Elbow Joint
• Type: Synovial joint of hinge variety
• Articular parts:
a) trochlea and capitulum of the humerus proximally
b) trochlear notch of the ulna and the superior surface of the
head of the radius distally
• Capsule:
1. Anteriorly it is attached above to the humerus along the
upper margins of the coronoid and radial fossae and to the
front of the medial and lateral epicondyles and below to
the margin of the coronoid process of the ulna and to the
anular ligament, which surrounds the head of the radius.
2. Posteriorly it is attached above to the margins of the
olecranon fossa of the humerus and below to the upper
margin and sides of the olecranon process of the ulna and
to the anular ligament.
• Ligaments:
1. The lateral ligament is triangular and is attached by
its apex to the lateral epicondyle of the humerus and
by its base to the upper margin of the anular ligament
2. The medial ligament is also triangular and consists
principally of three strong bands: the anterior band,
which is attached to the medial epicondyle of the
humerus and the medial margin of the coronoid
process; the posterior band, which is attached to
the medial epicondyle of the humerus and the medial
side of the olecranon; and the transverse band,
which passes between the ulnar attachments of the
two preceding bands.
• Synovial membrane: This lines the capsule and
covers fatty pads in the floors of the coronoid, radial,
and olecranon fossae
• Nerve supply: articular branches from the median,
ulnar, musculocutaneous, and radial nerves
• Movements
1. Flexion is performed by the brachialis, biceps
brachii, brachioradialis, and pronator teres muscles.
It is limited by the anterior surfaces of the forearm
and arm coming into contact.
2. Extension is performed by the triceps and anconeus
muscles. It is checked by the tension of the anterior
ligament and the brachialis muscle.
N.B. The long axis of the extended forearm lies at an
angle to the long axis of the arm. This angle, which
opens laterally, is called the carrying angle and is
about 170° in the male and 167° in the female. The
angle disappears when the elbow joint is fully flexed.
Relations
• Anteriorly: The brachialis, the tendon of the
biceps, the median nerve, and the brachial
artery
• Posteriorly: The triceps muscle, a small bursa
intervening
• Medially: The ulnar nerve passes behind the
medial epicondyle and crosses the medial
ligament of the joint.
• Laterally: The common extensor tendon and
the supinator.
Proximal Radioulnar Joint
• Type: Synovial joint of pivot variety
• Articular parts:
1. the circumference of the head of the radius
2. the anular ligament and the radial notch on the ulna
• Capsule: The capsule encloses the joint and is
continuous with that of the elbow joint.
• Ligament: The anular ligament is attached to the
anterior and posterior margins of the radial notch on
the ulna and forms a collar around the head of the
radius. It is continuous above with the capsule of the
elbow joint. It is not attached to the radius.
• Synovial membrane: This is continuous above with
that of the elbow joint. Below it is attached to the
inferior margin of the articular surface of the radius
and the lower margin of the radial notch of the ulna.
• Movements
• The movements of pronation and supination of the forearm
involve a rotary movement around a vertical axis that passes
through the head of the radius above and the attachment of
the apex of the triangular articular disc below.
1. In pronation, the head of the radius rotates within the anular
ligament. This movement results in the palm comes to face
posteriorly and the thumb lies on the medial side. Pronation
is performed by the pronator teres and the pronator
quadratus.
2. The movement of supination is a reversal of this process so
that the hand returns to the anatomic position and the palm
faces anteriorly. Supination is performed by the supinator
and biceps brachii (only when the elbow is flexed).
Because supination is the more powerful movement, screw
threads and the spiral of corkscrews are made so that the
screw and corkscrews are driven inward by the movement of
supination in right-handed people.
Middle radioulnar joint
Interosseous membrane
• It is a broad, thin, collagenous sheet. Its fibres is
directed distomedially between the radial and ulnar
interosseous borders. The membrane is deficient
proximally, starting distal to the radial tuberosity.
• Openings: An oval aperture near its distal margin
conducts the anterior interosseous vessels to the back
of the forearm. A gap between its proximal border and
the oblique cord conducts the posterior interosseous
vessels
• Functions:
1. The membrane provides attachments for the deep
forearm muscles and connects the radius and ulna.
2. Its fibres appear to transmit forces which act
proximally from the hand to the radius, thence to the
ulna and humerus.
