S2_L3: Kinesiology of the Elbow Joint Complex

Question 1

Where does the ulnar nerve pass at the level of the elbow?

Answer 1

Medial epicondyle

Note: The ulnar nerve passes superficially to the medial epicondyle. It is susceptible to injury, where pain is felt over the medial elbow or radiating down the forearm to the little finger. Friction on the nerve within the ulnar groove produces a prickling sensation; this bone structure is the funny bone.

Question 2

Contents of the antecubital fossa from medial to lateral
a. tendon of the biceps brachii, median nerve, bifurcation of brachial artery, radial nerve and its deep branch
b. median nerve, bifurcation of brachial artery, tendon of the biceps brachii, radial nerve and its deep branch
c. radial nerve and its deep branch, tendon of the biceps brachii, median nerve, bifurcation of brachial artery
d. bifurcation of brachial artery, tendon of the biceps brachii, median nerve, radial nerve and its deep branch

Answer 2

b. median nerve, bifurcation of brachial artery, tendon of the biceps brachii, radial nerve and its deep branch

Question 3

Where does the radial nerve pass at the level of the elbow?

Answer 3

Lateral epicondyle

Question 4

Which nerve passes between the cubital fossa & the 2 heads of the pronator teres?

Answer 4

Median nerve

Question 5

Which nerve gives rise to the posterior interosseous branch?

Answer 5

Radial nerve

Question 6

The median nerve originates from the posterior cord. At the level of the elbow, it is compressed at the carpal tunnel.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false

Answer 6

D. Both statements are false

Question 7

Pronator teres syndrome can cause weakness of which muscle?
a. biceps brachii
b. flexor carpi ulnaris
c. flexor pollicis longus
d. anconeus

Answer 7

c. flexor pollicis longus

Note: The nerve affected in pronator teres syndrome is the median nerve

Question 8

Radial tunnel syndrome can cause weakness of of which muscle?
a. palmaris longus
b. extensor carpi ulnaris
c. pronator teres
d. flexor carpi radialis

Answer 8

b. extensor carpi ulnaris

Note: The nerve affected in radial tunnel syndrome is the radial nerve

Question 9

Workhorse for humeroulnar joint extension

Answer 9

Medial head of triceps brachii

Question 10

Workhorse for humeroulnar joint flexion

Answer 10

Brachialis

Note: The biceps brachii is active in flexion especially in forearm supination, while the brachioradialis is active especially with the forearm in midposition.

Question 11

Pronators are most effective when in neutral position of the forearm when elbow is flexed to ___ degrees.

Answer 11

90

Note: During pronation, both pronators (pronator teres & quadratus) act as synergists to pronate the radius over the ulna at the proximal and distal radioulnar joints (Brunnstrom, 6th ed.)

Question 12

Greatest extension force is exerted in midrange at ___ degrees of elbow flexion

Answer 12

70-90

Question 13

In flexion and extension, the axis of the elbow joint passes horizontally through the center of trochlea and capitulum and near the ___ epicondyle.

Answer 13

lateral

Question 14

Normal range of active ROM of elbow flexion with a supinated forearm

Answer 14

135-145 degrees

Note: Passive ROM for elbow flexion with supinated forearm is 150-160 degrees. PROM is higher because of joint play.

Question 15

TRUE OR FALSE: During elbow flexion and extension, there is more ROM when the forearm is supinated than pronated or in neutral (midway).

Answer 15

True

Note: A pronated forearm during elbow flexion has a soft end feel because the bulky muscles bump into one another.

Question 16

Functional range of motion of the elbow complex during elbow flexion

Answer 16

100° arc of elbow flexion (30-130°)

Note: A total arc of about 100° of elbow flexion (between 30° and 130°) and about 100° of forearm rotation (50° supination and 50° pronation) is sufficient to accomplish most ADLs such as eating, drinking, brushing hair, brushing teeth, and dressing.

Question 17

Ages when the epiphysis closes around the elbow

Answer 17

14-15 years old

Source: Levangie and Norkin, 5th ed.

Question 18

Enumerate the factors affecting muscle activation patterns

Answer 18

1. Number of joints crossed
2. Type of muscle action (concentric, eccentric, isometric, isokinetic)
3. Speed of motion
4. Resistance
5. Requirements of the task
6. Direction of the stress
7. Activity of other muscles

Question 19

Enumerate the factors affecting elbow muscle activity

Answer 19

1. Number of joints crossed by the muscle
2. Physiological cross-sectional area (PCSA)
3. Location in relation to joint axis
4. Position of the elbow and adjacent joints
5. Position of the forearm
6. Magnitude of the applied load
7. Type of muscle action (concentric, eccentric, isometric, isokinetic)
8. Speed of motion
9. Moment arm at different joint positions
10. Fiber types

Question 20

The elbow joint is more mobile:

1. If performing PROM
2. If the forearm is supinated
3. If the individual has less pronounced muscle bulk & lower BMI
4. If pain and/or swelling is present
5. Full ROM is attempted at the shoulder and elbow joints simultaneously

A. True
B. False

Answer 20

1. A
2. A
3. A
4. B
5. B (Two or multi joint muscles, such as the triceps & biceps, do not have sufficient length to allow simultaneous full ROM at all joints crossed)

Question 21

The elbow joint is stable at the extremes of elbow flexion and extension. Full extension is the close-packed position where there is increased bony configuration and tautness of ligaments & partly by muscles.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false

Answer 21

C. Both statements are true

Note: In full flexion, the coronoid process fits on the coronoid fossa and the radial head fits on the radial fossa.

