Funny-bone Friday

Today’s the first in an occasional series where I feature one (or two) of our amazing bones.

In recent weeks I’ve seen a number of people who have pain and restricted movement in one or both of their shoulders.

So, instead of starting with a small, obscure, or strangely named bone I’ve begun with the clavicle, which most of you know as the collarbone. We have two of them, and I know you know that.

We don’t always think of our collarbones as forming an integral part of our shoulders (also called the shoulder or pectoral girdle), but they do.

Clavicle 3d Model

The animation nicely illustrates the bone structures of a shoulder girdle: the clavicle, the scapula (shoulder blade) and the humerus (upper arm bone).

If you look carefully, you’ll also see that the clavicle articulates with the breast bone (sternum). This is called the sternoclavicular joint.

Some clavicle-related facts:

The clavicle receives its name from the Latin: clavicula (“little key”) because the bone rotates along its axis like a key when the shoulder is abducted -moved away from the midline of the body.

The wishbone in birds is composed of two fused clavicles.

Our clavicles are the only long bones in our bodies which lie horizontally.

The clavicle has some important functions: it connects the arm to the body, and has been described as a strut which keeps the shoulder blade in place.

It transmits forces towards the sternum and spine, and provides protection for underlying nerves and blood vessels.

The clavicle can be congenitally reduced or absent and is differently shaped in women and men (shorter, thinner and less-curved in women, and heavier, longer and more curved in men).

It’s the most commonly fractured bone.

About the pectoral girdle:

It’s a remarkable, mobile structure designed to allow us to move our arms in multiple directions.

A number of muscles, tendons and ligaments (all soft tissues) are responsible for all this movement and also work hard at stabilising our shoulder girdle.

Some of these muscles originate on the spine, and others on the ribcage. If you’re thinking the pectoral (chest muscles) are involved here, you’re correct!

Because the soft tissues of the shoulder have to cope with more mechanical stress than they would on a more rigid, stable structure (such as the hips), they become prone to a variety of traumatic and degenerative problems.

A further complicating factor is posture. In our society (especially in the last hundred years…) so much of our activity and attention is focused on the area in front of our head and chest…with relatively little manual activity happening behind and above us…our posture tends to favour the area in front of us.

Our shoulders become rolled in and our arms become internally rotated. Often there is an increased forward curve in our necks resulting in greater tension at the back of or heads, necessary to hold our heads up. This position is a deviation from the mechanical ideal.

The most common shoulder symptoms are pain, especially on movement, and restricted range of movement.

Several conditions are likely to be present at the same time, especially if the problem has become chronic. Joint problems in the cervical and upper thoracic spine, rib disorder, myofascial trigger points, inflamed and damaged tissue, degenerative changes can all be present in a single patient.

David Legge, Close to the Bone: The Treatment of Musculo-skeletal Disorder with Acupuncture and other Traditional Chinese Medicine- 2nd Edition. p168

Due to these multiple contributing factors, people with a painful and restricted shoulder will do better if they have a mixed team of health practitioners looking after them such as acupuncturists, osteopaths, remedial massage therapists, myotherapists and exercise physiologists.

Obviously, the family doctor and/or an orthopaedic surgeon will also be involved in assessment and treatment recommendations.

Image-animation attribution: DrJanaOfficial [CC BY-SA 4.0], via Wikimedia Commons

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