Upper Limb, part II Cubital fossa, Forearm, and Hand

Objectives: Bones and joints of the upper limb Fascial compartments of arm, forearm and hand Special areas of upper limb - cubital fossa, wrist, carpal tunnel, anatomical snuffbox Arteries and veins of upper limb Nerves innervating upper limb Inside wrist: Carpal tunnel, anatomical snuffbox

humerus ulna radius carpal bones metacarpal bones phalanges {

Radiolulnar joints Radius and ulnar articulate via synovial joints at 2 positions. - name: radiolulnar joint (proximal and distal) Supination: Summoning Pronation: Engagement ring show off pose Interosseous membrane - Keeps bones together and from rubbing against each other

Which carpal bone is the most commonly fractured? scaphoid Wrist (radiocarpal joint) Intercarpal joints Carpometacarpal and intermetacarpal joints Carpometacarpal joint of the thumb Metacarpophalangeal joints Interphalangeal joints Responsible for wrist rotation Knuckles 8 short bones in the carpal. Know which bones are located in the proximal row (closer to forearm) and in the distal row 5 metacarpal bones (long bones). Must know names of the joints. 1. Only one bone articulates directly to the wrist (radialcarpal joint, aka the “wrist joint”): radius 2. Joints between the radiocarpal joint and the rest of the hand: intercarpal joint. 3. The intercarpal joints, carpometacarpal and intermetacarpal joint are responsible for the rotation of the wrist 4. Metacarpophalangeal joints are the knuckles Interphalangeal joints Most commonly fractured carpal bone? Scaphoid Why is the scaphoid the most commonly fractured carpal bone? - due to palming a floor after a fall

Proximal row of carpals (from lateral to medial): 1. scaphoid bone S Carpal bones: Proximal row of carpals (from lateral to medial): 1. scaphoid bone S 2. lunate bone L 3. triquetrum bone T 4. pisiform bone P Distal row of carpals (from lateral to medial): 1. trapezium bone T 2. trapezoid bone T 3. capitate bone C 4. hamate bone H Some Lovers Take Positions / That They Can’t Handle Proximal row of carpals (Lateral to medial): -Scaphoid Lunate Triquestrum Pisiform Distal Row (lateral to medial) Trapezium trapezoid capitate hamate

the anatomical position* Hand movements Flexion - Extension Abduction - Adduction *Be sure to reference the anatomical position*

Compartmentalization = Functionally related groups of muscles are enclosed within compartments defined by thick layers of deep fascia and intermuscular septa that attach to the bone. Compartments contain muscles sharing a common function (action) and a common innervation. What covers the muscles superficially? Fascia What is the common link between muscles in a compartment? - Common function and innervation

} } anterior FLEXORS biceps brachii, ARM coracobrachialis compartment anterior FLEXORS } biceps brachii, coracobrachialis brachialis musculocutaneous n. brachial a. EXTENSORS } Compartment - flexors of elbow or forearm - innervated via muscularcutaneous (lateral cord) - Blood via brachial artery Extensor - Innervated by radial artery (posterior cord) radial n. triceps brachii profunda brachii a. posterior

} } FLEXORS anterior median and ulnar nn. flexors, pronators, FOREARM compartment FLEXORS anterior } median and ulnar nn. flexors, pronators, palmaris longus ulnar and radial aa. brachioradialis radial n. EXTENSORS radial a. } Brachioradialis does not match any group (really weird) - starts somewhere in the humerus and goes the radius - functionally, it’s a flexor - innervated like an extensor - Flexes when half prone extensors, supinator, abductor radial n. posterior interosseus a. posterior

