The Elbow Flashcards
Joint classification of the elbow and describe its articular surfaces
synovial hinge = two articulations
humeroulnar joint:
- consists of the trochlea of the humerus (which is pulley shaped, and tilted inferiorly to the medial side creating the carrying angle) + convex surface in sagittal plane
- trochlea notch of the humerus (deep trochlear notch with ridge running from tip of olecranon to tip of coronoid process)
humero radial joint:
- capitulum of humerus (covered in HC, thickest centrally, incomplete hemispherical shape)
- superior concave head of the radius (concave surface for articulation with capitulum)
Carrying angle
trochlea is tilted inferiorly on the medial side leading to lateral deviation of ulna and radius
men = 10-15 degrees
women = 20-25 degrees
Ligaments of the elbow joint`
ulnar collateral + radial collateral
Bands of the ulnar collateral ligament
strong triangular band, blends with the joint capsule
anterior: from medial epicondyle to the coronoid process (limits extension)
posterior: from medial epicondyle to the olecranon
transverse band: coronoid process to olecranon
intermediate band: medial epicondyle to transverse band
all limit abduction
Radial collateral ligament
strong triangular band (not as strong as ulnar)
from lateral epicondyle
to: blends with annular ligament of the radius and margins of the radial notch of the ulna
limits adduction
ROMs available at the elbow + limitations
flexion = 145 (actively) to 160 (passively)
created by biceps brachii, brachialis, brachioradialis
limited by soft tissue apposition, tension in triceps, posterior joint capsule
extension = 0 degrees
limited by tension in elbow flexors, anterior joint capsule, possibly bony apposition
Factors for the medial side being more stable than the lateral side of the elbow
ulnar collateral ligament is stronger, greater surface area/reciprocity of articulation medially, the capsule has no bony attachments laterally
Articulations of the radioulnar joint
superior radioulnar joint, inferior radioulnar joint, interosseous membrane
Superior radioulnar joint articular surfaces + type
synovial pivot
head of radius: oval shaped, lined with HC
radial notch of the ulna: creates 1/5th of the ring (lined with HC)
annular ligament: creates 4/5th of the ring, lined with Fibrocartilage
ligaments of the superior radioulnar joint
annular ligament + quadrate ligament
annular ligament
- creates 4/5th of a ring
- strong and flexible and allows the head of the radius to rotate (around the ulna during pronation and supination)
- attached to anterior and posterior margins of radial notch (on ulna)
quadrate ligament
runs from the lower border of radial notch of the ulna
To adjacent medial surface of neck of radius proximal to radial tuberosity
limits both pronation and supination
fibres are crisscrossed meaning there is tension in all positions of supination and pronation
inferior radioulnar joint + articulations
synovial pivot joint
distal ulna = crescent shaped (lined with HC)
distal radius = bioconcave ulnar notch (line with HC)
articular disc =
the articular disc of the inferior radioulnar joint
triangular, thicker on its peripherally
from: (apex) lateral side of the base of the styloid process of the ulna
to: (base) sharp inferior edge of ulnar notch on radius
principle structure uniting the radius and ulna
increases stability of the joint
interosseous membrane:
strong fibrous sheet between interosseous borders of radius and ulna
fibres run down and medially in oblique fashion
transmits force from hand to radius/ulna/humerus
oblique cord superiorly and opening distally for vessles to pass
tightest in mid portion
Function:
- divides forearm into posterior and anterior
- shock absorption and force dissipation
- attachment site for muscles
limitations of pronation and supination at sup/inf radulnar joints
superior:
- movement = rotation of radius within the fibro osseous ring
- limited by the quadrate ligament
Inferior:
- movement = rotation of the lower end of radius around the head of the ulna
- very stable (due to articular disk, interossoeous mem, and quadrate)
Anterior nerves of the arm
musculocutaneous (C5,6,7)
median (C5-T1) = superior, middle, inferior trunks (anterior divisions) and lateral + medial cords
ulnar (C7-T1)
Posterior nerves of the arm
radial nerve (C5-T1)
Biceps Brachii
O:
long head = supraglenoid tubercle of the scapula
short head = apex of the coracoid process of the scapula
R: downwards (muscle bellies merge mid humerus)
I: posterior aspect of the radial tuberosity via flat tendon and bicepital aponeurosis
A: flexion of elbow, strong supinator at 90 degrees flexion, flexion of the GHJ
NS: musculocutaneous nerve C5,6,7
Brachialis
O: distal 2/3rds of the anterior humeral shaft
R: downwards
I: rough triangular brachialis impression, inferior to the tuberosity and coronoid process of the ulna
A: elbow flexion (strongest flexor)
NS: musculocutaneous nerve C5,6.7
Brachioradialis
Superficial and lateral forarm muscle
O: upper 2/3rds of the lateral supracondylar ridge + adjacent lateral intermuscular septum
R: downwards to form a long narrow tendon mid forarm
