Where things become something else

Subclavian a. becomes Axillary a.

at Lateral border of the 1st rib

The 1st rib is the MEDIAL boundary of the cervicoaxillary canal — the apex of the axilla — so crossing its lateral border is the moment the vessel leaves the neck and enters the axilla.

Clinical: Compression in the interscalene triangle or the costoclavicular space — at or proximal to this landmark — is thoracic outlet syndrome. The subclavian can be compressed against the 1st rib in the supraclavicular fossa to control upper-limb haemorrhage.

Artery Continuation ANI 2.4 slide 36 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: on the model

Corrected: First draft called the 1st rib the FLOOR of the cervicoaxillary canal; it is the medial boundary.

Show Subclavian a. in 3D →

Axillary v. becomes Subclavian v.

at Lateral border of the 1st rib

Mirrors the artery exactly — same rib, same border, opposite direction of flow.

Clinical: Target for central line placement: tethered to the 1st rib and clavicle, so it stays patent rather than collapsing.

Vein Continuation Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: on the model

Show Axillary v. in 3D →

Subclavian v. + Internal jugular v. join to form Brachiocephalic v.

at The venous angle, behind the medial end of the clavicle

Clinical: The thoracic duct drains into the LEFT venous angle, the right lymphatic duct into the right — the most testable fact about this junction.

Vein Formation Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: on the model

Show Subclavian v. in 3D →

C5 + C6 + C7 + C8 + T1 join to form Superior trunk + Middle trunk + Inferior trunk

at Between the anterior and middle scalene, in the posterior triangle

C5+C6 → superior, C7 alone → middle, C8+T1 → inferior. The interscalene gap is the gateway.

Clinical: Site of the interscalene block. Erb's point — where C5 and C6 unite — is the upper-trunk lesion of Erb-Duchenne palsy.

Nerve Formation Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Superior trunk + Middle trunk + Inferior trunk divide into Anterior divisions + Posterior divisions

at Posterior to the clavicle, at about its middle third

Each trunk splits into an anterior and a posterior division — anterior divisions will serve flexor compartments, posterior divisions extensors.

Clinical: Which is why a clavicular fracture can injure the plexus at the division stage.

Nerve Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Axillary a. becomes Brachial a.

at Inferior border of teres major

Teres major, in the POSTERIOR wall of the axilla, marks the distal limit of the axilla — so the vessel is renamed as it leaves the axilla and enters the arm. The same landmark names the vein in the opposite direction.

Clinical: The axillary artery's three parts are set by pectoralis minor — 1 branch, then 2, then 3 (ANI 2.4 slide 36).

Artery Continuation ANI 4.1 slide 33 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: partly on the model

Corrected: First draft called teres major the lower boundary of the axilla; it is part of the posterior wall.

Show Axillary a. in 3D →

Subscapular a. divides into Circumflex scapular a. + Thoracodorsal a.

at Inferior margin of subscapularis, at the lateral border of the scapula

Clinical: Circumflex scapular turns back through the triangular space — the key link in the scapular anastomosis, which connects the 1st part of the SUBCLAVIAN (thyrocervical trunk → suprascapular and transverse cervical) to the 3rd part of the axillary. Ligation between those two points is survivable because flow reverses through the subscapular; ligation DISTAL to the subscapular origin is not.

Artery Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Clinical line said the anastomosis spans the axillary artery; the thyrocervical trunk arises from the SUBCLAVIAN.

Brachial vv. + Basilic v. join to form Axillary v.

at Inferior border of teres major

The same landmark that renames the artery — but here two veins converge rather than one vessel being renamed.

Clinical: The basilic vein has already pierced the brachial fascia partway up the arm, so by the time it reaches teres major it is a deep vein.

Vein Formation ANI 2.4 slide 36 Moore's Clinically Oriented Anatomy 10e — verified 3D: partly on the model

Show Axillary v. in 3D →

Cephalic v. drains into Axillary v.

at Deltopectoral (clavipectoral) triangle — pierces the clavipectoral fascia

The cephalic vein runs up the lateral arm in the deltopectoral groove, then dives through the clavipectoral fascia. The axillary vein already exists — this is a tributary joining it, not part of its formation.

Clinical: The groove between deltoid and pectoralis major is a surface landmark, and the vein is a route for pacemaker leads.

Vein Tributary Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: partly on the model

Corrected: Was labelled Formation with a single From, which misdescribed a tributary as a constituent.

Show Axillary v. in 3D →

Anterior divisions + Posterior divisions join to form Lateral cord + Medial cord + Posterior cord

at Around the 2nd part of the axillary artery, deep to pectoralis minor

The cords are named for their position relative to the AXILLARY ARTERY, not to the body — lateral, medial and posterior to it.

Clinical: All three posterior divisions form the posterior cord (the inferior trunk's posterior division is small, occasionally absent). Anterior divisions of the superior and middle trunks form the lateral cord; the anterior division of the inferior trunk alone continues as the medial cord.

Nerve Formation Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Added the variant note: the inferior trunk's posterior division is small and occasionally absent.

