2. ELBOW COMPLEX
⦿ Hinge joint /
⦿ Joints and muscles of the elbow complex
provides mobility to the hands for ADLs.
⦿ Only 1 degree of freedom
› Flexion & Extension
› Occur in the Sagittal Plane, Around a Frontal
Axis.
3. Elbow Complex
⦿ Three articulations:
› Humeroulnar Joint
› Humeroradial Joint
› Proximal Radioulnar Joint
⦿ All are enclosed in the same
joint capsule
⦿ Reinforced by ligaments
4. ELBOW COMPLEX
⦿ Two major Ligaments: MCL and LCL
⦿ Five muscles are directly associated with
the elbow joint.
⦿ Muscles
⦿ Three muscles are Flexors
› that cross the anterior aspect of the joint.
⦿ Two muscles are Extensors
› that cross the posterior aspect of the joint
5. Elbow Complex
⦿ Bony structure:
⦿ provides about half of the elbow’s
stability
⦿ joint capsule and ulnar (MCL) and
radial (LCL) ligament complexes:
⦿ Provide remaining stability
6. FUNCTIONS OF THE ELBOW COMPLEX
⦿ The functions of the elbow joints are
› to add mobility of hand
› shortening and/or lengthening the arm
› rotating the forearm
› to provide control and stability
❖for skilled hand motions
11. HUMEROULNAR JOINT
⦿ Hinge joint
⦿ Trochlea Humerus ↔ Trochlear Fossa
Ulna
⦿ Flexion and Extension
⦿ Hyperextension
› Little, some individuals
⦿ Closed packed position
› Extension
12. ⦿ Sliding motion of the Ulnar trochlear ridge on
the Humeral trochlear groove.
13. ⦿ In extension
› sliding continues until the olecranon
process enters the olecranon fossa
⦿ In flexion
› Trochlear Ridge U slides along the
trochlear groove H , until the coronoid
process U reaches the floor of the
coronoid fossa H in Full Flexion
14. HUMERORADIAL JOINT
⦿ Lateral to the Humero-Ulnar Joint.
⦿ Capitulum Humerus ↔ Proximal end Radius
⦿ Close packed position
› Elbow flexed at 90o &forearm supinated
about 5o
15. ⦿ In full extension,
› no contact occurs between the
articulating surfaces
⦿ In flexion,
› rim of the radial head slides in the capitulo
trochlear groove and enters the radial
fossa as the end of flexion range is reached
16. JOINT CAPSULE
⦿ Fairly large, loose
⦿ Weak anteriorly and posteriorly
⦿ Laterally and medially, reinforced
› by the collateral ligaments.
⦿ Fat pads
› located between the capsule and the synovial
membrane adjacent to the olecranon, coronoid,
and radial fossae.
17. JOINT CAPSULE
Capsule’s Synovial Membrane
⦿ Lines the
› coronoid, radial, and olecranon fossa.
› flat medial trochlear surface
› lower part of the annular ligament.
⦿ A triangular synovial fold inserted
between the proximal radius and ulna
› partly divides the elbow joint into two joints.
18. JOINT CAPSULE
⦿ Anteriorly
› Proximally
● attach just above the
coronoid and radial
fossa
› Distally
● attach to margin of the
coronoid process Ulna
● blends with the proximal
border of the annular
ligament (except
posteriorly)
19. JOINT CAPSULE
⦿ Posteriorly
› Proximally
● attach to humerus
along the upper edge
of the olecranon fossa
› Distally
● passes deep below
the annular ligament
● attach to the posterior
& inferior margins of
the neck of the radius.
20. JOINT CAPSULE
⦿ Laterally,
› attach to radius
› blends with the fibers
of the LCL (lateral
collateral ligament)
⦿ Medially,
› blends with fibers of
the MCL (medial
collateral ligament)
22. MEDIAL COLLATERAL LIGAMENTS
1. Anterior
2. Posterior
3. Transverse/ Oblique
▪ Restraint of valgus stress: High degree of valgus stress,
› especially during throwing and golfing
23. MEDIAL COLLATERAL LIGAMENTS
⦿ Anterior portion of the MCL
› primary restraint of valgus stress
from 20o to 120o of elbow flexion
› Mechanoreceptors are densely distributed near attachments
.
⦿ Posterior portion of the MCL
› limits elbow extension
› but plays a less significant role than the anterior MCL in
providing valgus stability for the elbow
⦿ Oblique (Transverse) fibers of MCL
› assists in providing valgus stability and
› helps to keep the joint surfaces in approximation
24.
