Anatomy and Physical Examination of the Hand · 2 Hand, Elbow & Shoulder: Core Knowledge in...

$: Anatomy and Physical Examination of the Hand · 2 Hand, Elbow & Shoulder: Core Knowledge in Orthopaedics The Traumatized Hand Some fractures and dislocations are readily obvious because$
1

CH

APT

ER 1Anatomy and Physical

Examination of the HandJoseph A. Izzi, Jr.,* and Thomas E.Trumble†

*MD, St. Joseph’s Health Service of Rhode Island, North Providence, RI; Roger WilliamsMedical Center, Providence, RI; Former Fellow,The Hospital for Special Surgery,WeillMedical College of Cornell University, New York, NY†MD, Professor and Chief, Hand and Upper Extremity Surgery Service,Department of Orthopaedics, University of Washington School of Medicine, Seattle,WA

IntroductionGeneral Information

● The goal of any type of treatment of the hand is torestore function not only to the affected area but also tothe whole upper extremity.Whether obtained for theacutely traumatized hand or the smallest most chroniccondition, an accurate and complete history and physicalexamination are paramount to a successful outcome.

● The history should include information regarding thepatient’s age, occupation, hand dominance, andrecreational activities.Although all of these data areroutinely obtained in a standard orthopaedic history andphysical examination, there are several important aspects ofwhich the physician should be cognizant. For example, aninjury that could be detrimental to something as simple assmall finger abduction could severely compromise thecapabilities of someone who plays the piano.

● The patient’s past medical history is important.A history ofdiabetes mellitus can cause difficulties in the diagnosis of acompressive neuropathy and/or complicate wound healingin the surgical patient. One also must be aware ofconditions in the upper extremity that exist concomitantlywith the presenting problem. Does the patient with a handproblem have a prior history of shoulder or elbowproblems? Every examination of the hand should begin atthe shoulder, especially in patients who had long periods of

disuse or who protected the hand with a sling.The skin,nerves, tendons, muscles, bones, and joints should bethoroughly examined.The size of the muscles is indicativeof the amount of use of the hand, and the presence and/oramount of atrophy are indicative of a pathologic processes.

Nontraumatic Hand Conditions● A hand with a disability of gradual onset and without any

specific traumatic incident often presents a difficultdiagnostic problem. In the nontraumatized patient,determine the chief complaint. Is the primary problempain, stiffness, numbness, snapping, a painless mass, or acombination of these signs? When did the symptomsbegin, what makes them better and worse, and have theybeen progressive? Are there associated problems at night,such as pain or numbness, and do these problems cause thepatient to wake up or prevent sleep? Is the patient’sfunction worse in the morning and improve throughoutthe day, or is there a constant problem? Knowingunderlying medical conditions, such as gout, rheumatoidarthritis, or generalized osteoarthritis, can help in makingthe diagnosis and formulating a treatment strategy.Athorough history may reveal an unusual use of the handthat was a precipitating cause or the history of adegenerative process that reached a point where secondaryinjury occurred, as in an attritional tendon rupture.

2 Hand, Elbow & Shoulder: Core Knowledge in Orthopaedics

The Traumatized Hand● Some fractures and dislocations are readily obvious

because of gross deformity and swelling. One of the mostcommon pitfalls in treating hand injuries is overlookingthe damage to the soft tissue structures or an additionalinjury because of an obvious fracture or dislocation.Thehistory in acute injuries should include the time ofinjury, preliminary treatment by emergency medicaltechnicians or emergency department staff, medicationsgiven (especially tetanus and antibiotics if there are openwounds), mechanism of injury (crushing vs. sharp), settingof the injury (i.e., barnyard, kitchen), and whether theinjury was work related.

