Download The posterior interosseous nerve

Anatomy of The Forearm And
Ellbow
Dr. Fadel Naim
Orthopedic Surgeon
IUG
Extensor Muscles of the Forearm
• In the posterior (extensor-supinator) compartment of the
forearm
• All are innervated by the radial nerve
• Three functional groups:
1. Muscles that extend and abduct or adduct the hand at the wrist
joint
» Extensor carpi radialis longus
» Extensor carpi radialis brevis
» Extensor carpi ulnaris
2. Muscles that extend the medial four digits
» Extensor digitorum
» Extensor indicis
» Extensor digiti minimi
3. Muscles that extend or abduct the thumb
» Abductor pollicis longus [APL]
» Extensor pollicis brevis [EPB]
» Extensor pollicis longus [EPL]
Posterior compartment:
Superficial group
1. Extensor carpi radialis
brevis
2. Extensor digitorum
3. Extensor digiti minimi
4. Extensor carpi ulnaris
5. Anconeus muscle
Posterior compartment:
Deep group
1. Supinator
2. Abductor pollicis longus
3. Extensor pollicis brevis
4. Extensor indicis
Attached by a common
extensor tendon to the lateral
epicondyle
Brachioradialis
• Origin
– Proximal two-thirds of lateral
supracondylar ridge of humerus
• Insertion
– Lateral surface of distal end of radius
• Action
– Flexes forearm
• Innervation
– Radial nerve (C5, C6, and C7)
Brachioradialis
• This fusiform muscle forms the lateral border of the
cubital fossa
• Exceptional among muscles of the "posterior" (extensorsupinator) compartment in that
– It flexes the forearm at the elbow
» Especially when quick movement is required and when a weight is lifted
during slow flexion of the forearm.
– The brachioradialis and the supinator are the only muscles of the
compartment that do not cross the wrist.
• To test the brachioradialis:
– The elbow joint is flexed against resistance with the forearm in
the midprone position.
– If acting normally, the muscle can be seen and palpated.
Anconeus
• Origin
– lateral epicondyle of humerus
• Insertion
– olecranon and superior portion
of shaft of ulna.
• Action
– Extension forearm at elbow
joint
• Nerve supply
– radial nerve
Extensor Carpi Radialis Longus
• Origin
– Lateral supracondyle ridge of humerus
• Insertion
– Base of 2rd metacarpal
• Action
– Extend and abduct hand at wrist joint
• Innervation
– Radial nerve (C6 and C7)
Extensor Carpi Radialis Longus
• To test the extensor carpi radialis longus
– The wrist is extended and abducted with the
forearm pronated.
– If acting normally,
» The muscle can be palpated infero-posterior to the
lateral side of the elbow.
» Its tendon can be palpated proximal to the wrist.
Extensor Carpi Radialis Brevis
• Origin
– Lateral epicondyle of humerus
• Insertion
– Base of 3rd metacarpal
• Action
– Extend and abduct hand at wrist joint
• Innervation
– Deep branch of radial nerve (C7 and C8)
•The extensor carpi radialis brevis
and longus act together to steady the
wrist during flexion of the medial
four digits.
Extensor Digitorum
• Origin
– Lateral epicondyle of humerus
• Insertion
– Extensor expansions of medial four digits
• Action
– Extends medial four digits at
metacarpophalangeal joints;
Extends hand at wrist joint
• Innervation
– Posterior interosseous nerve (C7 and C8), the
continuation of the deep branch of the radial
nerve
Extensor Digitorum
• The principal extensor of the medial four digits
• Its four tendons proximal pass through a common synovial
sheath, deep to the extensor retinaculum with the tendon
of the extensor indicis
• Adjacent tendons are linked by intertendinous
connections.
• Because of presence of the intertendinous connections
extension of one finger is impossible
• The index finger has greater freedom because its tendon
is not connected to the other tendons
Extensor Digitorum
• To test the extensor digitorum:
– The forearm is pronated and the fingers are
extended.