Question 22

TRUE OR FALSE: Muscles that are active during supination and pronation, especially when gripping is involved and during resisted motion, include the flexor carpi ulnaris, extensor carpi ulnaris, brachioradialis, flexor carpi radialis, and extensor carpi radialis brevis.

Answer 22

True

Question 23

TRUE OR FALSE: The moment arms of all major supinators exhibit peak torque values in 40° to 50° of pronation.

Answer 23

True

Question 24

Ligament that is continuous with the anterior aspect of the articular disc holding the ulna to the ulnar notch of the radius and is taut during forearm supination.

Answer 24

Palmar radioulnar ligaments

Question 25

Ligament that is continuous with the posterior aspect of the articular disc holding the ulna to the ulnar notch of the radius and is taut during forearm pronation.

Answer 25

Dorsal radioulnar ligaments

Question 26

Its fibers are at right angles (perpendicular) to the fibers of the interosseous membrane to offer major stabilization to the proximal radioulnar connection a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 26

d. Oblique Cord

Question 27

Syndesmotic joint (false joint) that absorbs shock and actively transfer forces along the kinetic chain between radius and ulna (especially in CKC motions, such as arm propping) to protect them from injury (e.g., falls and fall on an outstretched hand [FOOSH]). a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 27

b. Interosseous Membrane

Question 28

It limits too much spinning of the radial head especially during pronation/supination. Its strong, anterior portion is a major stabilizer of proximal radioulnar joint during full supination and weaker, posterior component stabilizes full pronation. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 28

c. Quadrate Ligament

Question 29

It spans from the ulna’s radial notch up to the medial surface of the radial neck. It reinforces the inferior aspect of the joint capsule and helps maintain the radial head in apposition to the radial notch. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 29

c. Quadrate Ligament

Question 30

It is formed by longitudinally oriented collagen fiber bundles originating from the dorsal and palmar aspects of the ulnar notch of the radius. It stabilizes the distal radioulnar connection, reinforces the joint capsule by blending into it, and holds the ulna against the ulnar notch. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 30

a. Radioulnar Ligaments Note: These ligaments have limited cross-sectional areas and low structural stiffness

Question 31

Reinforces the proximal radioulnar articulation together with the annular ligament and quadrate ligament. It assists in preventing separation of the radius and ulna. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 31

d. Oblique Cord

Question 32

A flat fascial band on the ventral forearm extending from the inferior aspect of the ulna’s radial notch up to below the radial tuberosity. It is taut in full supination, providing additional stability to the radioulnar connection. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 32

d. Oblique Cord

Question 33

Its tract is taut in pronation and loose in supination. In pronation, the tract protects the ulnar head in a sling and provides stability for the joint by reinforcing the dorsal aspect of the joint capsule. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 33

b. Interosseous Membrane

Question 34

It maintains space between the radius and ulna during forearm rotation. It provides stabilization at both proximal and distal radioulnar joints without restricting pronation and supination by binding the radius and ulna together. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 34

b. Interosseous Membrane

Question 35

It is made up of fibrous tissue with an oblique orientation from the radius to ulna. It maintains transverse stability of the forearm during compressive load transfer from the hand to the elbow (wrist to proximal forearm) via fibers that run from the distal radius to proximal ulna. a. Radioulnar Ligaments b. Interosseous Membrane c. Quadrate Ligament d. Oblique Cord

Answer 35

b. Interosseous Membrane Note: It is taut at mid prone position of forearm and lax at the extremes of forearm pronation and supination.

Question 36

Its fibers run counter to the central band; obliquely from ulna to radius. It deforms at maximum pronation. a. membranous portion of the Interosseous Membrane b. central band of the Interosseous Membrane c. dorsal oblique cord of the Interosseous Membrane

Answer 36

c. dorsal oblique cord of the Interosseous Membrane

Question 37

It is soft and thin, and lies adjacent proximally and distally to the central band. It deforms at maximum supination and in the neutral position. a. membranous portion of the Interosseous Membrane b. central band of the Interosseous Membrane c. dorsal oblique cord of the Interosseous Membrane

Answer 37

a. membranous portion of the Interosseous Membrane

Question 38

It remains taut throughout forearm rotation, to keep the radius and ulna from splaying apart. It is maximally strained at neutral position of the forearm (midway), but lax in both full pronation and supination. a. membranous portion of the Interosseous Membrane b. central band of the Interosseous Membrane c. dorsal oblique cord of the Interosseous Membrane

Answer 38

b. central band of the Interosseous Membrane

Question 39

It is strong, thick, and ligamentous; its fibers run obliquely from the radius to the ulna. It has a very high collagen content arranged in fibrillar structures surrounded by elastin (more abundant proximally). a. membranous portion of the Interosseous Membrane b. central band of the Interosseous Membrane c. dorsal oblique cord of the Interosseous Membrane

Answer 39

b. central band of the Interosseous Membrane Note: It has little physiological ability to heal.

Question 40

Enumerate the 3 joints of the elbow complex that are enclosed in a single joint capsule, thus they share the same joint capsule

Answer 40

1. Humeroulnar joint 2. Humeroradial joint 3. Superior/proximal radioulnar joint

Question 41

TRUE OR FALSE: All four elbow complex joints work together as a functional unit with a common synovial membrane.

Answer 41

True Note: The inferior/distal radioulnar joint is anatomically closer to the wrist joint, but is considered with the elbow/forearm region because motions in the elbow complex influence this joint.

