Ch10: Shoulder Joint

Question 1

Shoulder Joint

Answer 1

A ball-and-socket joint with movement in all three planes and around all three axes. Therefore, the joint has three degrees of freedom. The humeral head articulating with the glenoid fossa of the scapula makes up the shoulder joint. It is one of the most movable joints in the body, and consequently, one of the least stable.

Question 2

Shoulder joint (anterior view).

Answer 2

.

Question 3

Four groups of motions possible at the shoulder joint

Answer 3

(1) flexion, extension, and hyperextension
(2) abduction and adduction
(3) medial and lateral rotation
(4) horizontal abduction and adduction.
(Flexion, extension, and hyperextension occur in the sagittal plane around the frontal axis)

Question 4

Shoulder Joint Flexion and Extension

Answer 4

Flexion is from 0 to 180 degrees
Extension is the return to anatomical position.

Question 5

Shoulder Joint Hyperextension

Answer 5

Approximately 45 degrees of hyperextension is possible from the anatomical position.

Question 6

Shoulder Joint Abduction and Adduction

Answer 6

Abduction and adduction occur in the frontal plane around the sagittal axis, with 180 degrees of motion possible.

Question 7

Shoulder Joint Medial and Lateral Rotation

Answer 7

Medial and lateral rotation occur in the transverse plane around the vertical axis. Sometimes the terms internal and external are used in place of medial and lateral, respectively. From a neutral position, it is possible to move 90 degrees in each direction.

Question 8

Shoulder Joint Horizontal Abduction and Horizontal Adduction

Answer 8

Also occur in the transverse plane around the vertical axis. From an arbitrary starting position for these motions of 90 degrees of shoulder abduction, there would be approximately 30 degrees of horizontal abduction (backward motion) and approximately 120 degrees of horizontal adduction (forward motion).

Question 9

Circumduction of the Shoulder Joint

Answer 9

A term used to describe the arc or circle of motion possible at the shoulder. Because it is really only a combination of all the shoulder motions, this term will not be used here.

Question 10

Shoulder joint motions.

Answer 10

Note: In lateral and medial rotation, the shoulder is abducted to 90 degrees only to show the rotation more clearly.

Question 11

Scaption

Answer 11

This motion is similar to flexion or abduction but occurs in the scapular plane as opposed to the sagittal or frontal plane

Question 12

Scapular Plane

Answer 12

Approximately 30 degrees forward of the frontal plane. It is not quite midway between flexion and abduction. With scaption of the shoulder, 180 degrees of up and down motion is possible. Most common functional activities occur in the scapular plane.

Question 13

What is the normal end feel for all shoulder joint motions?

Answer 13

Firm. This is due to tension from various ligaments and muscles and from the joint capsule. (end feel is the feel at the end of a joint’s passive range of motion when slight pressure is applied).

Question 14

Arthrokinematic Motion at the Glenohumeral Joint

Answer 14

the convex humeral head moves within the concave glenoid fossa. As stated by the convex-concave rule, this convex joint surface (humeral head) glides in a direction opposite to the movement of the distal end of the moving bone (the humerus). Therefore, when the shoulder joint flexes or abducts, the humeral head glides posteriorly or inferiorly, respectively. This keeps the head of the humerus articulating with the glenoid fossa. In extension and adduction, the humeral head glides anteriorly or superiorly, respectively. With medial rotation, the humeral head glides posteriorly. With lateral rotation, the opposite motions occur. The head rolls glides anteriorly.

Question 15

Glenohumeral Joint Open Packed Position

Answer 15

The greatest amount of arthrokinematic motion is possible when the glenohumeral joint is in the open packed position of 55 degrees abduction and 30 degrees horizontal adduction.
A mobilizing force that glides the humeral head into the direction of restriction can help restore movement between the joint surfaces and lengthen fibers of the joint capsule.

Question 16

Arthrokinematic motions during shoulder flexion and extension.

Answer 16

When the shoulder joint flexes, the humeral head glides posteriorly. During extension, the humeral head glides anteriorly.

Question 17

Linking Osteokinematics & Arthrokinematics

Answer 17

Arthrokinematic motion coupled with osteokinematic motion creates normal joint motion. When pathology such as capsular tightness interferes with joint motion, use of arthrokinematic motion can assist in restoring that motion by stretching the joint capsule. Take adhesive capsulitis as an example. With adhesive capsulitis, the following capsular pattern of range of motion loss may be seen: Severe loss of lateral rotation, moderate loss of abduction, and slight loss of medial rotation. Use of arthrokinematic motions (in the form of joint mobilizations) are often used to restore range of motion. For example, gliding the head of the humerus in the direction of restriction to stretch a particular part of the capsule, or by performing a long axis distraction where the head of the humerus is gently pulled away from the glenoid fossa, produces an effective stretch to the joint capsule as a whole. Specific application of these arthrokinematic motions in the use of joint mobilization is beyond the scope of this book.

Question 18

Left scapula.

Answer 18

.

Question 19

Left humerus.

Answer 19

.

Question 20

Joint Capsule

Answer 20

A thin-walled, spacious container that attaches around the rim of the glenoid fossa of the scapula and the anatomical neck of the humerus. The joint capsule is formed by an outer fibrous membrane and an inner synovial membrane.

Question 21

With the arm hanging at the side, the superior portion of the capsule is…

Answer 21

Taut, and the inferior part is slack.

Question 22

When the shoulder is abducted, the opposite occurs: The inferior portion is…

Answer 22

Taut, and the superior part is slack.

Question 23

The superior, middle, and inferior glenohumeral ligaments

Answer 23

Reinforce the anterior portion of the capsule. These are not well-defined ligaments but actually pleated folds of the capsule.

Question 24

Coracohumeral Ligament

Answer 24

Attaches from the lateral side of the coracoid process and spans the joint anteriorly to the medial side of the greater tubercle. It strengthens the upper part of the joint capsule.

Question 25

Glenoid Labrum

Answer 25

A fibrous ring that surrounds the rim of the glenoid fossa. Its function is to deepen the articular cavity.

Question 26

Bursae

Answer 26

There are several bursae in the shoulder joint area. The subdeltoid bursa is large and located between the deltoid muscle and the joint capsule. The subacromial bursa lies below the acromion and coracoacromial ligament, between them and the joint capsule, and it is frequently continuous with the subdeltoid bursa