– The person attempts to keep the fingers
extended at the metacarpo-phalangeal joints as
the examiner exerts pressure on the proximal
phalanges by attempting to flex them
– If acting normally, the extensor digitorum can
be palpated in the forearm, and its tendons can
be seen and palpated on the dorsum of the
hand.
Extensor Digiti Minimi
• Origin
– Lateral epicondyle of humerus
• Insertion
– Extensor expansion of 5th digit
• Action
– Extends 5th digit at metacarpophalangeal
and interphalangeal joints
• Innervation
– Posterior interosseous nerve (C7 and C8),
the continuation of the deep branch of
the radial nerve
Extensor Digiti Minimi
• This fusiform slip of muscle is a
partially detached part of the extensor
digitorum.
• The tendon of this extensor of the little
finger runs through a separate
compartment deep to the extensor
retinaculum
• Then divides into two slips;
– The lateral one is joined to the tendon of
the extensor digitorum
Extensor Carpi Ulnaris
• Origin
– Lateral epicondyle of humerus and
posterior border of ulna
• Insertion
– Base of 5th metacarpal
• Action
– Extends and adducts hand at wrist joint
• Innervation
– Posterior interosseous nerve (C7 and C8),
the continuation of the deep branch of
the radial nerve
Extensor Carpi Ulnaris
• Distally, its tendon runs in a groove between the ulnar
head and the styloid process
• Extends and adducts the hand at the wrist joint
simultaneously when acting independently.
• Acting with the extensor carpi radialis, it extends the
hand
• Acting with the flexor carpi ulnaris, it adducts the hand.
• Like the extensor carpi radialis longus, it is indispensable
when making the fist.
• To test the extensor carpi ulnaris:
– The forearm is pronated and the fingers are extended. The
extended wrist is then adducted against resistance.
– If acting normally:
» The muscle can be seen and palpated in the proximal part of the forearm
» The tendon can be felt proximal to the head of the ulna.
Supinator
• Origin
– Lateral epicondyle of humerus
– radial collateral and annular ligaments
– supinator fossa and crest of ulna
• Insertion
– surface of proximal 1/3 of radius
» Lateral
» Posterior
» Anterior
• Action
– Supinates forearm
• Innervation
– Deep branch of radial nerve (C5 and C6)
Abductor pollicis Longus
• Origin:
– Posterior surfaces of
» Ulna
» Radius
» Interosseous membrane
• Insertion:
– Base of 1st metacarpal
• Action:
– Abducts thumb
– Extends it at carpometacarpal joint
• Innervation:
– Posterior interosseous nerve (C7
and C8), the continuation of deep
branch of radial nerve
Abductor Pollicis Longus
• It acts with the abductor pollicis brevis
during abduction of the thumb
• With the extensor pollicis during extension
of this digit.
• To test the APL:
– The thumb is abducted against resistance at the
metacarpophalangeal joint.
– If acting normally the tendon of the muscle can
be seen and palpated
» At the lateral side of the snuffbox and on the lateral
side of the adjacent EPB tendon.
Extensor Pollicis Brevis
• Origin
– Posterior sufraces of radius and
interosseous membrane
• Insertion
– Base of proximal phalanx of thumb
• Action
– Extends proximal phalanx of thumb
at carpometacarpal joint
• Innervation
– Posterior interosseous nerve (C7 and
C8), the continuation of the deep
branch of the radial nerve
Extensor Pollicis Longus
• Origin
– Posterior surface of middle 1/3 of ulna
and interosseous membrane
• Insertion
– Base of distal phalanx of thumb
• Action
– Extends distal phalanx of thumb at
carpometacarpal and interphalangeal
joints
– Adducts the extended thumb and
rotates it laterally
• Innervation
– Posterior interosseous nerve (C7 and
C8), the continuation of the deep
branch of the radial nerve
Extensor Pollicis Longus
• The tendon of the EPL passes
medial to the dorsal tubercle of
the radius, using it as a trochlea
changing its line of pull as it
proceeds to the base of the distal
phalanx of the thumb..
