The Shoulder- Palastanga

Question 1

Shoulder is also known as what

Answer 1

The glenohumeral joint

Question 2

Classification of the shoulder joint

Answer 2

Synovial ball and socket

Question 3

Articular surfaces

Answer 3

Head of humerus and shallow glenoid fossa

Question 4

Angle of inclination of the humerus

Answer 4

135 degrees

Between axis of head and neck and anatomical axis of shaft

Question 5

Angle of retroversion of the humerus

Answer 5

30-40 degrees

Rotated backwards against the shaft (opposite of the femur which is anterverted)

Question 6

Describe the articular surfaces facings

Answer 6

Glenoid fossa faces laterally, anteriorly and slightly superiorly, is pear shaped and only slightly concave

Head of humerus faces medially, posteriorly and superiorly, represents 2/5 of a sphere

Question 7

What increases the congruency of the joint

Answer 7

The presence of the glenoid labrum

Question 8

Describe the joint capsule

Answer 8

Is thick and strong only really anteriorly where is strengthened by ligaments, otherwise is very lax and confers little stability

Has 2 openings, one to allow long head of biceps through, one to communicate with subscapular bura (deep to tendon suscapularis)

Question 9

What is the role of rotator cuff muscles regarding the shoulder joint

Answer 9

Act as extensible ligaments and fan over the joint capsule

Are of tantamount importance in maintaining/ creating joint stability and integrity

Question 10

Where are the glenohumeral ligaments

Answer 10

Anteriorly over the joint and only seen from the inside of the capsule

Question 11

Describe the glenohumeral ligaments

Answer 11

Superior
Middle
Inferior - usually most well developed

Have no real stabilising function but certain movements such as lateral rotation in particular, put them under increased tension

Question 12

Features of the synovial membrane

Answer 12

Hangs down in a lil pouch when arm is hanging by its side - due to lax capsule
Encloses the long head of biceps tendon as it passes through
Associated with a number of bursae

Question 13

Clinically significant bursa of the shoulder

Answer 13

The subacromial bursa which sits under the acromion and deltoid and over the rotator tendons
Adhesions can form and prevent free sliding mvoement, may affect underlying supraspinatous tendon

Question 14

Describe the glenoid labrum

Answer 14

Triangular in cross section, fibrocartilagenous rim, site of attachment for long head of biceps

Question 15

What are the accessory ligaments of the shoulder

Answer 15

Coracohumeral and coracoacromial

Question 16

What function does the coracoacromial ligament serve

Answer 16

Forms a ligamentous arch and together with the bony processes of the coracoid and acromion increases the surface on which head of humerus is supported during upward force transmission through the humerus

Question 17

How stable is the shoulder joint and what is the main contributor to this

Answer 17

Very unstable

Low bony congruency and little supporting ligaments
Tone of rotator cuff muscles most important in conferring stability

Question 18

Why does the shoulder dislocate relatively easily compared to other joints

Answer 18

Low stability as sacrificed for high mobility

Long humerus has great leverage in dislocating forces

Question 19

Which type of dislocation is most common and why

Answer 19

Anterior dislocation more common due to anterolateral facing of glenoid which is better suited to resist posterior forces, posteriorly capsule also reinforced by infraspinatous and teres minor

Question 20

Define the axes about which movement of the shoulder joint can occur

Answer 20

About the cardinal planes e.g. sagittal, coronal etc
OR
With respect to the plane of the glenoid fossa aka in the scapular plane (inclined approx 45 degrees to the frontal and sagittal planes

Question 21

Movement at the shoulder joint occurs through a combination of?

Answer 21

Gliding and rolling

EXCEPT for axial rotation

Question 22

Describe flexion/extension of the shoulder joint

Answer 22

Occurs about an axis perpendicular to the plane of the glenoid fossa so that in flexion arm moves anteromedially and in extension is opposite

Question 23

ROM of flexion extension

Answer 23

Flexion 110d
Extension 70d

Can be extended when combined with movement of the pectoral girdle to
Flexion 180d
Extension 90d

Question 24

Limits to flexion/ extension

Answer 24

Flexion has no limit really as moves through its full arc of 180d

Extension is limited by the greater tubercle of the humerus coming into contact with the coracoacromial arch

Question 25

Describe abduction and adduction of the shoulder

Answer 25

Occur in an oblique horizontal axis in the same plane as the glenoid fossa so that in abduction the arm moves anterolaterally away from the trunk and vice versa in adduction

Question 26

Abduction and adduction is accompanied by what other movement of the shoulder joint?

Answer 26

Is pure abduction for the first 25d of the arc then is accompanied by concomitant (lateral) rotation of the scapula between 30 and 180d

Question 27

What is the total ROM for abduction/ adduction at the shoulder joint

Answer 27

120d

Is augmented by scapular rotation to take this to 180d

Question 28

The terminal phase of abduction is accompanied by what movement

Answer 28

Lateral rotation of the humerus

Question 29

What produces the movement of abduction at the shoulder joint

Answer 29

Is initiated by supraspinatous and then deltoid takes over after the first 20d to produce the rest of the movement
The accompanying lateral rotation of the scapula is produced by lower part serratus anterior and upper fibres trapezius

Question 30

Describe medial and lateral rotation of the shoulder joint

Answer 30

Takes place about the longitudinal axis of the humerus, best seen with the elbow flexed. In lateral rotation the hand and forearm move outwards and anterior surface of the humerus is turned laterally

Question 31

What are the ROMs for medial/ lateral rotation

Answer 31

Medial rotation = in excess of 90d if forearm pulled behind trunk
Lateral rotation= 80d

Question 32

What limits medial/ lateral rotation

Answer 32

Limited by the extent of the articular surfaces as well as tension is the joint capsule and appropriate musculature

Question 33

Muscles medially rotating the arm at the shoulder

Answer 33

Subscapularis, pec major, lat dorsi, teres major and ant fibres deltoid

Question 34

Muscles laterally rotating the shoulder

Answer 34

Infraspinatous, teres minor, post fibres deltoid

Question 35

Muscles adducting the shoulder

Answer 35

Eccentric contraction of the abductor msucles-

serratus anterior, trapezius, deltoid and supraspinatous

Question 36

Muscles flexing the shoulder joint

Answer 36

Ant fibres deltoid, clavicular head pec major, coracobrachialis and biceps

Question 37

Muscles extending the shoulder

Answer 37

From flexed position is eccentric contraction of flexing muscles
Beyond neutral position is post fibres deltoid, teres major, lat dorsi