Physical Examination● Observation of the resting hand should precede any

physical examination. One should observe the attitude ofthe hand, posture of the digits, color of the skin, presenceof atrophy (particularly of the thenar, hypothenar, andfirst dorsal interosseous regions), calluses, swelling,bruising, vascularity of all the digits, and prior scars. Ifswelling is present, is the cause trauma, obstruction ofblood or lymphatic flow, a trophic condition resultingfrom injury to the nerves, vasomotor, or self-inflicted?The nails and nail folds should be inspected because theyoften show signs of undiagnosed systemic diseases,malnutrition, toxicity, and trauma.Additionally, anexamination of the unaffected hand is helpful prior to anexamination of the affected side.Always look for a secondor third coexisting condition that may not be the primarycomplaint. For example, patients with arthritis of thecarpometacarpal joint of the thumb can have coexistingcarpal tunnel syndrome and the associated sequelae.

Embryology and Development● Although it is beyond the scope of this chapter to go

into extensive detail about the embryology anddevelopment of the hand, there are several key periods ofdevelopment to keep in mind.The limb bud generallyforms during 4 weeks of gestation. By 33 days ofgestation, the hand forms into a paddle withoutindividual digits. Digital separation usually begins at7 weeks and progresses over the course of week 7.Thecondensation that will give rise to each of the bones ofthe hand also occurs at week 7.

● Ossification of the carpal bones begins at the capitateand proceeds in a clockwise direction. Ossification of thecapitate usually is present at age 1 year.The hamate isthe second carpal bone to ossify at approximately 1 to2 years, followed by the triquetrum at 3 years, the lunateat 4 to 5 years, the scaphoid at 5 years, the trapezium at6 years, the trapezoid at 7 years, and the pisiform at9 years.

Terminology● In true anatomic description, the palm is the anterior

surface of the hand; however, this descriptive term isseldom used.The hand and digits have a dorsal surface, apalmar or volar surface, and radial and ulnar borders.Thepalm is subdivided into the thenar, midpalmar, andhypothenar areas.The thenar mass or eminence is themuscular area overlying the palmar surface of the thumbmetacarpal.Atrophy of this muscle may be noted inpathologic conditions such as chronic carpal tunnelsyndrome.The hypothenar musculature is located overlyingthe small finger metacarpal.The digits are referred to as thethumb, index finger, long (middle) finger, ring finger, andsmall finger. Each finger possesses three joints: themetacarpophalangeal (MCP) joint, the proximalinterphalangeal (PIP) joint, and the distal interphalangeal(DIP) joint.The MCP joints of the fingers are located ata line drawn from the radial extent of the proximal palmarcrease to the ulnar extent of the distal palmar crease.This isimportant to bear in mind when placing a splint or castthat requires flexion of the MCP joints.The level of thefinger webs correlates to the middle third of the proximalphalanges.The thumb has an MCP joint and only oneinterphalangeal (IP) joint.The carpometacarpal (CMC) orbasal joint of the thumb is a unique structure in the handand is important for thumb mobility.

Motion● Active and passive measurements should be taken for

each motion of the entire upper extremity, and anydiscrepancies noted. Pronation and supination of theforearm are measured with the elbow firmly at the sideand at a right angle. In pathologic conditions, the amountof forearm rotation should be measured at the forearmbecause the radiocarpal joint may allow 10 to 20 degreesof motion without forearm rotation.Wrist motion ismeasured as degrees of dorsiflexion and palmar or volarflexion and radial or ulnar deviation. Ulnar deviation isdetermined by the angle between the midline of theforearm and the line from the center of the wrist to thethird metacarpal. Radial deviation should be measuredwith the hand in the plane of the forearm becauseabnormal values can be obtained as the wrist goes intodorsiflexion. Finger motion is measured in degrees ofmaximal extension and degrees of maximal flexion.Hyperextension is documented as a negative number forcalculations of total active motion (TAM) and totalpassive motion (TPM).

