Block 4 Objectives/Study Guide

• pectoral girdle: arm attaches to axial skeleton

  • at acromio-clavicular joint

  • clavicle:

    • sternal end is flatter, featureless (but has inferior impression for costoclavicular ligament

    • acromial end articulates with scapula

      • conoid tubercle, trapezoid line

• origins have wider, shorter tendons; insertions have longer cordlike tendons

• scapula parts

  • anterior: subscapular fossa, coracoid process (NOT THE SAME AS CORONOID), acromion process, superior angle, (supra)scapular notch, medial and lateral borders, inferior angle

  • posterior: scapular spine, supraspinous and infraspinous fossa, acromion process

  • anterolateral: coracoid process, acromion process, supraglenoid tubercle, glenoid cavity, infraglenoid tubercle

  • home to rotator cuff ms.

    • glenoid cavity has labrum (rim) of cartilage to increase depth of cavity

• humerus parts

  • proximal end: head, greater tubercle, anatomical neck, bicipital/intertubercular groove, lesser tubercle, surgical neck, deltoid tuberosity, radial (spiral) groove (seen posteriorly)

  • distal end: capitulum (cut marble), trochlea (weird looking), radial fossa (above capitulum), coronoid fossa (above anterior trochlea), olecranon fossa (posterior)

• ulna parts

  • proximal end: trochlear notch, coronoid process, radial notch, ulnar tuberosity (C-shaped end that fits into olecranon fossa)

  • distal end: styloid process, radial notch

  • plays more important role in elbow joint than wrist joint

• radius parts

  • proximal end: head, radial tuberosity (wheel-shaped head with fovea)

  • distal end: styloid process, ulnar notch (larger end)

  • R and U: head of R is proximal, head of R is distal

  • plays more important role in wrist joint than elbow joint

  • Colle’s fracture: styloid process is displaced proximally into bone, common in falls when hand extends to break the fall

• carpals

  • names (proximal to distal, lateral to medial then medial to lateral; C shape through bones): staphoid, lunate, triquetrum, pisiform, hamate (with hook of hamate), capitate, trapezoid, trapezium

    • mnemonic: straight line to pinky, here comes the thumb

    • note: pisiform and hook of hamate not visible from dorsal view

  • locations: wrist

• metacarpals

  • names: I, II, III, IV, V from thumb to pinky

  • locations: palm of hand joining carpals and phalanges

• phalanges

  • names: proximal, middle, and distal I-V

    • no middle phalange for thumb)

  • locations: fingers

• humerus fractures CS: most commonly occur at the surgical neck

  • injury to surgical neck → injury to axillary n.

  • midshaft fracture → possible injury to radial n. → wrist drop

  • distal humeral fracture → injury to median n.

  • fracture to medial epicondyle → injury to ulnar n.

• four shoulder joints:

  • 1 and location: acromioclavicular joint (scapula and clavicle)

  • 2 and location: glenohumeral joint (glenoid cavity of scapula and humerus)

  • 3 and location: sternoclavicular joint (sternum and clavicle)

  • 4 and location: scapulothoracic joint (anterior scapula and 2 ribs (mostly 3, some of 4))

• rotator cuff muscles

  • supraspinatus

    • abductor of arm

    • above scapular spine

    • O: scapula

    • I: humerus tubercles

    • innerv. by suprascapular n. (C4-C6)

  • infraspinatus

    • lateral rotator of arm

    • below scapular spine

    • O: scapula

    • I: humerus tubercles

    • innerv. by suprascapular n. (C5-C6)

  • teres minor

    • lateral rotator of arm

    • below supraspinatus (kind of blends in), above teres major

    • O: scapula

    • I: humerus tubercles

    • innerv. by axillary (circumflex) n. (C5-C6)

  • subscapularis

    • adductor, medial rotator of arm

    • on anterior side of scapula (subscapular fossa)

    • O: scapula

    • I: humerus tuberosity

    • innerv. by upper and lower subscapular ns. (C5-C7)

  • mnemonic: SITS

• teres major

  • location: below teres minor (which is below infraspinatus), above latissimus dorsi

  • function: internal rotation, adduction, extension

  • origin: inferior angle of scapula

  • insertion: crest of humeral lesser tuberosity

  • innervation: lower subscapular n. (C5-C7)

• latissimus dorsi

  • location:

  • function: internal rotation, adduction, extension, respiration (coughing m.)