Superficial group (5): Deep group (3): Three functional groups: Forearm muscles - anterior/flexor-pronator compartment Three functional groups: 1. Muscles which pronate the forearm and hand *pronator teres *pronator quadratus 2. Muscles that flex the hand *flexor carpi radialis/abduct *flexor carpi ulnaris/adduct *palmaris longus 3. Muscles that flex the digits *flexor digitorum superficialis (FDS) *flexor digitorum profundus (FDP) *flexor pollicis longus Superficial group (5): *pronator teres *flexor carpi ulnaris *flexor carpi radialis *palmaris longus *flexor digitorum spf. (FDS) Deep group (3): .: pronator quadratus .: flexor digitorum prof. (FDP) .: flexor pollicis longus Pronators: - main function: pronate forearm and wrist Group 2 main function: flex the hand one on radial side (flexi carpi radialis muscle) one on ulnar side (flexi carpi ulnaris) Group 3 flexes the digits superficialis  muscle goes to medial pharynges. Just flexes base of index finger (ends in middle) FDP: flexes upper part of index finger FPL Way to remember: - flex digits, flex hand, rotate wrist - alternatively, can be placed into two groups: superficial or deep groups Flexor carpi ulnaris and medial half of FDS are innervated by ulnar nerve First two lumbricals, thenar muscles and … are innervated by the median nerve

Palmaris longus muscle Flexor digitum superficialis Teres: round 5 superficial muscles Pronator teres Flexor carpi radiales Flexor carpi ulnaris Palmaris longus muscle Flexor digitum superficialis Medial epicondyle is the place where 5 muscles attach (Note that these are the 5 superficial wrist muscles) - pronator teres - flexor carpi radiales - flexor carpi ulnaris - palmaris longus muscle - flexor digitum superficialis Ulnar side - neurovascular bundle like ulnar nerve Medial nerve is in the middle, but it’s not superficial. Must get between muscle

Flexor carpi ulnaris Flexor digitorum superficialis Palmaris longus What’s the missing superficial wrist muscle? Pronator teres Tendon of flexor carpi radialis Radial artery

Forearm muscles - posterior/extensor-supinator compartment Three functional groups: 1. Muscles that extend the hand *extensor carpi radialis longus/abduct *extensor carpi radialis brevis/abduct *extensor carpi ulnaris/adduct 2. Muscles that extend the digits *extensor digitorum *extensor digiti minimi *extensor indicis 3. Muscles that extend the thumb *extensor pollicis longus EPL *extensor pollicis brevis EPB *abductor pollicis longus ABL/abduct Superficial group: *extensor carpi radialis brevis extensor carpi radialis longus *extensor carpi ulnaris *extensor digitorum *extensor digiti minimi brachioradialis Deep group: supinator EPL EPB APL extensor indicis Both flexor and extensor on ulnar side do adduction Both flexor and extensor on radial side do abduction Superficial posterior muscles attach to the medial condyle Superficial anterior muscles attach to the lateral condyle

5 1 3 2 4 Lateral epicondyle 8 7 6 Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Abductor policis longus Extensor pollicis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris

Cubital fossa - borders and contents Borders: (4; it’s a “cube) * medially - pronator teres m. * laterally – brachioradialis m. * the roof – deep fascia, subcutaneous tissue, and skin * the floor – supinator m. laterally and brachialis m. medially. Contents from medial to lateral side: (5) * median n. * bifurcation of the brachial a. * (deep) accompanying veins of the arteries * tendon of biceps brachii m. * radial n. and its branches (within the floor of the fossa) Picture is where the “cubital fossa” is Superficially, in the subcutaneous tissue overlying the fossa: *median cubital vein (connects cephalic vein to basilar vein) *medial and lateral antebrachial (forearm) cutaneous nerves

Don’t spend too much time finding this stuff

Structure most medially: median nerve Adjacent to that is the brachial artery Splits into radial and ulnar, radial goes further?

Tendon of biceps brachii Superficial branch of radial nerve Brachial artery Tendon of biceps brachii Biceps brachii Brachioradialis Median nerve Anatomical section of cuboidal fossa Medial epicondyle Pronator teres

Muscles of the hand – 4 compartments 1. Thenar compartment: * abductor pollicis brevis * flexor pollicis brevis median n. – recurrent branch * opponens pollicis 2. Adductor compartment: * adductor pollicis ulnar n. – deep branch, 3. Hypothenar compartment: * abductor digiti minimi * flexor digiti minimi ulnar n. – deep branch * opponens digiti minimi 4. Central compartment: * lumbricals : 1st and 2nd median n. – digital branches 3rd and 4th ulnar n. – deep branch * interossei- 3 PAD and 4 DAB ulnar n. – deep branch Thenar: a raised fleshy area on the palm of the hand near the base of the thumb Thenar compartment: short muscles Note that median nerve does only a few things in the hand. It’s primarily the ulnar nerve that controls the hand.

