Elbow

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For other uses, see Elbow (disambiguation). Elbow_sentence_0

Elbow_table_infobox_0

ElbowElbow_header_cell_0_0_0
DetailsElbow_header_cell_0_1_0
IdentifiersElbow_header_cell_0_2_0
LatinElbow_header_cell_0_3_0 articulatio cubitiElbow_cell_0_3_1
MeSHElbow_header_cell_0_4_0 Elbow_cell_0_4_1
TA98Elbow_header_cell_0_5_0 Elbow_cell_0_5_1
TA2Elbow_header_cell_0_6_0 Elbow_cell_0_6_1
FMAElbow_header_cell_0_7_0 Elbow_cell_0_7_1

The elbow is the visible joint between the upper and lower parts of the arm. Elbow_sentence_1

It includes prominent landmarks such as the olecranon, the elbow pit, the lateral and medial epicondyles, and the elbow joint. Elbow_sentence_2

The elbow joint is the synovial hinge joint between the humerus in the upper arm and the radius and ulna in the forearm which allows the forearm and hand to be moved towards and away from the body. Elbow_sentence_3

Medical Subject Headings defines the elbow specifically for humans and other primates, though the term is frequently used for the anterior joints of other mammals, such as dogs. Elbow_sentence_4

The name for the elbow in Latin is cubitus, and so the word cubital is used in some elbow-related terms, as in cubital nodes for example. Elbow_sentence_5

Structure Elbow_section_0

Joint Elbow_section_1

The elbow joint has three different portions surrounded by a common joint capsule. Elbow_sentence_6

These are joints between the three bones of the elbow, the humerus of the upper arm, and the radius and the ulna of the forearm. Elbow_sentence_7

Elbow_table_general_1

JointElbow_header_cell_1_0_0 FromElbow_header_cell_1_0_1 ToElbow_header_cell_1_0_2 DescriptionElbow_header_cell_1_0_3
Humeroulnar jointElbow_cell_1_1_0 trochlear notch of the ulnaElbow_cell_1_1_1 trochlea of humerusElbow_cell_1_1_2 Is a simple hinge-joint, and allows for movements of flexion and extension only.Elbow_cell_1_1_3
Humeroradial jointElbow_cell_1_2_0 head of the radiusElbow_cell_1_2_1 capitulum of the humerusElbow_cell_1_2_2 Is a ball-and-socket joint.Elbow_cell_1_2_3
Proximal radioulnar jointElbow_cell_1_3_0 head of the radiusElbow_cell_1_3_1 radial notch of the ulnaElbow_cell_1_3_2 In any position of flexion or extension, the radius, carrying the hand with it, can be rotated in it. This movement includes pronation and supination.Elbow_cell_1_3_3

When in anatomical position there are four main bony landmarks of the elbow. Elbow_sentence_8

At the lower part of the humerus are the medial and lateral epicondyles, on the side closest to the body (medial) and on the side away from the body (lateral) surfaces. Elbow_sentence_9

The third landmark is the olecranon found at the head of the ulna. Elbow_sentence_10

These lie on a horizontal line called the Hueter line. Elbow_sentence_11

When the elbow is flexed, they form a triangle called the Hueter triangle, which resembles an equilateral triangle. Elbow_sentence_12

At the surface of the humerus where it faces the joint is the trochlea. Elbow_sentence_13

In most people, the groove running across the trochlea is vertical on the anterior side but it spirals off on the posterior side. Elbow_sentence_14

This results in the forearm being aligned to the upper arm during flexion, but forming an angle to the upper arm during extension — an angle known as the carrying angle. Elbow_sentence_15

The superior radioulnar joint shares the joint capsule with the elbow joint but plays no functional role at the elbow. Elbow_sentence_16

Joint capsule Elbow_section_2

The elbow joint and the superior radioulnar joint are enclosed by a single fibrous capsule. Elbow_sentence_17

The capsule is strengthened by ligaments at the sides but is relatively weak in front and behind. Elbow_sentence_18

On the anterior side, the capsule consists mainly of longitudinal fibres. Elbow_sentence_19

However, some bundles among these fibers run obliquely or transversely, thickening and strengthening the capsule. Elbow_sentence_20

