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human anatomy > m4: shoulder and elbow > Flashcards

m4: shoulder and elbow Flashcards

1
Q

● 20 muscles
● 3 bony articulations
● 3 soft tissue moving surface (functional joints)
● Permit the greatest mobility of any joint area found in the body
● 16,000 different positions (hand placement)
● stabilizes the upper extremity for hand motions
● lifts and pushes objects
● elevates the body
● assists with forced respiratory inspirations and expirations
● bears weight when walking with crutches or performing handstands
● Mobility > Stability

A

shoulder

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2
Q

only bony attachment of UE to trunk.

A

sternoclavicular joint

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3
Q

primary support and stabilizer of the shoulder

A

muscles and ligaments

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4
Q

● ___ joint = glenohumeral joint
● Shoulder ___ = all structures which make up the shoulder.

A

shoulder ; complex

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5
Q

4 bones of shoulder

A

manubrium
clavicle
scapula
humerus

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6
Q

● Shoulder girdle
○ Manubrium
○ Right and left ____
○ Right and left ____
● ___ girdle (does not have bony connection posteriorly)

A

clavicles
scapulaes
incomplete

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7
Q

● Clavicular facet
● Sternal/jugular notch
● Facets for attachment of the first ribs

A

manubrium

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8
Q

● Lateral strut to the scapula and the humerus.
● This increases glenohumeral mobility to permit greater motion in reaching and climbing activities.
● Medial end
● Costal facet
● Costal tuberosity
● Acromial end

A

clavicle

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9
Q

● a flat, triangular-shaped bone
● 3 sides and 3 angles
● sits against the posterior thorax.
● Lies on the posterior ribs
● Conforms to the upper thorax
● Does not lie in a pure frontal plane
● Inferior angle (T7)
● Vertebral border (medial border)
● Axillary border (lateral border)
● Glenoid fossa (the most lateral aspect of the scapula) ● Supraglenoid tubercle (attachment for LH of biceps) ● Infraglenoid tubercle (attachment for LH of triceps) ● Superior border
● Scapular spine (T3)
● Supraspinatus fossa
● Infraspinatus fossa
● Acromion process
● _____ (crow’s beak)

A

scapula
coracoid process

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10
Q

● Dense fibrous connective tissue rim that surrounds the glenoid fossa.
● Increase joint congruence.
● Tilted _ ° upward relative to the scapular vertebral border.
● Teardrop or pear-shaped appearance
● Orientation: _ , _ , _
● (Concave)

A

glenoid labrum

5°

LAS

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11
Q

● Head of humerus
○ Convex
○ 1/3 to 1⁄2 sphere
○ Orientation: _
● Humeral neck (anatomic neck)
● Humeral shaft
● Angle of inclination = humeral head is angled at _° to the long axis of the humeral shaft
● Angle of torsion = _°
● Resting position of the humeral head in posterior rotation relative to the distal condyles of the humerus allows the head to be aligned in the scapular plane while maintaining proper elbow joint alignment; this relative position of posterior rotation = _
● Greater tubercle
● Lesser tubercle
● _ (intertubercular groove)
○ through which the LH of biceps runs from its proximal insertion on the supraglenoid tubercle.

A

humerus

medial, superior, posterior (PMS)

135

30

Retroversion

Bicipital groove

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12
Q

● Circumferential area on the proximal humerus.
● Distal to the _ _
● Common site for humeral fractures, especially in the elderly, when a fall occurs and the individual lands on an outstretched arm.

A

surgical neck

bicipital groove

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13
Q

synovial joints of shoulder

A

● Sternoclavicular joint
● Acromioclavicular joint
● Glenohumeral joint
● Scapulothoracic joint

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14
Q

a joint responsible for the majority of the scapular movement.

A

sternoclavicular joint

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15
Q

provides minimal movement and acts more as a fine tuner of scapular motion than a producer of its motion.

A

acromioclavicular joint

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16
Q

the result of sternoclavicular and acromioclavicular joint movements.

