The Elbow and Forearm Flashcards
ORIANS BICEPS BRACHII
Biceps Brachii • Fusiform muscle with two heads O: Long head: Supraglenoid tubercle of scapula Short head: Apex of coracoids process of scapula (w/coracobrachialis) R: Downwards (muscle bellies merge mid-humerus) I: • Posterior aspect of radial tuberosity via flat tendon • Bicipital aponeurosis A: • Elbow flexor • Powerful supinator (supinator magnus) • Flexor of GHJ. FA: • Flexion in supinated position • Eating • Screwdriver • Lifting NS: • Musculocutaneous nerve (C5-C7)
ORIANS BRACHIALIS
Brachialis
• Deep to biceps brachii in the anterior arm
• Thick tendon insertion forms the floor of the cubital fossa
O:
• Distal 2/3 of the anterior humeral shaft
• Medial and lateral intermuscular septa
R:
Downwards
I:
• Rough triangular brachialis impression, inferior to ulnar tuberosity and coronoid process.
• Joint capsule of elbow.
A:
• Elbow flexion
FA:
• Flexion in pronation
• Rolling dough, rowing
NS:
• Musculocutaneous nerve (C5-C7)
ORIANS BRACHIORADIALIS
Brachioradialis
• Superficial and lateral forearm muscle
• Upper part is deep to brachialis
• Forms lateral border of the cubital fossa
O:
• Upper 2/3 of the anterior lateral supracondylar ridge
• Adjacent lateral intermuscular septum
R:
• Downwards to form a long, narrow tendon mid-forearm.
I:
Proximal to the styloid process on lateral radius.
A:
• Flexor (especially mid-position)
• Returns forearm to mid-position from extreme pronated and supinated positions.
FA: • Flexion in mid-pronated position • Lifting a glass, hammering. NS: • Radial nerve (C5-T1)
ORIANS TRICEPS BRACHII
Triceps brachii
O:
Long head (most medial)
• Infraglenoid tubercle of scapula
• Glenoid labrum and joint capsule
Medial head:
• Infero-medial aspect of spiral groove on posterior humerus
• Posterior aspect of the medial and lateral intermuscular septa
Lateral head
• Superior and lateral aspect of spiral groove on posterior humerus
R:
• Inferiorly (three heads merge to create a broad tendon)
I:
• Via tendon (deep and superficial laminae) to posterior aspect of proximal olecranon
• Deep fascia of forearm medio-laterally
A:
• Extends elbow
• Extension from flexed position @ GHJ (long head)
• Adduction at GHJ. (long head)
FA:
• Punching, pushing, lowering BW into chair.
NS:
• Radial nerve (C5-T1)
ORIANS ANCONEUS
Anconeus • Small triangular muscle O: • Posterior aspect of lateral epicondyle of humerus • Adjacent joint capsule R: • Medially and distally I: • Lateral surface of olecranon and upper ¼ of the posterior ulna. A: • Assists elbow extension • Abducts and extends ulna during pronation. NS • Radial nerve (C5-T1)
ORIANS SUPINATOR
Supinator • Deep muscle w/two heads O: • Inferior aspect of lateral epicondyle of the humerus • Radial collateral ligament and annular ligament • Supinator crest of ulna R: • Infero-laterally I: • Upper 1/3 of the anterior, posterior, and lateral aspects of the radius • Attachment of pronator teres A: • Supinates forearm FA: Non-powerful • Opening door handle NS: • Radial nerve (C5-T1)
ORIANS PRONATOR TERES
Pronator Teres • Forms medial border of cubital fossa • Two heads and most lateral of superficial forearm flexors O: Humeral: • Lower aspect of medial supracondylar ridge • Medial intermuscular septum • Common flexor tendon (CFT) on medial epicondyle Ulnar: • Pronator ridge inferior to coronoid process of ulna. R: Infero-laterally I: • Flattened oval area on middle of lateral radius A: • Pronation of forearm • Weak elbow flexor FA: • Petting a dog. NS • Median nerve (C5-T1)
ORIANS PRONATOR QUADRATUS
Pronator Quadratus
• Quadrangular muscle on anterior aspect of forearm
O: • Lower ¼ of anterior surface of ulna R: • Transversely I: • Lower ¼ of anterior surface of radius A: • Initiates pronation • Stabilizes inferior radio-ulnar joint FA: • Touching NS: • Median nerve (C5-T1)
DESCRIBE CUBITAL FOSSA
LOCATION
BORDERS
CONTENTS
The Cubital Fossa • Triangular hollow area on anterior surface of the elbow Important clinical area containing: • Biceps tendon • Brachial artery and veins • Radial and ulnar arteries • Median and radial nerves
Medial border • Lateral aspect of pronator teres Lateral border • Medial aspect of brachioradialis Superior border • Imaginary line from medial to lateral epicondyles Floor • Brachialis
Roof
• Deep fascia of forearm and bicipital aponeurosis
LIST THE MUSCLES OF THE FOREARM FOR: FLEXION EXTENSION SUPINATION PRONATION
FLEXION 1. Biceps brachii 2. Brachioradialis 3. Brachialis 4. Pronator teres 5. Palmaris longus* 6. Flexor carpi radialis 7. Flexor carpi ulnaris 8. Flexor digitorum superficialis EXTENSION 1. Triceps brachii 2. Anconeus 3. Extensors carpi radialis lonug 4. Extensor carpi radialis brevis 5. Extensor carpi ulnaris 6. Extensor digitorum 7. Extensor digiti minimi SUPINATION 1. Biceps brachii 2. Supinator 3. Brachioradialis PRONATION 1. Pronator Teres 2. Pronator Quadratus 3. Brachioradialis 4. Flexor carpi radialis
Describe the Elbow Joint
JAAJIEMS
The Elbow Joint (Cubital joint)
Joint classification • Synovial Hinge (two articulations) Axis of movement • Uniplanar (transverse axis) Articular surfaces a) Humero-ulnar joint (medially)
Trochlea of humerus
• Trochlea is almost circular and pulley-shaped, with an oblique groove.
