The elbow is the region between the

arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

and the

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in ...

that surrounds the elbow joint. The elbow includes prominent landmarks such as the

olecranon The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...

, the

cubital fossa The cubital fossa, chelidon, or elbow pit, is the triangular area on the anterior side of the upper limb between the arm and forearm of a human or other hominid animals. It lies anteriorly to the elbow (Latin ) when in standard anatomical position ...

(also called the chelidon, or the elbow pit), and the

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

and the medial epicondyles of the humerus. The elbow joint is a hinge joint between the

and the

; more specifically between the humerus in the upper arm and the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

in the forearm which allows the forearm and hand to be moved towards and away from the body. The term ''elbow'' is specifically used for humans and other primates, and in other vertebrates forelimb plus

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

is used. 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.

Structure

Joint

The elbow joint has three different portions surrounded by a common joint capsule. These are joints between the three bones of the elbow, the humerus of the upper arm, and the

and the

of the forearm. When in anatomical position there are four main bony landmarks of the elbow. 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. The third landmark is the

found at the head of the ulna. These lie on a horizontal line called the ''Hueter line''. When the elbow is flexed, they form a triangle called the ''Hueter triangle'', which resembles an

equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each oth ...

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

trochlea Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel. Related to joints Most commonly, trochleae bear the articular surface of saddle and other joints: * Trochlea of humerus (part of ...

. In most people, the groove running across the trochlea is vertical on the anterior side but it spirals off on the posterior side. 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. The superior radioulnar joint shares the

joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint.

Joint capsule

The elbow joint and the superior radioulnar joint are enclosed by a single fibrous capsule. The capsule is strengthened by ligaments at the sides but is relatively weak in front and behind. On the anterior side, the capsule consists mainly of longitudinal fibres. However, some bundles among these fibers run obliquely or transversely, thickening and strengthening the capsule. These bundles are referred to as the capsular ligament. Deep fibres of the

brachialis muscle The brachialis (brachialis anticus), also known as the Teichmann muscle, is a muscle in the upper arm that flexes the elbow. It lies deeper than the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow p ...

insert anteriorly into the capsule and act to pull it and the underlying membrane during flexion in order to prevent them from being pinched. On the posterior side, the capsule is thin and mainly composed of transverse fibres. A few of these fibres stretch across the olecranon fossa without attaching to it and form a transverse band with a free upper border. On the ulnar side, the capsule reaches down to the posterior part of the annular ligament. The posterior capsule is attached to the

triceps The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of 3 parts: the medial, lateral, and long head. It is the muscle principally responsibl ...

tendon which prevents the capsule from being pinched during extension.

Synovial membrane

The synovial membrane of the elbow joint is very extensive. On the humerus, it extends up from the articular margins and covers the coronoid and

radial fossa The radial fossa is a slight depression found on the humerus above the front part of the capitulum. It receives the anterior border of the head of the radius when the forearm is flexed. Structure The joint capsule of the elbow attaches to th ...

e anteriorly and the

olecranon fossa The olecranon fossa is a deep triangular depression on the posterior side of the humerus, superior to the trochlea. It provides space for the olecranon of the ulna during extension of the forearm. Structure The olecranon fossa is located on ...

posteriorly. Distally, it is prolonged down to the neck of the radius and the superior radioulnar joint. It is supported by the

quadrate ligament In human anatomy, the quadrate ligament or ligament of Denucé is one of the ligaments of the proximal radioulnar joint in the upper forearm. Structure The quadrate ligament is a fibrous band attached to the inferior border of the radial notch on ...

below the annular ligament where it also forms a fold which gives the head of the radius freedom of movement. Several synovial folds project into the recesses of the joint. These folds or plicae are remnants of normal embryonic development and can be categorized as either anterior (anterior humeral recess) or posterior (olecranon recess). A crescent-shaped fold is commonly present between the head of the radius and the capitulum of the humerus. On the humerus there are extrasynovial

fat pad A fat pad (aka haversian gland) is a mass of closely packed fat cells surrounded by fibrous tissue septa.TheFreeDictionary > Fat padCiting: Mosby's Medical Dictionary, 8th edition. 2009 They may be extensively supplied with capillaries and nerve end ...

s adjacent to the three articular fossae. These pads fill the radial and coronoid fossa anteriorly during extension, and the olecranon fossa posteriorly during flexion. They are displaced when the fossae are occupied by the bony projections of the ulna and radius.