• To test the EPL:
– The thumb is extended against
resistance at the interphalangeal
Joint.
– If acting normally, the tendon of the
muscle can be seen and palpated on
the medial side of the anatomical
snuff box
Extensor Indicis
• Origin
– Posterior sufrace of ulna
– interosseous membrane
• Insertion
– Extensor expansion of 2nd digit
• Action
– Extends 2nd digit and helps to extend
hand
• Innervation
– Posterior interosseous nerve (C7 and
C8), the continuation of the deep
branch of the radial nerve
Arteries of Forearm
• 1 brachial
– 2 radial
» 3 radial recurrent
» 4 superficial radial
» 5 deep radial
– 6 ulnar
» 7 anterior ulnar recurrent
» 7 posterior ulnar recurrent
» 8 common interosseous
• 9 posterior interosseous
• 10 anterior interosseous
» 11 superficial branch
» 12 deep branch
• In the hand, the ulnar and radial arteries
anastomose, formiug the superficial and deep
palmar arterial arches.
Ulnar Artery
• The larger of the two terminal branches of the
brachial artery
• Begins in the cubital fossa just medial to the
biceps tendon
• Descends through the anterior compartment
of the forearm, deep to the pronator teres.
• Then passes distally over the anterior aspect
of the wrist to the palm.
Ulnar Artery
• Pulsations of the artery can be palpated on the lateral side
of the flexor carpi ulnaris tendon, where it lies anterior to
the ulnar head.
• The ulnar nerve is on the medial side of the ulnar artery
Branches of the Ulnar Artery in the Forearm
1.
–
–
–
–
Anterior and posterior ulnar recurrent
Just distal to elbow joint
Anterior ulnar recurrent artery passes
superiorly
Posterior ulnar collateral artery passes
posteriorly
Anastomose with ulnar collateral and
interosseous recurrent arteries
Branches of the Ulnar Artery in the Forearm
2.
Common interosseous artery:
–
–
3.
Just distal to bifurcation of brachial artery
After a short course, terminates by dividing into
anterior and posterior interosseous arteries
Anterior and posterior interosseous arteries:
–
Pass to anterior and posterior sides of
interosseous membrane
–
Anterior interosseous artery supplies both
anterior and posterior compartments in
distal forearm
–
The posterior interosseous artery gives off
the recurrent interosseous artery
»
Participates in the arterial anastomoses around
the elbow
Branches of the Ulnar Artery in the Forearm
4.
Dorsal and palmar carpal branches
–
Anastomose with corresponding branches of
radial artery to form dorsal and palmar
carpal arches, providing collateral circulation
at wrist
Radial Artery





Smaller than the ulnar artery
Begins in the cubital fossa near the neck of the
radius
It passes inferolaterally deep to the
brachioradialis
The course of the radial artery in the forearm is
represented by a line joining the midpoint of
the cubital fossa to a point just medial to the
radial styloid process.
The radial artery leaves the forearm by winding
around the lateral aspect of the wrist and
crosses the floor of the anatomical snuff box
The Branches Of The Radial Artery
1.
Radial recurrent artery
–
–
2.
Lateral side of radial artery, just distal
to its origin
Ascends on supinator and then passes
between brachioradialis and brachialis
Dorsal and palmar Radial artery
at level of wrist
•
Anastomose with corresponding
branches of ulnar artery to form
dorsal and palmar carpal arches
Median Nerve
• The median nerve is the principal
nerve of the anterior compartment of
the forearm
• It enters the forearm with the brachial
artery and lies on its medial side.
• It leaves the cubital fossa by passing
between the heads of the pronator
teres
• The nerve then passes deep to the FDS
and continues distally through the
middle of the forearm, between the
FDS and the FDP.