A

scapulothoracic motions

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17
Q

Shoulder Girdle Movements

A

● Elevation
● Depression
● Protraction
● Retraction
● Upward Rotation
● Downward Rotation ● Scapular Tilting
○ A-P
○ M-L

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18
Q

● The only joint that acts as a strut to connect the upper extremity directly with the axial skeleton.
● Medial end of the clavicle connects with the manubrium of the sternum and the medial first rib.

A

sternoclavicular joints

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19
Q

_____ has
○
○ 3 strong stabilizing ligaments
1
2
3

A

sternoclavicular joint ligaments

Fibrocartilaginous articular disc

anterior SC ligament
posterior SC ligament
superior SC ligament

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20
Q

2 Coracoclavicular Ligaments

A

● Conoid
● Trapezoid

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21
Q

____ Joint
● Plane synovial joint
● 3 DOF
○ Elevation/Depression
○ Abduction/Adduction
○ UR/DR
● Medial margin of the acromion and the lateral end of the clavicle
● Lined with fibrocartilage
● Superior AC ligament
● Inferior AC ligament

A

Acromioclavicular

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22
Q

● no bony articulations
● False joint/pseudo joint/functional joint
● Separating the scapula from the thorax are soft tissue structures, including a large subscapular bursa.

A

scapulothoracic joint

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23
Q

● Increasing the range of motion of the shoulder to provide greater reach
● Maintaining favorable length-tension relationships for the deltoid muscle to function above _ ° of glenohumeral elevation to allow better shoulder joint stability throughout a greater motion
● Providing glenohumeral stability through maintained glenoid and humeral head alignment for work in the overhead position
● Providing for injury prevention through shock absorption of forces applied to the outstretched

A

scapulothoracic function

90

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24
Q

● Shoulder joint
● Ball-and-socket
● 3 DOF
● Little bony stability
○ Convex:
○ Concave:
● Labrum
○ From neck of glenoid
○ To anatomic neck of humerus
● 10 to 15 mL
● Axillary pouch

A

Glenohumeral Joint

Humeral head (PMS)
Glenoid fossa (small/shallow) (LAS)

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25
Q

● Ligaments and tendons blend with and reinforce the glenohumeral joint capsule for added stability.
○ Coracohumeral ligament
○ Superior, Middle, Inferior GH ligament

A

Capsular Reinforcement (GH)

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26
Q

● coracoid process of the scapula → greater and lesser tubercles of the humerus
● where it forms a tunnel for the tendon of the long head of the biceps brachii.

A

Coracohumeral Ligament

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27
Q

● Capsular ligaments
● From the glenoid and its labrum, form capsular thickenings, and attach to the humeral neck and lesser tubercle.

A

Superior, Middle and Inferior GH Ligaments

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28
Q

● Support the dependent (hanging down) arm and limit lateral rotation in the lower ranges of abduction

A

Coracohumeral, Superior and Middle GH Ligaments

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29
Q

● Forms a hammock-like sling with anterior and posterior bands around the lower portion of the humeral head and is part of the axillary pouch.
● Main stabilizer of the abducted shoulder

A

Inferior Glenohumeral Ligament

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30
Q

Deep Muscles of the Shoulder
1.
2.
3.

A

● Tendon of the LH biceps brachii
○ Intra-articular and extrasynovial
● LH of triceps brachii
○ Blends with posterior capsule
● Tendons of 4 short rotator cuff muscles (S IT S)

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31
Q

● anterior acromion → lateral coracoid process
● osteoligamentous arch
● roof of the glenohumeral joint

A

Coracoacromial Arch

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32
Q

Subacromial Space
● Contains:

○
○
○
○

A

○ supraspinatus muscle and tendon,
○ long head of the biceps tendon
○ subacromial bursa
○ superior capsule

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33
Q

● Area under the coracoacromial
● Formed by the neck of the scapula, the acromion process, the rigid coracoacromial ligament, and the coracoid process

A

Supraspinatus Outlet

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34
Q

reduces friction between two structures.
● 8 bursae within the shoulder area
○ Subacromial bursa
○ Subdeltoid bursa

A

bursa

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35
Q

● Scapular plane glenohumeral abduction
● Occurs _ ° to _° anterior to the frontal plane

A

scaption

30 & 40

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36
Q

● LH of biceps tendon
● Retained by the coracohumeral ligament and by the transverse humeral ligament

A

bicipital groove

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37
Q

● They found that the early phase of abduction was individually variable.
● This early stage of motion was termed the “____.” After about 30° of abduction, a 2:1 ratio occurred: For every 2° of glenohumeral motion, 1° occurred at the scapulothoracic joint.