Ligaments

The elbow, like other joints, has ligaments on either side. These are triangular bands which blend with the joint capsule. 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. The

ulnar collateral ligament Ulnar collateral ligament (or UCL), may refer to: * Ulnar carpal collateral ligament * Ulnar collateral ligament of elbow joint The ulnar collateral ligament (UCL) or internal lateral ligament is a thick triangular ligament at the medial aspec ...

has its apex on the medial epicondyle. 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

. 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. 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. The ulnar nerve crosses the intermediate part as it enters the forearm. The radial collateral ligament is attached to the lateral epicondyle below the

common extensor tendon The common extensor tendon is a tendon that attaches to the lateral epicondyle of the humerus. Structure The common extensor tendon serves as the upper attachment (in part) for the superficial muscles that are located on the posterior aspect o ...

. 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 The radial notch of the ulna (lesser sigmoid cavity) is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius. It is concave from before bac ...

of the ulna.

Muscles

Flexion

There are three main flexor muscles at the elbow: * 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. *

Brachioradialis The brachioradialis is a muscle of the forearm that flexes the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm. It is attached to the distal styloid process of the radius by ...

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. * 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 The coracoid process (from Greek κόραξ, raven) is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula (hence: coracoid, or "like a raven's beak"). Pointing laterally forward, it, together with the ...

at the top of the scapula. Its main insertion is at the

radial tuberosity Beneath the neck of the radius, on the medial side, is an eminence, the radial tuberosity; its surface is divided into: * a ''posterior, rough portion'', for the insertion of the tendon of the biceps brachii. * an ''anterior, smooth portion'', on w ...

on the radius. Brachialis is the main muscle used when the elbow is flexed slowly. 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. 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°. 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. 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 The head of the radius has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum of the humerus. The circumference of the head is smooth; it is broad medially where it articulates with the ra ...

being pressed against the

and the coronoid process being pressed against the

coronoid fossa Superior to the anterior portion of the trochlea is a small depression, the coronoid fossa, which receives the coronoid process of the ulna during flexion of the forearm. It is directly adjacent to the radial fossa The radial fossa is a slight d ...

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

Extension

Elbow extension is simply bringing the forearm back to anatomical position. This action is performed by

triceps brachii The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of 3 parts: the medial, lateral, and long head. It is the muscle principally respon ...

with a negligible assistance from

anconeus The anconeus muscle (or anconaeus/anconæus) is a small muscle on the posterior aspect of the elbow joint. Some consider anconeus to be a continuation of the triceps brachii muscle. Some sources consider it to be part of the posterior compartmen ...

. Triceps originates with two heads posteriorly on the humerus and with its long head on the scapula just below the shoulder joint. It is inserted posteriorly on the olecranon. Triceps is maximally efficient with the elbow flexed 20–30°. As the angle of flexion increases, the position of the olecranon approaches the main axis of the humerus which decreases muscle efficiency. In full flexion, however, the triceps tendon is "rolled up" on the olecranon as on a pulley which compensates for the loss of efficiency. Because triceps' long head is biarticular (acts on two joints), its efficiency is also dependent on the position of the shoulder. Extension is limited by the olecranon reaching the

, tension in the anterior ligament, and resistance in flexor muscles. 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.

Blood supply

The

arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

supplying the joint are derived from an extensive

circulatory anastomosis A circulatory anastomosis is a connection (an anastomosis) between two blood vessels, such as between arteries (arterio-arterial anastomosis), between veins (veno-venous anastomosis) or between an artery and a vein (arterio-venous anastomosis) ...

between the brachial artery and its terminal branches. The superior and inferior ulnar collateral branches of the brachial artery and the

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

and middle collateral branches of the

profunda brachii artery The deep artery of arm (also known as arteria profunda brachii and the deep brachial artery) is a large vessel which arises from the lateral and posterior part of the brachial artery, just below the lower border of the teres major. Structure It ...

