PART 3: THE ROTATOR CUFF MUSCLES OF THE SHOULDER
Rotator cuff injuries are a common problem in both the athletic and nonathletic population. Early diagnosis is essential to identify causes, implement effective treatment, and prevent further injury.
In Part 3 of “Shoulder Injuries- The Big Seventeen”, we will review the very important Rotator Cuff muscles and the impact that injury or restrictions to these structures can have when dealing with shoulder problems. We will also cover some of the diagnostic procedures that should be followed before beginning treatment.
The rotator cuff is made up of four major muscles along with their associated tendons. These are:
This group of muscles is often referred to as SITS (the first letter of their names). The SITS muscles are used used to perform a range of upper extremity actions including flexion, abduction, internal rotation, and external rotation.
ANATOMY & BIO-MECHANICS
Let's start with some basic anatomy and bio-mechanics of the rotator cuff (SITS) muscles.
Origin on Scapulae: Supraspinous fossa.
Insertion: Superior facet of the greater tubercle.
Primary Function: Abducts the humerus.
Innervation: Suprascapular nerve (C5).
Origin on Scapulae: Infraspinous fossa.
Insertion: Middle facet of the greater tubercle.
Primary Function: Externally rotates the humerus.
Innervation: Suprascapular nerve (C5-C6).
Teres minor Muscle
Origin on Scapulae: Middle half of lateral border
Insertion: Inferior facet of the greater tubercle
Primary Function: Externally rotates the humerus
Innervation: Axillary nerve (C5)
Origin on Scapulae: Subscapular fossa
Insertion: Lesser tubercle
Primary Function: Internally rotates the humerus.
Innervation: Upper and Lower subscapular nerve (C5-C6)
Note: With the exception of the Supraspinatus, all the muscles of the rotator cuff act to ensure that the humeral head stays in position (depressed). This downward pressure balances the upward pull of the deltoid muscle during glenohumeral abduction.
Want to learn more about shoulder anatomy. Click on our video "Shoulder Anatomy - the Muscles" to the right.
To truly understand the incredible degree of inter-connections that exist between the muscles of the rotator cuff, we must first understand their fascial inter-relationships. For example:
There are continuous planes of fascia (both superficial and deep) that connect multiple structures.
These fascia play important roles during force transmission and for neurological communication.
Think of these fascial connections as a three-dimensional web that connects multiple structures, often into areas that do not associate as being anatomically inter-connected.
Image: Stecco, Carla; Stecco, Carla. Functional Atlas of the Human Fascial System E-Book Elsevier Health Sciences. Note: If you are a practitioner, we highly recommend that you purchase the "Functional Atlas of the Human Fascial System"
For example, some of the deep shoulder fascia is formed from the connective tissue of two rotator cuff muscles (supraspinatus and infraspinatus).
This rotator cuff fascia directly connects into the neck (cervical spine), via two other muscles the levator scapulae and omohyoid muscles. Often patients will experience neck pain, but practitioners do not realize that the pain is caused by restrictions in the fascial connections within the muscles of the rotator cuff (or vice versa). (11)
This deep fascia of the shoulder also connects into the patient's chest (clavipectoral fascia) and even down their arm (short head of the biceps muscle and coracobrachialis muscle). Again when patients experience arm pain, the practitioners needs to realize that the cause may be due to restrictions in the shoulder structures. (11)
In addition, the deep shoulder fascia connects into the fascia that covers the ribs (serratus anterior). This connection could affect respiratory function. (11)
As practitioners learn to follow the fascial planes of force transmission, they will find that they are able to resolve even complex mechanical problems. Fascial connect is a key aspect of all MSR protocols and is covered in detail during our live 2-day MSR Courses. In these classes we teach practitioners how to identify these issues of both Local & Global Tensegrity.
ROTATOR CUFF INJURIES
Rotator cuff injuries are often caused by micro-trauma, degenerative changes, traumatic injuries (fall with outstretched hands, dislocations, etc.) and some secondary dysfunctions. (7,8,9)
The most common types of rotator cuff injuries include tears, tendinitis, tendinopathy, and impingement syndrome.
Higher incidences of rotator cuff tears occur in smokers, individuals with Type 1 Diabetes, inflammation of the joint capsule, frozen shoulder, rheumatoid arthritis, thyroid conditions, and patients with poor vascularization.
Symptoms of a Rotator Cuff Injury
Patients suffering from a Rotator Cuff Injury will often present with (7,8):
Pain when performing overhead activities or when the arm is placed in a forward flexed position.
Severe pain at time of injury, as well as at night
Positive Painful Arc Sign (The Painful Arc Test is used to identify a possible subacromial impingement (Note that this test is not definitive, as many orthopedics test are not but they lead you in a direction).
Weakness of specific torn muscle.
Pain related to specific location, for example Supraspinatus pain.
It is also common for patients to complain of clicking, catching, stiffness, and crepitus.
