Download THE SHOULDER JOINT

THE SHOULDER JOINT
Learning Objectives
At the end of the presentation, the student should be able to :
 Classify the type of shoulder joint.
 Describe the structure of shoulder joint.
 Name the muscles acting on the joint/rotator cuff muscles.
 Explain the range of motion.
 Let know the movements of shoulder joint.
 What is clinical aspect of the structure?
THE SHOULDER JOINT
LECTURE OUTLINE
The Human Shoulder:
The shoulder is a highly mobile joint that allows large range of motion in
all planes to provide a variety of overhead activities.
The shoulder complex as a whole is unique in that it
relies very little on bony and ligamentous structures for
stability - with a majority of support coming from 18
muscles acting on the shoulder complex.
The Shoulder Joint:
 Multiaxial spheroidal joint.
 Skeletally
the
joint
is
weak,
depends
for
support
on
surrounding muscles more than on
its shape and ligaments.
 Articular
surfaces;
spheroidal
humeral head and concave glenoid
cavity.
 Glenoid
labrum
deepens
the
cavity..
 Both articular surfaces are covered
with hyaline cartilage.
 Wide
range of motion of the
shoulder joint in many different
planes require a significant amount
of laxity.
 The price of mobility is reduced stability.
 The more mobile a joint is, the less stable it is & the more stable it is the
less mobile.
Factors Stabilizing The Joint:
Coracoacromial arch or Secondary socket for the head of humerus.
Glenoid labrum.
Musculotendinous cuff of the shoulder.
Ligaments:
CAPSULAR LIGAMENT.
CORACOHUMERAL LIGAMENT.
TRANSVERSE HUMERAL
LIGAMENT.
GLENOID LABRUM.
Articular Capsule Of The Glenohumeral Joint:
The loose fibrous capsule surrounds the glenohumeral joint and is
attached medially to the margin of the glenoid
cavity and laterally to the anatomical neck.
Superiorly this part of the articular capsule
encroaches on the root of the coracoid process so
that the fibrous capsule encloses the proximal
attachment of the long head of the biceps brachii supraglenoid tubercle of the scapula - within the
joint. The capsule is lined with synovial membrane
which forms a tubular sheath for tendon of biceps.
Ligaments Of The Glenohumeral Joint:
The coracohumeral ligament is a strong, broad band
that passes from the base of the coracoid process to
the anterior aspect of the greater tubercle of the
humerus. This ligament resists the pull of gravity
and limits external rotation of the shoulder.
The glenohumeral (shoulder) ligaments, which strengthen the anterior
aspect of the articular capsule of the joint, and the coracohumeral
ligament, which strengthens the capsule superiorly, are intrinsic ligaments
- part of the fibrous capsule.
The glenohumeral ligaments are three fibrous bands - evident only on the
internal aspect of the capsule - that reinforce the anterior part of the
articular capsule.
They radiate laterally and inferiorly from the glenoid
labrum at the supraglenoid tubercle of the scapula and blend distally with
the fibrous capsule as it attaches to the anatomical neck of the humerus.
Superior Glenohumeral Ligament
 From Upper origin of the glenoid.
 To Anatomical neck of the humerus.
This ligament is taut during external rotation
and plays a small role in the stability of the
shoulder.
Middle Glenohumeral Ligament
 From Upper origin of the glenoid
 To Humerus
This ligament is taut during external rotation
and plays a small role in stability of the
shoulder.
Inferior Glenohumeral Ligament :
 Anterior edge of glenoid
 Below the head of the humerus
This ligament is taut during external rotation, and plays a small role in
stability of the shoulder.
 The transverse ligament is not a “true” ligament of the joint.
 It is a broad fibrous band that runs more or less obliquely from the
greater to the lesser tubercle of the humerus, bridging over the
intertubercular groove.
 This ligament keeps the biceps tendon in its groove during movements.
Glenoid labrum:
 Fibrocartilagenous rim which deepens the glenoid
cavity.
 Slightly enhances stability.
Glenohumeral Joint:
 Frequently injured due to anatomical design:
– Shallowness of glenoid fossa.
– Laxity of ligamentous structures.
– Anterior or anteroinferior glenohumeral
subluxations & dislocations –
common.
– Posterior dislocations – rare.
– Posterior instability problems somewhat common.
Bursae:
 Subacromial bursa(subdeltoid bursa)
 Subcapsular bursa, communicates with the
joint cavity.
 Others related to corachobrachialis, long
head of triceps.
Rotator cuff muscles:
 Take origin from scapula and inserted
to greater and lesser tubercles of
humerus.
 Their tendons become flattened and
blend with each other and the capsule
while crossing the joint.
Supraspinatus:
O: Supraspinous fossa.
I: Superior facet on greater tubercle of humerus.
A: Initiates and assists Deltoid in abduction; acts
with other rotator cuff muscles.
N: Suprascapular Nerve.
Infraspinatus:
O: Infraspinous fossa.
I: Middle facet on greater tubercle of humerus.
A: Laterally rotates the arm.
N: Suprascapular Nerve.
Teres minor:
O: Superior part of the lateral border of the scapula
I: Inferior facet on greater tubercle of humerus
A: Laterally rotates the arm
N: Axillary Nerve
Subscapularis:
O: Subscapular fossa.
I: Lesser tubercle of humerus.
A: Medial rotation of arm and adduction.
N: Upper and Lower Subscapular.
Movements:
 Abduction:
– upward lateral movement of humerus out to the
side, away from body
 Adduction:
– downward movement of humerus medially toward
body from abduction
• Flexion:
– movement of humerus straight anteriorly.
• Extension:
– movement of humerus straight posteriorly.
• Horizontal adduction (transverse flexion):
– movement of humerus in a horizontal or
transverse plane toward & across chest.
• Horizontal abduction (transverse extension):
– movement of humerus in a horizontal or
transverse plane away from chest
• External rotation:
– movement
of humerus laterally around its long
axis away from midline
• Internal rotation:
– movement of humerus medially around its
long axis toward midline.
Muscles:
• Anterior:
– Pectoralis major
– Corachobrachialis.
– Subscapularis.
• Superior:
– Deltoid.
– Supraspinatus.
Deltoid Muscle:
Anterior fibers: abduction, flexion, horizontal adduction, & internal rotation.
Posterior
fibers:
abduction,
extension, horizontal abduction, &
external rotation.
Middle fibers: abduction
Pectoralis Major Muscle:
Upper fibers (clavicular head): internal rotation, horizontal adduction,
flexion, abduction (once arm is abducted 90 degrees, upper fibers assist
in further abduction), &
adduction (with arm below
90 degrees of abduction).
Lower fibers (sternal head):
internal rotation, horizontal
adduction, extension, &
adduction
Latissimus Dorsi Muscle:
Adduction.
Extension.
Internal rotation.
Horizontal abduction.
Coracobrachialis Muscle:
Flexion.
Adduction.
Horizontal adduction
Rotator Cuff Tendonitis:
 Rotator cuff tendonitis, also knows as
"BURSITIS"
OR
"IMPINGEMENT
SYNDROME"
OCCURS
WHEN
THE
ROTATOR CUFF GETS irritated on the
undersurface of the acromion.
Chief
complaints are pain, popping, weakness
and the inability to sleep on the affected
limb.
Rotator Cuff Tear:
A rotator cuff tear occurs when the
tendonitis in the rotator cuff gets so bad
that it wears a hole through the rotator cuff
tendon. It can be acute or chronic. Chief
complaints are pain, popping, stiffness,
weakness, and inability to sleep on the
affected limb.
Frozen shoulder:
•
No visible abnormality detected on X-RAYS.
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