● Motion of the thumb has flexion and extension at theMCP and IP joints but becomes more complex whenmeasuring motion of the CMC joint.Thumb CMC jointmotions include palmar and radial abduction, opposition,and retropulsion (Figure 1–1).The thumb should beexamined through the full range of circumduction, from

CHAPTER 1 Anatomy and Physical Examination of the Hand 3

the back of the hand to opposition and to touch of thefifth metacarpal head. It also should be fully extended andfully flexed, and it should be able to make the OK signwith the index finger.Abduction of the thumb ismeasured by the angle between the first and secondmetacarpals with the thumb spread at right angles to thepalm. Opposition is a combination of flexion, adduction,and pronation.Thumb adduction can be measured as thedistance between the tip of the thumb and the head ofthe fifth metacarpal.

● By knowing the normal range of motion of these joints,one can quickly determine what the patient cannot doand where the disability may lie (Table 1–1). Examinationof the contralateral limb is particularly important if thepatient has hypermobility of the other joints.

Hand and Forearm AnatomySkin

● The skin on the volar aspect of the palm and fingers istough and thick and possesses no hair follicles (glabrous).It covers a layer of fat with many fibrous septa that holdthe skin firmly to the deeper tissues.The septa allowtraction when gripping but necessitate a system of creasesto prevent the skin from bunching as the hand is closed(Figure 1–2).The skin on the dorsal surface is thin, soft,and pliable, permitting motion of the joints. Because theveins are located dorsally, the dorsum of the hand is acommon site for edema, which can limit flexion.Theskin on the fingers is fixed to the bone by small ligamentsalong the radial and ulnar sides of the fingers.Theligaments dorsal to the neurovascular bundles are calledCleland’s ligaments and those volar to the neurovascularbundles are called Grayson’s ligaments.

Nail Bed and Fingertip● The nail bed complex, also called the perionychium,

consists of the paronychium and the nail bed itself(Figure 1–3). Proximally the nail fits into a depressioncalled the nail fold.The eponychium is the thinmembrane that extends onto the dorsum of the nail. Justdistal to the eponychium beneath the nail is the lunula, a

Figure 1–1:The biconcave surfaces of the thumb carpometacarpal jointallow thumb rotation, flexion/extension, and abduction/adduc-tion. MCI,Thumb metacarpal; Tz, trapezium. (From TrumbleTE, editor: Principles of hand surgery and therapy. Philadelphia,2000,WB Saunders Company.)

Table 1–1: Approximate Normal Ranges of Motion

Elbow Range of MotionActive range of motion

Flexion: 135+ degreesExtension: 0 to −5 degreesSupination: 90 degreesPronation: 90 degrees

Wrist Range of MotionActive range of motion

Flexion: 80 degreesExtension: 70 degreesUlnar deviation: 30 degreesRadial deviation: 20 degrees

Finger Range of MotionMetacarpophalangeal joint flexion and extension

Flexion: 90 degreesExtension: 30–45 degrees

Proximal interphalangeal joint flexion and extensionFlexion: 100 degreesExtension: 0 degrees

Distal interphalangeal joint flexion and extensionFlexion: 90 degreesExtension: 20 degrees

Finger abduction and adductionAbduction: 20 degreesAdduction: 0 degrees

Thumb abduction and adductionAbduction (palmar abduction): 70 degreesAdduction (dorsal adduction): 0 degrees

OpposingThumb toFinger

Flexion

Extension

PalmarAbduction

RadialAbduction

PA−Palmar Abduction

RA−Radial Abduction

R−Retropulsion

A−Adduction

O−Opposition

O

PA

RA

R

A

O

PA

RA

R

A

Tz

MC Ι

curved white opacity at the junction of the proximalgerminal and distal sterile matrixes on the nail floor.Bacterial infections (paronychia) of the nail mostcommonly involve the paronychium and can bediagnosed easily on physical examination.

● The fingertip is the area of the digit distal to the insertionof the flexor and extensor tendons on the distal phalanx.The tuft of the distal phalanx is covered by adipose tissueand highly innervated skin tethered to the distal phalanxby numerous fibrosepta.The tuft and the fibrosepta areimplicated in infections of the pulp of the distal phalanxcalled a felon.