Question 42

The medial and lateral collateral ligaments are specialized thickenings of the joint capsule that provide vital stability to the capsule medially and laterally and offer stability in the frontal plane. Distraction and compression forces are created if either one of the collateral ligaments is overstretched or torn; if one side of the joint is subjected to abnormal tensile stresses, the other side is subjected to abnormal compressive forces. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 42

C. Both statements are true Note: The radial head does not appear to play a major role in elbow stability if an intact ulnar collateral ligament (MCL) exists.

Question 43

Primary purpose is to allow stabilization of the elbow joint against each other producing joint approximation. It also assists the anterior bundle and has a little valgus stabilization function. a. Anterior bundle/oblique of the MCL b. Transverse band of the MCL c. Posterior bundle/oblique of the MCL

Answer 43

b. Transverse band of the MCL

Question 44

It generally limits flexion (Brunnstrom) but also limits hyperextension when the elbow is extended. It is not as distinct and blends with medial joint capsule, with a less significant role in producing valgus restraint. a. Anterior bundle/oblique of the MCL b. Transverse band of the MCL c. Posterior bundle/oblique of the MCL

Answer 44

c. Posterior bundle/oblique of the MCL

Question 45

In 90° of flexion, it provides the primary resistance to both distraction and valgus stress. It also provides the primary restraint for valgus forces most especially at 20-120º of elbow flexion (primary restraint of valgus force at 30º, 60º, and 90º of flexion, and the coprimary restraint up to 120º according to Brunnstrom). a. Anterior bundle/oblique of the MCL b. Transverse band of the MCL c. Posterior bundle/oblique of the MCL

Answer 45

a. Anterior bundle/oblique of the MCL

Question 46

It limits extension and is overlaid by the flexor carpi ulnaris, pronator teres, and flexor digitorum superficialis muscles. The FCU, FDS, and FCR function as dynamic stabilizers, with the FCU being the primary stabilizer for elbow valgus. a. Anterior bundle/oblique of the MCL b. Transverse band of the MCL c. Posterior bundle/oblique of the MCL

Answer 46

a. Anterior bundle/oblique of the MCL Note: The anterior bundle/oblique can be further divided into anterior and posterior bands. The anterior band provides most of valgus restraint between 30-90º of elbow flexion, while the posterior band provides restriction to extension.

Question 47

TRUE OR FALSE: The annular ligament has 2 components. Its anterior component is taut during extreme supination, while the posterior component is taut during extreme pronation.

Answer 47

True

Question 48

Enumerate the 9 elbow flexors

Answer 48

1. Brachialis* 2. Biceps brachii* 3. Brachioradialis (Supinator longus)* 4. Pronator teres 5. Supinator (teres) 6. Flexor Carpi Radialis Longus 7. Flexor Carpi Ulnaris 8. Flexor Digitorum Superficialis 9. Palmaris longus Note: Asterisk means primary/strong elbow flexor

Question 49

This secondary elbow flexor provides significant reinforcement for the MCL during throwing activities since it is the only muscle anterior to it in 90-120º elbow flexion

Answer 49

Flexor carpi ulnaris

Question 50

This secondary elbow extensor is the prime mover for wrist extension for supination torques and a stabilizer for gripping during pronation torques.

Answer 50

Extensor Carpi Radialis Brevis Note: The ECRL, ECRB, and ECU are active in gripping, hammering, and sawing

Question 51

TRUE OR FALSE: Normal accessory motions require muscle relaxation because any muscle contraction causes joint compression and restricts accessory motions.

Answer 51

True

Question 52

Enumerate the 3 parts of the Lateral Collateral Ligamentous Complex

Answer 52

1. Lateral/Radial Collateral Ligament (LCL) 2. Lateral Ulnar Collateral Ligament (LUCL) 3. Annular ligament

Question 53

1. Large and major stabilizing ligament, the primary stabilizer of the elbow. 2. Serves as primary restraint for varus forces that would force the forearm medially A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 53

1. D 2. A

Question 54

1. Key structure that is always disrupted when people suffer from elbow dislocations 2. Adheres closely to supinator, extensor, anconeus muscles; acting as a dynamic stabilizer together with related muscles A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 54

1. A 2. B

Question 55

1. At risk for injury either from sudden traumatic valgus force or repetitive valgus forces (e.g., pitching a baseball, throwing a javelin, spiking a volleyball) 2. A circular ligament that forms ⅘ of a ring around the radial head and is attached to the posterior and anterior edges of the radial notch that completes the ring formation A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 55

1. D Note: Injury to MCL usually occurs with the shoulder in external rotation and the elbow flexed. 2. C

Question 56

1. Prevents excessive radial distraction, maintains integrity of proximal radioulnar articulation, and prevents proximal radioulnar joint dislocation 2. Provide reinforcement for humeroradial articulation and allows stabilization of radius in place 3. Assists the LRCL in resisting varus stress and providing lateral support A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 56

1. C 2. A 3. B

Question 57

1. Its inner surface is covered w/ cartilage and serves as a joint surface 2. Lies posterior to the lateral collateral ligament and contributes to posterolateral stabilization by securing ulna to humerus A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 57

1. C 2. B

Question 58

1. Encircles the radial head and neck in place so that it won’t move away from the ulna 2. Extends from lateral epicondyle to lateral aspect of ulna and attachment site of annular ligament; provides support to the annular ligament A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 58

1. C 2. B

Question 59

It assists in providing resistance to distraction forces. The position of both the forearm and the elbow affect the length of the ligament and therefore affect the posterolateral stability of the elbow (the ligament is long between 0-30º and at 90º flexion when forearm was in neutral position). A. Lateral/Radial Collateral Ligament (LCL) B. Lateral Ulnar Collateral Ligament (LUCL) C. Annular ligament D. Medial/Ulnar Collateral Ligament (MCL)

Answer 59

A. Lateral/Radial Collateral Ligament (LCL)

Question 60

TRUE OR FALSE: The lateral ulnar collateral ligament and annular ligament are secondary soft tissues restraints to combined forced varus and supination stresses and forces valgus stress.