These bundles are referred to as the capsular ligament. Elbow_sentence_21

Deep fibres of the brachialis muscle insert anteriorly into the capsule and act to pull it and the underlying membrane during flexion in order to prevent them from being pinched. Elbow_sentence_22

On the posterior side, the capsule is thin and mainly composed of transverse fibres. Elbow_sentence_23

A few of these fibres stretch across the olecranon fossa without attaching to it and form a transverse band with a free upper border. Elbow_sentence_24

On the ulnar side, the capsule reaches down to the posterior part of the annular ligament. Elbow_sentence_25

The posterior capsule is attached to the triceps tendon which prevents the capsule from being pinched during extension. Elbow_sentence_26

Synovial membrane Elbow_section_3

The synovial membrane of the elbow joint is very extensive. Elbow_sentence_27

On the humerus, it extends up from the articular margins and covers the coronoid and radial fossae anteriorly and the olecranon fossa posteriorly. Elbow_sentence_28

Distally, it is prolonged down to the neck of the radius and the superior radioulnar joint. Elbow_sentence_29

It is supported by the quadrate ligament below the annular ligament where it also forms a fold which gives the head of the radius freedom of movement. Elbow_sentence_30

Several synovial folds project into the recesses of the joint. Elbow_sentence_31

These folds or plicae are remnants of normal embryonic development and can be categorized as either anterior (anterior humeral recess) or posterior (olecranon recess). Elbow_sentence_32

A crescent-shaped fold is commonly present between the head of the radius and the capitulum of the humerus. Elbow_sentence_33

On the humerus there are extrasynovial fat pads adjacent to the three articular fossae. Elbow_sentence_34

These pads fill the radial and coronoid fossa anteriorly during extension, and the olecranon fossa posteriorly during flexion. Elbow_sentence_35

They are displaced when the fossae are occupied by the bony projections of the ulna and radius. Elbow_sentence_36

Ligaments Elbow_section_4

The elbow, like other joints, has ligaments on either side. Elbow_sentence_37

These are triangular bands which blend with the joint capsule. Elbow_sentence_38

They are positioned so that they always lie across the transverse joint axis and are, therefore, always relatively tense and impose strict limitations on abduction, adduction, and axial rotation at the elbow. Elbow_sentence_39

The ulnar collateral ligament has its apex on the medial epicondyle. Elbow_sentence_40

Its anterior band stretches from the anterior side of the medial epicondyle to the medial edge of the coronoid process, while the posterior band stretches from posterior side of the medial epicondyle to the medial side of the olecranon. Elbow_sentence_41

These two bands are separated by a thinner intermediate part and their distal attachments are united by a transverse band below which the synovial membrane protrudes during joint movements. Elbow_sentence_42

The anterior band is closely associated with the tendon of the superficial flexor muscles of the forearm, even being the origin of flexor digitorum superficialis. Elbow_sentence_43

The ulnar nerve crosses the intermediate part as it enters the forearm. Elbow_sentence_44

The radial collateral ligament is attached to the lateral epicondyle below the common extensor tendon. Elbow_sentence_45

Less distinct than the ulnar collateral ligament, this ligament blends with the annular ligament of the radius and its margins are attached near the radial notch of the ulna. Elbow_sentence_46

Muscles Elbow_section_5

Flexion Elbow_section_6

There are three main flexor muscles at the elbow: Elbow_sentence_47

Elbow_unordered_list_0

  • Brachialis acts exclusively as an elbow flexor and is one of the few muscles in the human body with a single function. It originates low on the anterior side of the humerus and is inserted into the tuberosity of the ulna.Elbow_item_0_0
  • Brachioradialis acts essentially as an elbow flexor but also supinates during extreme pronation and pronates during extreme supination. It originates at the lateral supracondylar ridge distally on the humerus and is inserted distally on the radius at the styloid process.Elbow_item_0_1
  • Biceps brachii is the main elbow flexor but, as a biarticular muscle, also plays important secondary roles as a stabiliser at the shoulder and as a supinator. It originates on the scapula with two tendons: That of the long head on the supraglenoid tubercle just above the shoulder joint and that of the short head on the coracoid process at the top of the scapula. Its main insertion is at the radial tuberosity on the radius.Elbow_item_0_2

