29. The elbow Flashcards by Farha Hamza

What are the two articulations of the elbow joint?

 The humeroulnar joint between the trochlea of the humerus and the trochlear notch (or sigmoid notch) of the ulna
 The humeroradial joint between the capitellum of the humerus and the radial head

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What is the proximal radio-ulnar an articulation between?

Between the side of the head of the radius and the radial notch of the ulna (not part of the elbow joint)

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What do the two condyles of the distal humerus support?

The distal humerus has two condyles (medial and lateral) that support the articular elements: the trochlea and capitellum

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What do the epicondyles of the distal humerus provide attachment for?

Lateral: extensor group in the posterior forearm
Medial: flexor-pronator group of muscles in the anterior forearm

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Which structures accommodate the the radial head and the coronoid process of the ulna in flexion?

radial and coronoid fossae of the humerus

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What structure accommodates the olecronon in extension?

Olecronon fossa on posterior distal humerus

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What part of the ulna does the radial head articulate with?

The radial head articulates with the capitellum of the ulna.

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Describe the radial kneck

Inferior to the radial head is the radial neck; this is thin and consequently vulnerable to fracture

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What inserts into the radial tuberosity?

biceps brachii tendon

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How dos the ulna and distal humerus articulate?

The ulna has a sigmoid notch that articulates with the trochlea of the distal humerus

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What inserts into the olecronon?

triceps brachii muscle

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What originates from the supinator crest (on the ulnar)?

ulnar head of the supinator muscle

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Which ligaments strengthen the Joint capsule of the elbow joint medially and laterally?

Radial (lateral) collateral ligament

Ulnar (medial) collateral ligament

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What are the attachments of the lateral collateral ligament and what is its function?

This fan-shaped structure attaches between the lateral epicondyle of the humerus and annular ligament of the radius with which it blends.
It keeps the head of the radius and the capitellum in close association during pronation and supination of the forearm

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What are the attachments of the ulnar (medial) collateral ligament and what are the 3 bands?

This triangular ligament stretches between the medial epicondyle of the humerus and the coronoid process and olecranon of the ulna.

It consists of three bands: the ‘anterior band’, which is the strongest component; the fan like ‘posterior band’, which is weak; and the slender oblique (inferior) band which deepens the socket for the trochlea of the humerus

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What is the proximal radioulnar joint stabilised by?

annular ligament

What is the annular ligament?

forms a collar around the radial head within which the radial head can rotate whilst maintaining its contact with the radial notch of the ulna

What movements is the elbow joint capable of?

Flexion and extension

WHat angle does the ulna make in full extension?

a valgus angle (Remember: vaLgus = Lateral angulation) with the long axis of the humerus

What is the carrying angle and what are the normal values?

Angle between long axis of the humerus and the ulnar - VALGUS ANGLE

men: 5-10°
women: 10-15°

Why is the carrying angle important?

Permits the forearm to clear the hips in swinging movements of the arm during walking

What is an excessive carrying angle called

cubitus valgus

What is a carrying angle that deviates towards the body called?

cubitus varus

What provides dynamic stability to the elbow joint?

Whilst the structure of the bones and ligaments makes the elbow a relatively stable joint, additional dynamic stability is provided by surrounding muscles.

What are the flexors of the elbow joint?

- Brachialis, Biceps brachii, Brachioradialis - The muscles originating from the common flexor origin on the medial humeral epicondyle are also weak flexors of the elbow

What are the extensors of the elbow joint?

- The major extensor of the elbow joint is triceps brachii. - Anconeus is a relatively weak extensor. - The muscles originating from the common extensor origin on the lateral humeral epicondyle are also weak extensors of the elbow.

Which muscles are responsible for pronation at the proximal and distal radio-ulnar joints?

pronator quadratus and pronator teres

Which muscles are responsible for supination at the proximal and distal radio-ulnar joints?

- absence of resistance to movement, is performed by supinator - when there is resistance, supination is performed by biceps brachi

at the proximal and distal radio-ulnar joints

olecranon bursa: subcutaneous olecranon bursa lies in the subcutaneous connective tissue overlying the olecranon subtendinous bursa: lies between the triceps tendon and the tip of the olecranon

What is the function of the olecranon and subtendinous bursa?

The role of these bursae is to reduce friction between bone and skin / subcutaneous tissue (e.g. olecranon bursa), or between tendon and bone (e.g. subtendinous bursa), during movements of the elbow joint

Where is the distal radio-ulnar joint (DRUJ) located? What type of joint is it?

located immediately proximal to the wrist joint. It is a pivot joint in which the ulnar notch of the radius rotates anteriorly around the head of the ulna

Where is the axis of rotation in the forearm?

axis of rotation passes longitudinally though the head of the radius proximally and through the styloid process of the ulna distally

What binds the radius and ulnar together at the distal end?

fibrocartilaginous articular disc called the triangular fibrocartilage complex (TFCC) binds the radius and ulnar together and also separates the distal radioulnar joint from the wrist joint

What connects the shaft of the radius and ulnar?

Interosseous membrane

How do the fibres of the interosseous membrane run and what is its function?

interosseous membraneforms a fibrous joint between the radius and ulna. The fibres run diagonally, from the radius proximally to the ulna more distally. This membrane keeps the bones together during the movements of pronation and supination, and also prevents proximal displacement of the radius a force is applied to the outstretched hand