Answer 60

True

Question 61

1. Prevents subluxation of the humeroulnar joint 2. Stabilizes against combined varus and supination torques 3. Limits extension at the end of the elbow extension range of motion 4. Stabilizes radial head, thus providing a stable base for rotation 5. Limits excessive valgus stress that would force the forearm laterally A. Medial/ulnar collateral ligament B. Lateral collateral ligamentous complex C. Both

Answer 61

1. C 2. B 3. A 4. B 5. A

Question 62

1. Reinforces humeroradial joint and maintains posterolateral rotatory stability 2. Provide some resistance to longitudinal distraction of the articulating surfaces 3. Guides joint motion throughout flexion range of motion 4. Entheses is fused at the lateral epicondyle, together with the common extensor tendon 5. Attached distally to the coronoid process anteriorly and olecranon process posteriorly A. Medial/ulnar collateral ligament B. Lateral collateral ligamentous complex C. Both

Answer 62

1. B 2. C 3. A 4. B 5. A

Question 63

TRUE OR FALSE: The greatest degree of valgus laxity of the MCL occurs with the forearm in neutral rotation at all elbow flexion angles.

Answer 63

True

Question 64

TRUE OR FALSE: The lateral collateral ligamentous complex prevents the forearm from rotating off of the humerus in valgus and supination during flexion from the fully extended position.

Answer 64

True

Question 65

____ stability is largely maintained by the anterior and medial bundles of the lateral collateral ligament and the annular ligament.

Answer 65

Posterolateral

Question 66

TRUE OR FALSE: The medial aspect of the trochlea extends far more distally than the lateral aspect and capitulum, pushing the forearm laterally to valgus in relation to the humeral shaft.

Answer 66

True

Question 67

TRUE OR FALSE: Functional use of the carrying angle results from a combination of shoulder lateral rotation, elbow extension, and forearm supination.

Answer 67

True

Question 68

Normal value of the carrying angle/cubitus valgus

Answer 68

15º (~8-15° for Levangie & Norkin; 5-15° for Brunnstrom) Note: The dominant hand will have a slightly larger angle than the nondominant hand.

Question 69

TRUE OR FALSE: Females have a higher carrying angle than males.

Answer 69

True (Females: ~13-16°; Males: ~5-19°) Note: Females have a wider pelvis and shorter forearm bones, thus a greater carrying angle. The average height of women is smaller than men, and the proximal end of the ulna angulate more and the medial flange of the trochlea grows longer in a smaller person. Additionally, the flexion angle of women is smaller than men (mean flexion angle in women: 5.26 degrees). Thus, women reach a greater natural physiological extension + exhibit a larger ROM = greater carrying angle.

Question 70

TRUE OR FALSE: Normally, the carrying angle disappears when doing forearm pronation with an extended elbow or when doing forearm supination with a flexed elbow.

Answer 70

True

Question 71

1. Stretch the lateral collateral ligament too much 2. Stretch the medial collateral ligament too much 3. Turned inward; less than the normal 5-15° or 8-15° angle 4. Increased carrying angle A. pathologic cubitus valgus B. cubitus varus/gun-stock deformity

Answer 71

1. B 2. A 3. B 4. A

Question 72

An acute angle formed medially by the longitudinal axis of humerus and ulna that provides a variability in excursion and allows for smooth instantaneous elbow flexion within multiple forearm positions so functional motion is easily performed. This alignment provides a better joint, called a loose hinge joint.

Answer 72

Carrying angle/Cubitus Valgus Note: The joint axis is not perpendicular to the shaft of the humerus.

Question 73

Secondary forearm supinator that aids supination from pronation to midpostion with the elbow in flexion, but the action is quite weak.

Answer 73

Brachioradialis Note: It is also a secondary forearm pronator from a supinated position to midposition (in the face of heavy resistance, especially when the elbow is flexed).

Question 74

The only muscle whose sole action is forearm supination which crosses posterior aspect of interosseous membrane.

Answer 74

Supinator Note: It is always recruited for forearm supination, regardless of the speed or load.

Question 75

TRUE OR FALSE: The secondary supinators (biceps brachii, brachioradialis, abductor pollicis longus, extensor pollicis brevis, & extensor indicis) do not assist in slow supination or supination when the elbow is extended.

Answer 75

True Note: The supinator muscle is the only one able to supply enough force when supination occurs slowly, when resistance is light, or when the elbow is extended. This muscle acts alone during unresisted slow supination in all positions of the elbow of forearm and in unresisted fast supination when the elbow is extended.

Question 76

TRUE OR FALSE: The supinator muscle is a stronger forearm supinator than the biceps brachii because of its line of pull and it is a single-jointed muscle.

Answer 76

True

Question 77

It is a powerful participator in heavily resisted supination, but supinates best when the elbow is flexed. It has 4x supination torque with 90º elbow flexion and 2x supination torque with a supinated forearm and an extended elbow (with some resistance).