Brachialis is the main muscle used when the elbow is flexed slowly. Elbow_sentence_48

During rapid and forceful flexion all three muscles are brought into action assisted by the superficial forearm flexors originating at the medial side of the elbow. Elbow_sentence_49

The efficiency of the flexor muscles increases dramatically as the elbow is brought into midflexion (flexed 90°) — biceps reaches its angle of maximum efficiency at 80–90° and brachialis at 100–110°. Elbow_sentence_50

Active flexion is limited to 145° by the contact between the anterior muscles of the upper arm and forearm, more so because they are hardened by contraction during flexion. Elbow_sentence_51

Passive flexion (forearm is pushed against the upper arm with flexors relaxed) is limited to 160° by the bony projections on the radius and ulna as they reach to shallow depressions on the humerus; i.e. the head of radius being pressed against the radial fossa and the coronoid process being pressed against the coronoid fossa. Elbow_sentence_52

Passive flexion is further limited by tension in the posterior capsular ligament and in triceps brachii. Elbow_sentence_53

A small accessory muscle, so called epitrochleoanconeus muscle, may be found on the medial aspect of the elbow running from the medial epicondyle to the olecranon. Elbow_sentence_54

Extension Elbow_section_7

Elbow extension is simply bringing the forearm back to anatomical position. Elbow_sentence_55

This action is performed by triceps brachii with a negligible assistance from anconeus. Elbow_sentence_56

Triceps originates with two heads posteriorly on the humerus and with its long head on the scapula just below the shoulder joint. Elbow_sentence_57

It is inserted posteriorly on the olecranon. Elbow_sentence_58

Triceps is maximally efficient with the elbow flexed 20–30°. Elbow_sentence_59

As the angle of flexion increases, the position of the olecranon approaches the main axis of the humerus which decreases muscle efficiency. Elbow_sentence_60

In full flexion, however, the triceps tendon is "rolled up" on the olecranon as on a pulley which compensates for the loss of efficiency. Elbow_sentence_61

Because triceps' long head is biarticular (acts on two joints), its efficiency is also dependent on the position of the shoulder. Elbow_sentence_62

Extension is limited by the olecranon reaching the olecranon fossa, tension in the anterior ligament, and resistance in flexor muscles. Elbow_sentence_63

Forced extension results in a rupture in one of the limiting structures: olecranon fracture, torn capsule and ligaments, and, though the muscles are normally left unaffected, a bruised brachial artery. Elbow_sentence_64

Blood supply Elbow_section_8

The arteries supplying the joint are derived from an extensive circulatory anastomosis between the brachial artery and its terminal branches. Elbow_sentence_65

The superior and inferior ulnar collateral branches of the brachial artery and the radial and middle collateral branches of the profunda brachii artery descend from above to reconnect on the joint capsule, where they also connect with the anterior and posterior ulnar recurrent branches of the ulnar artery; the radial recurrent branch of the radial artery; and the interosseous recurrent branch of the common interosseous artery. Elbow_sentence_66

The blood is brought back by vessels from the radial, ulnar, and brachial veins. Elbow_sentence_67

There are two sets of lymphatic nodes at the elbow, normally located above the medial epicondyle — the deep and superficial cubital nodes (also called epitrochlear nodes). Elbow_sentence_68

The lymphatic drainage at the elbow is through the deep nodes at the bifurcation of the brachial artery, the superficial nodes drain the forearm and the ulnar side of the hand. Elbow_sentence_69

The efferent lymph vessels from the elbow proceed to the lateral group of axillary lymph nodes. Elbow_sentence_70

Nerve supply Elbow_section_9

The elbow is innervated anteriorly by branches from the musculocutaneous, median, and radial nerve, and posteriorly from the ulnar nerve and the branch of the radial nerve to anconeus. Elbow_sentence_71

Development Elbow_section_10

The elbow undergoes dynamic development of ossification centers through infancy and adolescence, with the order of both the appearance and fusion of the apophyseal growth centers being crucial in assessment of the pediatric elbow on radiograph, in order to distinguish a traumatic fracture or apophyseal separation from normal development. Elbow_sentence_72

