Elbow Joints, Muscles, Ligaments, Biomechanics, Neuro

Question 1

What is the closed packed position (CPP) and capsular pattern (CP) of the Ulnohumeral joint?

Answer 1

CPP: Full ext. and supination.
CP: Flexion > Extension

Question 2

What is the closed packed position (CPP) and capsular pattern (CP) of the Radiohumeral joint?

Answer 2

CPP: 90° Elbow Flexion, 5° supination.
CP: Flexion > Extension > Supination > Pronation

Question 3

What is the closed packed position (CPP) and capsular pattern (CP) of the Superior Radioulnar joint?

Answer 3

CPP: 5° Supination
CP: Equal limit of pronation & supination.

Question 4

What are the articulating surfaces on the humerus? What is the carrying angle and what is the normal carrying angle in degrees?

Answer 4

Medial: Trochlea
Lateral: Capitulum
The carrying angle is the angle that the trochlea makes that causes the axis of humerus and forearm to be shifted laterally at the elbow. Normal is 5° in males and 10-15° in females.

Question 5

What are the articulating surfaces on the proximal radius and ulna?

Answer 5

Proximal radius: Concave cup shaped surface on the head of the radius
Proximal ulna: Olecranon and coronoid process

Question 6

What is the main reason elbows are hard to rehab?

Answer 6

The 3 joints (humeral-ulnar, humeral-radial, and superior radio-ulnar) are all in the same joint capsule.

Question 7

Which of the 3 joints at the elbow is primarily responsible for the osteokinematic and arthrokinematic motion at the elbow?

Answer 7

humero-ulnar joint with the spiral configuration of the trochlear grove guiding the arthrokinematics.

Question 8

In open chain, is the arthrokinematic motion at the humero-ulnar joint concave-on-convex or convex-on-concave in flex/ext? in adduction/abduction? How about for the radio-ulnar joint in flex/ext?

Answer 8

Flex/Ext of humero-ulnar joint is concave-on-convex.
Adduction and Abduction is convex-on-concave
Flex/Ext of radio-ulnar joint is concave-on-convex.

Question 9

Does adduction or abduction happen with flexion at the humero-ulnar joint? with extension? Also, is supination or pronation the conjunct position of the forearm in flexion? in extension?

Answer 9

Flexion: Adduction & Supination
Extension: Abduction & Pronation

Question 10

Normal ROM of humero-ulnart joint in flexion? extension?

Answer 10

Flex: 140-150° (Joel and Eric K. like 90° because of ‘roids).
Extension: 0° to 10° hyperextension.

Question 11

Describe the arthrokinematic motion of the superior and inferior radio-ulnar joints.

Answer 11

Superior joint: In supination: Head of radius spins in ulnar notch until quadrate ligament tightens, then the beveled edge of the radius slides in the capitulotrochlear groove and the head shifts laterally to provide room for the motion of the radial tuberosity medially. Ulna shifts backward with extension and abduction.
Inferior: distal end of radius along with articular disc swings medially over the ulnar head.

Question 12

What are the 5 muscles involved with flexion of the elbow? What is their innervation (nerve & roots)?

Answer 12

1. Brachialis - Musculocutaneous - C5-6 (7)
2. Biceps Brachii - Musculocutaneous - C5-6
3. Brachioradialis - Radial - C5-6 (7)
4. Pronator Teres - Median - C6-7
5. Flexor Carpi Ulnaris - Ulnar - C7-8

Question 13

What are the 2 muscles involved with extension of the elbow? What is their innervation (nerve & roots)?

Answer 13

1. Triceps - Radial - C6-8

2. Anconeus - Radial - C7-8 (7)

Question 14

What are the 2 muscles involved with supination of the forearm? What is their innervation (nerve & roots)?

Answer 14

1. Supinator - Post. Interosseous (Radial) - C5-6

2. Biceps Brachii - Musculocutaneous - C5-6

Question 15

What are the 3 muscles involved with pronation of the forearm? What is their innervation (nerve & roots)?

Answer 15

1. Pronator Quadratus - Ant. Interosseous (Radial) - C5-6
2. Pronator Teres - Median - C6-7
3. Flexor Carpi Radialis - Median - C6-7

Question 16

What are the 2 main muscles involved with flexion of the wrist? What is their innervation (nerve & roots)?

Answer 16

1. Flexor Carpi Radialis - Median - C6-7

2. Flexor Carpi Ulnaris - Ulnar - C7-8

Question 17

What are the 3 main muscles involved with extension of the wrist? What is their innervation (nerve & roots)?

Answer 17

1. ECRL - Radial - C6-7
2. ECRB - Post. Interosseous - C7-8
3. Extensor Carpi Ulnaris - Post. Interosseous - C7-8

Question 18

1. What muscle is the primary flexor of the arm?
2. What muscle performs adduction at the same time as flexion?
3. When is the 2° supination of the arm greatest during flexion?

Answer 18

1. Biceps
2. Brachialis
3. 90° of flexion.

Question 19

What are the Osteokinematic and Arthrokinematic motions of the radius and ulna on the humerus?

Answer 19

Osteo:
radius & ulna: both posteriorly and laterally.
Arthro:
radius: posteriorly and laterally.
ulna: posterior and medially (due to sellar aspect of humeroulnar joint).

Question 20

What are the shapes and O & I of the MCL and LCL ligaments of the elbow?

Answer 20

MCL: Triangular shaped, O: medial epicondyle of humerus. I: coronoid & olecranon processes.
LCL: Fan shaped, O: lateral epicondyle of humerus: I: olecranon process & annular ligament (which circles superior radioulnar joint).

Question 21

What ligaments provide valgus stability in extension? In flexion?

Answer 21

Extension: MCL, Ant. capsule & bony configuration.
Flexion: Post. band of MCL and bony configuration.

Question 22

What ligaments provide varus stability in the elbow?

Answer 22

Mostly bony configuration with some contribution of ant. capsule and LCL (especially when flexed).

Question 23

What ligaments provide stability in distraction of the elbow in extension? in flexion?

Answer 23

Extension: MCL and Ant. capsule
Flexion: MCL only.

Question 24

1. What dermatomes especially give rise to lateral elbow pain?
2. Injury to which nerve in the arm is purely motor?
3. Injury to the radial nerve mimics what condition?
4. What part of the radial nerve is most problematic?

Answer 24

1. C5-6
2. Median nerve
3. Tennis Elbow
4. Post. interosseous branch as it passes between the radial head and goes into the supinator muscle.

Question 25

Know Radiology on pages 109-110

Answer 25

Study ‘em!