  • origins

    • vertebral part: spinous process of t7-T12, thoracolumbar fascia

    • scapular part: inferior angle of scapula

    • costal part: ribs 9-12

    • iliac part: posterior 1/3 of iliac crest

  • insertion: crest of humeral lesser tuberosity (anterior angle)

  • innervation: thoracodorsal n. (C6-C8)

• trapezius

  • descending part

    • function: bring scapula obliquely up, rotate glenoid cavity superiorly, tilt head to same side, rotate head to opposite side

    • location: along neck to clavicle

    • O: occipital bone, spinous process of C1-C7

    • I: lateral 1/3 of clavicle

  • transverse part

    • function: draw scapula medially

    • location: along clavicle and scapula

    • O: aponeurosis at T1-T4 spinous processes

    • I: acromion

  • ascending part

    • function: draw scapula medially down

    • location: from ribcage-spine up to acromion

    • O: spinous process of T5-T12

    • I: scapular spine

  • entire m. keeps scapula steady on thorax

  • entire m. is innervated by accessory n. (CN XI) and cervical plexus (C3-4)

• levator scapulae

  • location: along neck from atlas to scapula

  • function: draws scapula medially upward, moves inferior angle medially; inclines neck to same side

  • origin: transverse process of C1-C4

  • insertion: superior angle of scapula

  • innervation: dorsal scapular n. (C4-C5)

• rhomboid major

  • location: beneath rhomboid minor

  • function: steadies scapula, draws scapula medially upward

  • origin: spinous process of T1-T4 vertebrae

  • insertion: medial border of scapula below scapular spine

  • innervation: dorsal scapular n. (C4-C5)

• rhomboid minor

  • location: between levator scapulae and rhomboid major

  • function: steadies scapula, draws scapula medially upward

  • origin: spinous process of C6-C7

  • insertion: medial border of scapula above scapular spine

  • innervation: dorsal scapular n. (C4-C5)

• deltoid

  • location: shoulder, round meaty part laterally

  • function: adductor of arm at shoulder (most important) up to 90*

    • anterior part flexes arm + does medial rotation of arm

    • middle part abducts arm

    • posterior part extends + laterally rotates arm

  • origin

  • insertion

  • innervation: axillary n. (C5-C6)

• coracobrachialis

  • location: from shoulder (coracoid process) down the brachium

  • function: flexion of arm at elbow, adduction, internal rotation

  • origin: coracoid process of scapula

  • insertion: humerus (in line with crest of lesser tuberosity)

  • innervation: musculocutaneous n. (C6-C7)

• pectoralis major

  • location: chest

  • function: adduction, internal rotation

    • clavicular and sternocostal parts flex and assist in respiration when shoulder is fixed

    • note: fibers cross at insertion point (flipped to allow extension of arm)

  • origin:

    • clavicular part: medial half of clavicle

    • sternocostal part: sternum, costal cartilages 1-6

    • abdominal part: anterior layer of rectus sheath

  • insertion: crest of humeral greater tuberosity)

  • innervation: medial and lateral pectoral ns. (C5-T1)

• pec minor

  • location: deep to pec major

  • function: draws scapula down, causes inferior angle to move posteromedially, rotates glenoid inferiorly, assists in respiration

  • origin: 3rd-5th ribs

  • insertion: coracoid process

  • innervation: medial and lateral pectoral ns. (C6-T1)

• serratus anterior

  • location: from spine to shaft of ribs, serrated

  • function: draws scapula laterally forward, elevates ribs when shoulder is fixed

    • superior part lowers raised arm

    • inferior part rotates scapula laterally

  • origin: 1st-9th ribs

  • insertion: medial border of scapula

  • innervation: long thoracic n. (C5-C7)

  • winged scapula CS

    • 2 ways it can happen

      • paralysis/injury to serratus anterior: cannot lift arm over 90*

      • injury to rhomboid major: no issue with lifting arm over 90*

• subclavius

  • location: hidden under clavicle

  • function: steadies clavicle in sternoclavicular joint

  • origin: 1st rib

  • insertion: inferior surface of clavicle

  • innervation: N. to subclavius (C5-C6)

