Week 5 Flashcards
Which is larger proximally? Radius or ulna?
Ulna
Which is larger distally? Radius or ulna?
Radius
Which bones serve as proximal attachments for muscles that flex and extend the elbow?
Scapula and humerus
Which bones serve as distal attachments for muscles that flex and extend the elbow?
Radius and ulna
Which bones serve as proximal attachments for muscles that pronate and supinate the radioulnar joints?
Scapula, humerus, and ulna
on which bones are the distal attachments of radioulnar joint muscles?
radius
Bony landmarks of the radioulnar joint
Medial condyloid ridge
olecranon process
coranoid process
radial tuberosity
key bony landmarks for wrist and hand muscles
medial epicondyle
lateral epicondyle
lateral supracondylar ridge
Elbow joint
hinge or ginglymus type
allows only flexion and extension
2 interrelated joints in the elbow
humeroulnar
radiohumeral
Elbow motions primarily involve movement between…
articular surfaces of humerus and ulna. Radial head has relatively small amount of contact with capitulum of humerus
As elbow reaches full extension…
olecranon process is received by olecranon fossa. Increased joint stability when elbow is fully extended.
as elbow is flexed 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)
Ulnar collateral ligament is critical in…
providing medial support to prevent elbow from abducting when stressed in physical activity.
Many contact sports and throwing activities place stress on medial aspect of joint, resulting in injury
Ulnar Collateral Ligament (UCL)
particularly crucial to high-velocity sporting activities requiring optimal medial elbow stability like baseball pitching
compromise of this structure often requires surgery
TOMMY JOHN PROCEDURE- UCL reconstruction using a graft such as palmaris longus tendon
Radial collateral ligament provides…
lateral stability and is rarely injured
Annular ligament provides…
a sling effect around radial head for stability
Elbow moves from 0 degrees at full extension to…
145 to 150 degrees of flexion
Radioulnar joint
- Trochoid or pivot-type joint
- radial head rotates around at proximal ulna
- distal radius rotates around distal ulna
Annular ligament maintains radial head in its joint
Radioulnar joint supinating and pronating capacity
supinate 80 to 90 degrees from neutral
pronate 70 to 90 degrees from neutral
Radioulnar joint between shafts of radius and ulna held tightly together between proximal and distal articulations by…
an interosseus membrane (syndesmosis)
substantial rotary motion between the bones
synergy between glenohumeral, elbow, and radioulnar joint muscles
-conversely, when loosening a tight screw with pronation, we tend to internally rotate and extend the elbow and glenohumeral joints, respectively
WE depend on both the agonists and antagonists in the surrounding joints to assist in an appropriate amount of stabilization and assistance with the required task
Elbow flexors
Biceps brachii
brachialis
brachioradialis
weak assistance from pronator teres
Elbow extensors
triceps brachii
Anconeus (provides assistance)
Radioulnar pronators
pronator teres
pronator quadratus
brachioradialis
Radioulnar supinators
biceps brachii
supinator muscle
brachioradialis
Anterior muscles that take part in elbow movement
Primarily flexion and pronation
Biceps brachii
brachialis
brachioradialis
pronator teres
pronator quadratus
Posterior muscles that take part in elbow movement
primarily extension and supination
triceps brachii
anconeus
supinator
Biceps brachii
Origin- SH: coracoid process
LH: supraglenoid tubercle
Insertion: radial tuberosity
Bicipical aponeurosis
Location: anterior
Movements: Elbow flexion, supination of the forearm, weak shoulder flexion
Brachialis
Origin- Distal half of the anterior shaft of the humerus
Insertion- coracoid process of the ulna
location- anterior
Movements- elbow flexion
Brachioradialis
Origin- distal 2/3rds of lateral condyloid ridge of humerus
Insertion- lateral surface of the distal end of the radius at styloid process
Location- anterior
Movements- elbow flexion (best in neutral position), pronation from supination to neutral, supination from pronated position to neutral
Triceps Brachii
Origin: LH: infraglenoid tubercle of scapula
LatH: Upper half of posterior surface of the humerus
MH: distal 2/3rds of posterior surface of the humerus
Insertion- Olecranon process of ulna
Location- posterior
Movements- Elbow extension
Long head only: GH extension, GH horizontal abduction, GH adduction
Anconeus
Origin- posterior surface of lateral condyle of the humerus
Insertion- posterior surface of upper ulna and olecranon
location- posterior
Movements- elbow extension
Pronator Teres
Origin- distal part of the medial condyloid ridge of humerus, medial side of the proximal ulna
Insertion- middle third of lateral surface of the radius
Location- anterior
Movements- pronation, weak flexion of elbow
Pronator Quadratus
Origin- Distal 1/4th of anterior side of ulna
Insertion- Distal fourth of anterior side of radius
Location- anterior
Movements- pronation
Supinator muscle
Origin- lateral epicondyle
Insertion- lateral surface of proximal radius, just below head
Location- lateral
Movements- supination
Elbow flexion agonists
Biceps brachii
brachialis
brachioradialis
Ex: biceps curl
Elbow extension agonists
Triceps brachii
anconeus
Ex: push-up
Radioulnar pronation agonists
pronator teres
pronator quadratus
brachioradialis (from supination to neutral)
Ex: loosening a screw
Radioulnar supination agonists
biceps brachii
supinator muscle
brachioradialis (from pronation to neutral)