A

Scapulohumeral Rhythm

setting phase

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38
Q

5 Scapular Stabilizers of the Shoulder Complex

A

● Serratus anterior
● Trapezius
● Rhomboids major and minor
● Pectoralis minor ● Levator scapulae

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39
Q

● Primary scapular protractor
● “saw muscle”
● lowest five digitations is the strongest portion of the muscle
● XXX: ___ winging of the scapula

A

Serratus Anterior

medial

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40
Q

● superficial muscle of the neck and upper back
● “Shawl” muscle or “musculus cucullaris”
● Full abduction with scapular rot: All fibers
○ Mid = ret
○ Upper and Lower = upward
rot.
● XXX: ___ winging of the scapula
○ Elevation is limited to \ degrees (only by GH)

A

Trapezius

lateral

120

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41
Q

● connect the scapula with the vertebral column lie under the trapezius.
● The more cranial portion is known as rhomboid ____
● The larger, more caudal portion is the rhomboid ____
● XXX: scapula in protracted position
● scapula positioned farther laterally from the thoracic spinous processes
● than the normal 6 cm from the thoracic spinous processes

A

rhomboid major and minor

cranial- minor
caudal- major

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42
Q

● located anteriorly on the upper chest by the pectoralis major.
● XXX: Weakness of this muscle results in reduced strength during scapular depression and downward rotation of the scapula against resistance.

A

Pectoralis Minor

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43
Q

● An elevator of the scapula, an action it shares with the upper trapezius and with the rhomboids.
● Elevation + DR
● XXX: reduced ability to elevate and downwardly rotate the scapula.

A

Levator Scapulae

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44
Q

5 Glenohumeral Stabilizing Muscles in the
Shoulder

A

● Rotator Cuff
● Biceps brachii
● Triceps brachii
● Teres major
● Coracobrachialis

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45
Q

○ provide glenohumeral stability as well as glenohumeral motion.

A

Rotator cuff

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46
Q

● located above the spine of the scapula.
● capable of performing the total motion of abduction without the assistance of the deltoid.

A

Supraspinatus

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47
Q

● Infraspinatus @ ____
● Teres minor @ ____
● External rotators of the shoulder
● Different innervations

A

Infraspinatus and Teres Minor

infra @ infraspinatus fossa
tm @ lateral border of the scapula

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48
Q

● located on the anterior scapula.
● ___ = primary medial rotation function
● But can also flex, extend, adduct, or abduct the glenohumeral joint

A

Subscapularis

IR =

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49
Q

● Lies distal to the teres minor on the lateral scapula border
● It acts in most pulling activities when the the shoulder is extended or adducted against resistance.

A

Teres Major

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50
Q

2 muscles that also stabilize the GH joint

A

Biceps Brachii and Triceps Brachii

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51
Q

● Their proximal attachments on the trunk and their distal attachments on the humerus, having little or
no attachment to the scapula.
● They act on the humerus as primary movers

A

Large Muscle Movers of the Shoulder

52
Q

4 Large Muscle Movers of the Shoulder

A

● Deltoid
● Latissimus Dorsi
● Teres Major
● Pectoralis Major

53
Q

● A large, superficial muscle consisting of three parts: anterior, middle, and posterior.
● The muscle covers the glenohumeral joint on all sides except in the inferior
● Axillary region
● Comprises 40% of the mass of the scapulohumeral muscles

A

Deltoid

54
Q

● This muscle is the broadest muscle of the low back and the lateral thoracic region
● If the arms are stabilized, as in pushing down on crutch handles or in a seated press down, the distal attachment aids to lift the pelvis.