• Tilted inferiorly on the medial side to create the carrying angle.
• Concave medial-lateral.
• Convex anterior to posterior
Trochlear notch of ulna
• Deep trochlear notch with ridge running from tip of olecranon to tip of coronoid process
• Congruent fit to groove on trochlea.
• All surfaces covered in hyaline cartilage
b) Humero-radial joint (laterally)
Capitulum of humerus
• Incomplete hemispherical shape with variable radius of curvature
• Covered in hyaline cartilage, thickest centrally.
Head of radius
• Superior concave surface for articulation with capitulum
• Raised edge for capitulo-trochlear groove
Carrying Angle
Trochlea tilted inferiorly on the medial side leads to a lateral deviation called the carrying angle.
Trochlea bulges anteriorly, allowing more flexion by delaying contact between the bones.
Men = 10-15°
Women = 20-25°
Joint capsule • Single fibrous capsule lined with synovial membrane • Blends with collateral ligaments • No direct attachment to radius, shared with superior radioulnar joint • Weaker anteriorly and posteriorly Ligaments • Two sets of strong triangular bands on each side of the joint, blending with the joint capsule Ulnar collateral ligaments 1. Anterior band O: Medial epicondyle (anterior) I: Coronoid process 2. Posterior band O: Medial epicondyle (posterior) I: Olecranon 3. Intermediate band O: Medial epicondyle I: Transverse band 4. Transverse band O: Coronoid process I: Olecranon
A:
Limits abduction
Anterior fibers limit extension.
Radial collateral ligament
O:
Lateral epicondyle (deep to common extensor tendon)
I:
Blends with annular ligament of the radius and margins of radial notch of ulna
A:
Limits adduction
MOVEMENTS Flexion = 145° Caused by: • Brachialis • Biceps brachii • Brachioradialis
Limited by: • Tension in triceps • Soft tissue apposition • Posterior joint capsule Extension = 0° Caused by: • Triceps • Anconeus
Limited by:
• Tension in flexors
• Anterior joint capsule
• Bony apposition (olecranon in it’s fossa)
SUPERIOR RADIOULNAR JOINT JAAJIEMS
a) Superior Radioulnar Joint
Joint classification
• Synovial pivot
Axis of movement
• Vertical
Articular surfaces
a) Head of radius
• Oval shaped, lined with hyaline cartilage
b) Radial notch on ulna
• Creates 1/5 of ring, lined with hyaline cartilage
c) Annular ligament
• Creates 4/5 of ring, lined with fibrocartilage
Joint capsule
• Extensive, shared with elbow
Synovial membrane
• Hangs as fold inferior to the annular ligament – allows for rotation of radius
Ligaments
1. Annular ligament
• Creates 4/5 ring
• Attached to anterior and posterior margins of radial notch of the ulna
• Upper part lined with fibrocartilage continuous with hyaline cartilage of radial notch
• Lower part is lined with synovial membrane
• Superior support provided by radial collateral ligament
A:
Prevents displacement of radial head and stabilizes joint
- Quadrate Ligament
O:
• Lower aspect of radial notch of the ulna
I:
• Adjacent medial surface of radial neck, proximal to radial tuberosity
A:
• Limits pronation and supination
• Fibers run in criss-cross direction, meaning that in any position of pronation or supination, some fibers are under tension
INFERIOR RADIOULNAR JOINT JAAJIEMS
b) Inferior Radioulnar Joint
Joint classification
• Synovial pivot joint
Axis of movement
• Vertical
Articular surfaces
1) Distal ulna
• Crescent shaped, lined with hyaline cartilage
2) Distal radius
• Biconcave ulnar notch, lined with hyaline cartilage
3) Articular disk
• Triangular fibrocartilage. See below……
Joint capsule
• Loose to allow movement.
