Anatomy - elbow and forearm Flashcards

1
Q

Which direction is the distal humeral articulation angled in the axial plane?

A

5-7 degrees internally rotated

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2
Q

How much is the distal humerus rotated in the sagittal plane?

A

30 degrees flexed

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3
Q

How much varus/valgus is there at the distal humerus?

A

6-8 degrees valgus

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4
Q

What is the normal angle of the articular surface angle at the elbow?

A

82-84 degrees

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5
Q

What is the plane and flexion angle of the capitellum?

A

Plane: 30 degrees anteriorFlexion: 60 degrees flexed

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6
Q

What is the normal carrying angle in men and women?

A

Men: 10-15 degreesWomen: 15-20 degrees

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7
Q

What angles are the medial and lateral columns of the elbow at?

A

Medial: 45 degreesLateral: 20 degrees

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8
Q

What is the safe zone for radial head fixation?

A

90 degree arc between Lister’s tubercle & Radial styloid with the arm in neutral rotationGenerally, posterolateral forearm

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9
Q

Describe the bowing of the radius

A

Apex dorsal bow: 5 degrees (in sagittal plane)Radial bow: 10 degrees (in coronal plane)

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10
Q

What is the bare area of the ulna?

A

Non-articular portion of the ulna between the olecranon articular facet and the coronoid articular facet.Located ~2cm from triceps insertion, between the tendons of FCU/ECUImportant because you aim for there when doing olecranon osteotomies

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11
Q

What is the proximal ulnar dorsal angulation (PUDA)?

A

~5 degrees located ~50mm distal to the tip of the olecranonImportant because it is a landmark for comparing to the contralateral side in patients with comminuted or distorted anatomy

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12
Q

What are the components of the lateral ligamentous complex of the elbow?

A

Annular ligamentRadial collateral ligamentLateral ulnar collateral ligament

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13
Q

What are the components of the annular ligament? Its attachments?

A

Superior & inferior oblique bandsAnnular ligament band itself?Attachments: anterior and posterior portions of the sigmoid notch of the proximal radius

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14
Q

What are the attachments of the lateral radial collateral ligament?

A

Lateral epicondyleDistally, blends with the annular ligament above the equator of the radial head

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15
Q

What are the attachments of the lateral ulnar collateral ligament?

A

Lateral epicondyleDistally, at the supinator crest of the ulna

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16
Q

What are the components of the medial ligamentous complex of the elbow?

A

Anterior bundlePosterior bundleTransverse bundle

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17
Q

What are the components of the anterior bundle of the MCL of elbow?

A

Anterior band Posterior band Central band

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18
Q

What is the role of the anterior band of the anterior bundle?

A

It is the primary static stabilizer to valgus stress at 20-120 degrees of elbow flexion

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19
Q

What is the primary static stabilizer of the elbow to valgus stress from 20-120 degrees of elbow flexion?

A

Anterior band of the anterior bundle

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20
Q

What is the primary stabilizer to valgus stress at >120 degrees of elbow flexion?

A

Ulnohumeral articulation, specifically the intrinsic osseous restraint between the ulna and trochlea

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21
Q

In extension, which part of the ulnar collateral ligament is most susceptible to valgus overload?

A

Anterior band of the anterior bundle

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22
Q

In flexion, which part of the ulnar collateral ligament is most susceptible to valgus overload?

A

Posterior band of the anterior bundle

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23
Q

When is the central band tight?

A

It is isometric throughout the ROM

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24
Q

What is the role of the posterior BUNDLE (not band)?

A

Secondary stabilizer of the elbow at high degrees of flexion

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25
Q

What is the role of the transverse bundle of the ulnar collateral ligament?

A

Unknown - it doesn’t cross the joint (ulna-ulna)I think it’s a labrum type structure that deepens the joint

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26
Q

Which bundle of the ulnar collateral ligament does not play a significant role in elbow stability? Why not?

A

Transverse bundle of the ulnar collateral ligamentBecause it doesn’t cross the elbow joint

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27
Q

How does the radial head affect varus stability?

A

Indirectly provides varus stability by tensioning the LCL

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28
Q

What innervates the muscles of the deep flexor compartment of the forearm?

A

AIN

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29
Q

What is the innervation of flexor digitorum profundus?

A

Radial 2: AINUlnar 2: ulnar

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30
Q

What is the innervation of FPL?

A

AIN

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31
Q

What is the innervation of pronator quadratus?

A

AIN

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32
Q

What innervates the superficial flexor compartment of the forearm?

A

Median nerve

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33
Q

Where does ECRL insert?

A

2nd metacarpal

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34
Q

Where does ECRB insert?

A

3rd metacarpal (it’s shorter than ECRL)

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35
Q

Where does brachioradialis insert?

A

styloid process

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36
Q

What innervates ECRB?