A

Latissimus Dorsi

55
Q

● Large muscle of the chest
● Two parts
○ ?
○ ?

A

Pectoralis Major

○ Clavicular
○ Sternocostal

56
Q

“RoTonDa CuBao”

A

● Roots
● Trunks
● Divisions
● Cords
● Branches

57
Q

● All 3 cords of the brachial plexus lie above and lateral to the first part of the axillary artery
● The _ cord crosses behind the artery to reach the medial side of the second part of the artery
● The _ cord lies behind the second part of the artery, and the lateral cord lies on the lateral side of the second part of the artery

A

Cord of the Brachial Plexus

medial
posterior

58
Q

Blood Supply of the Upper Limb
Artery:
Veins:
○
○

A

● Artery: Brachial Artery
● Veins:
○ Deep (Venae Comitantes)
○ Superficial (Cephalic and Basilic Veins)

59
Q

● 3 individual joints
● Surrounded by 1 capsule
● Humeroulnar joint + humeroradial joint = “elbow joint”
● Proximal radioulnar joint (PRUJ)

A

Elbow Complex

60
Q

● Modified uni-axial hinge joint
● 1 DOF
● HU = flexion + extension
● PRUJ = supination + pronation

A

Humeroulnar joint + Humeroradial joint

61
Q

5 Main Muscles of the Elbow Complex

A

● 2 extensors (triceps brachii and anconeus)
● 3 flexors (Biceps brachii, brachialis, brachioradialis)

62
Q

Radioulnar joint motions from:

A

● A pair of supinators
● A pair of pronators

63
Q

type of elbow ligament that holds the head of radius in proper relation to the ulna and humerus

A

● Annular ligament

64
Q

type of elbow ligament that connects the radius and ulna, running from the lateral side of the ulnar tuberosity to the radius slightly below the radial tuberosity

A

● Oblique cord

65
Q

3 Branches of the Brachial Plexus

A

● Musculocutaneous
● Radial
● Median

66
Q

4 Pathological conditions of the Elbow and FA region (Acute):

A

● Fracture
● Strain
● Sprain
● Distraction injuries

67
Q

2 Pathological conditions of the Elbow and FA region (Chronic):

A

● Overuse
● Repetitive microtrauma

68
Q

● Middle link of the UE
● Prone to distraction injuries
● Series of the acute or chronic processes involving muscles, tendons, ligaments and peripheral nerves.

A

Location of Elbow Complex

69
Q

● Congruent
● Bones possesses notches, ridges, grooves that fit like jigsaw puzzle pieces
● Stability and Function

A

Elbow bones

70
Q

● The proximal articulating bone of the elbow, a long bone with several distinct markings on its distal end, some of which are palpable.
● Medial epicondyle
● Attachment site for
○ primary forearm pronator (pronator teres)
○ major stabilizing ligament (the ulnar collateral ligament)
○ most of the wrist and finger flexor muscles
● Lateral epicondyle
● Attachment site for
○ wrist and finger/thumb extensors
○ forearm supinator.
● _ _ _
○ landmark that is palpable between the lateral head of the triceps posteriorly and the brachioradialis muscle anteriorly

A

Humerus

Lateral supracondylar ridge- landmark

71
Q

Distal Humerus that forms the proximal portion of the elbow joint
●
●
●
●

A

● Trochlea
● Trochlear groove
● Capitulum
● Capitulo Trochlear groove

72
Q

Fossa
● _ fossa
● _ fossa

A

● Coronoid fossa
● Radial fossa

73
Q

● Providing a deep and stable articulating surface for the superior ulna when the elbow is in full extension

A

Olecranon fossa

74
Q

● Providing a deep and stable articulating surface for the superior ulna when the elbow is in full extension

A

Olecranon fossa

75
Q

● The _ is the more integral articulating bony partner with the humerus at the elbow, forming the humeroulnar joint.

A

Ulna

76
Q

● The _ is the more integral articulating bony partner with the humerus at the elbow, forming the humeroulnar joint.

