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Student ID: 1055468
Student Number
1055468
Name of lecturer
Jim Odell
Assignment Title
“Evaluate the structure and function of the shoulder
girdle with particular attention to essential
movements that occur in lateral flexion of the arm
and the role of various structures in enabling this
movement.
Discuss two shoulder pathologies of your choice.
Outline the structures affected and appraise the
impact this would have on lateral flexion of the arm
and how a Chiropractor may help in management
of your chosen pathologies”.
Module Number/Name
Year 2: Biomechanics
Word Count
Word Count 1,649
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Student ID: 1055468
Introduction
This essay will examine the structures of the shoulder joint and girdle, and the
dynamics responsible for creating lateral flexion at the glenohumeral joint,
while briefly discussing the movements simultaneously occurring at other
related articulations. Two conditions that notably affect lateral flexion, the
symptoms and consequences of each, and how Chiropractic may possibly
assist in recovery will also be explored.
Structure and Function of Shoulder joint + Lateral flexion and its
components.
The shoulder is regarded as the most complex joint in the human body (Hall,
2012) largely because it includes five separate articulations: the glenohumeral
joint (GHJ), the sternoclavicular joint, the acromioclavicular joint, the
coracoclavicular joint, and the scapulothoracic joint. The biomechanical
interaction of these five joints, their associated muscles, ligaments, cartilage,
capsule and soft tissue, make up what is commonly referred to as the
‘shoulder girdle’.The glenohumeral joint (GHJ) - the articulation between the
head of the humerus and the glenoid fossa of the scapula (which is a ball and
socket synovial joint) - is typically considered the major shoulder joint (Hall,
2012). The GHJ is has the greatest range of motion of any joint in the body
(Sanderson & Odell, 2012, pp.45) (see Appendix 1). While it is considered as
a joint in its own right, the GHJ is intricately linked with the sternoclavicular
and acromioclavicular joints, which contribute to specific and overall arm
movement.
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Flexion describes the movement that occurs at the GHJ when the arm is
raised in an anterior (forward) or lateral (outward) direction, resulting in a
typical degree range of 120 degrees for anterior flexion and 150 degrees for
lateral flexion (McHardy, et al., 2008). “The muscles crossing the
glenohumeral joint anteriorly participate in flexion at the shoulder. The prime
flexors are the anterior deltoid and the clavicular portion of the pectoralis
major. The small coracobrachialis assists with flexion, as does the short head
of the biceps brachii” (Hall, 2012) (see Appendix 2) Additional movements that
also occur at the shoulder girdle in conjuction with the GHJ are elevation and
upward rotation (initiated by upper trapezius and levator scapula activation).
Lateral ‘flexion’ of the arm and shoulder involves the GHJ and several key
muscles, notably the middle portion of the deltoid, the upper trapezius, and
the supraspinatus, one of the four rotator cuff muscles (which is involved in
the first ten to fifteen degrees of abduction) (Ticker & Warner, 1997) (see
Appendix 3).
Because of the anatomical complexity of the shoulder muscles and ligaments
that support a multitude of articulations, a greater risk of trauma exists through
anatomical wear and tear of muscles and ligaments and / or injury. The
supraglenoid fossa in particular is an anatomical weak point in the shoulder .
Its vulnerability to pathology or dysfunction means a greater risk of
impingement syndrome or supraspinatus tears (Keener, et al, 2009) (see
Appendix 4).
Pathology 1)
Shoulder Impingement Syndrome (SIS)
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Shoulder Impingement Syndrome (SIS) is a very common cause of shoulder
pain in presenting patients (Souza, 2001). SIS occurs when there is
impingement of any structures (such as the supraspinatus tendon or sub
acromial bursa) that pass through the coraco-acromial arch (Will, 2005), the
passageway formed by the union between the acromion and the coracoid
processes. The causes are thought to be pathological variations in structure,
such as sub-acromial spurs, or traumatic events, e.g. resulting from repetitive
overhead movements in some job roles and in some sports (painting, lifting,
swimming, tennis), resulting in conditions such as tendinitis or strains of the
supraspinatus tendon (Ticker & Warner, 1997). Faulty mechanics of the
shoulder, often caused by muscle imbalances, are another contributing factor
(Hall, 2012).
