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Home , Bicipital groove, Extensor expansion

Anatomy – – Muscles

Rotator cuff/scapulohumeral muscles 4 muscles (SITS) form musculotendinous around glenohumeral joint, provide stability of joint

Supraspinatus Course: med 2/3 supraspinatous fossa → high ant greater tuberosity Action: initiates abduction Nerve and artery: suprascapular

Infraspinatus Course: infraspinatous fossa → middle post greater tuberosity Action: laterally rotates Nerve and artery: suprascapular

Subscapularis Course: med 2/3 subscapular fossa → ant lesser tuberosity Action: medially rotates arm, extension Nerve: upper and lower subscapular Artery: subscapular

Teres Major (not SITS) Course: inf angle → medial lip bicipital groove Action: medially rotates arm, adducts Nerve: lower subscapular Artery: circumflex scapular

Teres Minor Course: mid 1/3 lat border scapula → low post greater tuberosity Action: lat rotates arm Nerve: axillary Artery: circumflex scapular

Anterior Chest Muscles

Pectoralis Major Clavicular head: med → lat lip bicipital groove Sternocostal head: manubrium, sternum, 2-6 costal cartilages, of ext oblique. Inserts via bilaminar tendon Action: flex, adduct, int rotate Nerve supply: lat/med pectoral nerves (5 segments plexus) Artery: pectoral branch thoracoacromial trunk

Pectoralis Minor Course: ribs 3-5 → coracoid Action: scapula forward, medial, down Nerve: medial pectoral Artery: pectoral branch thoracoacromial trunk

Deltoid Course: lat 1/3 clav, , lower spine scapula → deltoid tub Action: abducts, flex/extend, med/lat rotate Nerve: axillary Artery: post circumflex humeral

Serratus Anterior Course: ribs 1-9 → med aspect of costal surface scapula Action: protraction and lat rotation scapula Nerve and artery: long thoracic

Subclavius Course: 1st rib → inf mid 1/3 clavicle Nerve: nerve to subclavius 1 Anterior arm All nerve = musculocutaneous (C5-6); all artery = brachial

Biceps brachii Long head: supraglenoid tub, intertub groove → radial tub/bicip aponeurosis Short head: coracoid (lat to coracobrach) → radial tub/ Action: flex (long head) and elbow, supinates (best elbow flexed) Factoid: supination more powerful when elbow flexed 2 heads unite just distal to 1/2 way down arm no attachment to , acts on 3 joints longs head is intracapsular but extrasynovial

Brachialis Course: ant lower ½ hum/intermusc sept/supracond ridge → ulnar coronoid process/tubercle Action: flexes elbow (MAIN flexor)

Coracobrachialis Course: coracoid (med to ) → ant/med midshaft humerus Action: adduct/flex shoulder Pierced by

Posterior Arm

Triceps Long head: → descends between teres minor/major Lateral head: postlat humerus/lat intermuscular septum

Medial head: postmed inf 1/2 humerus All to process via common tendon Action: extends , long head extends and adducts arm Nerve: radial Artery: deep brachial

Anconeus Course: lat epicondyle humerus → lat olecranon Action: extends elbow Nerve: nerve to anconeus Artery: interosseous recurrent

Flexor Muscles Forearm Superf: All artery = ulnar, All nerve = median (except FCU = ulnar) All origin = med epicondyle, but ulnar head pron teres = ulnar, ulnar head FCU = olecranon, radial head FDS =

1. FDS Humeroulnar head: med epicondyle → shafts MP’s Radial head: mid 1/3 radius → shafts MP's Action: flexes MCP and PIPJ's Factoid: median nerve/ulnar artery pass between 2 heads

2. FCU Humeral head: med epicondyle Ulnar head: med olecranon/upper 2/3 shaft post Both to pisiform; via ligs to hook hamate, base 5th MC Action: flexes wrist, adducts Factoid: ulnar artery/nerve passes between 2 heads

3. FCR Course: medial epicondyle humerus → bases 2nd + 3rd MC's Action: flexes wrist, abducts hand Factoid: tendon begins mid forearm, pierces flexor retinaculum, passes thru groove in in own sheath 2 4. Palmaris Longus Course: med epicondyle → Action: flexes wrist

5. Pronator Teres Humeral head: med → lat midshaft radius Action: pronation, adducts radius Factoid: less powerful pronator than pronator quadratus Median nerve passes between 2 heads; ulnar artery NOT between 2 heads

Deep: All artery and nerve = Ant IO branch med, plus FDP also ulnar

1. FDP Course: post border/prox 2/3 med border ulnar and IO membrane → base DP’s Action: flexes MCP, PIP and DIPJ's Factoids: does NOT arise from radius origins of lumbricals arise from tendons most powerful and bulky muscle of forearm; incr action by wrist extension tendon for IF separates from others in forearm

2. FPL Course: ant radius and IO membrane → base DP T Action: flexes MCP and IPJ Factoid: only muscle that flexes IPJ of T; separate synovial sheath in carpal tunnel

3. Pronator Quadratus Course: from ant lower 1/3 shaft of ulna → ant lower 1/3 shaft radius Space of Parona: in front of pronator quadratus, deep to long flexor tendons fingers limited proximally by oblique origin of FDS proximal parts of flexor synovial sheaths protrude into it can become involved in synovial sheath infections Order from ulnar to radial: FCU... UN... UA... FDS... PL... MN... FCR... RA... ... sup rad nerve