A

Ulna

77
Q

● The distinctive posterior prominence of the superior ulna and is the most posterior portion of the elbow when the joint is flexed.

A

Olecranon process

78
Q

● The concave ulnar trochlear notch articulates with the more proximal humeral trochlea to form the medial elbow joint.
● Also known as the _ notch.

A

Trochlear notch

semilunar notch

79
Q

● The concave _ _ _articulates with the more proximal humeral trochlea to form the medial elbow joint.
● Also known as the _ notch.

A

ulnar trochlear notch

semilunar notch

80
Q

● This large articulating ulnar surface is divided in the center by a prominent trochlear or longitudinal ridge that articulates with the trochlear groove of its humeral companion.

A

Trochlear and longitudinal ridge

81
Q

● The anterior surface of the ulna is marked by a distinctive, sharp, medial superior process called the _ _.
● When the elbow flexes, this ulnar process moves to fit snugly into the _ _of the humerus, providing stability in that position.

A

Coronoid process and coronoid fossa

82
Q

● Inferior to the coronoid process is the _ _, an attachment site for a primary elbow flexor muscle, the _.
● Radial notch articulates with the radius to form the proximal radioulnar joint

A

Ulnar tuberosity

brachialis

83
Q

● Although the _ contributes to proximal forearm function, it plays a more important role at the distal radioulnar joint and at the wrist.

A

Radius

84
Q

● At the proximal end, the _ is located just distal to the humeral lateral condyle.

A

head of the radius

85
Q

● The superior surface of the radial head has a deep concave _ , which articulates with the round convex head of the humeral capitulum to form the humeroradial joint

A

fovea

86
Q

● Just distal to the radial head on the anterior radial neck is the _ _.
● It is the attachment site for the _ _

A

radial tuberosity

biceps brachii

87
Q

● Three joints are within the elbow joint capsule. These joints include the elbow and proximal forearm joints.
● The elbow joints include the:
○
○
● The proximal forearm joint is the proximal _ joint.

A

elbow:
○ Humeroulnar
○ Humeroradial

proximal forearm joint:
proximal radioulnar joint

88
Q

● The primary articulating segments at the elbow joint are the humerus and ulna.
● Although the radius moving on the humerus offers important companion motion, it does not contribute substantially to the elbow joint’s function.

A

Humeroulnar and Humeroradial joints

89
Q

● Ginglymus
● Uniaxial hinge joint
● 1 DOF
● Flexion and extension in sagittal plane around the frontal axis

A

Elbow

90
Q

● A large, olecranon _ is located in the olecranon _, buffering the locking of the elbow when it moves into full extension.

A

● A large, olecranon bursa is located in the olecranon fossa, buffering the locking of the elbow when it moves into full extension.

91
Q

● Since the joint axis is not perpendicular to the shaft of the humerus, the forearm alignment angles laterally in
relation to the shaft of the humerus in the anatomical position.
● Cubital angle

A

Carrying angle

92
Q

Carrying angle
● This angle is approximately 15°
● Greater angle usually in women than in men.
● Male (Magee):
● Female (Magee):
● Cubitus valgus:
● Cubitus varus:
● Gun stock deformity

A

● Male (Magee): 5 to 10 degrees
● Female (Magee): 10 to 15 degrees
● Cubitus valgus: More than 15 degrees
● Cubitus varus: Less than 5 to 10 degrees

93
Q

Cubital Fossa
BOUNDARIES:
● Laterally:
● Medially:
● Base:
● Floor:
● Roof:

CONTENTS:
●
●
●
●

A

● Laterally: Brachioradialis muscle
● Medially: Pronator teres
● Base: Formed by an imaginary line drawn between the two epicondyles of the humerus.
● Floor: Formed by the supinator muscle laterally and the brachialis muscle medially.
● Roof: Formed by skin and fascia and is reinforced by the bicipital aponeurosis.