25. MEDIAL COLLATERAL LIGAMENTS
Functional Summary for MCL
1. Stabilizes the elbow against valgus
torques at med. elbow
2. Limits extension at the end of the elbow
extension ROM
3. Guides joint motion throughout flexion
ROM
4. Provides some resistance to longitudinal
distraction of joint surfaces
27. LATERAL COLLATERAL LIGAMENTS
Functional Summary
1. Stabilizes elbow against varus
torque
2. Stabilizes against combined varus
and supination torques
3. Reinforces humeroradial joint and
assists in providing some resistance
to longitudinal distraction of the
articulating surfaces
28. 4. Stabilizes radial head, thus providing
a stable base for rotation
5. Maintains posterolateral rotatory
stability
6. Prevents subluxation of humeroulnar
joint by securing ulna to humerus
7. Prevents forearm from rotating off of
the humerus in valgus and supination
during flexion from fully extended
position
29. Muscles
⦿ 9 muscles cross
the anterior
aspect of the
elbow joint but
only three of
these muscle
have primary
functions at the
elbow joint
31. MUSCLES
⦿ The remaining muscles:
› arise by a common tendon
from the medial epicondyle
of the humerus,
› considered to be weak flexors
of the elbow
› Flexor Carpi Radialis,
› Flexor Carpi Ulnaris,
› Flexor Digitorum Superficialis,
› Palmaris Longus
35. AXIS OF MOTION FOR FLEXION &
EXTENSION
⦿ passes horizontally through the center of the
trochlea and capitulum and intersects the
longitudinal axis of the shaft of the humerus
36. CARRYING ANGLE
⦿ The angle between the longitudinal
axes of the humerus and the ulna
when the arm is in anatomical position
⦿ The angulations in the frontal plane
⦿ This lateral deviation (or valgus
angulation) of the ulna in relation to
the humerus is called the Carrying
Angle or Cubitus Valgus.
37. CARRYING ANGLE
⦿ Ranges from 10° to 15° in
adults
⦿ Larger in females than in
males
⦿ The carrying angle
changes with skeletal
growth
⦿ Greater on the side of the
dominant hand
38. CARRYING ANGLE
⦿ An increase in the carrying
angle beyond the average
is considered to be
abnormal, especially if it
occurs unilaterally.
⦿ An abnormal varus
angulation at the elbow is
known as Cubitus Varus .
39. RANGE OF MOTION
⦿ A number of factors determine the
amount of motion i.e. available at the
elbow joint.
⦿ These factors include
› Type of motion
● active or passive
› Position of the forearm
● relative pronation-supination
› position of the shoulder.
40. RANGE OF MOTION
⦿ Range of Flexion
› active motion < passive motion
● Bulk of the contracting flexors on the anterior
surface of the humerus may interfere with the
approximation of the forearm with the humerus.
⦿ Active ROM for elbow flexion with the
forearm supinated
› about 135o to 145o
⦿ ROM of passive flexion
› 150oand 160o
41. RANGE OF MOTION
⦿ Position of the forearm also affects the
flexion ROM.
› When the forearm is either in pronation or
midway between supinaiton and pronation, the
ROM is less than it is when the forearm is
supinated.
⦿ Position of the shoulder may affect the ROM
available to the elbow.
⦿ Two joint muscles
● such as the Biceps Brachii and the Triceps,
● that cross both the shoulder and elbow joints
may limit ROM at the elbow if a full ROM is
attempted at both joints simultaneously.
42. RANGE OF MOTION
⦿ Other factors that limit the ROM but
provide stability for the elbow
› joint surfaces: the ligaments, and joint
capsule.
⦿ The elbow has inherent articular stability at
the extremes of extension and flexion
⦿ In full extension, the humeroulnar joint is in a
close-packed position.
⦿ Configuration of the joint structures helps
provide valgus and varus stability.
43. RANGE OF MOTION
⦿ Valgus stress in full extension
› Bony components, MCL, and anterior joint
capsule contribute equally to resist
⦿ Varus stress in full extension
› Bony components provide half of the
resistance
› Lateral collateral complex and joint capsule
provide the other half of the resistance.
⦿ Joint distraction in full extension
› Resistance is provided entirely by soft tissue
structures.
44. FACTORS AFFECTING ELBOW MUSCLE
ACTIVITY
› number of joints crossed by the muscle
one joint or two joint muscles
› physiologic cross-sectional area (PCSA)
› location in relation to joint
› position of the elbow and adjacent joints
› position of the forearm
› magnitude of the applied load
› type of muscle action
● concentric, eccentric, isometric, isokinetic
› speed of motion
● slow or fast
› moment arm (MA) at different joint positions
› fiber types
46. FLEXORS
BICEPS BRACHII :
⦿ Mobility muscle
⦿ MA largest between 80o and 100o of elbow
flexion
› capable of producing its greatest torque in this
range
47. FLEXORS
⦿ Biceps brachii
⦿ When the elbow is in full extension
› MA small Less effective as an elbow flexor
⦿ Function is affected by the position of the
shoulder
⦿ If full flexion of the elbow is attempted with
the shoulder in full flexion, especially when the
forearm is supinated,
› the muscle’s ability to generate torque is
diminished
48. FLEXORS
BRACHIORADIALIS
⦿ inserted at a distance from the joint axis
› largest component of muscle force goes toward
compression of the joint surfaces
● provide stability.
