KINESIOLOGY (ELBOW COMPLEX PT. 1)

The role of the elbow

• allows adjustment in HEIGHT and LENGTH of the upper limb

• To help position of the hand in an appropriate position to perform its function

• Acts as a lever arm when positioning the hand

• Functions as a fulcrum for forearm lever

1. Distal end of the humerus

2. Radius

3. Ulna

Elbow are made up of 3 bones with end of bones that are covered by a cartilage and surrounded by a joint capsule , what are these bones?

Elbow

Contains 7 bursae

Elbow

Where radial, median, and redial nerve passes through

• radiohumeral joint

• Ulnohumeral joint

• Superior (proximal) radioulnar joint

Cubital articulations of the joints of the elbow

Axis of motion

The axis of flexion and extension is at medial-lateral (x-axis), represented by a line through the centers of the trochlea and capitulum

Axial loading

• in extended elbow

• 40% of weight is through ulnohumeral joint

• 60% of weight is through radiohumeral joint

Extension

The most mechanically stable position of the elbow

Triangular sign

At 90 Degrees of elbow flexion, the olecranon process, medial and lateral epicondyle forms an isosceles triangle, but when the elbow is fully extended, the three points normally form a straight line.

Golfer’s elbow

Medial epicondilitis is also known as what?

Tennis elbow

Lateral epicondilitis is also known as what?

Ulnohumeral/Humeroulnar (or trochlear) joint

• articulation formed between the trochlea of humerus and trochlear notch of ulna

• Classified as synovial uniaxial hinge joint

• Resting position is 70 degrees elbow flexion, 10 degrees supination

• Closed-packed position is extension with supination

• Capsular pattern is flexion more limited than extension

Radiohumeral/ Humeroradial joint

• articulation formed between the capitulum of the humerus and head of radius

• Resting position is full extension and full supination

• Closed-packed position is elbow flexed to degrees and forearm supinated 5 degrees

• Capsular pattern is flexion more limited than extension

Lateral (radial) collateral

• cord like structure that is attached at lateral epicondyle and base of annular ligament

• Primary restraint to posterolateral instability that resist vargus force or resists excessice cubitus varus

• Prevents humeroulnar subluxation, stabilizes the humeroradial joint

• Assist the annular ligament in stabilizing the radial head against the ulna

Valgus force

It is the “outside forces” (moving); outward movement

Medial (ulnar) collateral

• fan shaped ligament that resist valgus force or excessive cubitus valgus

• Primary stabilizer of the elbow; damage to it may result in an unstable elbow joint

• Has 3 bands

• anterior band

• Posterior band

• Transverse/oblique band

What are the 3 bands of medial (ulnar) collateral

Anterior band

Attach at medial epicondyle to medial margin coronoid process

Posterior band

Attach at medial epicondyle to medial side of olecranon

Transverse/ oblique band

Between the attachment of anterior and posterior band

Carrying angle

• formed by longitudinal axis of arm and forearm

• Ulnohumeral joint is responsible for the formation of __

• Normal value: male 5-10 degrees; female 10-15 degrees

• Functionally, the carrying angle results from a combination of glenohumeral lateral rotation, elbow extension, and forearm supination

Cubitus valgus

When carrying angle exceeds 15 degrees; maybe due to lateral supracondylar fracture

Cubitus varus

If carrying angle is less than 5 to 10 degrees-seen in pt with “Gunstock deformity”

Musculotaneous, medial, ulnar, and radial nerve

Nerve supple of the elbow joint (mmurn)

• flexion: biceps brachii, brachioradialis, brachialis, pronator teres

• Extension: triceps brachii and anconeus

Movements of the elbow joint Including the muscles.

Normal functional position of the elbow

90 degrees of elbow flexion with the forearm midway between supination and pronation

Forearm functional position

Forearm slightly pronated

Proximal (superior) radioulnar joint

• synovial uniaxial pivot joint

• Formed between head of radius and radial notch of ulna

• annular

• Quadrate

• Oblique cord

What are the 3 ligaments found in the proximal (superior) radioulnar joint

Annular

Attached at anterior and post margin of radial notch of ulna and forms a collar around the radial head, covers about 4/5 of the joint

Quadrate

Attached between neck of radius and ulna - limits spinning of head and maintains radial head against radial notch

Oblique Cord

• Narrow ligamentous structure below radial tuberosity to the apex of coronoid process

• Function is unknown

• Provides stability to the joint

• Prevent displacement of radius on ulnar during pulling movements

• Responsible for “pulling”

Nursemaid’s elbow

Pulled elbow seen on kids

False; vertical axis

The axis of motion of the radioulnar articulation is in the horizontal axis, represented by a line through the center of the radius proximally and through the center of head of ulna distally (true or false)

Resting position of the proximal (superior) radioulnar joint

35 degrees supination, 70 degrees elbow flexion

Close packed position of the proximal (superior) radioulnar joint

5 degrees supination

Capsular pattern of proximal (superior)

Equal limitation of supination and pronation