• biceps brachii

  • location: anterolateral brachium

    • short head is more medial, long head is more lateral (long head is lateral)

  • function: flexor of arm

    • at elbow: flexion, supination

    • at shoulder: flexion, stabilization of humeral head during contraction, abduction and internal rotation of humerus

  • origin:

    • long head on supraglenoid tubercle of scapula

    • short head on coracoid process of scapula

  • insertion: radial tuberosity

  • innervation: musculocutaneous n. (C5-C6)

• brachialis

  • location: deep to biceps brachii (part can still be seen with biceps in place)

  • function: flexor of arm at elbow

  • origin: distal half of anterior surface of brachialis

  • insertion: ulnar tuberosity

  • innervation: musculocutaneous n. (C5-C6) and radial n. (C7, minor)

• triceps brachii

  • location: posterior compartment of brachium

    • 3 heads: long head attaches at shoulder, medial head and lateral head surround long head)

      • lateral head is also large, medial head is mini

  • function: extension of arm at elbow

    • long head extends and adducts at shoulder

  • origin:

    • long head at infraglenoid tubercle of scapula

    • medial head: posterior humerus, distal to radial groove; medial intermuscular septum

    • lateral head: posterior humerus, proximal to radial groove; lateral intermuscular septum

  • insertion: olecranon of ulna

  • innervation: radial n. (C6-C8)

• anconeus

  • location: proximal corner of posterior superficial forearm

  • function: stabilizes; extends elbow, tightens elbow joint

  • origin: lateral epicondyle of humerus (variance: posterior joint capsule)

  • insertion: olecranon of ulna (radial surface)

  • innervation: radial n. (C6-C8)

• venipuncture

  • which veins are utilized: median cubital v. (only in forearm, not in arm)

  • easy to access, especially when engorged via tourniquet

• brachial plexus

  • 5 major branches:

    • musculocutaneous (C5-C7): flexion at shoulder and elbow

      • innervates anterior brachium

    • axillary (C5-C6): arm abduction, helps with shoulder rotation (shoulder and deltoid)

      • innervates deltoid and teres minor

    • median (C6-T1): movement in forearm and parts of hand

      • innervates most of anterior forearm (except what’s innervated by ulnar n.)

    • radial (C5-T1): movements in arm, elbow, forearm, hand (posterior; extensors)

      • innervates posterior compartment of brachium and antebrachium

    • ulnar (C8-T1): fine motor control in fingers

  • roots from where it originates: C5-T1 overall

  • additional nerves:

    • dorsal scapular

    • suprascapular

    • subclavius

    • lateral and medial pectorals

    • upper and lower subscapulars

    • thoracodorsal

    • medial brachial and antebrachial cutaneous

    • long thoracic

  • injuries: from least to most severe

    • neuropraxia (stretch): burning or stinging, addressed with rest

      • root is compressed usually by rotation of head (seen in older adults)

      • nerve contraction from downward pull (seen in adolescents and young adults)

    • rupture: forceful stretch → partial/complete tear of a nerve

      • assoc. w/ muscle weakness and pain

      • severity depends on location and extent

      • often requires surgery

    • neuroma: scar tissue forms a knot on a nerve → prevents self-healing

      • common when n. is cut during surgery

      • surgery required to remove scar tissue and reconnect nerve

    • avulsion: nerve root is separated from spinal cord (completely)

      • common during childbirth (2/1000 births, baby not mother), among athletes, or with blunt trauma

      • 2 types depending on nerves involved

        • upper (C5-6): most common

          • Erb-Duchenne paralysis

          • symptoms: numbness and loss of motion around shoulder, inability to flex elbow, paralyzed deltoid and supraspinatus (no arm abduction) → medial rotation of arm, biceps and brachialis paralyzed → no elbow flexion, weak supination, shoulder adductors mildly affected

        • lower (C8-T1): less common

          • Klumpke’s paralysis (Klumpke claw hand)

          • symptoms: loss of movement and/or sensation of wrist and hand, paralysis of intrinsic hand ms. → compromised finger movement, atrophic paralysis of forearm and small hand ms. (claw hand)

      • treatment depends on severity

  • trunks: superior, middle, inferior stacked in arm

  • cords: posterior (middle finger), lateral (index finger), medial (ring finger)

    • in relation to axillary a.

