The Elbow Flashcards
Joint classification of the elbow and describe its articular surfaces
synovial hinge = two articulations
humeroulnar joint:
- consists of the trochlea of the humerus (which is pulley shaped, and tilted inferiorly to the medial side creating the carrying angle) + convex surface in sagittal plane
- trochlea notch of the humerus (deep trochlear notch with ridge running from tip of olecranon to tip of coronoid process)
humero radial joint:
- capitulum of humerus (covered in HC, thickest centrally, incomplete hemispherical shape)
- superior concave head of the radius (concave surface for articulation with capitulum)
Carrying angle
trochlea is tilted inferiorly on the medial side leading to lateral deviation of ulna and radius
men = 10-15 degrees
women = 20-25 degrees
Ligaments of the elbow joint`
ulnar collateral + radial collateral
Bands of the ulnar collateral ligament
strong triangular band, blends with the joint capsule
anterior: from medial epicondyle to the coronoid process (limits extension)
posterior: from medial epicondyle to the olecranon
transverse band: coronoid process to olecranon
intermediate band: medial epicondyle to transverse band
all limit abduction
Radial collateral ligament
strong triangular band (not as strong as ulnar)
from lateral epicondyle
to: blends with annular ligament of the radius and margins of the radial notch of the ulna
limits adduction
ROMs available at the elbow + limitations
flexion = 145 (actively) to 160 (passively)
created by biceps brachii, brachialis, brachioradialis
limited by soft tissue apposition, tension in triceps, posterior joint capsule
extension = 0 degrees
limited by tension in elbow flexors, anterior joint capsule, possibly bony apposition
Factors for the medial side being more stable than the lateral side of the elbow
ulnar collateral ligament is stronger, greater surface area/reciprocity of articulation medially, the capsule has no bony attachments laterally
Articulations of the radioulnar joint
superior radioulnar joint, inferior radioulnar joint, interosseous membrane
Superior radioulnar joint articular surfaces + type
synovial pivot
head of radius: oval shaped, lined with HC
radial notch of the ulna: creates 1/5th of the ring (lined with HC)
annular ligament: creates 4/5th of the ring, lined with Fibrocartilage
ligaments of the superior radioulnar joint
annular ligament + quadrate ligament
annular ligament
- creates 4/5th of a ring
- strong and flexible and allows the head of the radius to rotate (around the ulna during pronation and supination)
- attached to anterior and posterior margins of radial notch (on ulna)
quadrate ligament
runs from the lower border of radial notch of the ulna
To adjacent medial surface of neck of radius proximal to radial tuberosity
limits both pronation and supination
fibres are crisscrossed meaning there is tension in all positions of supination and pronation
inferior radioulnar joint + articulations
synovial pivot joint
distal ulna = crescent shaped (lined with HC)
distal radius = bioconcave ulnar notch (line with HC)
articular disc =
the articular disc of the inferior radioulnar joint
triangular, thicker on its peripherally
from: (apex) lateral side of the base of the styloid process of the ulna
to: (base) sharp inferior edge of ulnar notch on radius
principle structure uniting the radius and ulna
increases stability of the joint
interosseous membrane:
strong fibrous sheet between interosseous borders of radius and ulna
fibres run down and medially in oblique fashion
transmits force from hand to radius/ulna/humerus
oblique cord superiorly and opening distally for vessles to pass
tightest in mid portion
Function:
- divides forearm into posterior and anterior
- shock absorption and force dissipation
- attachment site for muscles