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									Chapter 14
The Shoulder Complex

   The shoulder is a complex set of
    articulations that work together
    toward the common goal of
    positioning the hand in space, which
    allows an individual to interact with
    the environment and to perform fine
    motor functions
   Although the entire shoulder complex
    functions as an integrated unit, it is
    anatomically simpler to describe each joint
    separately. The shoulder joint complex
    consists of:
    – Three bones (the humerus, the clavicle, and the
    – Three joints (the sternoclavicular (S-C), the
      acromioclavicular (A-C), and the glenohumeral
      (G-H) joints)
    – One “pseudojoint”
    – One physiological area

   Glenohumeral Joint
    – The glenohumeral (G-H) joint is a true
      synovial-lined diathrodial joint that
      connects the upper extremity to the
      trunk, as part of a kinetic chain
    – The GH joint is formed by the humeral
      head and the glenoid fossa of the scapula

   Glenoid fossa
    – The glenoid fossa is flat, but is made
      approximately 50% deeper and more
      concave by a ring of fibrocartilage called
      a labrum
    – The labrum, which forms part of the
      articular surface, is attached to the
      margin of the glenoid cavity and the joint
      capsule, and contributes to joint stability

   Scapula
    – The scapula forms the base of the G-H joint
    – It is a flat blade of bone that lies along the
      thoracic cage at 30° to the frontal plane, 3°
      superiorly relative to the transverse plane, and
      20° forward in the sagittal plane
    – The scapula’s wide and thin configuration allows
      for its smooth gliding along the thoracic wall,
      and provides a large surface area for muscle
      attachments both distally and proximally
   Scapula
    – A prominent feature of the scapula in man is the
      large overhanging acromion, which, along with
      the coracoacromial ligament functionally
      enlarges the glenohumeral socket
    – The position of the acromion also places the
      deltoid muscle in a dominant position to provide
      strength during elevation of the arm
    – Although the acromion appears to be flat, three
      types of acromion morphology have been
      described, of which the hooked is associated
      with an increase in rotator cuff pathology
   Joint capsule
    – The voluminous joint capsule of the
      glenohumeral joint allows for large amounts of
      motion to occur at the G-H joint
    – The lateral attachment of the glenohumeral joint
      capsule attaches to the anatomical neck.
    – Medially, the capsule is attached to the
      periphery of the glenoid and its labrum
    – The overall strength of the joint capsule bears
      an inverse relationship to the patient’s age: the
      older the patient, the weaker the joint capsule
   The greater and lesser tuberosities
    – Located on the lateral aspect of the anatomical neck of the
    – Serve as attachment sites for the tendons of the rotator
      cuff muscles
    – The greater tuberosity serves as the attachment for the
      supraspinatus, infraspinatus and teres minor
    – The lesser tuberosity serves as the attachment for the
    – The greater and lesser tuberosities are separated by the
      intertubercular groove, through which passes the tendon
      of the long head of the biceps on its route to attach on the
      superior rim of the glenoid fossa
   The glenohumeral ligaments
    – At the anterior portion of the outer fibers of the
      joint capsule, three local reinforcements are
      present: the superior, middle and inferior G-H
      ligaments (>Z= ligaments)
          Superior - serves to limit external rotation and inferior
           translation of the humeral head with the arm at the
          Middle - serves to limit external rotation (Table 14-5)
           and anterior translation of the humeral head with the
           arm in 0° and 45° of abduction
          Inferior - consists of an anterior band, a posterior
           band, and an axillary pouch with varying functions

   The coracohumeral ligament
    – Covers the superior G-H ligament
      anterior-superiorly, and fills the space
      between the tendons of the
      supraspinatus and subscapularis muscle;
      uniting these tendons to complete the
      rotator cuff in this area

   The coracoacromial ligament
    – Consists of two bands that join near the
      acromion and is ideally suited, both
      anatomically and morphologically, to
      prevent separation of the A-C joint
   Coracoacromial Arch
    – Formed by the anterior-inferior aspect of the
      acromion process, coracoacromial ligament, and
      inferior surface of the A-C joint
          During overhead motion in the plane of the scapula,
           the supraspinatus tendon, the region of the cuff most
           involved in the degenerative process, can pass directly
           underneath the coracoacromial arch
          If the arm is elevated while internally rotated, the
           supraspinatus tendon passes under the coracoacromial
           ligament, whereas if the arm is externally rotated, the
           tendon passes under the acromion itself

   Suprahumeral/subacromial space
    – An area located on the superior aspect of
      the G-H joint
    – Contents include the long head of biceps
      tendon, supraspinatus and upper margins
      of subscapularis and infraspinatus,
      subdeltoid-subacromial bursa
    – The space is at its narrowest between 60°
      and 120° of scaption