• Near the wrist, the median nerve becomes
superficial by passing between the tendons of
FDS and flexor carpi radialis, deep to the
palmaris longus tendon
Branches of the Median Nerve
• No branches in the arm, other than small twigs to
the brachial artery
• The branches of the median nerve arise in the
forearm and hand as follows:
1. Articular branches to the elbow joint
2. Muscular branches supply:
1. The pronator teres
2. Pronator quadratus
3. All the flexor muscles
• Except the flexor carpi uluaris and the medial half of the FDP.
The anterior interosseous nerve
3. The anterior interosseous nerve
– Arises from the median nerve in the distal part of the
cubital fossa
– Passes distally on the interosseous membrane with the
anterior interosseous branch of the ulnar artery.
– It runs between the FDP and flexor pollicis longus to
reach the pronator quadratus.
• It supplies these muscles
– The FDP
» {lateral half sending tendons to digits 2 and 3) }
– Flexor pollicis longus
– Pronator quadratus
• Sends articular branches to the wrist joint.
4. The recurrent branch of the median
nerve (C8 and T1):
• Arises from the median nerve as soon as it passes distal to the
flexor retinaculum.
• It loops around the distal border of this retinaculum to supply the
thenar muscles.
5. Palmar coetaneous branch
of the median nerve.
The course of nerve may vary in 4 important ways
1.
Normally, the nerve branches off 5 cm proximal to the wrist. It runs along the
ulnar side of the tendon of the flexor carpi radialis before crossing the flexor
retinaculum.
»
2.
3.
4.
The nerve divides into two major branches, medial and lateral, while crossing the
flexor retinaculum to supply the skin of the thenar eminence
Less often, the nerve arises from the median nerve in two distinct branches,
which travel separately across the wrist.
The nerve may arise within the carpal tunnel and penetrate the flexor
retinaculum to supply the skin of the thenar eminence.
The nerve may be absent, replaced by a branch derived from the radial nerve,
the musculocutaneous nerve, or the ulnar nerve.
• At the distal border of the flexor retinaculum,
the median nerve divides into two branches
– The medial branch:
» sends cutaneous branches to the adjacent sides of
the ring and middle fingers, and to the adjacent
sides of the middle and index fingers.
– The lateral branch
» sends cutaneous branches to the radial side of the
index finger and to both sides of the thumb.
Ulnar Nerve
• It passes posterior
to the medial
epicondyle of the
humerus,
Ulnar Nerve
• The ulnar nerve enters
the forearm bypassing
between the heads of
the flexor carpi ulnaris
Ulnar Nerve
• It then passes inferiorly between the flexor carpi
ulnaris and FDP,
– supplying the ulnar (medial) part of the muscle that sends
tendons to digits 4 and 5.
• The ulnar nerve becomes superficial at the wrist and
supplies skin on the medial side of the hand
Ulnar Nerve
• The ulnar nerve runs on the medial side of the ulnar
artery and the lateral side of the flexor carpi ulnaris
tendon.
• At this level, the anatomic arrangement of these
structures can be remembered by the mnemonic
“ANT”:
– The artery is the most lateral structure, then the nerve,
and, finally, the tendon of the flexor carpi ulnaris
The Canal Of Guyon
• As the ulnar nerve crosses the flexor
retinaculum in the canal of guyon,, it is
covered with a tough fibrous tissue that is
continuous with the deep fascia of the
forearm, the volar carpal ligament.
• The boundaries of the canal of gyuon:
– The floor
» The flexor retinaculum (transverse carpal ligament)
– The medial wall
» The pisiform
– The lateral wall
» The hamate
– The roof,
» The volar carpal ligament (distal fascia of the forearm
Branches of the Ulnar Nerve
 Has no branches in the arm.