  • branches:

    • long thoracic n. branches off of roots directly (exception), not off of cords (roots C5-C7)

    • lateral pectoral n. branches off of lateral cord, innervates pec major

    • subscapular branches (upper, middle, lower from proximal to distal) innervate supscapularis and teres major (lower)

      • middle subscapular is aka thoracodorsal (innervs. latissimus dorsi)

    • medial pectoral n. innervates pec major and minor

    • medial cutaneous n. of arm innervates arm sensory

    • medial cutaneous n. of forearm innervates forearm sensory

    • ulnar n. innervates most of hand, some ms. in forearm (flexor carpi ulnaris, flexor digitorum profundus partly)

      • exceptions in forearm

• axillary lymph nodes

  • drain 75% of lymph from breast

  • 5 groups: pectoral, lateral, apical, central, posterior (shaped like a T anterolateral to breast, along shoulder-ish)

  • drain into subclavian lymph. trunk → R lymph. duct → R venous angle

superficial anterior compartment ms. of forearm

• primary flexors of hand at wrist or fingers

• blood is supplied by ulnar and radial as.

• all except 2 are innerv. by median n. (flexor carpi ulnaris and flexor digitorum profundus, partially by median and partially by ulnar n.)

• mnemonic: PFPF (from lateral to medial; up to down if looking at own R inner forearm)

  • pronator teres

    • location: superficial forearm, most lateral

    • function: weak flexor of elbow, pronator of forearm

    • innervation: median n.

    • origin: humeral head at median humeral epicondyle, ulnar head at coronoid process

    • insertion: lateral radius (distal to supinator insertion)

  • flexor carpi radialis (R before U)

    • location: superficial forearm, medial to pronator teres

    • function: flexion and abduction of hand

    • innervation: median n. (C6-C7)

    • origin: medial epicondyle of humerus

    • insertion: base of second metacarpal (sometimes third)

  • palmaris longus

    • location: superficial forearm, medial to flexor carpi radialis

    • function: weak flexion of elbow, flexion of wrist tightening palmar aponeurosis

    • innervation: median n. (C7-C8)

    • origin: median epicondyle of humerus

    • insertion: palmar aponeurosis

  • flexor carpi ulnaris (U after R)

    • location: superficial forearm, most medial

    • function: flexion and adduction of hand at wrist

    • innervation: ulnar n. (C7-T1)

    • origin: humeral head at medial epicondyle, ulnar head at olecranon

    • insertion: pisiform, hook of hamate, base of fifth metacarpal

• intermediate anterior compartment

  • flexor digitorum superficialis

    • location: beneath PFPF

    • function: weak flexor of elbow, flexion of wrist, MCP, and PIP joints of digits 2-5

    • innervation: median n. (C8-T1)

    • origin: humeral head at medial epicondyle, ulnar head at coronoid process

    • insertion: sides of middle phalanges of digits 2-5

• deep anterior compartment

  • flexor digitorum profundus

    • location: deep, most medial

    • function: flexion of wrist, MCP, PIP, and DIP of digits 2-5

    • innervation: median n. (C8-T1) and ulnar n. (C8-T1)

    • origin: ulna (2/3 of flexor surface) and interosseous membrane

    • insertion: distal phalanges of digits 2-5 (palmar surface)

  • flexor pollicis longus

    • location: deep, lateral

    • function: flexion and abduction of hand at wrist, flexion of carpometacarpal of thumb

    • innervation: median n. (C7-C8)

    • origin: radius (mid-anterior surface) and adjacent interosseous membrane

    • insertion: distal phalanx of thumb (palmar surface)

  • pronator quadratus

    • location: anterior “watch band” deep to tendons of flexor pollicis longus and flexor digitorum profundus

    • function: pronation of hand, stabilization of distal radioulnar joint

    • innervation: median n. (C7-C8)

    • origin: distal ¼ of ulna (anterior surface)

    • insertion: distal ¼ of radius (anterior surface)

• superficial posterior compartment: all radial n. innervation

  • extensor digitorum

    • location: superficial forearm, posterior, medial to ECRB

    • function: wrist extension, extension/abduction of fingers 2-5

    • origin: common head (lateral epicondyle of humerus)

