Superficial and deep groups. 5 superficial muscles cross elbow joint, 3 deep ones donÕt.
- all except pronator teres are flexor muscles.
Flexors are much bulkier than extensors due to necessity of grip strength.
Arise from common origin from anterior surface of medial
epicondyle.
- FCU only one to be supplied by ulnar nerve ¨ rest median
Aide memoire: hand on contralateral common origin ¨ fingers represent 5 muscles.
- in order from thumb to little finger:
Arises: Main epicondylar head joined by smaller ulnar head arising from coronoid process of ulna.
-
median nerve runs between these heads.
- ulnar artery passes deep to deep head.
Inserts: Forms medial border of cubital fossa; ¨ lateral convexity of radius (most prominent part)
Innervation: highest muscular branch of median nerve (C6-7).
Action: pronates; weak flexor
Test: pronate arm against resistance; palpate at medial edge of cubital fossa.
Arises: common origin.
Inserts: becomes tendinous at middle forearm, has own compartment in flexor retinaculum; lies on a groove of the trapezium and inserts into bases of 2nd & 3rd MCÕs.
- symmetrical with posterior extensors longus & brevis
- tendon distinguished from FPL tendon by absence of fleshy muscle fibres.
- Prominent landmark in lateral wrist, radial artery lateral, palmaris medial.
Innervation: median nerve (C6-7).
Action: flexor and radial abductor; stabilises wrist in finger / thumb motion.
Test: flex wrist against resistance and palpate it.
Arises: Common origin medial epicondyle and tubercle on medial coronoid process
- this muscle was formerly the f.d. sublimis, hence this is called the sublime tubercle
- fibrous arch continues this origin across the radius (whole length of anterior oblique line)
- origin forms the upper limit of the space of Parona (see later)
Frequently described as intermediate layer as fleshy tendon lies under other flexors
Median nerve is
plastered onto deep surface of tendons by loose areolar tissue.
Insertion: Tendons split around profunda tendons, insert into lateral aspects of middle phalanx of each digit (see hand section)
Innervation: Median nerve (C7,8)
Action: flexor of PIP jts, and secondarily MCP and wrist; even assists in elbow flexion.
Test: Keep DIPs extended, then flex fingers at PIP jts.
Phylogenetically degenerating; absent in 13%.
Tendon broadens in front of flexor retinaculum (adherent beneath), inserts into palmar aponeurosis.
- becomes the longitudinally directed fibres
- Lies anterior to the median nerve just proximal to the wrist
Innervation: median nerve (C7,8)
Action: weak wrist flexor; anchors skin/fascia of hand against shearing forces distally
- used in tendon transfers
Test: flex wrist; pads of thumb & little finger together, palpate tendon.
Arises: widely from common origin, medial olecranon and upper 3/4 of subcutaneous border of ulna;
- ulnar nerve passes between humeral & ulnar heads to enter flexor compartment
- tendon medial to nerve and artery at the wrist.
Inserts: into pisiform (& by way of pisohamate and pisometacarpal ligaments ¨ hamate & 5th met.)
**Innervation: from ulnar nerve (C7,8) but these fibres from lateral cord or middle trunk of BP in 95%.
Action: flexor and ulnar adductor of wrist
- in radial nerve paralysis, tendon can be transplanted to allow finger / thumb extension.
Test: flex and adduct wrist against resistance, and palpate the tendon.
Borders: Pronator teres, brachioradialis and line joining humeral epicondyles.
Roof: deep fascia of forearm + bicipital aponeurosis (medially).
- in front of the aponeurosis is the median cubital vein with medial cutaneous nerve of forearm
Floor: mainly by brachialis; and below by supinator around neck of radius.
Contents: (medial ¨ lateral:) median nerve, brachial artery, biceps tendon; lateral retraction reveals radial nerve and posterior interosseous branch.
- posterior interosseus n (terminal branch of radial n) gives branches to ECRB and upinator before disappearing from fossa between two heads of supinator into extensor compartment
- superficial branch of radial nerve then passes down forearm under brachioradialis.
Innervation: anterior interosseous branch of median nerve running deeply ¨ all 3 muscles;
- FDP also receives ulnar nerve innervation.
Hence essentially all anterior forearm = median supply besides FCU and 1/2 of FDP.
Largest / most powerful of all forearm muscles.
Arises: medial surface of olecranon, upper 3/4 of anteromedial ulna & narrow strip of inteross membrane.
Inserts: index tendon separates in forearm, other 3 separate after traversing flexor tunnel.