Lateral cord + Medial cord + Posterior cord divide into Musculocutaneous n. + Median n. + Ulnar n. + Radial n. + Axillary n.

at Lateral border of pectoralis minor, around the 3rd part of the axillary artery

The lateral and medial cords each send a root to the median nerve — the 'M' lying across the third part of the artery.

Clinical: The posterior cord's two TERMINAL branches are the axillary and radial nerves; its others are the subscapular and thoracodorsal nerves.

Nerve Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Axillary n. divides into Anterior branch of axillary n. + Posterior branch of axillary n.

at Quadrangular space, with the posterior circumflex humeral artery

The posterior branch gives the superior lateral brachial cutaneous nerve — the regimental badge patch.

Clinical: A surgical neck fracture of the humerus takes the axillary nerve: deltoid atrophy, flattened shoulder, numb badge patch.

Nerve Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Brachial a. divides into Radial a. + Ulnar a.

at Cubital fossa, at the neck of the radius

The bifurcation sits deep in the fossa, medial to the biceps tendon and lateral to the median nerve.

Clinical: Auscultation point for blood pressure. Haemostasis is taken at the mid-arm medial humerus, DISTAL to the profunda brachii origin — only then do the profunda and ulnar collaterals still feed the anastomoses around the elbow (ANI 4.1 slide 36).

Artery Division ANI 4.1 slide 33 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Clinical line did not state that mid-arm haemostasis works only DISTAL to the profunda origin.

Brachial a. gives off Deep brachial a. (profunda brachii)

at Just distal to the lower border of teres major

It leaves the brachial almost immediately and enters the radial (spiral) groove with the radial nerve. The brachial artery continues — this is a branch, not a termination.

Clinical: A mid-shaft humeral fracture takes the radial nerve and this artery together.

Artery Branch ANI 4.1 slide 33 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Was labelled Division, which teaches that the brachial artery ends here. It continues.

Deep brachial a. (profunda brachii) divides into Radial collateral a. + Middle collateral a.

at Radial (spiral) groove, mid-arm

The two branches part company here: the radial collateral pierces the lateral intermuscular septum with the radial nerve into the anterior compartment, while the middle collateral stays behind in the posterior compartment.

Clinical: Radial collateral meets the radial recurrent in FRONT of the lateral epicondyle; middle collateral meets the interosseous recurrent BEHIND it.

Artery Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Landmark was 'lateral intermuscular septum, above the elbow' — too distal, and true of only one branch.

Median cubital v. links Cephalic v. + Basilic v.

at Cubital fossa, crossing the bicipital aponeurosis

It shunts cephalic to basilic across the fossa, lying ON the bicipital aponeurosis — which is the only thing separating it from the brachial artery beneath.

Clinical: The standard venipuncture site, and usable for cardiac catheterisation. About 20% have a variant where the median antebrachial vein splits into median basilic and median cephalic veins (ANI 4.1 slide 38).

Vein Anastomosis ANI 4.1 slide 37–38 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Was a Passage from cephalic to basilic that never named the median cubital vein itself.

Radial n. divides into Deep branch of radial n. + Superficial branch of radial n.

at Cubital fossa, anterior to the lateral epicondyle

The split happens at the elbow, after the nerve has already supplied brachioradialis and ECRL — the deep branch takes the remaining extensors, the superficial branch is purely sensory.

Clinical: A lesion AT this level spares triceps, whose branches left higher up in the spiral groove.

Nerve Division ANI 4.1 slide 39 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Why claimed the split precedes all extensor supply; brachioradialis and ECRL are supplied before it.

Ulnar n. passes through Ulnar n. — deep to FCU, between its two heads

at Cubital tunnel, behind the medial epicondyle

A true tunnel: floor is the medial epicondyle and ulnar collateral ligament, roof is the cubital tunnel retinaculum (Osborne's ligament), continuing distally as the aponeurosis between the two heads of FCU.

Clinical: The 'funny bone', and the commonest site of ulnar neuropathy. The roof tightens in elbow flexion, which is why flexion reproduces the symptoms; a medial epicondyle fracture takes the nerve outright.

Nerve Passage Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Why said the nerve is subcutaneous and unroofed; it is roofed by Osborne's ligament, which is what compresses it.

Musculocutaneous n. becomes Lateral antebrachial cutaneous n.

at Just proximal to the elbow — pierces the brachial (deep) fascia lateral to the biceps tendon

It pierced coracobrachialis far proximal to here. Having supplied coracobrachialis, biceps and brachialis, what emerges through the deep fascia beside the biceps tendon is purely sensory, and is renamed.

Clinical: Which is why a musculocutaneous lesion gives weak elbow flexion PLUS numbness over the lateral forearm.

Nerve Continuation Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Landmark was 'after piercing coracobrachialis' — about 20 cm proximal to where the renaming happens.

Ulnar a. gives off Common interosseous a.

at Radial tuberosity, in the proximal forearm

Arises at or just distal to the tuberosity. A short, wide trunk and the ulnar artery's largest branch — it is gone within a couple of centimetres. The ulnar artery itself continues to the hand.

