What Lies Beneath

A large part of being an equipment manager is ensuring proper fit of protective equipment to minimize the risks of injury to athletes. While we cannot eliminate injuries from happening, putting players in properly fitting equipment and ensuring they wear it during practices and games may help reduce the occurrence and severity of injury. While the AEMA and major sports equipment companies provide a plethora of information on properly fitting athletes for every sport, equipment managers could benefit from an increased knowledge of anatomy and a better understanding of why protective equipment covers certain portions of the human body.

Not every manager has a strong background in anatomy. The AEMA Certification Manual provides some basic information on the acromioclavicular joint (AC joint) and burners or stingers (AEMA, 2004 p. 50,52) and Jerry Fife’s 2006 AEMA Journal article “Know it to Protect it,” further explored the bones and joints of the human body. Both of these articles provide a great starting point to understanding anatomy so that we can best protect the athletes we fit, but there is a lot more to the human body than what is covered in the current literature.

The purpose of this article is to expand AEMA literature on human anatomy in hopes that an increased knowledge pool will lead to better fitting equipment, and safer athletes. Though it will elaborate on some of the more important structures, it is by no means comprehensive. This article will focus specifically on football shoulder pads and the anatomy of the shoulder—the AC joint, the neck of the humerus, the rotator cuff, and the brachial plexus—and why these areas need to be protected.

THE ACROMIOCLAVICULAR JOINT: WHAT IS IT?
The AC joint is always at the center of discussion when it comes to fitting shoulder pads and for good reason. This joint connects arm to the rest of the body. It is formed by the articulation, or joining, of the acromion process of the scapula (the shoulder blade) and the clavicle (the collar bone).

The scapula is positioned on the back of the thoracic cage and forms the glenohumeral joint with the head of the humerus, the bone of the arm. The scapula and clavicle serve as attachment points for many of the muscles that create arm movements.

The strong and fibrous acromioclavicular ligament holds the two bones together and allows for normal arm movement. Damage to the AC ligament, typically sustained in a direct blow to the shoulder, can cause a weakened connection of the AC joint and lead to a decreased ability to properly move the arm (Drake, 2010).

WHY PROTECT IT?
The AC joint needs to be protected so that arm movement is not affected. This is especially important for players manning the skill positions, such as quarterbacks, wide receivers and defensive backs, which require an overhead arm motion to throw and catch.

The AC channel of the shoulder pad protects the AC joint. Typically this channel forms an arch over the AC joint and distributes compressive forces away from the joint itself. Equipment managers should check the manufacturer’s recommendations of each pad to make sure the AC channel fits properly to ensure the safety of the AC joint.

If spider pads are employed for further protection of the AC joint, care must be taken to ensure that the AC joint falls within the gaps of the spider pads. If the padding directly covers the AC joint, the forces will not be dispersed, and instead may be directed on it. Remember to always measure the distance between AC joints first when fitting for shoulder pads. This is how you determine initial shoulder pad sizing. Adjustments can always be made for a better fit, but shell size is dependent on distance between AC joints (AEMA, 2004).

THE SURGICAL NECK OF THE HUMERUS: WHAT IS IT?
The surgical neck of the humerus lies distal to (below) the humeral head, where it articulates with the scapula to form the glenohumeral joint. The surgical neck is a narrow, weaker part of the humerus that is commonly fractured. Fractures to the surgical neck can be very dangerous because nerves and arteries that provide voluntary movement, sensation and proper blood supply to the upper extremity can be damaged. If damage to the nerves and arteries is sustained during a fracture, long-term neurological and vascular issues can persist even after the bone has healed (Drake, 2010).

WHY PROTECT IT?
The surgical neck of the humerus needs to be protected so that voluntary movement, sensation and blood supply to the arm are not effected. The epaulets or flaps and the cups of the shoulder pads protect the surgical neck.

The protection of cups varies by manufacturer and by position. Typically, skilled positions have smaller cups to allow for more movement. Linemen should have larger cups as they typically make more contact with the shoulder and upper arm during play.

The AEMA Certification Manual does not specifically address cup size, but most shoulder pads provide adequate protection to this area. If you are fitting a lineman into lighter pads, check with your athletic trainer to ensure the upper part of the arm is well protected.

