment to the rest of the body.  One end of the clavicle is attached to the breastbone (sternum), forming the sternoclavicular joint (SC joint), while the other end attaches to the scapula at the acromion process, forming the acromioclavicular joint (AC joint).

The scapula serves as a broad, flat origin for the muscles of the rotator cuff as well as an attachment site for other back and shoulder muscles.  The spine of the scapula eventually forms the acromion process, where the clavicle attaches.  Just underneath (inferior) to the acromion process is the subacromial space, an area where tendons from the rotator cuff cross the shoulder to insert on the humerus.  Just below that lies the glenoid fossa, where the humerus articulates.

The humerus attaches to the scapula at the glenoid fossa to make up the glenohumeral joint (GH joint).  This is the main joint associated with the shoulder complex.  The humerus features a greater and lesser tubercle, which serve as attachments for muscles of the upper arm.  The biceps tendon runs between the two tubercles, forming the biceptial groove.  The humerus features many muscular attachments, including the four muscles of the rotator cuff, pectorals, deltoid and other upper body muscles.  The biceps and triceps originate on the humerus and scapula and attach past the elbow joint.

The shoulder gains stability from three major ligaments (pictured in blue): the superior, middle, and inferior glenohumeral (GH) ligaments.  These GH ligaments start on the scapula and attach to the humerus and help to control motion at the shoulder as well as provide stability.  Additionally, the shoulder is further stabilized by the labrum (pictured in green), a thin, cartilaginous ring around the glenoid fossa, and the muscles of the rotator cuff.  Both the labrum and the rotator cuff will be described in further detail in future blog entries.

Knowledge of the bony anatomy of the shoulder is very important if one wishes to fully understand the shoulder joint and the injuries associated with it.  This knowledge allows a person to visualize the shoulder, and how different problems affect the glenohumeral joint.

As always, if readers have any questions or comments about this topic, or past and future topics, please feel free to email me at anders.hendricks@aurora.org.  Thanks a bunch!

Follow the new Shoulder Series with weekly updates here at our fitness blog!

Part 1: Shoulders: An Introduction

Don’t give up the sport — give up the pain! Visit the Aurora Sports Medicine Institute at 13 Wisconsin locations, visit our website, follow us on Facebook, browse our YouTube channel, or call our hotline at 1-800-219-7776.

Advertisements

About Anders Hendricks

Anders Hendricks is a Licensed Athletic Trainer for the Aurora Sports Medicine Institute in Burlington and at Badger High School in Lake Geneva. Anders studied Kinesiology and Athletic Training at the University of Wisconsin-Eau Claire, and has worked as an athletic trainer at the University of Wisconsin at Parkside. In the summer and fall, he enjoys following the Green Bay Packers and Milwaukee Brewers, and ice hockey and downhill skiing in the winter. Anders started blogging to give people a better understanding of what athletic training is, and how licensed athletic trainers help the patients of Aurora Health Care live well.
This entry was posted in Fitness Training 101, Injury Prevention, Shoulder Safety Series and tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s