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



Its  landmarks include: the olecranon, the elbow pit, the lateral and medial epicondyles, and the elbow joint. 



It 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.



The elbow joint has three different portions surrounded by a common joint capsule: joints between the three bones of the elbow, the humerus of the upper arm, and the radius and the ulna of the forearm.



The humeroelbow joint is a simple hinge-joint, and allows for movements of flexion and extension only.



Humeroradial joint Is a ball-and-socket joint.



Proximal radioulnar joint movement includes pronation and supination.



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



The four main bony landmarks of the elbow: At the lower part of the humerus are the medial and lateral epicondyles, the third landmark is the olecranon found at the head of the ulna. 



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



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



The elbow joint and the superior radioulnar joint capsule are strengthened by ligaments at the sides but is relatively weak in front and behind.



Fibers  of the brachialis muscle insert anteriorly into the capsule and acts to pull it and the underlying membrane during flexion.



 On the posterior side of the elbow, the capsule is thin and mainly composed of transverse fibers.



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



The elbow’s synovial membrane is very extensive, extending from the humerus, the coronoid and radial fossae anteriorly and the olecranon fossa posteriorly, distally to the neck of the radius and the superior radioulnar joint. 



Synovial folds project into the recesses of the joint, and can be categorized as either anterior (anterior humeral recess) or posterior (olecranon recess).



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



The  humerus has extrasynovial fat pads adjacent to the three articular fossae, filling the radial and coronoid fossa anteriorly during extension, and the olecranon fossa posteriorly during flexion. 



The elbow, has ligaments on either side. 



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



Ligaments always lie across the transverse joint axis and are relatively tense and impose strict limitations on abduction, adduction, and axial rotation at the elbow.



There are three main flexor muscles at the elbow.



Brachialis acts exclusively as an elbow flexor.



The brachialis muscle has  a single function: It originates low on the anterior side of the humerus and is inserted into the tuberosity of the ulna.



Brachioradialis acts essentially as an elbow flexor but also supinates during extreme pronation and pronates during extreme supination. 



The brachioradialis muscle originates at the lateral supracondylar ridge distally on the humerus and is inserted distally on the radius at the styloid process.






The biceps brachii is the main elbow flexor but, as a biarticular muscle, also plays important secondary roles as a stabilizer 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. 



The biceps main insertion is at the radial tuberosity on the radius.



The brachialis is the main muscle used when the elbow is flexed slowly. 



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



Flexor muscle efficiency increases dramatically as the elbow is brought into midflexion at 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.



Elbow extension brings  the forearm back to anatomical position, performed by triceps brachii.



The 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. 



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



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



The arteries supplying the elbow joint are derived from a  circulatory anastomosis between the brachial artery and its terminal branches. 



Blood is brought back by vessels from the radial, ulnar, and brachial veins. 



There are two sets of lymphatic nodes located at the elbow, normally located above the medial epicondyle:  deep and superficial cubital nodes, called epitrochlear nodes



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



The elbow undergoes dynamic development of ossification centers through infancy and adolescence.



The-appearance and fusion of the apophyseal growth centers  are essential 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 of apophyseal growth centers capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle at ages 1, 3, 5, 7, 9 and 11 years. 



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



The ages of fusion of apophyseal centers occur at 13, 15, 17, 13, 16 and 13 years, respectively.



The elbow joint  functions to 


extend and flex the arm grasp and reach for objects:  its range of movement in the elbow is from 0 degrees of elbow extension to 150 of elbow flexion.



It properly places the hand in space by shortening and lengthening the upper limb. 



The muscles associated with elbow function:



Flexion muscles biceps brachiosaurus, brachialis, and brachioradialis.



Extension muscles triceps and anconeus.



When the arm is extended, with the palm facing forward or up, the bones of the humerus and forearm radius and ulna 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 allows the arm to be swung without contacting the hips. 



Women have a larger carrying angle than men due to smaller shoulders and wider hips than men.



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



The  carrying angle is a suitable secondary sexual characteristic.



The carrying angle is greater in the dominant limb than the non-dominant limb of both sexes.



Diseases most commonly seen at the elbow are due to injury: 



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



((Golfer’s elbow)) involves the tendon of the common flexor origin which originates at the medial epicondyle of the humerus.



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



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



Patients who can fully extend their arm at the elbow are unlikely to have a fracture (98%). 



Dislocations at the elbow constitute 10% to 25% of all injuries to the elbow. 



Dislocations at the elbow is one of the most commonly dislocated joints.



Dislocations at the elbow has an average annual incidence of acute dislocation of 6 per 100,000 persons.



Dislocations at the elbow is second only to a dislocated shoulder among injuries to the upper extremity.



A full dislocation of the elbow will require a recovery time of approximately 8–14 weeks.



Septic arthritis of the elbow is rare.



Elbow arthritis is usually seen in individuals with rheumatoid arthritis or following prior fractures of the joint itself. 



Elbow pain can occur due to injury, disease, and other conditions. 



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



Olecranon bursitis is associated with pain in posterior part of elbow, tenderness, warmth, swelling, pain in both flexion and extension.



((Tennis elbow))  is a common type of overuse injury. 



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



Chronic repetitive motions repetitions can injure the tendons that connect the extensor supinator muscles, which rotate and extend the forearm, to the elbow.



Tennis elbow pain occurs, often radiating from the lateral forearm, and is associated with weakness, numbness, and stiffness.along with tenderness upon touch.



Treatment for pain management is rest. 



A wrist brace can also be worn, keeping 


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



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



After the pain reduction, exercise therapy is important to prevent injury in the future. 



Exercises should be low velocity, and weight added progressively, stretching the flexors and extensors and adding strengthening exercises. 



Massage to extensor trigger points, may be helpful.



((Golfer’s elbow)) is very similar to tennis elbow, but less common. 



Golfer’s elbow is caused by overuse and repetitive motions.



Golfer’s elbow can also be caused by trauma. 



The movement of wrist flexion and rotating of the forearm causes irritation to the tendons near the medial epicondyle of the elbow.



Golfer’s elbow can cause pain, stiffness, loss of sensation, and weakness radiating from the inside of the elbow to the fingers. 



Management:  Rest is the primary intervention.



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



Surgery a last resort is rarely used. 



Exercises focuses  on strengthening and stretching the forearm, and utilizing proper form when performing movements.






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