Bones in elbow joint Flashcards
Distal humerus bony landmarks anterior
Capitulum (articulate with radius head)
Trochlea (articulate with ulna)
Coronoid fossa (for coronoid process of ulna during flexion)
Radial fossa (radial bone during flexion)
Supracondylar ridges
Distal humerus posterior landmarks
Olecranon fossa (articulates with olecranon of ulnar during extension) Trochlea
Medial and lateral epicondyles
Lateral - common extensor at elbow origin
Medial - common flexor at elbow origin
Proximal ulna parts
Coronoid process
Olecranon
Trochlear notch (trochlea of humerus)
Radial notch (head of radius)
Ulna tuberosity (for brachialis insertion)
Supinator fossa/crest - supinator muscle attaches
Where is trochlear notch?
Between olecranon and coronoid process
Proximal radius features
Head - covered in articular cartilage, concave (humerus capitulum articulates)
Defined neck
Radial tuberosity - attachment for biceps brachii
What is the thickened band around radial head?
Radial notch of ulna articulates here
Ulnar shape
Wide and tapers as you go down
Elbow joint type
Hinge synovial
Elbow joint bones involved
Distal Humerus
Proximal Ulnar
Proximal Radius
3 articulations elbow
Humeroradial
Humeroulnar
Radioulnar (proximal)
What structure allows for the hinge movements at elbow?
Rounded capitulum
What is the main stabilising factor of joint? (bony)
Trochlear notch on ulna
Acts as spanner/wrench gripping onto trochlea of humerus
Ligaments stabilising elbow
Radial (lateral) collateral ligament
Ulnar (medial) collateral ligament
Annular ligament
fuse to joint capsule
Annular joint function
Stabilise head of radius into radial notch of ulna
What does the fibrous capsule cover?
It is continuous with radioulnar joint
Where is capsule weak?
Anterior and posterior but strengthened by collateral ligaments
Proximal radioulnar joint
pivot synovial
radial head moves + radial notch on ulnar
How does annular ligament hold radial head in place?
Collar like
Wraps around radius head allowing rotation
Continuous with fibrous capsule
What can occur if annular ligament is damaged?
Subluxation/dislocation of radial head from radial notch
Are the radius and ulnar joined anywhere else?
Margins are joined along shaft by interosseus membrane
Distal radioulnar joint
Pivot synovial
Radius is the one that moves
What is within distal radioulnar joint?
Fibrocartilaginous disc - ‘triangular ligament’
What does triangular ligament do?
Separates radioulnar joint from wrist joint
What occurs during supination/pronation?
Ulnar is fixed in place
Capitulum of humerus and radial head allow rotation of radius
Radiocarpal joint allows radius to rotate and take hand with it
Resting position of hand
Mid-prone
Palm faces towards trunk of body
Movements at elbow joint
Flexion and extension
when is elbow joint most stable?
When fully flexed (muscles and coronoid process and coronoid fossa stabilise)
When fully extended (olecranon and olecranon fossa stabilise, prevent hyperextension)
Features contributing to elbow joint stability
Ligaments
Bony articulations (olecranon and coronoid process)
Muscles (anconeus)
Bursae within elbow joint (2)
Subtendinous bursae (between triceps tendon and olecranon, reduce flexion and extension friction)
Subcutaneous bursa (olecranon) - easily inflamed when leaning on elbow
Elbow flexors
Biceps Brachii (anterior arm)
Brachialis (anterior arm)
Brachioradialis (posterior forearm)
What is brachioradialis known as?
Beer raising muscle
Contributes to flexion when mid pronated
brachioradialis O and I
O: supraepicondylar ridge of humerus
I: Distal radius (proximal radial styloid process)
Brachioradialis A and I
A: Flexion when mid pronated
I: Radial nerve (posterior)
Where does pronation and supination occur?
Radioulnar joint