The order of appearance can be understood by the mnemonic CRITOE, referring to the capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle at ages 1, 3, 5, 7, 9 and 11 years. Elbow_sentence_73

These apophyseal centers then fuse during adolescence, with the internal epicondyle and olecranon fusing last. Elbow_sentence_74

The ages of fusion are more variable than ossification, but normally occur at 13, 15, 17, 13, 16 and 13 years, respectively. Elbow_sentence_75

In addition, the presence of a joint effusion can be inferenced by the presence of the fat pad sign, a structure that is normally physiologically present, but pathologic when elevated by fluid, and always pathologic when posterior. Elbow_sentence_76

Function Elbow_section_11

The function of the elbow joint is to extend and flex the arm grasp and reach for objects. Elbow_sentence_77

The range of movement in the elbow is from 0 degrees of elbow extension to 150 of elbow flexion. Elbow_sentence_78

Muscles contributing to function are all flexion (biceps brachii, brachialis, and brachioradialis) and extension muscles (triceps and anconeus). Elbow_sentence_79

In humans, the main task of the elbow is to properly place the hand in space by shortening and lengthening the upper limb. Elbow_sentence_80

While the superior radioulnar joint shares joint capsule with the elbow joint, it plays no functional role at the elbow. Elbow_sentence_81

With the elbow extended, the long axis of the humerus and that of the ulna coincide. Elbow_sentence_82

At the same time, the articular surfaces on both bones are located in front of those axes and deviate from them at an angle of 45°. Elbow_sentence_83

Additionally, the forearm muscles that originate at the elbow are grouped at the sides of the joint in order not to interfere with its movement. Elbow_sentence_84

The wide angle of flexion at the elbow made possible by this arrangement — almost 180° — allows the bones to be brought almost in parallel to each other. Elbow_sentence_85

Carrying angle Elbow_section_12

When the arm is extended, with the palm facing forward or up, the bones of the upper arm (humerus) and forearm (radius and ulna) are not perfectly aligned. Elbow_sentence_86

The deviation from a straight line occurs in the direction of the thumb, and is referred to as the "carrying angle" (visible in the right half of the picture, right). Elbow_sentence_87

The carrying angle permits the arm to be swung without contacting the hips. Elbow_sentence_88

Women on average have smaller shoulders and wider hips than men, which tends to produce a larger carrying angle (i.e., larger deviation from a straight line than that in men). Elbow_sentence_89

There is, however, extensive overlap in the carrying angle between individual men and women, and a sex-bias has not been consistently observed in scientific studies. Elbow_sentence_90

This could however be attributed to the very small sample sizes in those cited earlier studies. Elbow_sentence_91

A more recent study based on a sample size of 333 individuals from both sexes concluded that carrying angle is a suitable secondary sexual characteristic. Elbow_sentence_92

The angle is greater in the dominant limb than the non-dominant limb of both sexes, suggesting that natural forces acting on the elbow modify the carrying angle. Elbow_sentence_93

Developmental, aging and possibly racial influences add further to the variability of this parameter. Elbow_sentence_94

Pathology Elbow_section_13

The types of disease most commonly seen at the elbow are due to injury. Elbow_sentence_95

Tendonitis Elbow_section_14

Two of the most common injuries at the elbow are overuse injuries: tennis elbow and golfer's elbow. Elbow_sentence_96

Golfer's elbow involves the tendon of the common flexor origin which originates at the medial epicondyle of the humerus (the "inside" of the elbow). Elbow_sentence_97

Tennis elbow is the equivalent injury, but at the common extensor origin (the lateral epicondyle of the humerus). Elbow_sentence_98

Fractures Elbow_section_15

There are three bones at the elbow joint, and any combination of these bones may be involved in a fracture of the elbow. Elbow_sentence_99

Patients who are able to fully extend their arm at the elbow are unlikely to have a fracture (98% certainty) and an X-ray is not required as long as an olecranon fracture is ruled out. Elbow_sentence_100