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 ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial ar ...

; the radial recurrent branch of the

radial artery In human anatomy, the radial artery is the main artery of the lateral aspect of the forearm. Structure The radial artery arises from the bifurcation of the brachial artery in the antecubital fossa. It runs distally on the anterior part of th ...

; and the interosseous recurrent branch of the

common interosseous artery The common interosseous artery, about 1 cm. in length, arises immediately below the tuberosity of the radius from the ulnar artery. Passing backward to the upper border of the interosseous membrane An interosseous membrane is a thick den ...

. The blood is brought back by vessels from the

ulnar The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

, and brachial veins. 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). 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. The

efferent lymph vessel The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...

s from the elbow proceed to the lateral group of

axillary lymph nodes The axillary lymph nodes or armpit lymph nodes are lymph nodes in the human armpit. Between 20 and 49 in number, they drain lymph vessels from the lateral quadrants of the breast, the superficial lymph vessels from thin walls of the chest and th ...

Nerve supply

The elbow is innervated anteriorly by branches from the

musculocutaneous The musculocutaneous nerve arises from the lateral cord of the brachial plexus, opposite the lower border of the pectoralis major, its fibers being derived from C5, C6 and C7. Structure The musculocutaneous nerve arises from the lateral cor ...

, median, and radial nerve, and posteriorly from the ulnar nerve and the branch of the radial nerve to

Development

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. The order of appearance can be understood by the mnemonic CRITOE, referring to the

capitellum In human anatomy of the arm, the capitulum of the humerus is a smooth, rounded eminence on the lateral portion of the distal articular surface of the humerus. It articulates with the cupshaped depression on the head of the radius, and is limite ...

, radial head, internal epicondyle,

, olecranon, and external epicondyle at ages 1, 3, 5, 7, 9 and 11 years. These apophyseal centers then fuse during adolescence, with the internal epicondyle and olecranon fusing last. The ages of fusion are more variable than ossification, but normally occur at 13, 15, 17, 13, 16 and 13 years, respectively. In addition, the presence of a joint effusion can be inferenced by the presence of the

fat pad sign The fat pad sign, also known as the sail sign, is a potential finding on elbow radiography which suggests a fracture of one or more bones at the elbow. It is may indicate an occult fracture that is not directly visible. Its name derives from th ...

, a structure that is normally physiologically present, but pathologic when elevated by fluid, and always pathologic when posterior.

Function

The function of the elbow joint is to extend and flex the arm grasp and reach for objects. The range of movement in the elbow is from 0 degrees of elbow extension to 150 degrees of

elbow flexion The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the media ...

. Muscles contributing to function are all flexion ( biceps brachii, brachialis, and

brachioradialis The brachioradialis is a muscle of the forearm that flexes the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm. It is attached to the distal styloid process of the radius by ...

) and extension muscles (

and

). In humans, the main task of the elbow is to properly place the hand in space by shortening and lengthening the upper limb. While the superior radioulnar joint shares joint capsule with the elbow joint, it plays no functional role at the elbow. With the elbow extended, the long axis of the humerus and that of the ulna coincide. 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°. 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. 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.

Carrying angle

When the arm is extended, with the palm facing forward or up, the bones of the upper arm ( humerus) and

(

and

) are not perfectly aligned. The deviation from a straight line occurs in the direction of the thumb, and is referred to as the "carrying angle". The carrying angle permits the arm to be swung without contacting the hips. 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). 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. 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. Developmental, aging and possibly racial influences add further to the variability of this parameter.

Pathology

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

Tendonitis

Two of the most common injuries at the elbow are overuse injuries:

tennis elbow Tennis elbow, also known as lateral epicondylitis or enthesopathy of the extensor carpi radialis origin, is a condition in which the outer part of the elbow becomes painful and tender. The pain may also extend into the back of the forearm. Onse ...

and

golfer's elbow Golfer's elbow, or medial epicondylitis, is tendinosis of the medial epicondyle on the inside of the elbow. It is in some ways similar to tennis elbow, which affects the outside at the lateral epicondyle. The anterior forearm contains several ...