Answer 77

Biceps brachii

Question 78

Primary forearm pronators 1. Active in resisted and unresisted pronation and in slow and fast pronation 2. Muscle fibers cross obliquely from medial to lateral on the anterior forearm (from ulna to radius) 3. Consistent pronator activity in all elbow positions 4. Active in unresisted & resisted pronation, but highest contractile force during resisted or rapid pronation A. pronator teres B. pronator quadratus

Answer 78

1. B 2. A 3. B 4. A

Question 79

The strength of this primary forearm pronator decreases with full elbow extension. It is a strong pronator when the elbow is flexed.

Answer 79

Pronator teres Note: The pronator teres also acts as a weak flexor (secondary). It has a poor moment arm for elbow flexion, and only supplies added force when there is a significant resistance or a heavy load.

Question 80

The deep head of the pronator ____ is active during both resisted supination and resisted pronation and is thought to act as a dynamic stabilizer to maintain compression of the distal radioulnar joint.

Answer 80

quadratus Additional: The fibers of the superficial head pass transversely across the interosseous membrane, whereas the fibers of the deep head extend obliquely across the interosseous membrane to insert on the radius.

Question 81

The pronator teres is a cordlike, superficial muscle. It is also a single-jointed muscle. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 81

A. Only the 1st statement is true The pronator teres is a double-jointed muscle (humeroulnar and proximal radioulnar joints). Conversely, the pronator quadratus is a single-jointed muscle.

Question 82

TRUE OR FALSE: Pronator teres and quadratus originate on the stable ulna and attach to the radius, pulling the radius around the stationary ulna.

Answer 82

True

Question 83

Accessory and secondary muscle for elbow extension that adds only minimally to the total strength of elbow extension (10-15% of required extensor force). It is thought to act during early extension.

Answer 83

Anconeus Note: The anconeus is a small, triangular muscle located deep, adjacent to the joint, blending close to the fibers of the humeroulnar joint capsule.

Question 84

TRUE OR FALSE: The anconeus initiates most low-load elbow extension motions and acts as a stabilizer during pronation/supination.

Answer 84

True Additional: The anconeus contracts during elbow extension to tighten the loose posterior elbow capsule and prevent pinching of the capsule folds as the olecranon locks into olecranon fossa.

Question 85

1. Larger cross-sectional area compared to the lateral head; workhorse 2. Single-jointed (only crosses the elbow joint) and not affected by position of shoulder 3. Most muscular portion and strongest of the three heads a. long head of triceps brachii b. medial head of triceps brachii c. lateral head of triceps brachii d. B and C only

Answer 85

1. B 2. D 3. C

Question 86

1. Active in unresisted and resisted elbow extension 2. Distal to the posterior deltoid and assists in elbow extension 3. Double-jointed, affected by changing shoulder joint position a. long head of triceps brachii b. medial head of triceps brachii c. lateral head of triceps brachii d. B and C only

Answer 86

1. B 2. C 3. A

Question 87

Enumerate the active and passive insufficiencies of the long head of the triceps brachii

Answer 87

Active insufficiency: shoulder hyper extension, elbow extension Passive insufficiency: shoulder flexion, forearm/elbow flexion

Question 88

The triceps brachii is the principal extensor of the elbow and helps lift the elbow capsule out of the way during extension. All heads of the triceps brachii are active in resisted elbow extension. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 88

C. Both statements are true

Question 89

TRUE OR FALSE: The effectiveness of the triceps brachii as a whole is affected by changes in the position of the elbow but not by changes in position of the forearm, because the triceps attaches to the ulna and not the radius. Thus, the triceps extends the elbow regardless of forearm position.

Answer 89

True

Question 90

TRUE OR FALSE: The anterior bundle of the lateral collateral ligament was observed to be longest at 90° and shortest between 120° and 150° of elbow flexion, where the posterior bundle was the longest.

Answer 90

True Note: Some fibers remain taut throughout flexion ROM when either in a varus or valgus moment is applied.

Question 91

A fan shaped ligament that extends from the inferior part of the lateral epicondyle of the humerus to merge with the annular ligament and olecranon process of the ulna.

Answer 91

Lateral/Radial Collateral Ligament (LCL)

Question 92

Longest of the elbow flexors and is the only primary flexor whose belly lies in the forearm

Answer 92

Brachioradialis (Supinator longus)

Question 93

Enumerate the active and passive insufficiencies of the biceps brachii

Answer 93

Active insufficiency: shoulder flexion, elbow flexion, and forearm supination Passive insufficiency: shoulder hyperextension, elbow extension, and forearm pronation

Question 94

This muscle has the smallest physiologic cross-sectional area (PCSA) among the primary elbow flexors

Answer 94

Brachioradialis (Supinator longus)

Question 95

Close-packed position of the elbow joint complex joints 1. Full extension 2. 90º flexion, 5º supination 3. Either full supination or full pronation A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 95

1. B 2. A 3. C

Question 96

Resting position of the elbow joint complex joints 1. 70º elbow flexion with 35º forearm supination 2. Full elbow extension with full forearm supination 3. 70º elbow flexion, 10º forearm supination A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 96

1. C 2. A 3. B

Question 97

1. Has 2 degrees of freedom (along the sagittal & frontal planes) 2. Synovial, uniaxial pivot joint in anatomic considerations, but functional motion happens in sagittal plane 3. Synovial “modified” or “loose” hinge/ginglymus joint A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 97