1. Articular branches pass to the elbow joint
2. Muscular branches supply:
1. The flexor carpi ulnaris
2. The medial half of the FDP
3. The palmar cutaneous branch
• Arises from the ulnar nerve near the middle of
the forearm
• Supply skin on the medial part of the palm
4.
The dorsal cutaneous branch
–
Arises from the ulnar nerve in the distal half
of the forearm
Passes posteroinferiorly between the ulna and
the flexor carpi ulnaris
Supply the posterior surface of the medial
part of the hand and the digits
–
–
5.
The deep branch
–
–
»
»
»
Arises from the ulnar nerve at the wrist
It supplies
The hypothenar muscles (muscles of little finger
The interosseous muscles
The 3rd and 4th lumbrical muscles
Ulnar Innervated Muscles
• Forearm:
– Flexor Carpi Ulnaris (C7, C8, T1)
– Flexor Digitorum Profundus III & IV (C7, C8)
• Thenar:
– Hypothenar Muscles (C8, T1)
– Adductor Pollicis (C8, T1)
– Flexor Pollicis Brevis (C8, T1)
• Fingers:
– Palmer Interosseous (C8, T1)
– Dorsal Interosseous (C8, T1)
– III & IV Lumbricles (C8, T1)
• Digiti Minimi:
– Abductor Digiti Minimi (Quinti) (C8, T1)
– Opponens Dgiti Minimi (C8-T1)
– Flexor Digiti Minimi. : ( C8-T1)
Ulnar Nerve Injury at Wrist
• At the wrist, of the tendon of the flexor carpi
ulnaris, the ulnar artery, and the ulnar nerve
is particularly vulnerable to damage by
lacerations.
• When falling through a window with the
ulnar border of the wrist flung forward to
protect the face.
The Anatomical Snuff Box
• Anteriorly
– The tendons of the APL and EPB
• Posteriorly
– The tendon of the EPL
• The snuff box is visible when the thumb is fully extended
• This produces a concavity between the tendons
The Anatomical Snuff Box
• The radial artery lies in the
floor of the snuff box
• Radial styloid process can be
palpated proximally
• The base of the 1st
metacarpal can be palpated
distally in the snuffbox
• Scaphoid and trapezium can
be felt in the floor between
the radial styloid process and
the 1st metacarpal.
Radial Nerve
• The radial nerve cross the anterior aspect of the
lateral epicondyle of the humerus
• It appears in the cubital fossa between the brachialis
and brachioradialis.
• Soon after it enters the forearm, the radial nerve
divides into deep and superficial branches
Branches of the Radial Nerve
1.
The superficial branch of
the radial nerve
–
–
–
A cutaneous and articular
nerve that descends in the
forearm under cover of the
brachioradialis.
It emerges in the distal part of
the forearm and crosses the
roof of the anatomical snuff
box
Distributed to skin on the
dorsum of the hand and to a
number of joints in the hand
Radial Nerve
2. The deep branch of the radial nerve
–
–
–
–
The larger of the two terminal branches
The direct continuation of the radial nerve
The deep branch arises anterior to the lateral
epicondyle of the humerus and pierces the supinator
It winds around the lateral aspect of the neck of the
radius and enters the posterior compartment of the
forearm
Radial Nerve
3. The posterior interosseous
nerve
– The continuation of the deep
branch of the radial nerve.
4. The posterior cutaneous
nerve of the forearm
– Descends along the posterior
aspect of the forearm to the
wrist, supplying the skin
during its course.
Lateral epicondylitis (tennis elbow)
• An overuse injury commonly seen
in tennis players.
• The common extensor tendon:
– Gives rise to:
» The extensor carpi radialis brevis
» Extensor digitorum
» Extensor digiti minimi
» Extensor carpi ulnaris muscles
• With repetitive strain, the tendon,
periosteum, or radial collateral
ligament may become inflamed.
• Treatment is rest and avoidance of
precipitating activities.
Medial epicondylitis
(golfer or pitcher elbow)
• Less common than lateral epicondylitis.