. Golfer's elbow involves the tendon of the common flexor origin which originates at the

medial epicondyle of the humerus The medial epicondyle of the humerus is an epicondyle of the humerus bone of the upper arm in humans. It is larger and more prominent than the lateral epicondyle and is directed slightly more posteriorly in the anatomical position. In birds, whe ...

(the "inside" of the elbow). Tennis elbow is the equivalent injury, but at the common extensor origin (the

lateral epicondyle of the humerus The lateral epicondyle of the humerus is a large, tuberculated eminence, curved a little forward, and giving attachment to the radial collateral ligament of the elbow joint, and to a tendon common to the origin of the supinator and some of the e ...

Fractures

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

fracture is ruled out. Acute fractures may not be easily visible on X-ray.

Dislocation

Elbow dislocations constitute 10% to 25% of all injuries to the elbow. 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. Among injuries to the upper extremity, dislocation of the elbow is second only to a

dislocated shoulder A dislocated shoulder is a condition in which the head of the humerus is detached from the shoulder joint. Symptoms include shoulder pain and instability. Complications may include a Bankart lesion, Hill-Sachs lesion, rotator cuff tear, or inj ...

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

Infection

Infection of the elbow joint (

septic arthritis Acute septic arthritis, infectious arthritis, suppurative arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, h ...

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

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the ...

Arthritis

Elbow arthritis is usually seen in individuals with rheumatoid arthritis or after fractures that involve the joint itself. When the damage to the joint is severe, fascial arthroplasty or elbow joint replacement may be considered.

Bursitis

Olecranon bursitis, tenderness, warmth, swelling, pain in both flexion and extension-in chronic case great flexion-is extremely painful.

Elbow pain

Elbow pain occurs when the tenderness of the tissues in the elbow become inflamed. Frequent exercise of the inflamed elbow will assist with healing.

Clinical significance

Elbow pain can occur for a multitude of reasons, including injury, disease, and other conditions. Common conditions include tennis elbow, golfer's elbow, distal radioulnar joint rheumatoid arthritis, and cubital tunnel syndrome.

Tennis elbow

Tennis elbow Tennis elbow, also known as lateral epicondylitis or enthesopathy of the extensor carpi radialis origin, is a condition in which the outer part of the elbow becomes painful and tender. The pain may also extend into the back of the forearm. Onse ...

is a very common type of overuse injury. It can occur both from chronic repetitive motions of the hand and forearm, and from trauma to the same areas. These repetitions can injure the tendons that connect the extensor supinator muscles (which rotate and extend the forearm) to the

olecranon process The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...

(also known as “the elbow”). Pain occurs, often radiating from the lateral forearm. Weakness, numbness, and stiffness are also very common, along with tenderness upon touch. A non-invasive treatment for pain management is rest. If achieving rest is an issue, a wrist brace can also be worn. This keeps the wrist in flexion, thereby relieving the

extensor muscles In anatomy, extension is a movement of a joint that increases the angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extendin ...

and allowing rest. Ice, heat, ultrasound, steroid injections, and

compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression * Gas compression *Compression ratio, of a ...

can also help alleviate pain. After the pain has been reduced, exercise therapy is important to prevent injury in the future. Exercises should be low velocity, and weight should increase progressively. Stretching the flexors and extensors is helpful, as are strengthening exercises. Massage can also be useful, focusing on the extensor

trigger points Myofascial trigger points (MTrPs), also known as trigger points, are described as hyperirritable spots in the skeletal muscle. They are associated with palpable nodules in taut bands of muscle fibers. They are a topic of ongoing controversy, a ...

