Upper Limb #3:Elbow

Christopher Ramnanan, Ph.D.cramnana@uottawa.ca

November 5th , 2015

- Identify the bony structures of the humerus, radius and ulna.

- Describe the movements of the elbow joint and between the radius and ulna.

- Identify and describe the function of the muscles in the anterior and posterior compartment of the arm.

- Describe the course of the neurovascular structures in the arm (brachial artery and vein, and median, ulnar and radial nerves).

Osteology: Humerus (Focus Distally)

Anatomical Neck

Greater Tubercle

Lesser Tubercle

Surgical Neck

Bicipital Groove (Intertubercular sulcus)

Capitulum Trochlea

Lateral/Medial Epicondyles

Spiral (Radial) Groove

Olecranon fossa

Lateral/Medial Epicondyles

PosteriorAnterior

Trochlea

Lateral view

Medial view

Capitulum

Trochlear notch of ulna

Head of radius

Trochlea

Osteology: Ulna and Radius (Focus Proximally)

Capitulum

Head of radius

Trochlear notch of ulna

Trochlea

Olecrenon of ulna

Coronoid Process

Radial tuberosity

Capitulum

Head of radius

Trochlear notch of ulna

Trochlea

Elbow Joint

-Hinge synovial joint (flexion/extension)

-Articulation (2 sites; humeroulnar is primary):

Humeroulnar (trochlea of humerus; trochlear notch of ulna)

Humeroradial (capitulum of humerus; head of radius)

Articular cartilage

Ulnar Collateral Ligament

Synovial membrane

Joint Capsule

Radial Collateral Ligament

Lateral view

Medial view

Radial Collateral Ligament

Anterior view

Elbow Joint

Radio-Ulnar Joints

Distal (Pivot Synovial)

Proximal (Pivot Synovial)

Intermediate (Syndesmosis Joint)

Note in lab: Interosseous membrane

The pivoting of the radius about the ulna at the proximal and distal radio-ulnar joints results in pronation/supination

Supination Pronation

Proximal Radio-Ulnar Joint

-Pivot synovial joint

-Articulation: head of radius, radial notch of ulna

-Note: this joint is located within loose fibrous capsule of elbow joint; synovial membrane is extension of that of elbow joint

-Ligament: Anular Ligament of Radius (allow rotation of radius about the ulna)

Clinical correlation: nursemaid`s elbow in children (subluxation of head of radius)

All three anterior arm muscles supplied by

musculocutaneous nerve

Biceps brachii: supination + flexion (shoulder, elbow)

Coracobrachialis: weak flexion / adduction (shoulder)

Brachialis: flexes at the elbow, but does not cross the shoulder joint and therefore

does not function at shoulder

Anterior Arm Compartment: Flexors of Shoulder and Elbow

Biceps brachii Coracobrachialis

Brachialis

Posterior Arm Compartment: Extensors of Shoulder and Elbow

All three heads of triceps brachii muscles supplied by radial nerve, and extend at the elbow

Only the Long head crosses the shoulder joint and can extend the shoulder; the lateral and medial heads only cross the elbow the joint

Clinical Note: The radial nerve runs in the radial (spiral) groove as it innervates the triceps, and is subject to injury due to bony fractures at this point in its course.

Long head

Lateral head

Medial head (observed when lateral head has

been resected)

Radial N

Axillary N

Anterior Forearm Compartment: Wrist/Digit Flexors, Forearm Pronators

Note:Muscles organized into aSuperficial layer (4) and the Deep layers (4)

Muscles will flex at any joint that they cross (wrist and/or digits)

Dominant Nerve of compartment: Median Nerve Exception: flexor carpi ulnaris and the ulnar half of the flexor digitorum profundus are innervated by the ulnar nerve

Common Flexor Tendon

Superficial Layer of Anterior Forearm Muscles (4)

Pronator Teres

Palmaris Longus

Flexor Carpi Radialis

Flexor Carpi Ulnaris

Note:-Common Flexor Tendon and PFPF orientation will help you ID these muscles in lab-Pronator Teres is relatively short,and only pronates forearm (does not cross/function at the wrist)-Palmaris Longus attaches to palmar aponeurosis; important in cats, but not so much in humans (wrinkles skin over palm; may be absent)-Note brachioradialis, a muscle that flexes at the ELBOW but belongs to the posterior compartment (radial nerve innervation; physically located with extensor group)

Clinical Note: medial epicondylitis (Golfer’s elbow) involves wear of the common flexor tendon

Flexor Digitorum Superficialis (FDS): extends to middle phalanx of digits 2-5, will flex proximal interphalangeal (PIP) joint

Flexor Digitorum Profundus (FDP): extends to distal phalanx; will flex both proximal and distal interphalangeal joints (PIP, DIP)

Flexor pollicis longus (FPL): flexes IP joint of thumb

Pronator quadratus: pronates at distal radio-ulnar joint

Deep Layers of Anterior Forearm Muscles (4)

Flexion at the PIP can be produced by the FDS or the FDP

Flexion at the DIP can only be produced by the FDP

Posterior Forearm Compartment: Wrist Extensors, Forearm Supinator

Note:Muscles organized into aSuperficial layer (6) and a Deep layer (5)

Muscles will generally extend at any joint they cross (wrist and/or digits)