CONTENTS:
● Median nerve
● Bifurcation of the brachial artery into the ulnar and radial arteries
● Tendon of biceps
● Radial nerve

94
Q

2 Elbow and Forearm Ligaments

A

● Medial (ulnar) collateral ligament (MCL)
● Lateral (radial) collateral ligament (LCL)

95
Q

● Quite large and comprised of three distinct parts:
○ Anterior
○ Posterior
○ Transverse.
● It stabilizes the elbow against excessive valgus forces to restrict the forearm from excessive lateral displacement on the arm.
● The _ is the primary stabilizer of the elbow; damage to it may result in an unstable elbow joint.

A

Medial (Ulnar) collateral ligament (MCL)

○ Anterior
○ Posterior
○ Transverse.

96
Q

● fan-shaped structure.
● Like the MCL, the __ also has three parts; these segments extend from the humeral lateral epicondyle to the annular ligament surrounding the radial head and to the ulna’s olecranon process.

A

Lateral (Radial) collateral ligament (LCL)

97
Q

● This ligament stabilizes the elbow against excessive varus forces
● Prevents humeroulnar subluxation
● Stabilizes the humeroradial joint
● Assists the annular ligament in stabilizing the radial head against the ulna.

A

Lateral (Radial) collateral ligament (LCL)

98
Q

● The elbow complex contains seven _
● Three _ are associated with the triceps

A

Bursae

99
Q

● A large bursa lies between the olecranon and the olecranon fossa

A

Olecranon Bursae

100
Q

● PRUJ
● DRUJ
● Pronation/Supination
● 1 DOF
● Transverse plane, vertical axis

A

Radioulnar articulation

101
Q

Soft tissue of the proximal radioulnar joint complex

● PRUJ depends primarily on soft tissues for stability.
○
○
○
○
● Stability derived from the:
○
○
○

A

● PRUJ depends primarily on soft tissues for stability.
○ Annular ligament
○ LCL
○ Oblique cord
○ Quadrate ligament
● Stability derived from the:
○ Articular disc
○ Dorsal radioulnar ligaments
○ Palmar radioulnar ligaments

102
Q

● Located between radius and ulna.
● This thick membrane reinforces both radioulnar joints without restricting pronation or supination motions

A

Interosseous membrane

103
Q

● The _ ligament has firm, fibrous connections to the ulna, attaching to it on either side of the radial notch, anchoring firmly around the radial head and neck.

A

Annular ligament

104
Q

● The _ ligament is quite short but strong, arising from the ulna just inferior to the radial notch and attaching to the medial surface of the radial neck.

A

quadrate

105
Q

● Major stabilizer of the proximal radioulnar joint during full supination.

A

Anterior portion of the quadrate ligament

106
Q

● Weaker
● Stabilizes full pronation

A

Posterior portion of the quadrate ligament

107
Q

● A flat band of fascia on the ventral forearm running from the inferior aspect of the ulna’s radial notch to just below the ulna’s radial tuberosity.
● Its fibers run perpendicular to those of the interosseous membrane and become taut in full supination, providing additional stability to the radioulnar connection.

A

Oblique cord

108
Q

Muscles of the Elbow and Forearm Complex

A

● Flexor and extensor muscles @ Humeroulnar and humeroradial joints
● Supinator and pronator muscles @ forearm

109
Q

3 Elbow flexors

A

● Brachialis
● Biceps brachii
● Brachioradialis

110
Q

● “workhorse”
● Large work capacity due to a large cross section area.
● Largest of all of the elbow flexors.
● It crosses only the humeroulnar joint.

A

brachialis

111
Q

● A fusiform-shaped muscle with two heads located on the anterior arm.
● Functionally, the _ is selectively recruited when the task requires elbow flexion with forearm supination such as in carrying a loaded tray or bringing a spoon to the mouth.
● Greatest moment arm at _ to _ of flexion.
● Large cross section
● Beyond _ of flexion or when the elbow is close to full extension, the contractile force becomes more translatory.
● This _ _ provides joint compression to add stability to the elbow.

A

Biceps brachii

90° to 110°

100°

translatory force

112
Q

● The_ _ is a weak elbow flexor, predominantly contributing to flexion when the forearm is pronated.