• It is an overuse injury due to repetitive
strain of the common flexor tendon.
–
–
–
–
–
The pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor digitorum superficialis
• In some instances an avulsion fracture of
the medial epicondyle can mimic medial
epicondylitis and should be ruled out with
a radiograph.
• Treatment is avoidance of precipitating
activities.
Veins of the Forearm
•In the forearm, as in the arm, are
superficial and deep veins
•The superficial veins ascend in the
subcutaneous tissue.
•The deep veins accompany the deep
forearm (antebrachial) arteries.
Superficial Veins of The Forearm
•
1.
2.
3.
4.
•
The main superficial veins of the
forearm are the:
Cephalic vein
Basilic vein
Median cubital vein
Antebrachial vein
The cephalic vein:
–
–
–
Forms over the anatomical snuff box
from the tributaries that arise from the
lateral side of the dorsal venous
network (arch).
Ascends along the lateral border of the
forearm and communicates with the
basilic vein through the median
cubital vein.
Ascends along the lateral side of the
arm and empties into the axillary vein.
Superficial Veins of The Forearm
• The basilic vein:
– Arises from the medial side of the dorsal
venous arch
– Ascends posteromedially in the
forearm, reaching the anterior surface
just distal to the elbow
– Where it is joined by the median cubital
vein.
• The median antebrachial vein:
– Drains subcutaneous tissue in the
anterior aspect of the wrist and forearm.
– It begins in the superficial venous
palmar arch and usually ends in the
basilic vein.
Deep Veins of The Forearm
• Deep veins accompanying the arteries are
plentiful in the forearm
• Arise from a deep venous arcade in the
hand.
• Anastomose freely with each other.
• Communicate with the superficial veins.
• The deep interosseous veins unite with
the accompanying veins of the radial and
ulnar arteries.
• The deep veins in the cubital fossa are
connected to the median cubital vein
• These deep cubital veins also unite with
the accompanying veins of the brachial
artery.
Interosseous Membrane
• The interosseous membrane
connects the interosseous margins
of the radius and ulna, forming the
interosseous syndesmosis
• A proximal hole for the posterior
interosseus artery to enter the
posterior compartment of the
forearm
• A distal hole for the anterior
interosseus artery.
Interosseous
membrane
• The radius forms the load-bearing
articulation with the wrist
• The ulna forms the load-bearing
articulation with the humerus.
• The load thus needs to be
transferred from the wrist to the
elbow across the interosseous
membrane.
• The general direction of the fibers
of the interosseous membrane is
such that a superior thrust to the
hand is received by the radius and
is transmitted to the ulna.
Oblique Cord
• The oblique cord is an inconstant
fascial band coursing from the
lateral ulnar tuberosity to the radius
(just distal to the radial tuberosity)
• It has no known function and can be
cut without apparent consequence.
Articulation of the Elbow Joint
• A hinge type of synovial joint
• Articulation:
– The humerus
» The spool shaped trochlea
» The spheroidal capitulum
– The trochlear notch of the ulna
– The slightly concave superior
aspect of the head of the radius
Humeroulnar articulation
Humeroradial articulation
Articulation of the Elbow Joint
•The articular surfaces, covered
with hyaline cartilage,
•Fully congruent when the forearm
is in a position midway between
pronation and supination and is
flexed to a right angle.
Articular Capsule of the Elbow Joint
• Continuous inferiorly
with the synovial
membrane of the
superior radioulnar
joint.
• weak anteriorly and
posteriorly
• strengthened on each
side by collateral
ligaments
Articular Capsule of the Elbow Joint
• The fibrous capsule
• Attached at the margins of
the lateral and medial ends
of the articular surfaces of
the capitulum and trochlea
• Anteriorly and posteriorly it
is carried superiorly,
proximal to the coronoid
and olecranon fossae.
•Continuous inferiorly with the synovial membrane of the
superior radioulnar joint.