   The subacromial bursa
    – One of the largest bursa in the body
    – Provides two smooth serosal layers; one
      of which adheres to the overlying deltoid
      muscle and the other to the rotator cuff
      lying beneath

   Neurology
    – The shoulder complex is embryologically
      derived from C 5-8, except the A-C joint,
      which is derived from C 4. The
      sympathetic nerve supply to the shoulder
      originates primarily in the thoracic region
      from T 2 down as far as T 8

   Vascularization
    – The vascular supply to the rotator cuff
      muscles of the shoulder consists of three
      main sources: the thoracoacromial,
      suprahumeral, and subscapular arteries
    – The brachial artery provides the dominant
      arterial supply to each of the two heads
      of the biceps

   Glenohumeral joint
    – Close packed position
          The close packed position for the G-H joint is 90° of
           glenohumeral abduction and full external rotation; or
           full abduction and external rotation, depending on the
    – Open packed position
          Without internal or external rotation occurring, the
           open packed, or rest position of the G-H joint has
           traditionally been cited as 55° of semi-abduction and
           30° of horizontal adduction

   Glenohumeral joint
    – Capsular pattern
          According to Cyriax, the capsular pattern for
           the shoulder is external rotation the most
           limited, abduction the next most limited, and
           internal rotation the least limited in a 3:2:1
           ratio respectively

   The acromioclavicular joint
    – The acromioclavicular (A-C) joint is a
      diarthrodial joint, formed by the acromion
      and the lateral end of the clavicle
    – The joint serves as the main articulation
      suspending the upper extremity from the
      trunk, and it is at this joint about which
      the scapular moves

   Acromioclavicular joint
    – The articulating surface of the lateral end
      of the clavicle can be either convex or
      concave and corresponds with the
      articulating surface of the acromion.
      Consequently, although the joint is
      described as a planar joint, there is often
      a male-female relationship, with 3
      degrees of freedom

   A-C ligaments
    – The coracoclavicular ligaments (conoid
      and trapezoid) are the primary support
      for the A-C joint
    – These ligaments provide mainly vertical
      stability, with control of superior and
      anterior translation as well as anterior
      axial rotation

   A-C joint
    – Neurology. Innervation to this joint is
      provided by the suprascapular, lateral
      pectoral, and axillary nerves
    – Capsular pattern. Lacks a true capsular
    – Close and open packed positions.

   Sternoclavicular (S-C) joint
    – Represents the articulation between the medial
      end of the clavicle, the clavicular notch of the
      manubrium of the sternum, and the cartilage of
      the first rib, which forms the floor of the joint
    – Has been classified as a ball and socket joint, a
      plane joint, and as a saddle joint
    – A meniscus completely divides the joint into two

   Sternoclavicular (S-C) joint
    – Ligaments. A number of ligaments
      provide support to this joint:
        Anterior sternoclavicular ligament
        Posterior sternoclavicular ligament

        Interclavicular

        Costoclavicular

   Sternoclavicular (S-C) joint
    – Close packed position. The close packed position
      for the S-C joint is maximum arm elevation and
    – Open packed position. The open packed position
      for the S-C joint has yet to be determined, but is
      likely to be when the arm is by the side
    – Capsular pattern. Lacks a specific capsular

   Scapulothoracic Joint
    – Functionally a joint but it lacks the
      anatomic characteristics of a true synovial
    – Plays a significant role in all motions of
      the shoulder complex

   Muscles of the Shoulder Complex
    – For simplicity, the muscles acting at the
      shoulder may be described in terms of
      their functional roles: scapular pivoters,
      humeral propellers, humeral positioners,
      and shoulder protectors

   Muscles of the Shoulder Complex
    – Scapular pivoters
       Comprise the trapezius, serratus anterior,
        levator scapulae, rhomboid major, and
        rhomboid minor
       As a group, these muscles are involved with
        motions at the scapulothoracic articulation,
        and their proper function is vital to the
        normal biomechanics of the whole shoulder

   Muscles of the Shoulder Complex
    – Humeral propellers
         Comprise the latissimus dorsi, pectoralis
          major, and pectoralis minor

   Muscles of the Shoulder Complex
    – Humeral positioners. Comprised of the
      three parts of the deltoid muscle

   Muscles of the Shoulder Complex
    – Shoulder protectors
       Rotator cuff
       Biceps brachii

   Complete movement at the shoulder girdle
    involves a complex interaction between the
    glenohumeral, acromioclavicular,
    sternoclavicular, scapulothoracic, upper
    thoracic, costal and sternomanubrial joints,
    and the lower cervical spine
   During these motions, the scapula invariably
    acts as a platform upon which shoulder
    rotation and arm activities are based