THE ROTATOR CUFF: WHAT IS IT?
The rotator cuff is a group of four muscles—the supraspinatus, infraspinatus, teres minor and subscapularis—that originate on the scapula and attach to the humeral head. These muscles are critical in generating arm motions, as well as stabilizing the glenohumeral joint. The rotator cuff also stabilizes the head of the humerus in the glenoid fossa of the scapula to maintain the articulation of the humeral head with the scapula, which ensures that the glenohumeral joint moves properly. Throwing, catching and blocking with the arms are all aided by the rotator cuff. Damage to the rotator cuff can lead to dislocations of the shoulder and improper movement of the arm (Drake, 2010).

WHY PROTECT IT?
The rotator cuff needs to be protected to ensure arm movement is not affected. Without a healthy rotator cuff, overhead movements like throwing and catching are almost impossible.

The arch of the shoulder pad covers the scapula and muscle bellies of the rotator cuff and the cups of the shoulder pads protect the head of the humerus where the rotator cuff muscles attach. The pads will protect the muscles from trauma from a direct blow, but there is no way for padding to protect tearing of the rotator cuff muscles or shoulder dislocations.

These injuries can occur from improper technique with throwing or tackling, which can cause direct damage to the rotator cuff or put the arm in a position more prone to injury. To ensure protection from a direct blow always check to make sure the scapula and upper arm are covered (AEMA, 2004).

THE BRACHIAL PLEXUS: WHAT IS IT?
The brachial plexus is a network of nerves that controls all the movement of the shoulder, arm, forearm, wrist and hand. It extends from the spinal nerves in the neck and runs under the clavicle, into the axilla (armpit) and ends as several large nerves that supply the entire upper extremity. Damage to these nerves can cause a drastic loss in motion and sensation in one or more portions of the upper extremity.

Because these nerves run underneath the clavicle, clavicular fractures can cause neurological damage. Burners or stingers are common injuries where these nerves are overstretched, compressed or subject to a direct blow (Drake, 2010).

WHY PROTECT IT?
The brachial plexus needs to be protected to ensure proper movement and sensation of the shoulder, arm, forearm, wrist and hand. Because of its location in the axilla, the brachial plexus is not directly protected by shoulder pads. However, the collar and arch of shoulder pads reinforce the clavicle.

If the clavicle becomes damaged, the brachial plexus may in turn be damaged. Keep in mind that stinger injuries will not be prevented by pads, but protecting the clavicle will aid in preventing more severe injuries due to clavicular fractures or damage.

Properly fitting pads should completely cover the clavicle and redistribute direct forces away from it. Always check to make sure pads properly cover the clavicle, and that it is not exposed at the collar (AEMA, 2004).

CONCLUSION
Football is very much a contact sport, and improper fitting of shoulder pads can risk serious injury to the anatomical structures discussed above. The shoulder is a very complex joint with many muscles, nerves and blood vessels contributing to optimal function of the entire upper extremity.

Issues at the shoulder can cause deficits in function that extend down the arm and into the hand that can sideline a player on the field and in life. My hope is that by highlighting these critical structures in shoulder anatomy, equipment managers don’t just know how to fit equipment but why we fit it properly.

For further anatomical information, I recommend “Gray’s Anatomy for Students,” by Richard Drake, A. Wayne Vogl and Adam W.M. Mitchell and “The Atlas of Human Anatomy,” by Frank H. Netter, MD.

Jacob Manley SPT, EM,C, is a first year graduate student at Shenandoah University in Winchester Virginia. He is pursuing a dual degree—a master’s in athletic training and a doctorate in physical therapy. Jacob graduated in 2014 with a degree in kinesiology from the University of Virginia, where he worked as a student equipment manager for the football team and as a strength and conditioning intern. Jacob received his AEMA certification in June of 2014 and was a Jimmy Callaway Scholarship Award Winner.

Brad Dinklocker is a second year graduate student at Shenandoah University in Winchester, VA pursing a dual degree in a master’s in athletic training and doctorate of physical therapy. Brad graduated from Shenandoah University with a bachelor’s degree in kinesiology with a focus in exercise science. He is a current member of the American Physical Therapy Association (APTA) and the National Athletic Trainers’ Association (NATA).