{ Palmar aponeurosis Hypothenar fascia Flexor pollicis brevis Palmar aponeurosis is all about protection Hypothenar fascia Flexor pollicis brevis Abductor pollicis brevis Palmaris brevis Thenar fascia

Abductor pollicis brevis 1st lumbrical 1st dorsal interosseous Superficial palmar branch Adductor pollicis Abductor digiti minimi Flexor pollicis brevis Palmaris brevis Abductor pollicis brevis Ulnar artery Pisiform bone Superficial branch of radial artery Radial artery

Short muscles of the Hand Flexor digitor profundis Palmar muscles adduct Abduct the digits (4 DAB) Adduct the digits (3 PAD) Flex the digits at the metacarpophalangeal joints and extend the interphalangeal joints.

Abductor: Dorsal interossei muscles Lumbricals: .: What do they do? They flex the digits at the metacarpophalangeal joints and extend the interphalangeal joints Abductor: Dorsal interossei muscles How many are there? 4 Hence, 4 DAB Adductor: Palmar interossei How many are there? 3 Hence, 3 PAD Metacarpophalangeal joints are the knuckle joints

Carpal tunnel 4 tendons of flexor digitorum profundus 4 tendons of flexor digitorum superficialis tendons 1 flexor pollicis longus tendon Carpal tunnel is the space between the carpal bones and the flexor retinaculum. The flexor retinaculum (transverse carpal ligament) is a thick connective tissue ligament that bridges the space between the medial and lateral side of carpal arch.

Structures that pass anterior to the flexor retinaculum (from medial to lateral side): * ulnar n. * ulnar a. *tendon of palmaris longus m. Structures that pass beneath to the flexor retinaculum - pass the carpal tunnel (from medial to lateral side): * tendons of flexor digitorum superficialis and profundus *median n. *tendon of flexor pollicis longus m.

Anatomical snuffbox (visible, when the thumb is fully extended): Anteriorly (laterally) bounded by 2 muscles: extensor pollicis brevis (EPB) abductor pollicis longus (APL) Posteriorly (medially) bounded by 1 muscle: extensor pollicis longus (EPL) The radial artery lies in the floor of the snuff box. That depression formed when you extend your thumb all the way back

Anatomical snuffbox EPB APL EPL

BRACHIAL A (ANTERIOR COMPARTMENT) ARTERIAL ARCHES (HAND) ULNAR A RADIAL A CUBITAL FOSSA DEEP BRACHIAL A. = profunda brachi (POSTERIOR COMPARTMENT) INTEROSSEOUS AA (ANTERIOR AND POSTERIOR COMPARTMENTS) AXILLARY A. (SHOULDER REGION) Axillary artery is a continuation of the subclavian The axillary artery turns into the profunda brachi and the brachial artery. The brachial artery is the more anterior of the two. The brachial artery Highly vascular because of compression when flexing or extending the arm in so many different directions Which artery in the forearm is often used to palpate an arterial pulse? Radial artery (remember the thumb point)

Superficial palmar arch is formed mainly by the ULNAR ARTERY Deep palmar arch is formed mainly by the RADIAL ARTERY

Where is the common place for venipuncture? CEPHALIC VEIN BASILIC VEIN Cephalic and basilic veins are superficial and connect to the deep vein - deep veins travel with arteries Cephalic vein drains into the axillary Basilic vein goes to the deep brachial or deep axillary? Where is the common place for venipuncture? - median cubital vein MEDIAN CUBITAL VEIN Where is the common place for venipuncture?

Cutaneous innervation of the upper limb Branch of median nerve

= Dinner fork deformity

Questions of the day! Which muscle of the forearm has a double innervation? Flexor digitorum profundus Loss of pronation of the hand suggests a lesion of which nerve? Median Numbness to the skin on the lateral half of the palm of the hand would be caused by a lesion to which nerve? - Median Dorsal scapular