1. B Additional: A bit of axial rotation and side to side motion of the ulna occurs during flexion and extension. Also, valgus and varus motions when doing elbow flexion do not occur in the sagittal plane, but in the coronal plane. 2. A 3. B

Question 98

Articulation between olecranon process of ulna and olecranon fossa of humerus (in full elbow extension); articulation between trochlear notch of ulna and trochlea of humerus; and articulation between coronoid process of ulna and coronoid fossa of humerus (in full elbow flexion; known as the ulnotrochlear articulation). A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 98

B. Humeroulnar joint

Question 99

This joint is muscularly supported by the pronator quadratus and extensor carpi ulnaris tendon. Its non-muscular support is provided by the dorsal and palmar radioulnar ligaments, the interosseous membrane and its tract, and the articular disc. A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 99

D. Inferior/Distal radioulnar joint Additional: The radioulnar ligaments, the articular disc, and the pronator quadratus maintain the ulna within the ulnar notch and prevent the ulna from subluxating or dislocating. The interosseous membrane in combination with the TFCC provide important longitudinal stabilization.

Question 100

Synovial pivot/trochoid joint formed by the articulation between the ulnar notch (concave) of the distal radius, articular disc (TFC), and the head of the ulna (convex). A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 100

D. Inferior/Distal radioulnar joint Note: Ulnar notch of the radius slides around the convex ulnar head and rolls in the same direction (e.g., during pronation from a fully supinated position, the radius crosses over the ulna to roll anteriorly and slide anteriorly).

Question 101

Articulation involves sliding between the radial head and the convex surface of capitulum of humerus (occurs in full elbow extension; called radiocapitular articulation). There is no real/direct contact between these structures and joint surfaces are highly incongruent. A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 101

A. Humeroradial joint (Radiohumeral joint) Note: The capitulum is found laterally on the anterolateral surface of distal humerus and spherical/spheroid in shape. The concave proximal radial head rolls and glides over the convex rounded capitulum in the same direction (e.g., during extension, the radial head is rolling and gliding posteriorly).

Question 102

Articulation between radial head and radial fossa of the humerus (in full elbow flexion). The radial head slides into the capitulotrochlear groove until full flexion occurs when the radial head settles snugly into the radial fossa of humerus. A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 102

A. Humeroradial joint (Radiohumeral joint) Note: The capitulotrochlear groove: separates (or is in between) the capitulum from the trochlea.

Question 103

A synovial pivot/trochoid joint with 1 degree of freedom that is formed by the articulation between head of the radius with the radial notch of the ulna. A. Humeroradial joint (Radiohumeral joint) B. Humeroulnar joint C. Superior/Proximal radioulnar joint D. Inferior/Distal radioulnar joint

Answer 103

C. Superior/Proximal radioulnar joint Note: The convex radial head rolls & glides on the concave radial notch of the ulna in the opposite direction (e.g., in forearm supination, it rolls posteriorly and glides anteriorly/volarly).

Question 104

The ridge on the ulnar articulating surface (proximal part of trochlear notch) that will articulate with the trochlear groove of the humerus.

Answer 104

Trochlear/Longitudinal ridge Note: Articulation between the ulna and humerus (ulnotrochlear articulation of the humeroulnar joint) occurs primarily as a sliding motion of trochlear ridge on the humeral trochlear groove.

Question 105

TRUE OR FALSE: During pronation/supination with elbow extended, medial/lateral rotation of shoulder happens simultaneously and the palm can be turned through almost a full circle (approx. 360°).

Answer 105

True

Question 105

TRUE OR FALSE: If the forearm is in the midprone position, it may reach up to 90° pronation and 90° supination. The combined ROM of pronation/supination is 150 to 180°.

Answer 105

True Note: Most people only have up to 80° pronation. The full ROM of pronation from a fully supinated forearm is slightly less than 180° (average 170°).

Question 106

Pronation: crossing over of the radius over the ulna End feel is either hard if radius and ulna come into contact or firm because of stretch of soft tissue joint capsules and interosseous membrane Supination: the ulna and radius lie parallel to each other End feel is firm: secondary to tautness of stretched ligaments, interosseous membrane and both pronator muscles

Answer 106

1. 2. 3.

Question 107

TRUE OR FALSE: The axis of rotation of the radioulnar joints is a line from the center of the radial head through the center of the ulnar styloid process (Brunnstrom, 2012). Thus, the proximal axis of rotation is the radial head and the distal axis of rotation is the ulnar styloid process.

Answer 107

True Note: According to Levangie & Norkin (2011), the axis of motion for pronation and supination is a longitudinal axis extending from the center of the radial head to the center of the ulnar head.

Question 108

Pronation and supination allows motion in the transverse plane through the longitudinal axis (y-axis) of the forearm (anatomical body position). If the elbow is flexed to 90º, pronation and supination will occur on the coronal/frontal plane. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 108

C. Both statements are true Additional: A reciprocal relationship exists between the radius and ulna in axial force transmission (radius – least at supination to pronation, ulna – least at pronation to supination).

Question 109

TRUE OR FALSE: In the ulnotrochlear articulation, the concave trochlear notch of the ulna will be gliding and rolling anteriorly on the convex humeral trochlea during flexion; vice versa for extension. This smooth mobility and maximum stability is served well by the reciprocal concave-convex relationship.