- at this separation point the lumbricals take origin
- see hand for insertion points
(a) anterior interosseous branch of median nerve ¨ index & middle finger bellies
(b) ulnar nerve ¨ ring & little finger bellies
- this 2:2 distribution in 60%; 20% have 3:1, 20% have 1:3; lumbricals will match.
Action: flexion of DIPs, then roles fingers & wrist into flexion: gripper.
- most powerful when augmented by wrist extension.
Arises: anterior surface of radius below anterior oblique line above pronator quadratus insertion
- unipennate tendon forms on ulnar aspect (insertion of fibres distinguishes it from FCR)
- note on plate 420, also has a part arising from the coronoid process of the ulnar
Inserts: passes in carpal tunnel deep to median n and FCR, then spirals around FCR to insert into base of distal phalanx of thumb.
Nerve: Median (C7-8)
Action: Only flexor of IP jt of thumb; also flexes MCP and CMC jts at thumb and wrist.
Test: hold proximal phalanx steady, flex distal phalanx against resistance.
Arises: lower 1/4 of anteromedial ulna
Inserts: anterolateral surface of lower 1/4 of radius.
Action: forearm pronation (more powerful than teres); holds radius and ulna together.
Nerve: median (C7,8)
On top of pronator quadratus, but beneath long flexor tendons. Origin of FDS forms proximal limit.
Flexor synovial sheaths protrude into here ¨ synovial sheath infections extend proximally to here.
¨ drain via radial and ulnar incision to sides of flexor tendons.
A nerve runs down each border of the forearm (radial & ulnar);
Each corresponding branch of brachial artery approaches its nerve but doesnÕt cross it.
- radial nerve approaches its artery in middle 1/3 (417), ulnar in distal 2/3 (418)
Median nerve (on deep surface of FDS) crosses superficial to ulnar artery to lie centrally.
Hand supply: by radial & ulnar arteries by superficial & deep palmar arches.
Forearm arteries: anterior & posterior branches of ulnarÕs common interosseous branch.;
- latter is a ÒfailureÓ and is first augmented by, then distally replaced by the anterior branch which pierces the interosseous membrane to lie in the posterior compartment.
The anterior (from median) and posterior (from radial) interosseus nerves do stay in their own compartments (supply muscles) down to wrist; are again deep: neither reaches skin (see later for these).
Forearm nerves: 3 nerves; each pierces a muscle (median via PT and ulnar via FCU ¨ flexor compartment, radial via supinator ¨ extensor compartment).
- the posterior interosseus nerve supplies the extensor compartment
Brachial artery enters cubital fossa & branches 1/2way down it, 1cm distal to skin crease.
- radial branch appears to be the direct continuation; but ulnar is bigger
Passes laterally medial to biceps tendon ¨ crosses supinator, runs down on PT, FDS, FPL & PQ.
- then meets distal radius (exposed at this level to form A-V fistula)
- disappears posteriorly below tendons of ab pollicis longus and EPB to cross the snuffbox.
Is overlapped by brachioradialis (416) in upper forearm, radial n. runs lateral to it in middle 1/3 (442).
Passes between heads of PT and beneath arch of FDS ¨ lies on FDP with ulnar nerve on ulnar aspect. Runs down FDP to passes down over flexor retinaculum ¨ forms superficial palmar arch.
Surface marking: from medial to biceps tendon to radial side of pisiform (sl. convex medially).
- exposure possible at lower end: retract FCU and safeguard ulnar nerve (to ulnar side)
Main branch is common interosseous artery ¨ anterior & posterior interosseous branches;
- anterior runs deep b/n FDP and FPL, supplying each, gives perforators through interosseous membrane to deep extensor muscles, nutrient to ulnar and radius then pierces interosseous membrane at upper border of PQ.
- posterior disappears after passing back through interosseous space at upper membrane.
4 recurrent branches: radial recurrent, ant & post ulnar recurrent & recurrent interosseous arteries pass back around elbow.
4 collateral branches: radial and middle collaterals (of profunda brachii) and superior ulnar collateral & inferior ulnar collateral (of brachial) pass down from arm.
¨ these all anastomose in a ring around the elbow joint.
Radial & ulnar arteries ¨ palmar and dorsal carpal branches
¨ anastomose deep to long tendons.
- Palmar carpal arch sends branches into the hand to join the deep palmar arch; supplies carpal bones.
- Dorsal carpal arch sends dorsal metacarpal branches into hand; these branch to supply posterior fingers. (438). Anastomose b/n interosseous spaces with deep palmar arch and digital branches of superficial arch.
Deep veins accompany arteries by dual venae comitantes.