Golfer’s elbow

Golfer's elbow Golfer's elbow, or medial epicondylitis, is tendinosis of the medial epicondyle on the inside of the elbow. It is in some ways similar to tennis elbow, which affects the outside at the lateral epicondyle. The anterior forearm contains several ...

is very similar to tennis elbow, but less common. It is caused by overuse and repetitive motions like a golf swing. It can also be caused by trauma. Wrist flexion and pronation (rotating of the forearm) causes irritation to the tendons near the medial epicondyle of the elbow. It can cause pain, stiffness, loss of sensation, and weakness radiating from the inside of the elbow to the fingers. Rest is the primary intervention for this injury. Ice, pain medication, steroid injections, strengthening exercises, and avoiding any aggravating activities can also help. Surgery is a last resort, and rarely used. Exercises should focus on strengthening and stretching the forearm, and utilizing proper form when performing movements.

Rheumatoid arthritis

Rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...

is a chronic disease that affects joints. It is very common in the wrist, and is most common at the radioulnar joint. It results in pain, stiffness, and deformities. There are many different treatments for rheumatoid arthritis, and there is no one consensus for which methods are best. Most common treatments include wrist splints, surgery, physical and occupational therapy, and antirheumatic medication.

Cubital tunnel syndrome

Cubital tunnel syndrome, more commonly known as ulnar neuropathy, occurs when the ulnar nerve is irritated and becomes inflamed. This can often happen where the ulnar nerve is most superficial, at the elbow. The ulnar nerve passes over the elbow, at the area known as the “funny bone”. Irritation can occur due to constant, repeated stress and pressure at this area, or from a trauma. It can also occur due to bone deformities, and oftentimes from sports. Symptoms include tingling, numbness, and weakness, along with pain. First line pain management techniques include the use of nonsteroidal anti-inflammatory oral medicines. These help to reduce inflammation, pressure, and irritation of the nerve and around the nerve. Other simple fixes include learning more ergonomically friendly habits that can help prevent nerve impingement and irritation in the future. Protective equipment can also be very helpful. Examples of this include a protective elbow pad, and an arm splint. More serious cases often involve surgery, in which the nerve or the surrounding tissue is moved to relieve the pressure. Recovery from surgery can take awhile, but the prognosis is often a good one. Recovery often includes movement restrictions, and range of motion activities, and can last a few months (cubital and radial tunnel syndrome, 2).

Society and culture

The now obsolete length unit ell relates closely to the elbow. 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). It is unknown when or why the second "l" was dropped from English usage of the word. 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. The ell as a measure was taken as six handbreadths; three to the elbow and three from the elbow to the shoulder. Another measure was the ''

cubit The cubit is an ancient unit of length based on the distance from the elbow to the tip of the middle finger. It was primarily associated with the Sumerians, Egyptians, and Israelites. The term ''cubit'' is found in the Bible regarding ...

'' (from ''cubital''). This was taken to be the length of a man's arm from the elbow to the end of the middle finger.O.D.E. 2nd edition 2005

Other primates

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 difference. In

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

apes such as

orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...

s, the large forearm muscles originating on the epicondyles of the humerus generate significant transverse forces on the elbow joint. 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. 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.

Derived trait In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

s in

catarrhini The parvorder Catarrhini , catarrhine monkeys, Old World anthropoids, or Old World monkeys, consisting of the Cercopithecoidea and apes (Hominoidea). In 1812, Geoffroy grouped those two groups together and established the name Catarrhini, "Old ...

(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. The

proximal radioulnar joint The proximal radioulnar articulation, also known as the proximal radioulnar joint (PRUJ), is a synovial pivot joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament ...

is similarly derived in higher primates in the location and shape of the

on the ulna; the primitive form being represented by

New World monkey New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboidea ...

s, such as the

howler monkey Howler monkeys (genus ''Alouatta'', monotypic in subfamily Alouattinae) are the most widespread primate genus in the Neotropics and are among the largest of the platyrrhines along with the muriquis (''Brachyteles''), the spider monkeys (''Atele ...

, and by fossil catarrhines, such as ''

Aegyptopithecus ''Aegyptopithecus'' ("Egyptian ape", from Greek ''Αίγυπτος'' "Egypt" and ''πίθηκος'' "ape") is an early fossil catarrhine that predates the divergence between hominoids ( apes) and cercopithecids (Old World monkeys). It is kno ...

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

Notes

References

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