Distal Radioulnar Joint
• Type: Synovial joint of pivot variety
• Articular parts: Between the head of the ulna and the
ulnar notch on the radius
• Articular disc: This is triangular and composed of
fibrocartilage. It is attached by its apex to the lateral
side of the base of the styloid process of the ulna and
by its base to the lower border of the ulnar notch of the
radius. It shuts off the distal radioulnar joint from the
wrist.
• Synovial membrane: This lines the capsule passing
from the edge of one articular surface to the other.
• Movements: Pronation and supination of the forearm
Wrist Joint (Radiocarpal Joint)
• Type: Synovial joint of ellipsoid variety
• Articular parts:
1. the distal end of the radius and the articular disc above
2. the scaphoid, lunate, and triquetral bones below
• The proximal articular surface forms an ellipsoid concave
surface, which is adapted to the distal ellipsoid convex
surface.
• Capsule: The capsule encloses the joint and is attached
above to the distal ends of the radius and ulna and below
to the proximal row of carpal bones.
• Ligaments:
1. Anterior and posterior ligaments strengthen the capsule.
2. The medial ligament is attached to the styloid process of
the ulna and to the triquetral bone
3. The lateral ligament is attached to the styloid process of
the radius and to the scaphoid bone
• Synovial membrane: This lines the capsule and is
attached to the margins of the articular surfaces. The
joint cavity does not communicate with that of the distal
radioulnar joint or with joint cavities of intercarpal joints.
• Movements
1. Flexion by flexor carpi radialis, flexor carpi ulnaris, and
palmaris longus. These muscles are assisted by flexor
digitorum superficialis, flexor digitorum profundus, and
flexor pollicis longus.
2. Extension by extensor carpi radialis longus, extensor
carpi radialis brevis, and extensor carpi ulnaris. These
muscles are assisted by extensor digitorum, extensor
indicis, extensor digiti minimi, and extensor pollicis
longus.
3. Abduction by flexor carpi radialis and extensor carpi
radialis longus and brevis.
4. Adduction by flexor and extensor carpi ulnaris.
Intercarpal Joints
• Type: Synovial joints of plane variety
• Articulation: Between the individual bones of
the proximal row of the carpus; between the
individual bones of the distal row of the carpus;
and finally, the midcarpal joint, between the
proximal and distal rows of carpal bones
• Movements: A small amount of gliding
movement is possible.
Carpometacarpal Joint of the Thumb
• Type: Synovial joint of saddle variety
• Articular parts: Between the trapezium and the base
of the first metacarpal bone
• Movements
1. Flexion is the movement of the thumb across the
palm. The muscles producing the movement are flexor
pollicis longus and brevis and opponens pollicis.
2. Extension is the movement of the thumb in a lateral
or coronal plane away from the palm. The muscles
producing the movement are the extensor pollicis
longus and brevis.
3. Abduction is the movement of the thumb in an
anteroposterior plane away from the palm. The
muscles producing the movement are abductor pollicis
longus and brevis.
4. Adduction is the movement of the thumb in an
anteroposterior plane toward the palm. The muscle
producing movement is the adductor pollicis.
5. Opposition is the movement of the thumb across the
palm in such a manner that the anterior surface of the
tip comes into contact with the anterior surface of the
tip of any of the other fingers. The movement is
accomplished by the medial rotation of the first
metacarpal bone and the attached phalanges on the
trapezium. The muscle producing the movement is the
opponens pollicis.
Metacarpophalangeal Joints
• Type: Synovial joints of condyloid variety
• Articular parts: Between the heads of the
metacarpal bones and the bases of the proximal
phalanges of medial 4 fingers.
• Movements:
1. Flexion: by flexor digitorum superficialis and
profundus, the lumbricals and the interossei
2. Extension: by extensor digitorum, extensor
indicis, and extensor digiti minimi
3. Abduction: Movement away from the midline of
third finger is performed by the dorsal interossei.
4. Adduction: Movement toward the midline of the
third finger is performed by the palmar interossei.
Interphalangeal joints
• Type: Synovial joints of hinge variety
• Articular parts: Between the heads and the
bases of the adjacent phalanges.
• Movements:
1.Flexion: by flexor digitorum superficialis and
profundus, the lumbricals and the interossei
2. Extension: by extensor digitorum, extensor
indicis, and extensor digiti minimi