Acute fractures may not be easily visible on X-ray. Elbow_sentence_101

Dislocation Elbow_section_16

Elbow dislocations constitute 10% to 25% of all injuries to the elbow. Elbow_sentence_102

The elbow is one of the most commonly dislocated joints in the body, with an average annual incidence of acute dislocation of 6 per 100,000 persons. Elbow_sentence_103

Among injuries to the upper extremity, dislocation of the elbow is second only to a dislocated shoulder. Elbow_sentence_104

A full dislocation of the elbow will require expert medical attention to re-align, and recovery can take approximately 8–14 weeks. Elbow_sentence_105

Infection Elbow_section_17

Infection of the elbow joint (septic arthritis) is uncommon. Elbow_sentence_106

It may occur spontaneously, but may also occur in relation to surgery or infection elsewhere in the body (for example, endocarditis). Elbow_sentence_107

Arthritis Elbow_section_18

Elbow arthritis is usually seen in individuals with rheumatoid arthritis or after fractures that involve the joint itself. Elbow_sentence_108

When the damage to the joint is severe, fascial arthroplasty or elbow joint replacement may be considered. Elbow_sentence_109

Bursitis Elbow_section_19

Main article: Olecranon bursitis Elbow_sentence_110

Olecranon bursitis, pain in posterior part of elbow, tenderness, warmth, swelling, pain in both flexion and extension, in chronic case extreme flexion is painful Elbow_sentence_111

Clinical significance Elbow_section_20

Elbow pain can occur for a multitude of reasons, including injury, disease, and other conditions. Elbow_sentence_112

Common conditions include tennis elbow, golfer’s elbow, distal radioulnar joint rheumatoid arthritis, and cubital tunnel syndrome. Elbow_sentence_113

Tennis elbow Elbow_section_21

Tennis elbow is a very common type of overuse injury. Elbow_sentence_114

It can occur both from chronic repetitive motions of the hand and forearm, and from trauma to the same areas. Elbow_sentence_115

These repetitions can injure the tendons that connect the extensor supinator muscles (which rotate and extend the forearm) to the olecranon process (also known as “the elbow”). Elbow_sentence_116

Pain occurs, often radiating from the lateral forearm. Elbow_sentence_117

Weakness, numbness, and stiffness are also very common, along with tenderness upon touch. Elbow_sentence_118

A non-invasive treatment for pain management is rest. Elbow_sentence_119

If achieving rest is an issue, a wrist brace can also be worn. Elbow_sentence_120

This keeps the wrist in flexion, thereby relieving the extensor muscles and allowing rest. Elbow_sentence_121

Ice, heat, ultrasound, steroid injections, and compression can also help alleviate pain. Elbow_sentence_122

After the pain has been reduced, exercise therapy is important to prevent injury in the future. Elbow_sentence_123

Exercises should be low velocity, and weight should increase progressively. Elbow_sentence_124

Stretching the flexors and extensors is helpful, as are strengthening exercises. Elbow_sentence_125

Massage can also be useful, focusing on the extensor trigger points. Elbow_sentence_126

Golfer’s elbow Elbow_section_22

Golfer's elbow is very similar to tennis elbow, but less common. Elbow_sentence_127

It is caused by overuse and repetitive motions like a golf swing. Elbow_sentence_128

It can also be caused by trauma. Elbow_sentence_129

Wrist flexion and pronation (rotating of the forearm) causes irritation to the tendons near the medial epicondyle of the elbow. Elbow_sentence_130

It can cause pain, stiffness, loss of sensation, and weakness radiating from the inside of the elbow to the fingers. Elbow_sentence_131

Rest is the primary intervention for this injury. Elbow_sentence_132

Ice, pain medication, steroid injections, strengthening exercises, and avoiding any aggravating activities can also help. Elbow_sentence_133

Surgery is a last resort, and rarely used. Elbow_sentence_134

Exercises should focus on strengthening and stretching the forearm, and utilizing proper form when performing movements. Elbow_sentence_135

Rheumatoid arthritis Elbow_section_23

Rheumatoid arthritis is a chronic disease that affects joints. Elbow_sentence_136

It is very common in the wrist, and is most common at the radioulnar joint. Elbow_sentence_137

