Session 8: Functional Anatomy of the Elbow and Forearm Flashcards
How many articulations does the elbow joint consist of and which?
Two.
Humeroulnar joint
Humeroradial joint
Which parts articulate in the humeroulnar joint?
Between the trochlea of the humerus and the trochlear notch (also called sigmoid notch) of the ulna.
Which parts articulate in the humeroradial joint?
Between the capitellum and the radial head.
There is a joint close to the elbow joint which is not a part of it. Which? Which articulations?
Proximal radio-ulnar joint between the head of the radius and the radial notch of the ulna.
What are the two condyles of the distal humerus?
Trochlea articulating with the ulna and the capitellum articulating with the radial head.
What is located just above the condyles?
The epicondyles.
What’s the major role of the epicondyles? (each epicondyle)
The medial epicondyle provides attachment for the flexor-pronator group of muscles in the anterior forearm.
The lateral epicondyle provides attachment for the extension group in the posterior forearm.
During flexion and extension of the elbow certain parts of the elbow joint are accommodated into fossae of the humerus. Which?
During flexion the radial head is held in the radial fossa of the humerus. During flexion the coronoid process is held in the coronoid fossa.
During extension the olecranon is held in the olecranon fossa.
Where does the biceps tendon insert?
Into the radial tuberosity distal to the radial head and neck.
Where does the triceps brachii insert?
Onto the olecranon of the ulna.
What ligaments strengthen the elbow joint?
The radial (lateral) collateral ligament The ulnar (medial) collateral ligament
Describe the radial collateral ligament.
Attachment and role.
Fan shaped structure which attaches between the lateral epicondyle of the humerus and annular ligament of the radius for which it blends with.
Keeps the head of the radius and the capitellum in close association during pronation and supination of the forearm.
Describe the ulnar collateral ligament.
Attachment and role.
Triangular ligament.
Between the medial epicondyle of the humerus and the coronoid process and olecranon of the ulna.
It consists of three bands in total:
Anterior (strongest)
Posterior (weak)
Inferior (deepens the sockets for the trochlea of the humerus)
What ligament strengthens the proximal radioulnar joint?
Attachment and role.
The annular ligament.
It attaches only on the radial head. It 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.
This provides for safe supination and pronation of the forearm.
Movements of the elbow joint.
Flexion and extension.
What angle does the ulna make with the long axis of the humerus at full extension of the elbow joint?
What is another term for this angle? Why is it important?
The valgus angle (lateral angle)
Also called the carrying angle and is around 5-10 degrees in men and 10-15 degrees in women.
Permits the forearm to clear the hips swinging movements of the arm during walking.
What is an excessive carrying angle called?
What is a too small carrying angle called?
Excessive => cubitus valgus (away from the body)
Too small => cubitus varus
Major muscles that flex the elbow.
Minor muscles that flex the elbow.
Major:
Brachialis
Biceps Brachii
Brachoradialis
Minor:
Muscles originating from the common flexor origin on the medial humeral epicondyle
Major extensors of the elbow joint.
Minor extensors of the elbow joint.
Major:
Triceps brachii
Minor:
Anconeus
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Muscles originating from the common extensor origin on the lateral humeral epicondyle.
Movements of the proximal and distal radioulnar joints.
Pronation and supination.
Muscles the pronate the forearm.
Pronator quadratus
Pronator teres
Muscles the supinate the forearm.
Supinator (during no resistance) Biceps brachii (during resistance)
Two important bursae of the elbow:
Olecranon bursa
Subtendinous bursa
Location of the olecranon bursa.
Lies in subcutaneous connective tissue overlying the olecranon
Location of the subtendinous bursa.
Lies between the triceps tendon and the tip of the olecranon.
Role of the bursae.
Reduce friction between the bone and skin/subcutaneous tissue (olecranon bursa) or between tendon and bone (subtendinous bursa).
Location, articulations and role of the distal radio-ulnar joint.
Located immediately proximal to the wrist.
Pivot joint.
Ulnar notch of the radius rotates anteriorly around the head of the ulna to permit supination and pronation.
What separates the distal radioulnar joint from the wrist joint? What other role does this structure have?
A fibrocartilaginous disc called the triangular fibrocartilage complex which binds the radius and ulnar together.
There is another fibrous joint between the radius and ulna. Which?
The interosseous membrane.
Its fibres run diagonally from the radius proximally to the ulna more distally.
Role of the interosseous membrane.
Keeps bones together during the movements of pronation and supination.
Prevents proximal displacement of the radius as force is applied to the outstretched hand.