   The Scapulohumeral Rhythm
    – The combination and synchronization of the
      motions that occur between the scapula and the
      humerus during arm elevation
    – An early study by Inman determined that a 2:1
      ratio existed between the motion occurring at
      the G-H joint and scapula respectively
    – This ratio is not consistent throughout the range
      of motion

   Force couples
    – During the first 30° of upward rotation of the
      scapula, the serratus anterior muscle and the
      upper and lower divisions of the trapezius
      muscle are considered the principal upward
      rotators of the scapula
          Together these muscles form two force couples; one
           formed by the upper trapezius, and the upper serratus
           anterior muscles, the other formed by the lower
           trapezius, and lower serratus anterior muscles
   In the presence of shoulder girdle
    dysfunction (assuming systemic or
    orthopedic causes have been ruled out),
    there are three possible causes for shoulder
    girdle dysfunction
    – Compromise of the passive restraint components
      of the shoulder girdle
    – Compromise of the neuromuscular system’s
      production or control of shoulder girdle motion
    – Compromise to one or more of the of the
      neighboring joints that contribute to shoulder

   History
    – A good history is the cornerstone of proper
      diagnosis, especially since shoulder pain has a
      broad spectrum of patterns and characteristics
    – It is important to establish the patient’s chief
      presenting complaint (which is not always pain)
      as well as defining their other symptoms. The
      most common complaints associated with
      shoulder pathology include pain, instability,
      stiffness, deformity, locking, and swelling

   Systems review
    – Symptoms that are not associated with
      movement should alert the clinician to a
      more serious condition
    – Scenarios related to the shoulder that
      warrant further investigation by the
      clinician include an insidious onset of
      symptoms, and complaints of numbness
      or paresthesia in the upper extremity

   Observation
    – The clinician observes how the patient holds the
      arm, the overall position of the upper extremity,
      and the willingness of the patient to move the
    – Deformity is a common complaint with injuries of
      the A-C joint and fractures of the clavicle
    – A number of static tests for the scapular position

   Palpation
    – The optimal methods of palpating the shoulder
      tendons occur in regions where there is the least
      amount of overlying soft tissue
    – It is best to divide the shoulder complex into
      compartments for palpation
    – Symptoms reproduced by palpation in these
      compartments are frequently associated with a
      specific underlying pathology
   AROM, PROM with overpressure
    – McClure and Flowers classify limited shoulder
      motion into two categories:
          Decreased ROM secondary to changes in the
           periarticular structures, including shortening of the
           capsule, ligaments, or muscles as well as adhesion
           formation. Clinical findings for this category include a
           history of trauma, immobilization, presence of a
           capsular pattern, capsular end-feel, and no pain with
           the isometric testing
          Decreased ROM due to nonstructural problems,
           including the presence of pain, protective muscle
           spasm, or a loose body within the joint space. Clinical
           findings for this patient include a history of trauma or
           overuse, and the presence of a non-capsular pattern

   Examination of the Dynamic Scapula
    – Given the importance of the
      scapulothoracic joint to overall shoulder
      function, it is important to examine the
      scapulothoracic joint arthrokinematics,
      and muscle power

   Strength testing
    – Localized, individual isometric muscle
      tests around the shoulder girdle can give
      the clinician information about patterns of
      weakness other than from spinal nerve
      root or peripheral nerve palsies e.g.,
      instabilities, postural dysfunction, and
      also help to isolate the pain generators

   Examination of Movement Patterns
    – These tests are concerned with the
      coordination, timing, or sequence of
      activation of the muscles during

   Functional Testing
    – The assessment of shoulder function is an
      integral part of the examination of the
      shoulder complex
    – The term shoulder function can include
      tests for biomechanical dysfunction and
      tests assessing the patient’s ability to
      perform the basic functions of activities of
      daily living

   Other test for the shoulder complex
    – Muscle Length Tests
    – Examination of the passive restraint
      system and neighboring joints
    – Special Tests
    – Diagnostic and imaging studies
   Acute phase goals:
    – Protection of the injury site
    – Restoration of pain-free range of motion in the
      entire kinetic chain
    – Improve patient comfort by decreasing pain and
    – Retard muscle atrophy
    – Minimize detrimental effects of immobilization
      and activity restriction
    – Maintain general fitness
    – Patient to be independent with home exercise

   Functional phase goals:
    – Attain full range of pain free motion
    – Restore normal joint kinematics
    – Improve muscle strength to within normal
    – Improve neuromuscular control
    – Restore normal muscle force couples

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