Dominant Nerve of compartment: Radial Nerve

Superficial Layer of Posterior Forearm Muscles (6)Branchoradialis: innervated by radial nerve, but flexes at the ELBOWExtensor carpi radialis longus: originates above the common extensor tendon

Extensor carpi radialis brevis

Extensor digitorum: splits into four tendons, will extend four digits

Extensor minimi: muscle associated with belly of extensor digitorum, extends 5th digit

Extensor carpi ulnaris

Common Extensor Tendon

Note:Brachioradialis and Extensor carpi radialis longus originate above the common extensor tendon

Wear of the common extensor tendon (lateral epicondylitis) is termed tennis elbow

Deep Layer of Posterior Forearm Muscles (5)

Abductor Pollicis Longus

Extensor Pollicis Brevis

Extensor Pollicis Longus

Extensor indicis

Supinator: deep muscle that wraps around proximal radius

Pronated View

Supinated View

Biceps: powerful supinator, tendon attaches to radial tuberosity; musculocutaneous n.

Pronator Teres: pronator, median nerve

Pronator Quadratus: median nerve

Supinator: supinator, radial nerve

Arteries of the Upper Limb

Brachial A.

Axillary A. (continuation of Subclavian A.)

Radial A.

Ulnar A.

Cephalic V.(lateral, long)

Basilic V. (medial, short)

Median Cubital V.

Note: Deep veins in limbs run retrograde with, and named for, partner arteries (venae comitantes); limb veins are valved

Arteries of the Forearm

The Radial A. travels along the deep (medial) surface of the brachioradialis with the superficial branch of the radial nerve.

The Ulnar A. runs along the deep (medial) surface of the flexor carpi ulnaris with the ulnar nerve.

BoundariesSuperior: Imaginary line b/w medial and lateral epicondyles of humerusMedial: Lateral border of pronator teresLateral: medial border of brachioradialisRoof: superficial and deep fascia (including biceps aponeurosis)Floor: (not shown) supinator, brachialis muscles

As the biceps tendon progresses to the radial tuberosity, some fibers fan out to form biceps aponeurosis that helps protect the cubital fossa

ContentsBrachial A. bifurcation* into Radial A and Ulnar A.*note: location of bifurcation may be variableMedian NerveBiceps tendon

Biceps tendon

Brachial A.

Median N.

The Cubital Fossa

Note: Radial Nerve bifurcation and median cubital vein are near the cubital fossa, but usually not considered formally in the cubital fossa.The deep branch of the radial nerve dives into the supinator on its way to the posterior compartment of the forearm.

Motor to the anterior arm compartment (3 muscles; typically dives into coracobranchialis proximally)

Sensory to skin on lateral forearm (after innervating the arm muscles, emerges as the lateral cutaneous nerve of the forearm)

The Musculocutaneous Nerve

The Median Nerve

Dominant motor nerve of the anterior forearm compartment (except 1.5 muscles); minor motor nerve of the hand (thenar compartment and thumb-side lumbricals)

Sensory to most of skin on palmar surface of hand (lateral 3.5 digits) and dorsal aspects of lateral 3.5 fingertips

The Ulnar Nerve

Minor motor nerve of the anterior forearm compartment (1.5 muscles, including the flexor carpi ulnaris and the ulnar half of the flexor digitorum profundus); dominant motor nerve of the hand

Sensory to medial (ulnar-side) 1.5 digits (palmar and dorsal surfaces)

The Radial Nerve

Motor nerve to the posterior arm and posterior forearm muscles

Sensory to posterior arm, posterior forearm, and most of posterior hand (exception: medial 1.5 digits, all finger tips)

LAB 8 CHECKLIST - ELBOW

LIGAMENTS and CARTILAGE- Interosseus membrane- Annular ligament- Radial collateral ligament- Ulnar collateral ligament

BONES- Humerus

- Lateral epicondyle- Medial epicondyle- Trochlea- Capitulum- Olecrenon fossa

- Radius- Head of radius- Tuberosity

MUSCLESAnterior Upper Arm

- Biceps brachii- Brachialis- Coracobrachialis

Posterior Upper Arm- Triceps – long, lateral and medial

Superficial Anterior Forearm (4)- Pronator teres- Flexor carpi radialis- Palmaris longus- Flexor carpi ulnaris

Deep Anterior Forearm (4)- Flexor digitorum superficialis- Pronator quadratus- Flexor digitorum profundus- Flexor pollicis longus

Superficial Posterior Forearm (6)- Brachioradialis- Extensor carpi radialis longus- Extensor carpi radialis brevis- Extensor digitorum- Extensor digiti minimi- Extensor carpi ulnaris

Deep Posterior Forearm (5)- Extensor pollicis longus- Extensor pollicis brevis- Extensor indicis- Abductor pollicis longus- Supinator

NERVES- Musculocutaneous

nerve- Median nerve- Ulnar nerve- Radial nerve

ARTERIES- Brachial artery- Radial artery- Ulnar artery

VEINS- Axillary vein- Median cubital vein- Cephalic vein- Basilic vein- Brachial vein

SPACES- Cubital fossa

NB: Items italicized are conceptual, those denoted with a * are FYI

- Ulna- Olecrenon - Coronoid process- Trochlear notch