I: lateral surface of the radius just proximal to the styloid process of the radius
A: elbow flexion (especially in mid position) + returns froarm to mid position from extreme pronation and supination
NS: radial nerve 9C5-T1)
karate chop muscle (eccentric)
Triceps brachi
O:
long head = infraglenoid tubercle on the scapula and glenoid labrum (fibres blend with joint capsule)
lateral head = superior and lateral aspect of the spiral groove on posterior humerus
medial head = inferior and medial aspect of the spiral groove on posteiror humerus + posterior aspect of the medial and lateral supracondylar septas
R: inferiorly (three heads merge to create a layered tendon)
I: posterior aspect of the proximal olecranon + deep fascia of forarm on either side
A: extension of the elbow, long head extends the GHJ from a flexed position
NS: radial nerve C5-T1
Anconeus
small triangular muscle
O: posterior surface of lateral epicondyle of the humerus + adjacent joint capsule
R: medially and distally
I: lateral surface of the olecranon + upper 1/4th of posterior surface of the ulna
A: helps with extension of elbow + abducts the ulna/extends distal end of ulna during pronation
NS: radial nerve C5-T1
Pronator Teres
O:
humeral head: medial supracondylar ridge + adjacent intermuscular septum + common flexor tendon (CFT) on medial epicondyle
Ulnar head: pronator ridge inferior to coronoid process on ulna
R: laterally and downwards
I: middle of lateral surface of the radius
A: pronation of the forarm + weak elbow flexor
NS: median nerve C5-T1
Pronator Quadratus
O: lower 1/4th of anterior surface of the ulna
R: transverselly
I: lower 1/4th surface of the radius + some deep fibres insert into triangular area above ulnar notch of the radius
A: initiates forearm pronation + stabilizes inferior radioulnar joint
NS median nerve C5-T1
Supinator
O: inferior aspect of the lateral epicondyle of the humerus + radial collateral ligament/annular ligament + supinator crest of ulna
R: downwaards and laterally\
I: upper 1/3rd of radius on posterior, lateral and anterior aspects of radius
A: supination
NS: radial nerve C5-T1
Cubital Fossa
lateral: brachioradialis
medial: pronator teres
superior: imaginary line between the medial and lateral epicondyles
floor: brachialis
roof: deep fascia of the forarm + bicipital aponeurosis
triangular hollow space on anterior surface of the elbow
contains: biceps tendon, brachial artery, and terminal branches of radial + ulnar arteries, brachial veins and part of median an radial nerves
Musculocutaneous Nerve
- arises from the ventral rami of C5,6,7, which is the anterior divisions of the superior and middle trunks and the lateral cord
- runs laterally to the axillary artery in the axilla
- pierces corachobrachialis and descends into the arm
- runs distally between the biceps brachii and brachialis into the lateral side of the arm
- at the elbow it becomes the LATERAL CUTANEOUS NERVE OF THE FOREARM which emerges LATERALLY from underneath biceps
- motor supply: corachobrachialis, biceps brachii, brachialis
- sensory supply: lateral half of the forearm down to the base of the thumb (via lateral cutaneous nerve of the forearm)
Radial Nerve
- arises from the ventral rami of C5-T1, which is the posterior divisions of the superior, middle and inferior trunks and the posterior cord
- lies behind the axillary artery in the axilla + passes anteriorly to subscapularis, latissimus dorsi, and teres major tendons
- enters posterior aspect of the arm via quadrangular space
- travels along the radial groove of the humerus
- runs between the LATERAL n MEDIAL heads of the triceps
- pierces the intermuscular septum to enter the anterior compartment
- divides into the superficial and deep branches anterior to the lateral epicondyle
motor supply: triceps brachii, anconeus, brachioradialis, supinator, muscles of the forearm
sensory supply: skin on the posterior arm and forearm (via posterior cutaneous nerves of arm + lower lateral cutaneous nerve of arm + posterior cutaneous nerve of the forearm)
Median Nerve
- arises from the ventral rami of C5-T1, which is the anterior divisions of the superior, middle, and inferior trunks + lateral and medial cords
- it enters the arm from the axilla at the INFERIOR MARGINS OF TERES MAJOR
- passes down the medial side of the arm under COVER OF BICEPS BRACHII
- in the lower part it lies on brachialis and enters the cubital fossa
Motor supply: pronator teres, pronator quadratus, muscles of the forearm
Sensory supply: articular branches of the elbow joint
Ulnar Nerve
- arises from the ventral rami of C7/8 - T1, which is the anterior division of the inferior trunk and the medial cord
- runs medial to the axillary artery
- descends down medial to the brachial artery + anterior to triceps
- half way down the arm pierces the intermuscular septum to enter the posterior compartment of the arm
- lies on the medial head of the tricpes, running down to the medial epicondyle of the humerus
- lies in the ulnar groove behind the medial epicondyle (funny bone) before entering the forearm
motor supply: muscles of the forearm
sensory supply: articular branches of the elbow