•weak anteriorly and posteriorly
•strengthened on each side by collateral ligaments.
Ligaments of the Elbow Joint
• The collateral ligaments of the elbow joint are strong
triangular bands
– Medial and lateral thickenings of the fibrous capsule
The lateral, fanlike radial collateral ligament
• Extends from the lateral epicondyle of the
humerus and blends distally with the anular
ligament of the radius
The medial, triangular ulnar collateral ligament
• Extends from the medial
epicondyle of the
humerus to the coronoid
process and olecranon of
the ulna
• Consists of three bands:
1. The anterior cordlike band
is the strongest
2. The posterior fanlike band
is the weakest
3. The slender oblique band
deepens the socket for the
trochlea of the humerus
Carrying Angle
– The long axis of the fully
extended ulna makes an angle
of approximately 170 ° with the
long axis of the humerus
– The carrying angle is more
pronounced (approximately 10°
more acute) in women than
men.
– The carrying angle disappears
when the forearm is pronated
Muscles Moving the Elbow Joint
• Several muscles cross the elbow
and extend to the forearm and
hand:
• Chief flexors of the elbow joint
– Brachialis
– Biceps brachii
– Brachioradialis
• Chief extensors of the elbow
joint
– Triceps brachii
» Especially medial head, assisted by
anconeus
Blood and Nerve Supply of the Elbow Joint
• The arteries supplying the elbow joint are
derived from the anastomosis around the
elbow joint.
• The elbow joint is supplied by:
– The musculocutaneous nerve
– The radial nerve
– The ulnar nerve
Bursae Around the Elbow Joint
• The three olecranon bursae are the:
1. Intratendinous olecmnon bursa
» Which is sometimes present in the tendon of triceps brachii
2. Subtendinous olecranon bursa
» Which is located between the olecranon and the triceps tendon, just proximal to its
attachment to the olecranon
3. Subcutaneous olecranon bursa
» Which is located in the subcutaneous connective tissue over the olecranon.
Bursae Around the Elbow Joint
• The radioulnar bursa lies between:
–
–
–
–
The extensor digitorum
The radiohumeral articulation
The supinator muscle.
This bursa lies posterior to the supinator, lateral to the tendon of the biceps,
and medial to the ulna.
• The bicipitoradial bursa (biceps bursa)
– Lies between
» The biceps tendon
» The anterior part of the radial tuberosity.
Dislocation of the Elbow Joint
• Posterior dislocation of the elbow joint
– Fall on their hands with elbow flexed.
• The distal end of the humerus is driven
through the weak anterior part of the
fibrous capsule
– The radius and ulna dislocate posteriorly.
• The ulnar collateral ligament is often torn
• An associated fracture of the:
–
–
–
–
Head of the radius
Coronoid process
Olecranon process of the ulna
Injury to the ulnar nerve
Proximal Radioulnar Joint
• The proximal
radioulnar joint is a
pivot type of synovial
joint
– allows movement of
the head of the radius
on the ulna
Proximal Radioulnar Joint
• The head of the radius articulates with the radial notch of the ulna.
• The radial head is held in position by the anular ligament.
Articular Capsule of the Proximal Radioulnar Joint
• The fibrous capsule encloses the joint and is
continuous with that of the elbow joint.
• The synovial membrane lines the deep
surface of the fibrous capsule and nonarticulating aspects of the bones.
• The synovial membrane is an inferior
prolongation of the synovial capsule of the
elbow joint.
Ligaments of the Proximal Radioulnar Joint
• Anular ligament
– Attached to the ulna anterior and posterior to its radial
notch, surrounds the articulating bony surfaces forming
a collar or loop
– With the radial notch, forms a ring that completely
encircles the head of the radius.
Ligaments of the Proximal Radioulnar Joint
• Anular ligament
– The deep surface of the anular
ligament is lined with synovial
membrane, which continues
distally as a sacciform recess on
the neck of the radius.