It results in pain, stiffness, and deformities. Elbow_sentence_138

There are many different treatments for rheumatoid arthritis, and there is no one consensus for which methods are best. Elbow_sentence_139

Most common treatments include wrist splints, surgery, physical and occupational therapy, and antirheumatic medication. Elbow_sentence_140

Cubital tunnel syndrome Elbow_section_24

Cubital tunnel syndrome, more commonly known as ulnar neuropathy, occurs when the ulnar nerve is irritated and becomes inflamed. Elbow_sentence_141

This can often happen where the ulnar nerve is most superficial, at the elbow. Elbow_sentence_142

The ulnar nerve passes over the elbow, at the area known as the “funny bone”. Elbow_sentence_143

Irritation can occur due to constant, repeated stress and pressure at this area, or from a trauma. Elbow_sentence_144

It can also occur due to bone deformities, and oftentimes from sports. Elbow_sentence_145

Symptoms include tingling, numbness, and weakness, along with pain. Elbow_sentence_146

First line pain management techniques include the use of nonsteroidal anti-inflammatory oral medicines. Elbow_sentence_147

These help to reduce inflammation, pressure, and irritation of the nerve and around the nerve. Elbow_sentence_148

Other simple fixes include learning more ergonomically friendly habits that can help prevent nerve impingement and irritation in the future. Elbow_sentence_149

Protective equipment can also be very helpful. Elbow_sentence_150

Examples of this include a protective elbow pad, and an arm splint. Elbow_sentence_151

More serious cases often involve surgery, in which the nerve or the surrounding tissue is moved to relieve the pressure. Elbow_sentence_152

Recovery from surgery can take awhile, but the prognosis is often a good one. Elbow_sentence_153

Recovery often includes movement restrictions, and range of motion activities, and can last a few months (cubital and radial tunnel syndrome, 2). Elbow_sentence_154

Society and culture Elbow_section_25

The now obsolete length unit ell relates closely to the elbow. Elbow_sentence_155

This becomes especially visible when considering the Germanic origins of both words, Elle (ell, defined as the length of a male forearm from elbow to fingertips) and Ellbogen (elbow). Elbow_sentence_156

It is unknown when or why the second "l" was dropped from English usage of the word. Elbow_sentence_157

The ell as in the English measure could also be taken to come from the letter L, being bent at right angles, as an elbow. Elbow_sentence_158

The ell as a measure was taken as six handbreadths; three to the elbow and three from the elbow to the shoulder. Elbow_sentence_159

Another measure was the cubit (from cubital). Elbow_sentence_160

This was taken to be the length of a man's arm from the elbow to the end of the middle finger. Elbow_sentence_161

Other primates Elbow_section_26

Though the elbow is similarly adapted for stability through a wide range of pronation-supination and flexion-extension in all apes, there are some minor differences. Elbow_sentence_162

In arboreal apes such as orangutans, the large forearm muscles originating on the epicondyles of the humerus generate significant transverse forces on the elbow joint. Elbow_sentence_163

The structure to resist these forces is a pronounced keel on the trochlear notch on the ulna, which is more flattened in, for example, humans and gorillas. Elbow_sentence_164

In knuckle-walkers, on the other hand, the elbow has to deal with large vertical loads passing through extended forearms and the joint is therefore more expanded to provide larger articular surfaces perpendicular to those forces. Elbow_sentence_165

Derived traits in catarrhini (apes and Old World monkeys) elbows include the loss of the entepicondylar foramen (a hole in the distal humerus), a non-translatory (rotation-only) humeroulnar joint, and a more robust ulna with a shortened trochlear notch. Elbow_sentence_166

The proximal radioulnar joint is similarly derived in higher primates in the location and shape of the radial notch on the ulna; the primitive form being represented by New World monkeys, such as the howler monkey, and by fossil catarrhines, such as Aegyptopithecus. Elbow_sentence_167

In these taxa, the oval head of the radius lies in front of the ulnar shaft so that the former overlaps the latter by half its width. Elbow_sentence_168

With this forearm configuration, the ulna supports the radius and maximum stability is achieved when the forearm is fully pronated. Elbow_sentence_169


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Elbow.