Motor Units of the Hand and Wrist● Motion of the hand and wrist is facilitated through the

intrinsic and extrinsic motor units.The tendons andmuscles originating proximal to the wrist are extrinsicand those that originate within the hand are intrinsic.

Osseous Anatomy of the Hand and Wrist

● The radiocarpal joint is an ellipsoid joint composed of thedistal radius and its two articular facets for the scaphoidand lunate, respectively. Between the radius and the ulna isthe sigmoid notch of the radius, which allows an


DistalInterphalangeal(DIP) Crease

ProximalInterphalangeal(PIP) Crease

PalmarDigitalCrease

SmallFinger

Ulnar Border

Wrist Crease

RingFinger

LongFinger Index

Finger

DistalPhalanxSegment

MiddlePhalanxSegment

ProximalPhalanxSegment

Thumb

DistalPhalanxSegment

ProximalPhalanxSegment

Radial Border

Thena

rTh

enar

Cre

ase

Proximal Palmar C

rease

Distal Palmar Crease

Hypothenar

Figure 1–2:Surface anatomy of the palm. (From Trumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

Figure 1–3:Dorsal and lateral views of the finger with the anatomy of thenail and nail bed complex. (Courtesy of Jason R. Izzi, D.M.D.)

articulation with the distal ulna and 270 degrees ofrotation.The ulnar styloid is the attachment of thetriangular fibrocartilage complex. In the normal intactforearm with neutral ulnar variance and neutral rotation80% of the forces are transmitted through the distal radius(50% across the scaphoid fossa and 30% across the lunatefossa) and 20% through the distal ulna.These numberschange with wrist and forearm motion and ulnar variance.

Intercarpal Joints● The proximal carpal row is composed of the scaphoid,

lunate, and triquetrum.The pisiform is a sesamoid bonewithin the flexor carpi ulnaris (FCU) tendon thatarticulates with the triquetrum.This articulation canbecome a source of ulnar-sided wrist pain that is oftenoverlooked.The joints of the proximal row are primarilygliding joints.The scaphoid bone is the link between theproximal and distal rows and is the reason why pathologyoriginating from the scaphoid can cause problems withalmost all of the articulations in the wrist.The distalcarpal row is made up of the trapezium, trapezoid,capitate, and hamate.With the exception of thetrapezium, the bones of the distal carpal row are stronglyanchored by their attachments with the metacarpals.

Metacarpals and MetacarpophalangealJoints

● The MCP joints are condyloid joints and, unlike theIP joints, allow not only flexion and extension but alsoabduction and adduction of the proximal phalanx onthe metacarpal head.The collateral ligaments of the MCPjoints provide stability, where the volar plate preventshyperextension.All of the volar plates are connected bythe strong intermetacarpal ligaments, which help maintainlongitudinal and rotational alignment in the case of manymetacarpal fractures. Because of the camlike shape of themetacarpal head, the collateral ligaments are lax in extensionand taut in flexion.When the MCP joints are included ina cast, they should be flexed to maintain the length of theligaments, preventing permanent shortening and stiffness.

● Although index and long finger CMC joints are relativelyimmobile, there is 5 to 10 degrees of flexion at the ringfinger CMC joint and 15 to 20 degrees of flexion of thesmall finger CMC joint. Because of their articulationswith the distal hamate facets, the ring and small fingermetacarpals rotate toward the middle of the palm withflexion to enhance gripping. However, because of theshape of the articulations with the hamate, subluxationsand/or dislocations can occur easily in a fracture situationof the fourth and fifth metacarpal bases.

Phalanges and Interphalangeal Joints● The PIP and DIP joints are bicondylar ginglymus (hinge)

joints where the collateral ligaments and the volar plateallow only flexion and extension (Figure 1–4).