There is often a painful ‘arc’, a portion of anterior and or lateral flexion of the
GHJ, which provokes symptoms due to the approximation of irritated
structures. Thus movement of the GHJ is notably reduced and the function of
the shoulder is compromised on many levels. Diagnostically, orthopedic tests
specific to shoulder impingement (Hawkins Kennedy test) can be performed
to alert the clinician to the possibility of the condition. Plain film radiographs
(x-rays) may be used to rule out concurrent conditions such as calcific
tendinitis, calcific bursitis, and degenerative changes of the glenohumeral and
acromio-clavicular articulations. However, neither of these options is as
definitive as an MRI scan where evidence of possible soft tissue involvement
and other contributing factors such as hypertrophy associated with Shoulder
Impingement Syndrome (Morrison, Frogameni, & Woodworth, 1997) can be
analysed in greater detail. Imaging findings are also more sensitive in the
detection of anatomical impingement as compared to manual tests, although
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history and physical examination are often sufficient to detect the presence of
functional pathology (McHardy, et al., 2008).
Pathology 2
Rotator Cuff Tear (Supraspinatus)
Muscle tears (strains) are divided into three categories based on the severity
of damage sustained. Grade one involves pain and minimal tearing of muscle
fibres, grade two involves substantial pain and significant tearing of muscle
fibres, and grade three is a complete rupture (Fongemie, Buss & Rolnick,
1998). The rotator cuff is a group of four muscles (supraspinatus,
infraspinatus, teres minor, and subscapularis) that connect the humerus to the
scapula and articulate its movements(Ticker & Warner, 1997). The
supraspinatus, so termed as it is found above (supra) the ‘spine’ (bony
prominence) located on the posterior aspect of the scapula, is the most
frequently torn of the four (Ticker & Warner, 1997). Activities that involve
forceful hyperextension or external rotation of an adducted arm are thought to
cause this pathology (Ticker & Warner, 1997). These may include repeated
overhead movements such as those found in tennis, badminton, or squash
(Ticker & Warner, 1997). Other mechanisms that may lead to a supraspinatus
tear include loading the muscle beyond its limit, or creating explosive
movement under strain, e.g. in performing shoulder shrugs with excessive
dumb-bell weight in the hands. The pain pattern is persistent and present in
the arm in both lower and higher ranges of shoulder abduction (Ticker &
Warner, 1997).
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Effect on lateral flexion and how this may be assisted with chiropractic
treatment.
“Studies indicate conservative management of shoulder impingement
syndrome results in resolution of symptoms in 70-90% of patients (Morrison,
Frogameni & Woodworth, 1997). Conservative clinical management in
chiropractic may include the use of ice or cold packs (cryotherapy),
adjustments, soft tissue work, and muscular rehabilitation. Over 3 quarters of
Chiropractors use full spine and extremity manipulation management
protocols, highlighting the presence of treatment techniques for peripheral
joint problems (McHardy, et al., 2008).
Impingement syndrome results in limited anterior and lateral flexion capability
due to the irritation of either subacromial bursa and / or an inflamed
supraspinatus tendon, thus reducing the range from typically 120° anteriorly
and 150° laterally to becoming painful between 60° to 120° anteriorly and 60°
to 90° laterally (Warner et al, 1992). Tears of the supraspinatus are not as
limiting as shoulder impingement syndrome because the supraspinatus’s
primary role is to initiate the first ten to fifteen degrees of abduction, after
which the deltoid and other synergistic shoulder muscles take over (Ticker &
Warner, 1997).
Chiropractors may utilise ice or cold packs as part of the clinical management
of patients with shoulder inflammation to assist pain relief and reduction in
swelling. Typical application time of cold packs to the affected area is in a
range of 10 to 15 minutes, with a gap of at least an equivalent time after use
to allow ordinary blood-flow to re-establish before again applying a cold pack
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(Fongemie & Rolnick, 1998). When evaluating the shoulder, the emphasis
must always be on the whole shoulder girdle complex and not simply on the
‘shoulder’ or the glenohumeral joint (Sanderson & Odell, 2012). Therefore, the
entire shoulder girdle (including the upper rib cage) should be evaluated.
Dysfunctions through the costovertebral joints (ribs) can be responsible for
faulty scapula movement patterns due to muscular cross-links, and therefore
must be checked (Warner et al, 1992). Subluxations in the lower cervical and
upper thoracic region, by inference, may also have an effect on the patient’s
ability to laterally flex (abduct) the arm, and should be corrected by
chiropractic adjustive techniques (Souza, 2001). Additionally, the nerves from
the cervical region (or neck) innervate the shoulder muscles. Chiropractic
treatment of cervical subluxations and their potential neurological interference
is essential to ensuring proper musculoskeletal function of the shoulder girdle
(McHardy, et al., 2008). Shoulder mobilisations are thought to be effective in
both impingement syndrome and supraspinatus tears. Mobility of the shoulder
is crucial to initiating the rehabilitation process. Shoulder mobilizations that
increase the subacromial space may be helpful in shoulder impingement
(longitudinal traction), whereas those that reduce faulty anterior positioning of
the GHJ in response to protective muscle spasm patterns (notably as anterior
deltoid and pecs) (Keener, et al, 2009) such as anterior to posterior
movements may be helpful in supraspinatus tears.