– This arrangement allows the
radius to rotate within the anular
ligament without binding,
stretching, or tearing the
synovial capsule.
Movements of the Proximal Radioulnar Joint
• During pronation and supination of the
forearm, the head of the radius rotates
within the ring formed by the anular
ligament and the radial notch of the
ulna.
• The axis for these movements passes:
– Proximally through the center of the head
of the radius
– Distally through the site of attachment of
the apex of the articular disc ("triangular
ligament") to the head (styloid process) of
the ulna.
Movements of the Proximal Radioulnar Joint
• During pronation and
supination, it is the radius that
rotates
• Distally, the end of the radius
rotates around the head of the
ulna
• Almost always, supination and
pronation are accompanied by
synergic movements of the
glenohumeral and elbow joints
that produce simultaneous
movement of the ulna
– except when the elbow is flexed.
Muscles Moving the Proximal Radioulnar Joint
• Pronation
– The pronator quadratus
(primarily)
– Pronator teres (secondarily)
– With some assistance from
the FCR, PL, and
brachioradialis
» (when the forearm is in the
midprone position)
Muscles Moving the Proximal Radioulnar Joint
• Supination:
– The supinator (when resistance
is absent)
– The biceps brachii (when
power is required because of
resistance)
– With some assistance from the:
EPL and ECRL
Blood and Nerve Supply of the Proximal Radioulnar Joint
• The proximal radioulnar joint is supplied by the anterior and
posterior interosseous arteries
• The proximal radioulnar joint is supplied mainly by the:
– Musculocutaneous nerve
– Median nerve
– Radial nerve
• Pronation
– median nerve
• supination
– musculocutaneous and radial nerves.
Subluxation of the Radial Head (pulled elbow)
Cause :
 Often due to a sudden
jerk on the forearm,
such as when a child is
lifted up by one hand.
 The head of the radius
subluxes out of the
annular ligament.
Subluxation of the Radial Head (pulled elbow)
Treatment :
 It can be reduced by
supinating the forearm
sharply.
Madelung’s Deformity
• Abnormality of the palmar ulnar part of the distal radial
physis
• Progressive ulnar and volar tilt develops at the distal
radial articular surface, with dorsal subluxation of the
distal ulna
Congenital Radioulnar Synostosis
Distal Radioulnar Joint
• A pivot type of synovial joint.
• The radius moves around the relatively fixed
distal end of the ulna.
• The head of the ulna articulates with the ulnar
notch on the medial side of the distal end of the
radius.
Distal Radioulnar Joint
• A pivot type of synovial joint.
• The radius moves around the relatively fixed distal end of the ulna.
• The head of the ulna articulates with the ulnar notch on the medial
side of the distal end of the radius.
 During pronation and supination,the distal end of the radius moves
anteriorly and medially, crossing the ulna anteriorly.
Triangular
Ligament
• A fibrocartilaginous articular disc ("triangular ligament")
binds the ends of the ulna and radius together
• The main uniting structure of the joint
– The base is attached to the medial edge of the ulnar notch of the
radius,
– The apex is attached to the lateral side of the base of the styloid
process of the ulna.
• The articular disc separates the cavity of the distal
radioulnar joint from the cavity of the wrist joint.
Ligaments of the Distal Radioulnar Joint
• Anterior and posterior
ligaments strengthen the
fibrous capsule of the distal
radioulnar joint.
• These relatively weak
transverse bands extend from
the radius to the ulna across
the anterior and posterior
surfaces of the joint
• Movements of the Distal Radioulnar Joint
– During pronation and supination,the distal end of the radius
moves anteriorly and medially, crossing the ulna anteriorly.
• Blood Supply of the Distal Radioulnar Joint
– The anterior and posterior interosseous arteries supply the
distal radioulnar joint
• Innervation of the Distal Radioulnar Joint
– The anterior and posterior interosseous nerves supply the
distal radioulnar joint.