Answer 109

True Additional: At end of elbow flexion, the coronoid process of the ulna meets the coronoid fossa. The trochlea is a large and hour-glass shaped structure found medially. The trochlear notch is a deep, semicircular, concave notch of the ulna that articulates with trochlea to form medial elbow joint. The notch is shaped like a half-moon, also called the semilunar notch.

Question 110

1. Active during unresisted elbow flexion with forearm supinated or mid prone position 2. Inactive during slow, unresisted, concentric (shortening) elbow flexion A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 110

1. B 2. C

Question 111

1. Active during resisted elbow flexion in any forearm position 2. Tends to not be active when forearm is pronated 3. Single jointed and very efficient mobility muscle because its insertion is close to elbow joint axis (spurt muscle) A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 111

1. B 2. B 3. A

Question 112

1. Action is not affected by shoulder position or forearm position; only crosses humeroulnar joint (single-jointed) 2. Recruited in all tasks requiring elbow flexion 3. Active with and without resistance A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 112

1. A 2. A 3. A

Question 113

1. Helps lift the elbow capsule out of the way during flexion 2. Large peak moment arm is between 100-120º of elbow flexion 3. Moment arm is largest between 80-100º of elbow flexion A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 113

1. B 2. C 3. B

Question 114

1. Active on resisted elbow flexion in mid prone or fully pronated forearm position 2. Moment arm and torque produced is greatest at around 90-100° elbow flexion 3. Largest physiologic cross-sectional area and large work capacity (volume) A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 114

1. C 2. A 3. A

Question 115

1. Mobility muscle that is affected by shoulder position 2. Inserts far distally from elbow joint axis, some of its force compresses the joint, providing additional stability to the joint (shunt muscle) 3. Active on unresisted elbow flexion with forearm in mid prone position A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 115

1. B 2. C 3. C

Question 116

1. Position of elbow affects it only during voluntary maximum eccentric contraction 2. Acts as a weak supinator in a fully pronated forearm and a weak pronator in a fully supinated forearm 3. Has no direct connection with the humerus and can be passively moved about easily A. Brachialis B. Biceps Brachii C. Brachioradialis (Supinator longus)

Answer 116

1. C 2. C 3. B

Question 117

TRUE OR FALSE: The triceps brachii is active eccentrically to control elbow flexion as the body is lowered to the ground in a push-up during the down phase; active concentrically to extend the elbow during the up phase.

Answer 117

True Note: In a CKC push-up, all 3 heads of the triceps brachii are active. The triceps concentrically extends the elbow, eccentrically as a major stabilizer during elbow flexion, and a powerful stabilizer during any functional closed-chain activity.

Question 118

TRUE OR FALSE: The Extensor Carpi Ulnaris is a secondary elbow extensor. It exerts a depressive force when stretched during supination and helps maintain the position of the ulnar head.

Answer 118

True

Question 119

The elbow complex contains 7 bursae. 3 bursae are associated with the triceps, and a large bursa lies between the olecranon and the olecranon fossa, known as the ____.

Answer 119

olecranon bursa

Question 120

TRUE OR FALSE: The Elbow Joint Complex is considered as a compound joint designed to serve the hand because it allows positioning of the forearm and wrist in place to optimize hand function.

Answer 120

True Additional: Because of its location as the middle link of the UE, the elbow complex is prone to distraction injuries and acute/chronic processes involving muscles, tendons, ligaments and peripheral nerves.

Question 121

When the elbow is in the varus position (no contact between the radial head and capitulum), force is transmitted from the distal radius through the interosseous membrane to the proximal ulna. When the elbow is in the valgus position (contact between the radial head and the capitulum), the force is transmitted through the radius. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 121

C. Both statements are true

Question 122

TRUE OR FALSE: Elbow flexion of about 80° is considered to be the elbow position at which the least amount of tension is present in the joint capsule.

Answer 122

True

Question 123

This structure is seen between the elbow joint capsule and synovial membrane, adjacent to the coronoid, olecranon, and radial fossae. It serves to reduce too much frictional forces.

Answer 123

Fat pads

Question 124

TRUE OR FALSE: Generally, the elbow joint capsule is large, weak, and loose anteriorly and posteriorly.

Answer 124

True Note: Good reinforcements are seen on the medial and lateral sides, supported by medial and lateral collateral ligaments (Capsular strength is reinforced by ligaments).

Question 125

TRUE OR FALSE: During pronation/supination, the radius pivots around a stationary ulna. For this reason, a stable ulna is vitally important as it forms a rigid base, or bony lever, from which the forearm and wrist can function.

Answer 125

True Note: If a muscle attaches only to the ulna, it cannot perform pronation/supination.

Question 126

TRUE OR FALSE: The Proximal and Distal radioulnar joints are linked and functions as one joint.

Answer 126

True Additional: The distal radioulnar joint is linked to the wrist (where compressive loads transmit).

Question 127

TRUE OR FALSE: The elbow joint complex provides stability during closed kinematic chain activities (e.g. pushups, pullups).

Answer 127

True Note: The strong structural stability of the joint is from both bony configuration and strong collateral ligaments. Great joint stability is provided by the corrugated fit of the trochlea and capitulum with matching surfaces of ulna and radius as well as strong medial and lateral collateral ligaments.

Question 128

A triangular ____ inserted between the proximal radius and ulna partly divides the elbow joint into two joints.

Answer 128

synovial fold

Question 129

TRUE OR FALSE: The Medial/Ulnar Collateral Ligament (MCL) contains mechanoreceptors (i.e., golgi organs, ruffini's terminals, pacinian corpuscles, and free nerve endings) distributed in its attachment to the humerus and ulna.