Artery Branch Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Was labelled Division; the ulnar artery continues to the hand.

Common interosseous a. divides into Anterior interosseous a. + Posterior interosseous a.

at Proximal border of the interosseous membrane

The posterior branch passes backwards through the gap BETWEEN the oblique cord and the proximal border of the interosseous membrane to reach the extensor compartment; the anterior branch descends on the front of the membrane with the anterior interosseous nerve.

Artery Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Omitted the oblique cord, which forms the other half of the aperture.

Deep branch of radial n. becomes Posterior interosseous n.

at On emerging from between the two heads of supinator

Same nerve, new name once it has passed through supinator — which is why the muscle drills treat the two names as one nerve.

Clinical: Entrapment at the arcade of Frohse (the fibrous proximal edge of supinator) is MOTOR only: finger drop with no cutaneous sensory loss, because the superficial branch left before supinator. Wrist extension survives, with radial deviation, because ECRL and brachioradialis were supplied proximal to the arcade — so there is no wrist drop.

Nerve Continuation ANI 4.2 slide 42 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Clinical omitted that wrist extension survives (ECRL and brachioradialis are supplied proximal to the arcade).

Median n. gives off Anterior interosseous n.

at Distal to the two heads of pronator teres, in the proximal forearm

The AIN runs with the anterior interosseous artery on the front of the interosseous membrane. The median nerve itself continues to the wrist.

Clinical: AIN syndrome is motor in its visible deficit — FPL, radial half of FDP (index and middle) and pronator quadratus — so the pinch collapses and the patient cannot make a round OK sign, with no CUTANEOUS sensory loss (it does carry deep articular afferents, so a deep wrist ache is possible).

Nerve Branch Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Was labelled Division; and 'purely motor' overstated — the AIN carries deep articular afferents.

Radial a. becomes Deep palmar arch

at Between the two heads of the 1st dorsal interosseous, then between the heads of adductor pollicis

The radial artery reaches the palm the long way round — dorsally, across the snuffbox, then through two muscles rather than one. It is not the deep arch until it has passed adductor pollicis.

Clinical: In the snuffbox it lies on the scaphoid and trapezium, crossed by the superficial radial nerve (ANI 4.2 slide 42).

Artery Continuation ANI 4.2 slide 42 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Landmark stopped at the 1st dorsal interosseous, one muscle too early — adductor pollicis is the last gate.

Ulnar a. becomes Superficial palmar arch

at Distal to the pisiform, having passed through the ulnar (Guyon) canal

The ulnar artery enters the hand SUPERFICIAL to the flexor retinaculum alongside the ulnar nerve — it does not use the carpal tunnel.

Clinical: The superficial arch is the more distal of the two; its convexity reaches a line level with the distal border of the fully extended thumb.

Artery Continuation ANI 4.2 slide 33 Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Dorsal venous network of the hand divides into Cephalic v. + Basilic v.

at Dorsum of the hand — cephalic laterally, basilic medially

Lateral drains to cephalic, medial to basilic. The superficial veins of the limb begin on the BACK of the hand, not the palm.

Vein Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — verified 3D: no geometry

Median n. passes through Median n. (hand)

at Carpal tunnel, deep to the flexor retinaculum (transverse carpal ligament)

Nine tendons and one nerve share the tunnel — FDS ×4, FDP ×4, FPL ×1, plus the median nerve.

Clinical: Carpal tunnel syndrome SPARES THE PALM, because the palmar cutaneous branch leaves 5–8 cm proximal to the wrist and crosses superficial to the retinaculum (ANI 4.2 slide 32).

Nerve Passage ANI 4.2 slide 32 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Was one record claiming the median nerve divides INSIDE the tunnel. Split into the passage and the division below.

Median n. divides into Recurrent (thenar) branch + Common palmar digital branches

at Just distal to the distal border of the flexor retinaculum

The recurrent branch doubles back proximally and laterally around the distal edge of the retinaculum to reach the thenar muscles.

Clinical: Which is exactly why it is at risk in open carpal tunnel release. Sub-ligamentous and trans-ligamentous origins inside the tunnel are recognised variants, not the rule.

Nerve Division Not in the lectures yet Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Split out of median-carpal-tunnel: the branching is distal to the retinaculum, not inside the tunnel.

Ulnar n. divides into Superficial branch of ulnar n. + Deep branch of ulnar n.

at Ulnar (Guyon) canal, between the pisiform and the hook of hamate

ROOFED by the palmar carpal ligament and FLOORED by the flexor retinaculum and pisohamate ligament — so the ulnar nerve and artery run OVER the flexor retinaculum, not under it like the median nerve.

Clinical: Compression here (handlebar palsy, hook of hamate fracture) spares the dorsal cutaneous branch, which left 5–8 cm proximal to the wrist — so sensation over the dorsomedial hand is intact.

Nerve Division ANI 4.2 slide 33 Moore's Clinically Oriented Anatomy 10e — corrected on review 3D: no geometry

Corrected: Roof and floor were inverted — the flexor retinaculum is the FLOOR, the palmar carpal ligament the roof.