Metacarpophalangeal and Basal Jointsof the Thumb

● The thumb MCP joint is much more complex than theMCP joints of the other digits. Its complexity iscompounded by the presence of the sesamoid bones andthe thenar musculature.At the ulnar side, a collateralligament injury can become “complex” if the adductoraponeurosis becomes interposed between the tornligament and its bony insertion.This forms a “Stenerlesion,” where the avulsed ligament end cannot heal backto the bone, requiring operative reduction and fixation.

● The basal joint or CMC joint of the thumb is a complexstructure, which allows 360 degrees of motion.Thethumb metacarpal articulates with the trapezium onbiconcave saddle-shaped joints and the trapeziumarticulates with the scaphoid, trapezoid, and the radialfacet of the index finger (see Figure 1–1).This joint issupported by the capsule and the radial, volar, and dorsalCMC ligaments. Perhaps one of the more importantligaments of the basal joint is the volar oblique or “beak”ligament, named for its attachment to the articular marginof the ulnar side of the metacarpal beak. Its origin is thepalmar tubercle of the trapezium.The volar obliqueligament is implicated in pathologic conditions of theCMC joint, such as osteoarthritis.


Figure 1–4:Anatomy of the palmar plate of the proximal interphalangealjoint. (From Trumble TE, editor: Principles of hand surgery andtherapy. Philadelphia, 2000,WB Saunders Company.)

Ligaments of the Wrist● The ligaments of the wrist are divided into three groups:

the volar radiocarpal, the interosseous, and the dorsalintercapsular, although there is much diversity in thenomenclature of these ligaments.The volar wristligaments provide the majority of stability of theradiocarpal joint and maintenance of position of theindividual carpal bones.1 Although there are numerousintercarpal ligaments, the two most important are thescapholunate (SL) interosseous ligament and thelunotriquetral (LT) interosseous ligaments.Tearing of theSL interosseous ligament is implicated in the formation ofdorsal intercalated segment instability (DISI), where theSL angle on the lateral radiograph is greater than 60degrees. Usually, there is also an associated disruption ofthe volar radiocarpal ligament.Volar intercalated segmentinstability (VISI) usually results as a disruption of the LTinterosseous ligament and the dorsal radiocarpal (DRC)and ulnocapitate (UC) ligaments. In DISI the lunateassumes an extended posture, whereas in VISI the lunateassumes a flexed posture.

● The volar radiocarpal ligaments include theradioscaphocapitate (RSC), long and short radiolunate(LRL and SRL), radioscapholunate (RSL) (ligament ofTestut), ulnotriquetral (UT), UC, and ulnolunate (UL)(Figure 1–5).With some exceptions, most of theseligaments can be visualized during wrist arthroscopy.These ligaments are arranged in a double chevron patternthat allows them to adjust the carpal rotation and theulnar and radial heights of the carpus during ulnar andradial deviation. Between the RSC and LRL ligamentsis an area of potential weakness over the capitate-lunate articulation known as the space of Poirier, wherethe capitate can dislocate during a perilunate dislocation.

● The dorsal intercarpal (DIC) and DRC ligaments areimportant thickenings in the dorsal joint capsule (Figure1–6).These structures provide important stabilization ofthe carpal bones.The DRC originates from the dorsalmargin of the distal radius, and its radial fibers attach atthe lunate and LT interosseous ligament before insertingon the dorsal tubercle of the triquetrum.2 The DICoriginates from the triquetrum and attaches onto thelunate before inserting into the dorsal groove of thescaphoid with extension of the insertion to thetrapezium. Because of the importance of these ligaments,some authors recommend a ligament-sparing techniquewhen performing a dorsal capsulotomy.

Fibroosseous Tunnels of the Wrist● On the palmar side of the wrist, the carpal tunnel and the

Guyon’s canal allow the tendons, nerves, and arteries toenter the hand.The bony pillars of the carpal tunnel aremade up of the bony ridges of the trapezium and thescaphoid on the radial side and the hook of the hamateand the pisiform on the ulnar side.The roof of the carpaltunnel is the transverse carpal ligament.The contents ofthe carpal tunnel include the eight extrinsic flexortendons to the fingers, the flexor pollicis longus (FPL),and the median nerve.The Guyon’s canal is located ulnarto the carpal tunnel and contains the ulnar nerve andartery (Figure 1–7).The bony boundaries of the Guyon’scanal are the pisiform and the hook of the hamate.Thevolar carpal ligament forms the roof of Guyon’s canal.