Shoulder rehabilitation is absolutely essential in correcting an impingement
syndrome and in returning damaged muscle fibers of a supraspinatus muscle
to relative flexibility and strength. The primary causes of both these problems
need to be corrected and this correction facilitated through the rehabilitation
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process. Rehabilitation focuses on strengthening the shoulder and back
muscles (rhomboids, external rotators, middle fibers of trapezius, post deltoid,
back extensors) (Morrison et al., 1997) increasing flexibility in the neck
(through soft tissue and adjustive methods), chest and arm muscles (though
targeted stretches), evaluating and correcting any breathing or respiratory
dysfunctions (through postural retraining), and working on re-establishing
normality in the neurological component of the shoulder girdle (through
movement alteration exercises). Impingement syndrome involving
pathological components (i.e. bone spurs), or in cases involving extensive
damage, then the supraspinatus may require surgical intervention in place of
conservative care.
Conclusion
The shoulder joint is the most complex joint in the body. Due in part to its
many articulations with other joints in the body, it is susceptible to dysfunction
and injury. Two pertinent conditions that affect lateral flexion of the shoulder
are impingement syndrome and supraspinatus tears. These both create pain
and limitations in movement, notably lateral flexion. Chiropractic may assist in
a range of shoulder cases using adjustive techniques, specific shoulder
mobilizations, cryotherapy as well as targeted rehabilitation programmes that
look to address strength and flexibility deficits.
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References
Fongemie, A., Buss, D., Rolnick, S.,1998. Management of shoulder
impingement syndrome and rotator cuff tears. American Family Physician, 57
(4): 667–74, 680–2.
Hall, S. 2012. Basic Biomechanics (6th ed). McGraw-Hill.
Keener, J., Wei, A., Kim, M., May, K., Yamaguchi, K.,2009. Proximal Humeral
Migration in Shoulders with Symptomatic and Asymptomatic Rotator Cuff
Tears. Journal of Bone and Joint Surgery, 91 (6): 1405-1413.
Maitland, G.,1984. Vertebral Manipulation (4th ed). Butterworth & Co.
McHardy, A., Hoskins, W., Pollard, H., Onley, R., Windsham, R., 2008.
Chiropractic Treatment of Upper Extremity Conditions: A Systematic Review.
Journal of Manipulative and Physiological Therapeutics, 31: 146-159.
Morrison, D., Frogameni, A., Woodworth, P.1997. Non – operative treatment
of subacromial impingement syndrome. Journal of Bone and Joint Surgery, 79
(5): 732-7.
Sanderson, M., Odell, J.,2012. The Soft Tissue Release Handbook; Reducing
Pain and Improving Performance. Lotus Publishing.
Souza, T.,2001. Differential Diagnosis and Management for the Chiropractor,
protocols and algorithms. Aspen Publishers.
Ticker, J., Warner, J.,1997. Single Tendon Tears of The Rotator Cuff.
Orthopaedic Clinics of North America, vol 28 (1): 99-116.
Warner, J., Michelli, L., Arslanian, L., Kennedy, J., Kennedy, R. (1992).
Scapulothoracic Motion in Normal Shoulders and Shoulders with
Glenohumeral instability and Impingement Syndrome: A study using moire
topographic analysis. Clinical Orthopaedics and Related Research, vol 285.
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Appendix: I
Shoulder Girdle Complex
SANDERSON, M. AND ODELL, J.
Shoulder girdle complex. Illustration.
In-text: (Sanderson and Odell)
Bibliography: Sanderson, Mary, and Jim Odell. Shoulder girdle complex. 2012. Print
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Appendix: II
Shoulder Girdle Muscles
SANDERSON, M. AND ODELL, J.
Shoulder girdle muscles. Illustration.
In-text: (Sanderson and Odell)
Bibliography: Sanderson, Mary, and Jim Odell. Shoulder girdle muscles. 2012. Print
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Appendix: III
Gross Observational Movements
SANDERSON, M. AND ODELL, J.
Gross Observational Movements. Illustration.
In-text: (Sanderson and Odell)
Bibliography: Sanderson, Mary, and Jim Odell. Gross observational movements. 2012. Print
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Appendix: IV
Muscle Movement at the Shoulder Girdle
SANDERSON, M. AND ODELL, J.
Muscle movement at the shoulder girdle. Table.
In-text: (Sanderson and Odell)
Bibliography: Sanderson, Mary, and Jim Odell. Muscle movement at the shoulder girdle.
2012. Print
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