    • insertion: dorsal digital expansion of digits 2-5

  • extensor digiti minimi

    • location: superficial posterior forearm medial to extensor digitorum

    • function: extension and ulnar abduction of hand at the wrist, extension and abduction of pinky

    • origin: common head (lateral epicondyle of humerus)

    • insertion: dorsal digital expansion of fifth digit

  • extensor carpi ulnaris

    • location: superficial posterior forearm, medial to extensor digiti minimi

    • function: extension, adduction of hand

    • origin: common head (lateral epicondyle of humerus) and ulnar head (dorsal surface)

    • insertion: base of fifth metacarpal

• deep posterior compartment

  • supinator

    • location: deep to brachioradialis

    • function: supination of RU joints

    • origin: olecranon, lateral humeral epicondyle, radial collateral ligament, radial annular ligament

    • insertion: radius (between radial tuberosity and insertion of pronator teres)

  • abductor pollicis longus

    • location: deep to superficial posterior forearm, running beside extensor carpi radialis brevis

    • function: abduction of hand at the radiocarpal joint, abduction at the carpometacarpal joint of thumb

    • origin: radius and ulna (dorsal surfaces, interosseous membrane)

    • insertion: base of 1st metacarpal

  • extensor pollicis brevis

    • location: medial to abductor pollicis longus, btwn abductor and extensor pollicis longus

    • function: abduction of hand at radiocarpal joint, extension at carpometacarpal and MCP of thumb

    • origin: radius (posterior surface) and interosseous membrane

    • insertion: base of proximal phalanx of thumb

  • extensor pollicis longus

    • location: medial to extensor pollicis brevis

    • function: extension and abduction of hand at wrist, adduction of carpometacarpal of thumb, extension at MCP and IP of thumb

    • origin: ulna (posterior surface) and interosseous membrane

    • insertion: base of distal phalanx of thumb

    • very little is visible, tendon more likely to be pinned (extends to nail of thumb)

      • m. itself is short, but tendon is very long, hence longus

  • extensor indicis

    • location: deep posterior compartment of forearm, located medial (btwn pinky and ring) but wraps over to help extend index finger

    • function: extension at wrist, MCP, PIP, and DIP of second digit

    • origin: ulna (posterior surface) and interosseous membrane

    • insertion: posterior digital extension of second digit

• radialis group

  • brachioradialis

    • location: superficial lateral forearm, btwn anterior and posterior compartments

    • function: flexion of forearm at elbow, semipronation

    • origin: distal humerus

    • insertion: radial styloid process

    • “beer drinking” muscle

  • extensor carpi radialis longus

    • location: superficial posterior compartment of forearm, lateral (beside brachioradialis)

    • function: weak flexion of elbow, extension and abduction at wrist

    • origin: lateral supracondylar ridge of distal humerus

    • insertion: second metacarpal base

  • extensor carpi radialis brevis

    • location: superficial posterior forearm beside extensor carpi radialis longus (slightly more medial)

    • function: weak flexion of elbow, extension and abduction of wrist

    • origin: lateral epicondyle of humerus

    • insertion: 3rd metacarpal base

• carpal tunnel

  • carpal tunnel: formed by carpal bs. and “hammock” of flexor retinaculum (ligament)

    • flexor retinaculum inserts on tubercle of scaphoid, pisiform, tubercle of trapezium, and hook of hamate

  • associated tendons inside: tendons of flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longus

    • and median nerve

  • CS of carpal tunnel syndrome: compression of median nerve → pain, tingling, numbness, m. weakness

    • can be due to hypothyroidism, RA, pregnancy, amyloidosis, overuse

    • treated with rest or surgery: cut flexor retinaculum to open it up

      • not optimal, but sometimes necessary

• scaphoid fractures/dislocations CS

  • common in falls when hand extends to break the fall

  • most commonly fractured carpal (because of narrow waist)

    • can be deadly: nonunion and avascular necrosis of not addressed because proximal segment blood supply is compromised

• lunate fractures/dislocations CS

  • most commonly dislocated carpal

• thenar ms.: intrinsic hand movement for thumb

  • opponens pollicis

    • location: along most lateral edge of thumb meat

    • function: opposition of thumb, flexion at CMC joint of thumb

    • innervation: median n.

  • abductor pollicis brevis

    • location: down meat of thumb anterior

    • function: abducts thumb

    • innervation: median n.