Answer 129

True, so the ligament can perceive joint position, pressure and traction forces, and pain

Question 130

Primary bone for the elbow joint that plays a very prominent role at the elbow, but provides minimal function at the wrist.

Answer 130

Ulna

Question 131

Joint structure that contains folds that are able to expand to allow for full elbow motion. It also blends with ligaments (MCL, LCL, annular ligament) and provides static stabilization.

Answer 131

Elbow joint capsule Note: It passes below the annular ligament and attach to the posterior and inferior margins of the neck of radius.

Question 132

TRUE OR FALSE: According to the recruitment principle, single-jointed muscles are recruited before double-jointed ones.

Answer 132

True Note: Since single-jointed muscles are recruited first, their recruitment time is longer (greater recruitment time because they are continuously being recruited) as compared to the muscles recruited last.

Question 133

TRUE OR FALSE: When the brachioradialis contracts, its upper portion rises from the underlying structures so its perpendicular distance to the elbow joint increases, thus increasing the moment arm to add more leverage to its function.

Answer 133

True

Question 134

TRUE OR FALSE: The tendon of the long head of the biceps brachii passes within the glenohumeral joint capsule under the subacromial arch. Within the intertubercular/bicipital groove, it is at risk for entrapment and subsequent pathology.

Answer 134

True

Question 135

TRUE OR FALSE: The biceps brachii is less effective as an elbow flexor in a fully extended elbow due to its closeness to the joint axis. It is also a weak rotator and a strong translator in full elbow extension, where translatory force provides joint compression to add to stability (also applicable in ROM beyond 100° of flexion).

Answer 135

True Additional: Activation of the biceps was found to be significantly affected by elbow joint angle during concentric and isometric contractions but not during eccentric or isokinetic contraction.

Question 136

The two heads of the biceps brachii have separate bellies in the proximal arm but fuse to form one belly in the midarm. The fibers of the short head make the medial part of the common belly, while the fibers of the long head make the lateral part. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 136

C. Both statements are true Note: The biceps brachii has a smaller PCSA than the brachialis. The long head of the biceps brachii has the largest volume among the elbow flexor muscles.

Question 137

TRUE OR FALSE: The distal radioulnar joint has one degree of freedom for pronation/supination. In full supination, the ulnar head will rest on the palmar surface of ulnar notch & in full pronation, the ulnar head will rest on the dorsal surface of ulnar notch.

Answer 137

True Note: The radius plays a more important role at the distal radioulnar joint and at wrist.

Question 138

TRUE OR FALSE: The distal end of the humerus lies in 30º anterior rotation in respect to the humeral shaft, while the proximal ulna lies in 30º posterior rotation in relation to the ulnar shaft. This matching relationship provides 145º flexion ROM (normal variability ranges from 120-160 degrees), as well as stability in full extension.

Answer 138

True Additional: The primary articulating segments at the elbow joint are the humerus and ulna. Many muscles are attached to the distal end of the humerus to afford mobility.

Question 139

This structure acts as a cushion in allowing compression force transmission from the carpals to the ulna and acts as a stabilizer of the ulnar side of the carpals. It follows radial motion and is seen on the ulnar side of the distal radioulnar joint.

Answer 139

Articular disc / triangular fibrocartilage complex (TFCC) Note: Continuous with the anterior and posterior portions of the disc are the anterior/palmar and posterior/dorsal radioulnar ligaments. Distal radioulnar joint stability is from the TFCC and dorsal and palmar radioulnar ligaments.

Question 140

The articular disc / TFCC allows transmission of compressive force from radius to ulna, but strain distribution is dependent on forearm position (strain decreases in supination, but increases in pronation). The disc also resembles a shelf whose medial border is embedded in a wedge of vascular connective tissue containing fine ligamentous bands that join the disc to the ulna and articular capsule.

Answer 140

True Note: Both proximal/superior and distal/inferior surfaces of articular disc are concave, and the proximal surface is more concave to better accommodate rounded ulnar head. The proximal surface articulates with ulnar head at distal radioulnar joint, while the distal surface articulates with carpal bones as part of radiocarpal joint.

Question 141

TRUE OR FALSE: Average extension motion is 0º with only few degrees in normal variation.

Answer 141

True Note: People who are heavily muscled or have tight ligaments lack a few degrees of extension, while people with lighter structure or joint laxity have 5 or more degrees of normal hyperextension.

Question 142

A large olecranon bursa is located at the olecranon fossa, which buffers the locking of the elbow during full extension. It is vitally important in absorbing force and reducing shock occurring when the elbow extends forcefully, compressing the olecranon process into the olecranon fossa. A. Only the 1st statement is true B. Only the 2nd statement is true C. Both statements are true D. Both statements are false

Answer 142

C. Both statements are true Note: Elbow extension has a hard end feel with contact between the ulna’s olecranon process and humeral olecranon fossa.

Question 143

TRUE OR FALSE: Active flexion ROM is less when the forearm is not in full supination.

Answer 143

True Additional: Flexion is usually stopped by contact between forearm and arm muscles with a soft end feel. In heavily muscled and obese people, flexion ROM may be reduced significantly that they may not be able to place the fingers on the shoulder. Conversely, people with little soft tissue may have a hard end feel with bone contact of the ulnar coronoid process with the humeral coronoid fossa.

Question 144

TRUE OR FALSE: The Inferior/Distal radioulnar joint can be a source of limitation of motion when invaded by a scar tissue after injury.

Answer 144

True