Innervation● The sensation on the palmar aspect of the hand is provided

by the median and ulnar nerves. On the dorsal aspect ofthe hand, the radial and ulnar nerves provide sensation.Theulnar nerve is the major motor innervation to the intrinsic


Figure 1–5:Palmar extraarticular wrist ligaments. C, Capitate;H, Hamate; L, Lunate; P, Pisiform; R, Radius;S, Scaphoid; Tp, Trapezoid; Tz, Trapezium;U, Ulna. (From Trumble TE, editor: Principles ofhand surgery and therapy. Philadelphia, 2000,WBSaunders Company.)

musculature of the hand, except for the muscles suppliedby the motor branch of the median nerve.

Extrinsic Tendons of the Wrist● On the dorsal aspect of the wrist are six discrete

compartments for the extrinsic extensor tendons(Figure 1–8).The compartments prevent bowstringingand provide reliable landmarks for surgical approaches.Additionally, each compartment can have its own uniquepathologic process. On the volar aspect of the wrist, thetendons are not arranged as discretely.

Anatomy of the Extrinsic ExtensorTendons

● Knowledge of the surface anatomy and location of theextensor tendons is crucial for understanding pathologicconditions of the tendons themselves. In addition, theextensor tendon compartments are important intervals foropen surgical approaches to the wrist and forearm andfor placement of arthroscopy portals.

First Dorsal Compartment● The first dorsal compartment contains the abductor

pollicis longus (APL) and the extensor pollicis brevis(EPB) tendons.These tendons represent the radial borderof the anatomic snuffbox.As the thumb is brought intoradial abduction, the individual tendons can be palpatedas they exit distal to the retinaculum.Toward the insertionof these tendons on the thumb metacarpal, the EPB lieson the ulnar side of the APL.The APL can possess two tofive separate tendon slips. In up to 60% of the population,there is a separate subcompartment for the EPB or one ofthe slips of the APL. If all of the compartments are notreleased during surgery for tenosynovitis, surgical failuremay result.Tenosynovitis of the wrist is most commonlyseen at the first dorsal compartment and is referred to asde Quervain’s disease.The provocative maneuver fordiagnosis of de Quervain’s disease is the Finkelstein test.The Finkelstein test is performed by tucking the patient’sthumb inside the closed fingers of a fist (Figure 1–9).Thewrist then is brought into ulnar deviation as the forearmis stabilized. Sharp pain in the area of the first dorsalcompartment is strong evidence for de Quervain’s disease.

● Pathologic Condition—de Quervain’s disease

Second Dorsal Compartment● The second dorsal compartment is located on the radial

side of the Lister’s tubercle and contains the extensorcarpi radialis longus (ECRL) and the extensor carpiradialis brevis (ECRB).The ECRL inserts on the baseof the second metacarpal, and the ECRB inserts on thebase of the third metacarpal.To examine the tendons,ask the patient to make a clenched fist.The tendons willbe palpable on the radial side of the Lister’s tubercle(Figure 1–10).The two tendons are powerful wrist


Figure 1–6:Diagrammatic representation of the extraarticular dorsal wristligaments. C, Capitate; H, Hamate; L, Lunate; R, Radius; S,Scaphoid; Tp, Trapezoid; Tz, Trapezium; U, Ulna. (FromTrumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

Figure 1–7:Schematic representation of the Guyon’s canal and itscontents. FCU, Flexor carpi ulnaris. (Courtesy of Jason R.Izzi, D.M.D.)


extensors that also cause radial deviation because oftheir insertions on the radial aspects of the metacarpalbases. However, the ECRB remains the primary locationfor transfer of a tendon to provide wrist extensionbecause of its more central location causing less radialdeviation. Intersection syndrome is tenosynovitis of thesecond dorsal compartment. Symptoms of intersectionsyndrome are pain and swelling where the APL andEPB tendons cross the ECRL and the ECRB,approximately 4 cm proximal to the wrist joint.