Most blood of the hand passes through to a superficial
venous network on the dorsum.
- radial side of dorsal venous arch ¨ cephalic vein beginning in snuffbox & running up lateral side of forearm ¨ passes lateral to biceps in arm ¨ deltopectoral groove.
- The cephalic initially runs in the superficial fascia along the preaxial limb border, then under the deep fascia in the deltopectoral groove ¨ pierces clavipectoral fascia ¨ axillary vein.
- ulnar side of dorsal venous arch ¨ basilic vein ¨ postaxial (medial) border ¨ pierces deep fascia halfway between elbow & axilla ¨ joins brachial to form axillary vein at lower border of teres minor
Median forearm vein drain wrist & forearm ¨ divides at elbow into median cephalic & median basilic veins; latter is larger since it is joined by a deep vein.
Median cubital vein may
drain from cephalic into basilic.
Superficial ¨ veins.
Ulnar aspect of hand & forearm ¨ first to supratrochlear nodes.
Radial aspect ¨ deltopectoral ¨ axillary nodes.
Deep ¨ arteries (¨ lateral group of axillary nodes).
Continuation of musculocutaneous.
Pierces deep fascia at elbow lateral to biceps tendon ¨ pre & post-axial borders of forearm to thenar.
From medial cord; pierces fascia again at elbow, in middle of arm.
- divides into ant and post nerves, supplies anterior / medial forearm.
- In the upper arm comes down between median and ulnar, branches over the common origin.
Minimal overlap across anterior axial line between these two cutaneous nerves.
= cutaneous continuation of main nerve under cover of brachioradialis.
- runs beside and lateral to radial artery in the middle forearm
Leaves flexor compartment by passing under brachioradialis tendon several cm above radial styloid
¨ 2-3 terminal branches palpable over EPL tendon (supplies radial 2/3 of dorsum of hand & proximal parts of dorsal surfaces of thumb and lateral 2-3 1/2 fingers)
Supplies PT then passes between its heads ¨ joins ulnar artery passing deep to fibrous arch of FDS (nerve superficial) ¨ passes distally attached to undersurface of FDS by loose fascia
- emerges between palmaris longus and FCR ¨ passes between flexor ret, to enter hand.
Surface marking: from midpoint of cubital fossa medial to brachial artery to ulnar side of FCR.
Anterior interosseous branch (given off deep to FDS) runs down with its namesake artery ¨ index & middle bellies of FDP, FPL and PQ (ie deep muscles).
Palmar branch to skin of thenar eminence runs above flexor retinaculum.
Passes between heads of FCU (most easily compressed against coronoid process)
¨ runs down under FCU with ulnar artery on radial aspect, on surface of FDP ¨ nerve and artery pass over flexor retinaculum into hand.
Before entering hand, gives dorsal branch (medially between tendon of FCU and ulnar ¨ dorsal hand.
Palmar cutaneous br. ¨ pierces deep fascia prox to flexor retinac & supplies hypothenar eminence.
-
branch to FCU is C7;
branch to FDP is C8,T1
Surface Marking:
along line from medial epicondyle humerus to radial side of pisiform.
Uniaxial synovial pivot between head of radius & annular ligament and radial notch of ulnar
- inner annular ligament lined by hyaline cartilage
- shares synovial membrane with elbow jt Ð its ligaments attach to annular
- Radial neck is intracapsular, supported below by quadrate ligament
Uniaxial synovial pivot between convex head of ulnar and concave ulnar notch of radius.
- triangular cartilaginous articular disc attaches by base to lower margin of ulnar notch of radius & by its apex to a fossa at the base of the ulnar styloid. (see 425 lower Ð lies across carpus.
- Synovial membrane projects proximally as recessus sacciformis posterior to PQ, and anterior to interosseous membrane.
Interosseous membrane connects radius and ulnar at an oblique angle
- oblique cord (see 409) = flat band running opposite to the membrane from radial to ulnar tubercles. The posterior interosseus vessels run through here.
Nerve: proximal shares elbow supply, distal = posterior & anterior interosseus nerves.
Movements: pronation, supination
- in pronation, radial head rotates in fibrous ring, while distal radius rotates in front of ulna head
- axis of movement of radius relative to ulna is through the radial head and ulnar styloid.
- Distal ulnar also moves slightly: posterolaterally in pronation, anteromedially in supination.
- Supination is more powerful, hence this is the way screws are designed (biceps & supinator)
- Pronation = quadratus and teres.
- 140o of the movement occurs at radioulnar jts, with 30o humeral / scapular movement, hence total ROM near 360.