elbow rajat mathur
DESCRIPTION
Elbow kinesiologyTRANSCRIPT
Elbow Anatomy and Kinesiology
Rajat Mathur M.D.October 2013
PGY2
Elbow Overview● Hinge joint made up of
humerus, ulna and the radius bones
● Function: properly place hand in space by shortening and lengthening the upper limb
● Most upper extremity movements involve the elbow and radioulnar joints
Bones● Ulna is much larger
proximally than radius● Radius is much larger
distally than ulna● Scapula and humerus
serve as proximal attachments for muscles that flex and extend the elbow.
● Ulna and radius serve as distal attachments for these same muscles
Bones● Scapula, humerus, and ulna
serve as proximal attachments for muscles that pronate and supinate the radioulnar joints.
● Distal attachments of the radioulnar joint muscles are located on radius
● Bony Landmarks○ Lateral and medial
epicondyle○ Olecranon process○ Radial head
Joints● 3 joints enveloped by common capsule
Joint From To Description
Humeroulnar joint
trochlear notch of the ulna
trochlea of humerus
- simple hinge joint- allows movement of flexion & extension only
Humeroradial joint
head of the radius
capitulum of the humerus
- synovial ball and socket hinge type joint- allows flexion, extension, pronation and supination
Proximal radioulnar joint
head of the radius
radial notch of the ulna
- tochoid (pivot) joint- flexion or extension- pronation and supination
Ligaments● Ulnar collateral ligament
○ medial side of the elbow○ extends from medial
epicondyle of humerus to proximal portion of ulna
○ function is to prevent excessive abduction of elbow joint
● Radial collateral ligament○ lateral side of the elbow○ extends from lateral epicondyle
of humerus to head of radius○ function is to prevent excessive
adduction of elbow joint
Ligaments● Ulnar collateral ligament
is critical in providing medial support to prevent the elbow from abducting when stressed in physical activity.○ Many contact sports and
throwing activities place stress on the medial aspect of the joint, resulting in injury.
Ligaments● Radial collateral
ligament provides lateral stability and is rarely injured
● Annular ligament provides stability for radial head during pronation and supination○ commonly injured in children
when arm pulled forcefully
Interosseous MembraneThe joint between shafts of radius & ulna held tightly together between proximal and distal articulations by an interosseous membrane
Kinesiology of the elbow● The elbow moves from
0 degrees of extension to 145-150 degrees of flexion.
Elbow motions● Primarily involve movement
between articular surfaces of humerus and ulna
● The humeral trochlea fits into the ulna trochlea notch
● Radial head has a relatively small amount of contact with humerus
● As the elbow reaches full extension, the olecranon process fits into the olecranon fossa○ allows increased joint
stability when fully extended
Elbow motions● As the elbow flexes 20
degrees or more, its bony stability is unlocked, allowing for more side to side laxity.
● Stability in flexion is more dependent on the lateral (radial collateral ligament) and the medial (ulnar collateral ligament).
Movements● Flexion
○ movement of forearm to shoulder by bending the elbow to decrease its angle
● Extension○ movement of
forearm away from shoulder by straightening the elbow to increase its angle
Movements● Pronation
○ internal rotary movement of radius on ulna that results in hand moving from palm-up to palm-down position
● Supination○ external rotary
movement of radius on ulna that results in hand moving from palm-down to palm-up position
Pronation/Supination● Radioulnar joint
○ trochoid or pivot joint○ radial head rotates
around proximal ulna○ distal radius rotates
around distal ulna○ annular ligament
maintains radial head in its joint
○ Supinate: 80-90 degrees from neutral
○ Pronate 70-90 degrees from neutral
Nerves● All elbow and radioulnar joints muscles are
innervated from median, musculocutaneous, and radial nerves of brachial plexus
Radial Nerve● Radial nerve:
originates from C5, C6, C7, & C8○ Triceps brachii○ Brachioradialis○ Supinator (posterior
interosseous nerve)○ Anconeus○ Sensation to
posterolateral arm, forearm, & hand
Median Nerve● Median nerve -
originates from C6 & C7○ Pronator teres○ Pronator
quadratus (anterior interosseus nerve)
○ Sensation to palmar aspect of hand & first three phalanges, palmar aspect of radial side of fourth finger, dorsal aspect of index & long fingers
Musculocutaneous Nerve● Musculocutaneous
nerve - Originates from C5 & C6○ Biceps brachii○ Brachialis
Muscles overview● Elbow flexors
○ Biceps brachii○ Brachialis○ Brachioradialis○ Weak assistance from
pronator teres● Elbow Extensor
○ Triceps brachii○ Anconeus provides
assistance
● Radioulnar pronators○ Pronator teres○ Pronator quadratus○ Brachioradialis
● Radioulnar supinators○ Biceps brachii○ Supinator muscle○ Brachioradialis
Muscles● Anteriorly
○ Primarily flexion and pronation■ Biceps brachii■ Brachialis■ Brachioradialis■ Pronator teres■ Pronator
quadratus
Muscles● Posterior
○ Primarily extension & supination■ Triceps brachii■ Anconeus■ Supinator
Biceps Brachii ● Flexion of elbow● Supination of
forearm● Weak flexion of
shoulder joint ● Weak abduction of
shoulder joint when externally rotated
Brachialis● True flexion of the
elbow
Brachioradialis Muscle● Flexion of elbow● Pronation from
supinated position to neutral
● Supination from pronated position to neutral
Triceps Brachii● All heads: extension
of elbow● Long head:
extension of shoulder joint; adduction of shoulder joint, horizontal abduction
Anconeus● Small contribution
towards extension of elbow
Pronator Teres ● Pronation of
forearm● Weak flexion of
elbow
Pronator Quadratus● Pronation of
forearm
Supinator● Supination of
forearm
MRI Anatomy of the Elbowhttp://gme.bridgeporthospital.com/portals/7/cchip_client/anatomywiz/awiz.aspx?TID=1
Thank you