A

PIN

37
Q

What innervates the mobile wad, aside from ECRB?

A

radial nerve

38
Q

What innervates ECU?

A

PIN

39
Q

What is the Space of Parona?

A

Potential space in the forearm between FPL, FDP and pronator quadratus

40
Q

Name the common sites of compression of the median nerve?

A

Ligament of StruthersLacertus fibrosis (bicipital aponeurosis)Pronator teres (between the 2 heads)Subliminus bridge (fibrotendinous arcade that marks the start of FDS)”Ladies Love Poontang Sauce”(then in the wrist - carpal tunnel)

41
Q

Name the common sites of compression of the AIN?

A

Two heads of pronator teresFDSAberrant vesselsAccessory muscles of Ganzter (accessory FPL)

42
Q

What are the common sites of compression of the radial nerve?

A

Fibrous bands anterior to radial headRecurrent radial vessels (Leash of Henry)ECRBArcade of Frohse (proximal edge of supinator)Supinator (distally as PIN exits) FREAS

43
Q

What are the common sites of compression of the ulnar nerve?

A

Ligament of Struthers Arcade of StruthersHypertrophied medial tricepsMedial intermuscular septumAnconeus epitrochlearisCubital tunnel 2 heads of FCULigament of Spinner (aponeurosis between FDS of ring finger and humeral head of FCU)Deep flexor pronator aponeurosis

44
Q

What are the two origins of FCU

A

Humeral head: common flexor originUlnar head: medial margin of olecranon

45
Q

What is the Kocher interval?

A

The posterolateral interval: ECU and anconeus

46
Q

What is the Kaplan interval?

A

EDC & ECRL

47
Q

What is associated with distal radial shaft fractures occuring within 7.5cm of the radiocarpal joint?

A

Galeazzi fracture (DRUJ injury)

48
Q

What is a Galeazzi fracture?

A

radial shaft fracture with a DRUJ injury

49
Q

What is a Monteggia fracture?

A

Ulnar shaft fracture with a dislocated radial head

50
Q

Where does the AIN originate?

A

4cm distal to medial Epicondyle, but generally quite variable where it branches off the median n proper

51
Q

What is the column theory of the distal humerus?

A

3 columns make up distal humerus- Medial: diverges from humeral shaft at 45 deg angle- Lateral: diverges from humeral shaft at 20 deg angle- Distal: connect 2 columns. The “spool”. Is the articular part

52
Q

What is the definition of the normal articular surface angle (on x-ray)?

A

Angle between long axis of humerus and articular surface. 82-84 deg - remember b/c there is 6-8deg valgus at elbow

53
Q

What is the Baumann angle? What is the normal Baumann angle?

A

Angle between capitellar growth plate (of lateral condyle) and long axis of humerus64-81 deg Mean of 72deg

54
Q

Where should the anterior humeral capitellar line intersect the capitellum?

A

Central 1/3

55
Q

What are the landmarks of the coronoid?

A

6mm from capsule (proximal to capsule)12mm from brachialis (proximal to it)18mm from MCL (proximal and ulnar to it)

56
Q

What attaches to the coronoid tip?

A

Nothing

57
Q

What is the function of the lateral ligamentous complex of the elbow?

A

Key stabilizers against posterolateral rotatory instability (PLRI)

58
Q

What is the function of the medial collateral ligament complex?

A

Provide valgus stability

59
Q

What is the function of the anterior bundle of the MCL?

A

Primary static stabilizer to valgus stress from 20-120 deg of elbow flexion

60
Q

What is the function of the posterior bundle of the MCL?

A

A secondary stabilizer in high degrees of flexion

61
Q

What are the primary stabilizers of the elbow?

A

Ulnohumeral articulationMCLLCL

62
Q

What are the secondary stabilizers of the elbow?

A

Radial headJoint capsuleCommon flexor and extensor origins

63
Q

What is the primary stabilizer of axial forearm stability?

A

Intact radial head

64
Q

What are secondary stabilizers of axial forearm stability?

A

Triangular fibrocartilage complex (TFCC)Interosseous membrane

65
Q

Describe the axial force transmittance from wrist to elbowie. force distribution through radius and ulna at elbow vs. at wrist, and why

A

In ulnar neutral variance, radiocarpal joint absorbs 80% of axial load transmitted at wrist - Remaining 20% transmitted to ulna Interosseous membrane redistributes load so that at elbow, radiocapitellar joint sees 60% and ulnohumeral joint sees 40%

66
Q

What are the components of the interosseous membrane?

A

5 ligaments:- Central band- Accessory band- Distal oblique bundle- Proximal oblique cord- Dorsal oblique accessory cord

67
Q

What is Wartenberg’s Syndrome

A

AKA Cheiralgia parestheticaSuperficial radial nerve compressionPresent with pain or dysthesia on dorsal radial forearm radiating to thumb. - Tinel’s sign over superficial radial nerve is most common finding

68
Q

How do you differentiate between radial tunnel syndrome, PIN syndrome and lateral epicondylitis?