The pain the patient is experiencing should be defined in terms of:
Examination of the Rotator Cuff and Other Shoulder Injuries
Examination of the shoulder must include comprehensive orthopedic and neurological assessment. Diagnostic imaging is always indicated in traumatic cases, in cases that do not respond to manual therapy within a set period of time (3 to 6 weeks), and those in an aging population.
During the diagnosis of a shoulder injury:
It is critical that the clinician takes a comprehensive history whenever diagnosing any shoulder injury.
Always ensure that you are actually dealing with a musculoskeletal injury, and not dealing with a visceral disorder, or a serious or potentially life-threatening injury.
Shoulder injuries must be differentiated from other conditions, some of the differentials are (7,8,9):
Calcific Tendonitis of Shoulder.
Cervical nerve root injury, Cervical Radiculopathy, Cervical Spondylosis.
Glenohumeral ligament tears.
Glenoid labrum tear : Slap lesion, Bankart lesion.
Shoulder dislocation, in cases of trauma.
TOS (Thoracic Outlet Syndrome).
Orthopedic tests can be valuable for diagnosing a shoulder injury, while also aiding in ruling out other differentials.
Use the appropriate combination of test for your patient. Each test is linked to a specific video. Please be aware orthopedic testing has its limitations and often must be combined with appropriate imaging. That being said here are some common tests that we use in clinical practice.
Muscle Testing for the Shoulder
The follow video gives examples of muscle testing procedures that we recommend using during orthopedic evaluations.
It is extremely important to perform a through neurological examination. This examination should include:
Using Diagnostic Imaging
We recommend diagnostic imaging for your patients when indicated (based on patient history and physical examination) to rule out fractures (in all cases of trauma), infection, degenerative joint conditions, osteoporosis, and underlying pathology in chronic conditions that do not respond to conservative care.
MRI (Magnetic Resonance Imaging) can provide the best information from degeneration changes to partial or complete tears.
See the following links for useful information.
CONCLUSION - PART 3
The rotator cuff muscles are a common cause of shoulder pain. Remember that they do not function in isolation. Each rotator cuff originate from the shoulder blade, but they are only four out of 17 muscles that attach to the shoulder girdle. In turn, each each of these muscles is affected by fascial restrictions, joint dysfunction, and various neurological structures that innervate the shoulder.
Each case of shoulder injury should be assessed and treated as if it is a unique dysfunction, that is specific to that individual. Certain cases will only involve local structures, while other cases can involve a much larger kinetic chain. In Motion Specific Release (MSR) we use the terms Local Tensegrity to denote issues that are limited to a localized area, and Global Tensegrity for issues that involve the larger kinetic chain.
In the final blog of this 4-Part series, we will provide a logical framework for developing both the therapy and exercises that are required to effectively resolve a shoulder injuries.
REFERENCES - PART 3
Leffert RD, and G Gumley. (1987). The relationship between dead arm syndrome and thoracic outlet syndrome. Clin Orthop, 223, pp. 20-31.
Gerber C, and Ganz R. (1984). Clinical assessment of instability of the shoulder. J Bone Joint Surg Br, 66, pp. 551-556
Neer CS, and Welsh RP. (1977). The shoulder in sports. 8(3), pp. 583-591.
Kibler WB. (1998). The role of the scapula in athletic shoulder function.
Davies GJ, Gould JA, and Larson RL. (1981). Functional examination of the shoulder girdle. Phys Sports Med, 26(2), pp. 325-337. 9, pp. 82- 104.
Yergason RM. (1931). Supination sign. J Bone Joint Surg. 13, pp. 160.
Jobe FW, and Moynes DR. (1982). Delineation of diagnostic criteria and a rehabilitation program for rotator cuff injuries. 10(6), pp. 336-339.
Moseley HF. (1960). Disorders of the shoulder. Clin Symp
Boody SG, Freedman L, and Waterland JC. (1970). Shoulder movements during abduction in the scapular plane. Arcg Phy Med Rehabil, 12, pp. 1-30. 51(10), pp. 595-604.
Kuhn JE, Plancher KD, and Hawkins RJ. (1995). Scapular winging. J m Acad Orthop Surg, 3(6), pp 319-325
Stecco, Carla; Stecco, Carla. Functional Atlas of the Human Fasical System. Elsevier Health Sciences.
DR. BRIAN ABELSON DC.
Dr. Abelson is the developer of Motion Specific Release (MSR) Treatment Systems. His clinical practice in is located in Calgary, Alberta (Kinetic Health). He has recently authored his 10th publication which will be available later this year.
Dr. Abelson believes in running an Evidence-based, Patient-centered, Inter-professional and Collaborative clinical practice.
Kinetic Health strives to adhere to the best research evidence available, while combining clinical expertise with the specific values of each patient, in a inter-professional and collaborative care environment.
Dr. Abelson is the owner of Kinetic Health, a partner in BKAT Motion Specific Release, and a partner in Rowan Tree Books.