Chapter 14
The Shoulder Complex
Overview

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
Anatomy

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
scapula)
– Three joints (the sternoclavicular (S-C), the
acromioclavicular (A-C), and the glenohumeral
(G-H) joints)
– One “pseudojoint”
– One physiological area
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

The greater and lesser tuberosities
– Located on the lateral aspect of the anatomical neck of the
humerus
– 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
subscapularis
– 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
Anatomy

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
side
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
Anatomy

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
Anatomy

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
surfaces
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
source
– 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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

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
Anatomy

A-C joint
– Neurology. Innervation to this joint is
provided by the suprascapular, lateral
pectoral, and axillary nerves
– Capsular pattern. Lacks a true capsular
pattern
– Close and open packed positions.
Undetermined
Anatomy

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
cavities
Anatomy

Sternoclavicular (S-C) joint
– Ligaments. A number of ligaments
provide support to this joint:
Anterior sternoclavicular ligament
 Posterior sternoclavicular ligament
 Interclavicular
 Costoclavicular

Anatomy

Sternoclavicular (S-C) joint
– Close packed position. The close packed position
for the S-C joint is maximum arm elevation and
protraction
– 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
pattern
Anatomy

Scapulothoracic Joint
– Functionally a joint but it lacks the
anatomic characteristics of a true synovial
joint
– Plays a significant role in all motions of
the shoulder complex
Anatomy

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
Anatomy

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
complex

Anatomy

Muscles of the Shoulder Complex
– Humeral propellers

Comprise the latissimus dorsi, pectoralis
major, and pectoralis minor
Anatomy

Muscles of the Shoulder Complex
– Humeral positioners. Comprised of the
three parts of the deltoid muscle
Anatomy

Muscles of the Shoulder Complex
– Shoulder protectors
Rotator cuff
 Biceps brachii

Biomechanics


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
Biomechanics

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
Biomechanics

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
Examination

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
girdle
Examination

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
Examination

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
Examination

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
arm
– 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
exist
Examination

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
Examination

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

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
Examination

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

Examination of Movement Patterns
– These tests are concerned with the
coordination, timing, or sequence of
activation of the muscles during
movement
Examination

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
Examination

Other test for the shoulder complex
include:
– Muscle Length Tests
– Examination of the passive restraint
system and neighboring joints
– Special Tests
– Diagnostic and imaging studies
Intervention

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
inflammation
– Retard muscle atrophy
– Minimize detrimental effects of immobilization
and activity restriction
– Maintain general fitness
– Patient to be independent with home exercise
program
Intervention

Functional phase goals:
– Attain full range of pain free motion
– Restore normal joint kinematics
– Improve muscle strength to within normal
limits
– Improve neuromuscular control
– Restore normal muscle force couples