  • flexor pollicis brevis

    • location: along medial meat of thumb

    • function: flexes thumb (windshield wiping across palm)

    • innervation: superficial head by median n., deep head by ulnar n.

  • adductor pollicis

    • location: in web of thumb and index

    • function: adducts thumb

    • innervation: ulnar n.

• lumbricals: 4 of them for digits 2-5

  • responsible for flexion at MCP joints, extension at PIP and DIP joints

  • numbers of lumbricals DON’T coincide with numbers of digits

  • 1 and 2 innerv. by median n., 3 and 4 innerv by ulnar n.

• hypothenar ms.: fine intrinsic muscles for pinky control

  • opponens digiti minimi

    • location: connecting carpals to pinky, most lateral

    • function: draws metacarpal in palmar direction

    • innervation: ulnar n.

  • flexor digiti minimi

    • location: between opponens and abductor digiti minimi

    • function: flexion of MCP joint of pinky

    • innervation: ulnar n.

  • abductor digiti minimi

    • location: most medial of pinky trio

    • function: flexion and abduction at MCP joint of pinky, extension at PIP and DIP joints of pinky

    • innervation: ulnar n.

  • palmaris brevis

    • location:

    • function

    • innervation: ulnar n.

• anatomical snuffbox CS

  • borders: tendons of abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus

  • contents: radial a. (main blood supply to thumb), superficial radial n.

• nerve damage symptoms

  • radial nerve damage: no arm extension (posterior compartment)

    • proximal to origin of triceps: no elbow extension, no triceps reflex, wrist drop (paralyzed extensors and supinator), flexed/adducted thumb, sensory loss in dorsolateral lower brachial region+posterior forearm surface+dorsum of hand and radial side of proximal phalanges

    • in radial groove: humeral fracture, triceps usually functioning, wrist drop, sensory loss in dorsolateral forearm and hand

    • in forearm: wrist drop (deep radial n. injured), disturbed extension of thumb and metacarpals, sensation usually preserved

    • (more proximal injury → more structures compromised)

  • median nerve damage

    • above elbow: only ms. in forearm and hand affected

      • wrist flexors paralyzed (except flexor carpi ulnaris and part of flexor digitorum profundus)

      • thumb flexors and abductor paralyzed, not adductor

      • possible flexion at metacarpophalangeal joints

      • Hand of Benediction: 1st and 2nd lumbricals lose function, unable to fully flex

      • pronation of forearm is paralyzed, sensory loss over median n. area

    • at wrist joint: short ms. of thumb paralyzed, not adductor

    • thenar ms. atrophy → flattened, ape hand

    • flexor pollicis longus stays functioning

    • sensory loss of medial n. area

  • ulnar nerve damage: lack of fine finger control (digits 3-5)

    • at wrist: fingers are hyperextended at metacarpophalangeal joints, flexed at interphalangeal joints (claw hand)

      • tendon of flexor digitorum profundus is paralyzed → flexion of digits 4 and 5 not possible at distal phalangeal joints

      • small ms. of pinky and interossei ms. are paralyzed

      • adduction and abduction of fingers are impaired

      • sensory loss over ulnar n. area

    • at elbow: paralysis of flexor carpi ulnaris and medial flexor digitorum profundus

      • weakened ulnar deviation of wrist

      • hand is abucted and extended

• PFPF/F: lateral to medial forearm ms.

  • pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis (deep to the first four)

for deep posterior antebrachium:

EEAEE (extensor vs abductor)

CrCrPPP (carpi radialis vs pollicis)

LBLBL (longus vs brevis)

R crosses over U (ulna under)

hand ms. acronym: oafala

arteries:

subclavian become axillary at first rib, then becomes brachial a. after teres major

deep brachial a. (branch of brachial a.) goes around spiral groove

2 branches of brachial a. at elbow: radial a. and ulnar a.

radial and ulnar as. come together at wrist, form superficial palmar arch (on palmar side)

on dorsal side of hand: dorsal arterial arch gets blood from radial and ulnar as.

veins:

axillary forms from merged basilic v. (down) and cephalic v. (out and down, lateral)

    basilic and cephalic branch from median cubital v. (for blood draws)

axillary v. → subclavian v. at first rib