Intra-articular Disc
• Triangular fibrocartilaginous disc
• Thicker on it’s periphery
O (Apex)
Lateral side of the base of the styloid process of the ulna
I: (Base)
Inferior aspect of ulna notch of the radius
A:
• Unites the radius and ulna
• Increases stability of joint
DESCRIBE THE INTEROSSEUS MEMBRANE
Interosseus Membrane
• Strong, fibrous sheet between interosseus borders of radius and ulna
• Direction of fibers: infero-medially oblique
• Oblique cord superiorly and opening distally for vessels to pass
• Tightest in mid-position
Functions
• Divides forearm into anterior and posterior compartments
• Shock absorption and dissipation
• Attachment site for deep muscles
Describe pronation and supination, and what is happening at the respective superior and inferior radioulnar joints
- Pronation
• Involves rotation of radius around ulna so the two bones cross in space - Supination
• The reverse action brings bones back to parallel
¬
ROM = 180° (full supination/pronation)
Movement = rotation of the lower end of radius around the head of the ulna
Superior radioulnar joint
Movement = rotation of head of radius within fibro-osseuous ring
Limited by:
• Tension in quadrate ligament
Inferior radioulnar joint
Movement = rotation of the lower end of radius around the head of ulna
• Very stable joint due to articular disk, interosseus membrane, and pronator quadrates
MUSCULOCUTANEOUS NERVE
PMS
Musculocutaneous nerve
Pathway
• Arises from ventral rami C5-C7, the superior and middle trunks (anterior division, and lateral cord.
• In the axilla it lies lateral to the axillary artery
• It descends into the arm by piercing coracobrachialis
• It then runs distally between biceps 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
• Biceps brachii
• Medial aspect of brachialis and coracobrachialis
Sensory supply
• Skin on the lateral half of the forearm down to the base of the thumb (via lateral cutaneous nerve of the forearm)
MEDIAN NERVE PMS?
Median nerve
• Arises from ventral rami C5-T1, superior, middle, and inferior trunks (anterior division), and the lateral and medial cords.
• Enters the arm from the axilla at the inferior margin of teres major, and passes down the medial side of the arm under cover of biceps brachii
• In the lower part of the arm, it lies on brachialis and enters the cubital fossa.
Motor supply:
• Pronator teres, pronator quadratus, and muscles of the forearm
Sensory supply:
Articular branches of the elbow joint
ULNAR NERVE PMS?
Ulnar Nerve
• Arises from ventral rami C8-T1, the inferior trunk (anterior division), and the medial cord
• Runs medially to axillary artery, then descends down medial to brachial artery and anterior to tricep
• Halfway down the arm, pierces the intermuscular septum to enter posterior compartment of arm
• Descends down medial head of triceps and continues posterior to medial epicondyle of humerus in the ulnar groove, before entering the forearm.
Motor supply:
• Muscles of the forearm
Sensory supply
• Articular branches of the elbow joint
RADIAL NERVE PMS?
THE RADIAL NERVE
• Arises from ventral rami C5-T1, superior, middle, and inferior trunks (posterior divisions), and the posterior cord
• In the axilla, lies posterior to the axillary artery, and passes anterior to subscapularis, latissimus dorsi, and teres major tendons (posterior axillary border)
• Enters the posterior aspect of the arm via the triangular space
(formed by the humerus laterally, the long head of triceps medially
and teres major superiorly
- Runs inferiorly down the radial groove of the humerus (medial to lateral)
- Runs between the lateral and medial heads of the triceps
- It pierces intermuscular septum to enter the anterior compartment
- Anterior to the lateral epicondyle, it divides into the superficial and deep branches.
Motor supply • Triceps • Anconeus •Brachioradialis • Supinator • Muscles of the forearm
Sensory supply:
• Skin on posterior arm and forearm (via posterior cutanous nerve of arm/forearm, and lower lateral cutaneous nerve of arm).
• Articular branches to elbow.
BRACHIAL ARTERY
Brachial Artery
• Continuation of the axillary artery
• Rising inferior to teres major to the cubital fossa
• Travels across the front crease of elbow and splits into two branches just below the elbow: ulnar artery and radial artery.
• These branches continue into the hand
• Damage to the brachial artery can be very serious as it is the only blood supply to the hand
What is the position of the elbow joint line?
• Draw a line running from a point 1 cm below the
lateral epicondyle to a point 2 cm below the medial
epicondyle
• Line follows skin crease, up and lateral
How do you palpate the brachial pulse?
• In the cubital fossa, the brachial artery lies lateral to the median nerve and medial to the large biceps tendon
What is the position of the radiohumeral joint line?
The radiohumeral joint can be palpated directly in the dimple on the posterior aspect of the extended elbow joint.
Draw a horizontal line
What is the position of the superior radioulnar joint
Identify head of radius, then a vertical groove between the radius and ulna can be felt medially.
