Functional Anatomy of the Upper Extremity

KINE 3050

The design of the shoulder complex is related to what?

directly to the overall function of the upper limb 

What are the 3 articulations and 1 mechanism of the shoulder

1. Strenoclavicular Joint

2. Acromioclavicular Joint

3. Glenohumeral Joint

1. Scaupulothoracic Mechanism 

The shoulder joint mechanism allows what?

placement, function and control of hand directly in front of the body

Shoulder movement involves integration of

static and dynamic stabilizers

The Sternoclavicular Joint articulation is?

Synovial

The Sternoclavicular Joint function resembles a

ball and socket articulation

The Sternoclavicular Joint articular surfaces lack?

congruity 

The Sternoclavicular Joint articular disc separates what?

the joint into the superior and inferior compartment

In the Sternoclavicular Joint, the medial end of the clavicle attaches to what?

first rib and costal cartilage

The Sternoclavicular Joint​ stabilizing structures function to ?

• Resist the tendency for medial displacement of the clavicle​

• Limit the clavicular component of arm movement via the articular disc and the costoclavicular ligament ​

The Sternoclavicular Joint​ articular disc and its attachment function as a?

hinge

• Stabilizes the joint against applied forces to the shoulder that are transmitted medially through the clavicle to the axial skeleton​

In the Sternoclavicular Joint​, areas of compression are between?

articular surfaces and intra-articular discs vary clavicular motion

The clavicle does what?

Elevates, Depresses, Protracts, or Retracts

• Elevation & depression → motion between clavicle & disc​ (shoulder shrugs)

• Protraction & retraction → motion between disc & sternal end​ ( Rows )

In the Sternoclavicular Joint​, ligaments are on same side are ____________ and opposite side are _________?

lax ; taut

Forces acting on the clavicle from the upper limb

rarely cause dislocation of the sternoclavicular joint

Excess applied force to the clavicle are most likely to cause what?

a fracture medial to attachment of the coracoclavicular ligament

The Acromioclavicular Joint is a ________ plane joint

synovial

The Acromioclavicular Joint line is

oblique and slightly curved

• forces transmitted through the arm will tend to drive the acromion UNDER the distal end of clavicle

The Acromioclavicular Joint contributes to

total arm movement

The acromioclavicular ligament stabilizes

the joint and binds the clavicle to the scapula

The Coracolavicular Ligament has 2 parts

• Trapezoid Ligament

• Conoid Ligament

A fall on the outstretched hand would tend to drive the

acromion UNDER the clavicle because of the tilt of the articular surfaces

• resisted by the trapezoid ligament

  

During full abduction (180 degrees) of the arm, the clavicle rotates ?

50 degrees axially

• Permits the glenoid fossa of scapula to continue to elevate and increase the possible degree of arm elevation​

• When the clavicle is prevented from rotating, the arm can be abducted actively to only 120° ​

Movement of the Acromioclavicular Joint​ is an important component of

total arm movement

In the Acromioclavicular Joint​, what are the 3 degrees of freedom?

• vertical axis

• frontal axis

• sagittal axis

What are the movements at the Acromioclavicular Joint​

Gliding Motion: shoulder flexion/extension

Elevation and Depression: relationship between scapula and humerus

The Glenohumeral Joint is what kind of joint?

multiaxial ball and socket synovial joint

• Only part of the humeral head articulates with the glenoid fossa in any position of the joint​

The Glenohumeral Joint surface makes an angle of

130 degrees to 150 degrees with the shaft

• Retroverted about 30° to 40° with respect to the axis of flexion of the elbow​

In the Scapulothoracic Mechanism, without bony or ligamentous attachments to the thorax, its a 

physiologic joint

The scapula can be

protracted, retracted, elevated, depressed, and rotated about a variable axis perpendicular to its flat surface

The Glenoid Labrum is a

Fibrocartilaginous tissue attached around the margin of the glenoid fossa​

• Shape of the labrum adapts to accommodate rotation of the humeral head​

• Adds flexibility to the edges of the glenoid fossa​

Joint capsule surrounds what

the joint

Maintenance of normal glenohumeral relationship depends on:​

• Reinforcement of capsule by ligaments​

• Attachment of muscle tendons of rotator cuff ​

Superior capsule and coracohumeral ligament do what

Strengthen superior aspect of the joint​

Resist the effect of gravity on the dependent limb

The coracohumeral ligament is what

one of the most important ligamentous structures

• Located anterior to the vertical axis about which the humerus rotates axially​

• Checks lateral rotation and extension​

What is the anterior aspect off the Glenohumeral Ligaments?

thickened parts of capsule

The Superior glenohumeral ligament​ assists in

preventing downward displacement of the humeral head​

The Middle glenohumeral ligament​ limits 

lateral rotation up to 90° abduction​

• Anterior stabilizer of the shoulder joint​

The Inferior glenohumeral ligament​ supports

joint in abduction ​

• Prevents anterior subluxation and dislocation​

The Coracoacromial Ligament/Arch​ is an important

protective arch

• Forms a secondary restraining socket ​

  • Protecting joint from trauma from above​

  • Prevents dislocation of humeral head superiorly​

Abduction and Flexion of the Coracoacromial Ligament/Arch​

Greater tuberosity of the humerus may apply pressure against the anterior edge​

Inferior surface of anterior third of the acromion and coracoacromial ligament

Scapularthoracic Motion Equation

SC Motion + AC Motion

Shoulder Motion Equation

ST Motion + GH Motion 

What are the rotator cuffs?

Supraspinatus (superiorly)

Infraspinatus (posteriorly)

Teres MINOR (posteriorly)

Subscapularis (anteriorly)

The rotator cuffs are what kind of units ?

Dynamic and Compound Musculotendinous

• Plays an essential role in movements of the glenohumeral joint​

The Subacromial/Subdeltoid Bursa ​does not communicate with the

joint

• Communication may develop if the rotator cuff is ruptured​

The in first 30 degrees of arm elevation, the humeral head is

translating as

• sliding and displacing

After the first 30 degrees of elevation of arm, there is movement in the

scapulothoracic mechanism

The in first 30 degrees of arm elevation, the movement of motion is in the

glenohumeral joint

Elevation of the arm/abduction is movement in

Glenohumeral and Scapulothoracic

The Subscapular bursa​ communicates with

the joint cavity between the superior and middle glenohumeral ligaments​

Movements of Shoulder Complex​ has a

extensive range of movement

Movements of the Humerus and Scapula occur due to

• Convex ovoid surface (head of humerus) relative to ​

• Concave ovoid surface (glenoid fossa)​

The articular humeral head does what

rolls, slides, and spins

What is the plane of scapula 

30-45 degrees anterior to frontal plane

Movements of humerus in relation to the glenoid fossa:​

• Frontal and coronal planes ​

• Plane of the scapula​