A

Radial tunnel syndrome: presents with lateral forearm pain, 3-4cm distal to lateral epicondylePIN Syndrome: present with weakness or paralysis as chief complaintLateral epicondylitis: Focal tenderness on lateral epicondyle at insertion of ECRB

69
Q

What are the borders of the cubital tunnel?

A

Floor:- MCL of elbow- Joint capsule- OlecranonRoof:- Arcuate ligament of osborne

70
Q

What is the arcade of struthers?

A

Thickening of the deep investing fascia of the arm - Extends from the medial head of triceps to the intermusular septum Present in 70% of the population 1.5-2cm in width, 8-10cm proximal to the medial epicondyle.where the ulnar n crosses lateral IM septum to go from anterior to posterior compartment - potential site of compression

71
Q

What is Froment’s sign? What does it indicate?

A

Indicates loss of ulnar nerve- Froment’s sign shows weak adductorsAsk patient to hold paper in 1st webspace (adduction of thumb). Patient will instead flex the IP joint to compensate for loss of adduction

72
Q

Describe the pathogenesis of ulnar claw:

A

AKA Hand of benediction:- Hyperextension of MCPs & Flexion of IP joint- Due to loss of intrinsics and ulnar 2 lumbricalsCaused Low lesion of ulnar nerve causing above paralysis. MCP hyperextension: loss of intrinsics (MCP flexion)IP Flexion: Unopposed action of long extensors. Loss of lumbricals causes IP flexion

73
Q

What is the ulnar paradox?

A

High ulnar nerve lesion causes a paradoxically more benign looking hand (although the pathology is worse)- High ulnar nerve lesion takes out FDP also, causes less of an IP flexion contracture and a less worse looking hand

74
Q

What is a Martin-Gruber Anastomosis?

A

Median nerve/AIN anatamosis with ulnar nerve- Median innervates the intrinsic muscles of handPresent in 15-30% of population

75
Q

In patient’s with a Martin-Gruber Anastomosis, what are the outcomes of high nerve lacerations of median and ulnar?

A

High ulnar nerve laceration - Preservation of intrinsic muscle function - Loss of FCU, FDP to the ulnar 2 fingers High median nerve laceration - Loss of intrinsic muscles usually innervated by ulnar

76
Q

What is an anconeus epitrochlearis?

A

Anomalous muscle found in 10% of patients - Arises from medial border of olecranon & adjacent triceps - Inserts into medial epicondyle May be a muscular or fibrous structurelike a “muscular osborne’s ligament”

77
Q

What is pronator syndrome?

A

Compression of median nerve at elbowMain dDx: CTS- Parasthesia in median nerve distributionDifferent from CTS b/c:- Aching pain over proximal volar forearm- Sensory disturbance over palmar cutaneous branch distribution (this arises 4-5cm proximal to carpal tunne)- Lack of night symptoms

78
Q

What is a Gantzer’s accessory FPL muscle?

A

An accessory long head of FPL- May cause compression of AIN

79
Q

What is AIN syndrome

A

Compression of AINWeakness of FPL, FDP to middle and index fingers, and PQCannot make OK sign

80
Q

When can you see the “Hand of Benediction”

A

Low ulnar nerve palsyHigh median nerve palsy (Can only flex 2 ulnar fingers)

81
Q

What are the borders of the cubital fossa? What are its contents?

A

Proximal: horizontal line connecting med/lat epicondylesUlnar: Lateral border of pronator teresRadial: medial border of brachioradialisContents:- Biceps brachii tendon- Brachial artery and branches- Median nerve

82
Q

At the elbow, where do you find the:Brachial arteryRadial arteryUlnar artery

A

Brachial artery:- Deep to bicipital aponeurosis (lacertus fibrosis)Radial artery:- Over pronator teres, under brachioradialisUlnar artery:- Deep to pronator teres between FDS and FDP muscles

83
Q

Where does the radial artery enter the wrist?

A

Between brachioradialis and FCR

84
Q

Distally, what does the ulnar artery travel with?

A

With ulnar nerve, between FDS and FCU

85
Q

Where is the medial antebrachial cutaneous nerve found?

A

3.5cm distal to the medial Epicondyle

86
Q

Where can you find the posterior branch of the median antebrachial cutaneous nerve?

A

1.5cm distal to the medial Epicondyle

87
Q

what are the boundaries and contents of the antecubital fossa?

A

superior: transepicondylar linemedial: pronator tereslateral: BRcontents: biceps tendon, brachial a, median n (lateral to medial)

88
Q

what are the major superficial veins of the arm and forearm?

A

cephalic v (lateral)basilic v (medial)each give off branch at proximal forearm that joins together forming median interbrachial v