A

pronator teres

113
Q

2 Elbow extensors

A

● Triceps brachii
● Anconeus

114
Q

● Extends the elbow regardless of forearm position
● Its greatest extension force is exerted in midrange at _ to _ of elbow flexion.
● Acts _ to extend the elbow.
● Acts _ as a major elbow stabilizer during elbow flexion.
● Powerful stabilizer of the upper extremity during any functional closed-chain activity

A

Triceps brachii

70° to 90°

concentrically

eccentrically

115
Q

● The_ is a small muscle located deep, adjacent to the joint, blending close to the fibers of the humeroulnar joint capsule.
● Contracts during elbow extension to tighten the loose posterior elbow capsule
● Perhaps helping to prevent pinching of the capsule folds as the olecranon locks into the olecranon fossa

A

anconeus

116
Q

2 Forearm Supinators

A

● Biceps brachii
● Supinator

117
Q

● The _ is able to supply adequate force when
○ supination occurs slowly
○ the resistance is light
○ the elbow is extended
● The only muscle whose sole action is forearm supination.
● Always recruited for forearm supination, regardless of the speed or load.
● Acts alone during slow supination or when the elbow is extended.

A

supinator

118
Q

● Powerful participator but supinates best when the elbow is flexed.
● Or when the motion occurs against a heavy resistance.

A

biceps brachii

119
Q

● Aids supination from pronation to midposition with the elbow in flexion, but its action is quite weak.

A

Brachioradialis

120
Q

2 Forearm Pronator

A

● Pronator teres
● Pronator quadratus

121
Q

● Primarily a forearm pronator.
● It runs rather close to the axis of the elbow joint so that it has a poor moment arm for elbow flexion
● This muscle supplies added force to elbow flexion only when there is a significant resistance or a heavy load.

A

Pronator Teres

122
Q

● This one-joint muscle performs forearm pronation regardless of elbow position.
● Acts as a dynamic stabilizer of the distal radioulnar joint

A

Pronator Quadratus

123
Q

● Injuries to the _ _ affect movements and cutaneous sensations in the upper limb
● Disease, stretching, and wounds in the lateral cervical region (posterior triangle) of the neck or in the axilla may produce brachial plexus injuries.
● Signs and symptoms depend on the part of the plexus involved.
● Injuries to _ parts of the brachial plexus (C5 and C6) usually result from an excessive increase in the angle between the neck and shoulder.
● These injuries can occur in a person who is thrown from a motorcycle or a horse and lands on the shoulder in a way that widely separates the neck and shoulder
● When thrown, the person’s shoulder often hits something (e.g., a tree or the ground) and stops, but the head and trunk continue to move.
● Injuries to _ parts of the brachial plexus (Klumpke paralysis) are much less common.
● _ _ _ injuries may occur when the upper limb is suddenly pulled superiorly—for example, when a person grasps something to break a fall or a baby’s upper limb is pulled excessively during delivery

A

Brachial Nerve Palsy

brachial plexus

superior parts (C5-C6)

inferior parts (klumpke paralysis)

Inferior brachial plexus injuries (upper limb)

124
Q

● _ _ involving the proximal ulna and distal humerus most frequently occur in a posterolateral direction and are a result of a fall on an outstretched arm with the elbow in hyperextension
● When a posterolateral elbow dislocation occurs, associated injuries include disruption of the ulnar and radial collateral ligaments of the elbow, and occasionally disruption of the flexor pronator forearm musculature, or periarticular and intraarticular fractures.

A

Elbow Dislocation

125
Q

● _ _ involving the proximal ulna and distal humerus most frequently occur in a posterolateral direction and are a result of a fall on an outstretched arm with the elbow in hyperextension
● When a posterolateral elbow dislocation occurs, associated injuries include disruption of the ulnar and radial collateral ligaments of the elbow, and occasionally disruption of the flexor pronator forearm musculature, or periarticular and intraarticular fractures.

A

Elbow Dislocation

human anatomy (12 decks)

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