Extensor Forearm Muscles Superficial: All nerve = radial; if ulnar in name = ulnar artery, if radial in name = radial artery, ED/EDM = interosseous recurrent

1. Brachioradialis Course: lat supracondylar ridge upper 2/3 humerus/lat IM septum → lat styloid process radius Action: flexes elbow, pro/supination Factoid: overlapped by AbPL and EPL in lower ; overlies radial N/art as lie on supinator 3 2. ECU Humeral Head: lat epicondyle humerus → med base of MC of LF Ulnar Head: mid 1/2 post ulna → med base of MC of LF Action: extends wrist, adducts hand Factoid: tendon runs in groove between ulnar head/ulnar styloid

3. ECRB Course: lat epicondyle, radial collat lig, aponeurosis, IM septa → post base MC of MF Action: extends wrist, abducts hand Factoid: covered by ECRL; overlapped by AbPL, EPB, EPL in lower forearm; immediately behind radial styloid

4. ECRL Course: from lower 1/3 lat supracondylar ridge humerus and lat IM septum → post base MC of IF Action: extends wrist, abducts hand Factoid: overlapped by AbPL, EPB and EPL in lower forearm becomes tendon in upper 1/3 forearm lies immediately behind radial styloid

5. EDM Course: lat epicondyle and IM septum → extensor expansion LF Action: extends MCP, PIP and DIPJ LF Factoid: lies medial to respective ED

6. ED Course: from lat epicondyle humerus → extensor expansions Action: extends MCP, PIP and DIPJ's, extends wrist

7. Anconeus

Deep: All nerve – deep radial; All artery – post interosseous

1. Extensor Indicis Course: IO membrane and postlat distal ulna → extensor expansion IF Action: extends MCP, PIP and DIPJ IF

2. Supinator Course: lat epicondyle, rad collat/ulnar ligs/crest ulna → prox 1/3 radius Factoid: humeral head more superficial/vertical than ulnar head Post IO nerve passes between 2 heads; forms floor of antecubital fossa

3. EPB Course: IO membrane and post distal radius → base PP T Action: extends MCPJ T

4. EPL Course: IO membrane and mid postlat ulna → base DP T Tendon passes med to tubercle of radius and uses as pulley Action: extends IPJ thumb Factoid: boundary of ASB

5. AbPL Course: mid 1/3 post radius/IO membrane/postlat mid ulnar → radial base MC T Action: abducts T at CMCJ

Order from radial to ulnar is: ECRL..ECRB..EPL..ED..EI..ECU..FCU 4 Thenar Muscles All nerve = recurrent branch of median C8/T1; All artery = sup palmar branch of radial

1. FPB Origin: superficial head from flexor retinaculum/trapezium, deep head from trapezoid/capitate Insertion: radial sesamoid and radial side base prox phalanx of thumb Action: flexes CMC and MCPJ of thumb

2. AbPB Origin: flexor retinaculum, scaphoid tubercle and trapezium Insertion: radial side of base proximal phalanx of thumb Action: abducts thumb

3. OP Origin: flexor retinaculum and trapezium Insertion: whole of radial side of 1 st MC Action: opposes thumb (medially rotates and flexes)

Other Thumb Muscles AdP Origin: Oblique head from capitate /base 2nd and 3rd MC's; Transverse head shaft 3rd MC Insertion: ulnar sesamoid, ulnar side base prox phalanx, tendon of EPL Action: adducts thumb Nerve: deep branch of ulnar C8/T1 Artery: deep palmar arch

Hypothenar Muscles All nerve = deep branch of ulnar; All artery = ulnar

FDMB - hook hamate/flexor retinaculum → ulnar side base proximal phalanx Action: flex CMC and MCPJ little finger

AbDM - pisiform → ulnar side base prox phalanx LF Action: abduct little finger at MCP

OPM - hook hamate/flexor retinaculum → ulnar side 5th MC Action: opposition (flexion and lateral rotation) little finger at CMC joint

Intrinsic Hand Muscles

Interossei Palmar (4): ant/inner aspects shafts MC's; smaller than dorsal; unipennate Dorsal (4): post/inner aspects shafts MC's; 2 heads – one from each metacarpal Insertion: extensor expansions and proximal phalanx of respective finger Action: flex MCPJ, extend IPJ (created by palmer adduction and dorsal abduction - PAD, DAB) Nerve supply: deep branch of ulnar C8/T1 Artery: dorsal and palmar metacarpal

Lumbricals Origin: each of 4 FDP tendons Insertion: passes along radial side of corresponding MCPJ on palmer surface of deep transverse MC ligament Ulnar lumbricals bicipital, median lumbricals unicipital. Inserts into extensor expansion on dorsum of first phalanx. Action: weakly flex MCPJ, extend IPJ Nerve: deep branch ulnar except lat 2 = median Artery: sup palmar arch Factoid: 1st /2nd unipennate - from lateral side and 1st and 2nd FDP tendons 3rd /4th bipennate (eg. 3rd lumbrical from lat ring finger and med middle finger FDP tendon)

5 Finger flexion/extension ED → extends all joints FDP → flex DIP and MCP FDS → flex PIP and MCP Lumbricals → flex MCP, ext IPJs Dorsal int → abduct; palmar int → adduct → together flex

Hand muscles All For One And One For All (Med → lat: AbDM,FDM, ODM, AdP, OP, FPB, AbPB)

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