⦿ peak MA occurs between 100o and 120o of
elbow flexion
⦿ OTHER FLEXORS:
⦿ The Pronator Teres ,Palmaris Longus, Flexor
Digitorum Superficialis, Flexor Carpi Radialis,
Flexor Carpi Ulnaris,
› weak elbow flexor
› with primary actions at the radioulnar and wrist joints
49. EXTENSOR
TRICEPS
⦿ Effectiveness affected
› by changes in the position of the elbow
› not by changes in position of the forearm
⦿ When full elbow extension is attempted
› with the shoulder in hyperextension.
› long head’s ability to produce torque may
diminish
●muscle is shortened over both the elbow and
shoulder simultaneously.
50. ⦿ Because of the shape of the olecranon
process, the triceps moment arm also
varies with the position of the elbow.
⦿ Triceps moment arm is larger when the
arm is fully extended than when it is
flexed past 90°.
52. RADIOULNAR JOINT
⦿ Proximal & Distal Radioulnar Joints
› Pivot Joints
⦿ When Pronation and Supination of the
forearm occur, the radius pivots
around the ulna.
53. SUPERIOR RADIOULNAR JOINT
⦿ The articulating surfaces
⮚ the ulnar radial notch, the
annular ligament, the
capitulum of the humerus,
and the head of the radius.
⮚ A circular ligament called
the annular ligament is
attached to the anterior and
posterior edges of the radial
notch.
54. INFERIOR RADIOULNAR JOINT
⦿ The articulating surfaces
▪ The ulnar notch of the radius is located at
the distal end of the radius along the
interosseous border
▪ The radius of curvature of the concave
ulnar notch is 4 to 7 mm larger than that of
the ulnar head.
▪ Articular disk
● sometimes referred to as either the triangular
fibrocartilage(TFC)
● because of its triangular shape or as a part of the trian-
gular fibrocartilage complex (TFCC) because of its
extensive fibrous connections.
› Head of the ulna
56. LIGAMENTS
⦿ 3 ligaments associated with the proximal
radioulnar joint
⦿ annular ligament : helps to maintain stability of
the proximal radioulnar joint by holding the
radius in close approximation to the radial notch
⦿ quadrate ligament: limits spin of the radial head
in both pronation and supinaiton, and the
⦿ oblique cord
57.
58. MUSCLES
⦿ The primary muscles associated with the
radioulnar joints are the
› Pronator teres,
› Pronator quadratus,
› Biceps brachii
› Supinator.
59. ⦿ Pronator Teres :
› major action at RUJ , but the long head, as a two-
joint muscle, plays a slight role in elbow flexion.
› stabilization of the proximal RUJ
› maintain contact of radial head with the
capitulum.
⦿ Pronator Quadratus
› a one-joint muscle, is unaffected by changing
positions at the elbow.
› active in unresisted and resisted pronation
60. ⦿ Supinators:
› act by pulling the shaft and distal
end of the radius over the ulna
› act alone during unresisted slow supination in all
positions of the elbow or forearm.
› act alone during unresisted fast supination when
the elbow is extended.
⦿ Biceps:
› when supination is performed against resistance
and during fast supination when the elbow is
flexed to 90.
61. AXIS OF MOTION AT RUJ
⦿ Longitudinal axis
› extending from the center of the radial
head to the center of the ulnar head
62. RANGE OF MOTION
⦿ Total ROM 150o at radioulnar joints.
⦿ The ROM of pronation and supination is
assessed with the elbow in 90o of flexion.
This position of the elbow stabilizes the
humerus,
⦿ When the elbow is fully extended, active
supination and pronation occur in
conjunction with shoulder rotation.
63. RANGE OF MOTION
Limitation of pronation
⦿ When the elbow is extended
› by passive tension in the biceps brachii.
Limitation of Supination
⦿ by passive tension in the palmar
radioulnar ligament and the oblique
cord.
66. Loads on the Elbow
⦿ Not considered to be a weight-bearing joint
⦿ Regularly sustains large loads during ADL
Activities Compressive load
Dressing and eating 300 n (67 lb)
Rising from a chair
(Body is supported by the
arms)
1700 n (382 lb)
Pulling table
Across the floor
1900 n (427 lb)
Gymnastic skills two times body weight
67. LOADS ON THE ELBOW
⦿ Gymnastic skills
⦿ such as the handspring and the vault,
⦿ maximal isometric flexion when the elbow is fully
extended can produce joint compression forces of
as much as two times body weight
⦿ baseball pitching
⦿ the elbow undergoes a valgus torque of as
much as 64 N-m, with muscle force as large
as 1000 N required to prevent dislocation.
› The amount of valgus torque generated is most
closely related to the pitcher’s body weight.