● Pathologic Condition—Intersection syndrome

Third Dorsal Compartment● The third dorsal compartment contains the extensor

pollicis longus tendon (EPL) (Figure 1–11).The EPLtendon defines the ulnar border of the anatomic snuffbox.

Figure 1–8:The six dorsal compartments ofthe extensor tendons. APL,Abductor pollicis longus; ECRB,extensor carpi radialis brevis;ECRL, extensor carpi radialislongus; ECU, extensor carpiulnaris; EDC, extensor digitorumcommunis; EDM, extensor digitiminimi; EIP, extensor indicis pro-prius; EPB, extensor pollicis bre-vis; EPL, extensor pollicis longus;MC, metacarpal. (From TrumbleTE, editor: Principles of hand sur-gery and therapy. Philadelphia,2000,WB Saunders Company.)

Figure 1–9:Clinical photograph of the Finkelstein’s test.

At Lister’s tubercle, the EPL tendon takes a 45-degreeturn before attaching on the base of the distal phalanx ofthe thumb. Placing the patient’s hand flat on a table andthen asking the patient to lift only the thumb can allowevaluation of the EPL tendon. Pain and crepitus over theEPL tendon, especially at the Lister’s tubercle, canrepresent impending rupture of the tendon, especiallyafter a fracture of the distal radius.Another cause ofattritional rupture of the EPL tendon is rheumatoidarthritis.

● Pathologic Condition—Attritional tendon rupture

Fourth Dorsal Compartment● The fourth dorsal compartment contains the extensor

digitorum communis (EDC) and the extensor indicisproprius (EIP).The EDC inserts on the extensor hoodsof all four fingers, and the EIP inserts on the ulnaraspect of the extensor tendon to the index.The ulnarlocation of the EIP is important for identifying thetendon for transfers. Additionally, the EIP allows fullindependent extension of the index finger, whereas theEDC provides combined extension of all four fingers(Figure 1–12).The juncturae tendineae are links that

typically occur between the extensor of the middlefinger and the index and ring finger. For 80% of thepopulation, the EDC of the small finger consists of onlya slip of junctura from the ring finger.The EDC causesMCP joint extension and can be evaluated by asking thepatient to extend the fingers.The EIP can be tested byasking the patient to extend the index finger whilemaking a fist. Except in cases of rheumatoid arthritis,primary symptomatic tenosynovitis of the fourthcompartment is rare.

● Pathologic Condition—Rheumatoid synovitis

Fifth Dorsal Compartment● The fifth dorsal compartment contains the extensor digiti

minimi (EDM) or extensor digiti quinti (EDQ) tendonand overlies the dorsal radioulnar articulation.The EDQtendon attaches to the extensor hood on the ulnar side ofEDC.The EDQ, similar to the EIP, allows independentextension of the small finger. Because of its location nearthe radioulnar joint, the tendon can become involved


Figure 1–10:The extensor carpi radialis longus (ECRL) and extensor carpiradialis brevis (ECRB) extend and radially deviate the wrist.(From Trumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

Figure 1–11:The extensor pollicis longus (EPL) tendon extends the inter-phalangeal joint of the thumb and brings the thumb out ofthe plane of the palm. (From Trumble TE, editor: Principles ofhand surgery and therapy. Philadelphia, 2000,WB SaundersCompany.)

Figure 1–12:The fourth dorsal compartment consists of the extensor digi-torum communis (EDC) and the extensor indicis proprius(EIP).The fifth compartment contains the extensor digiti min-imi.The tendons provide metacarpophalangeal joint extensionand extension of the proximal interphalangeal and distal inter-phalangeal joints in conjunction with the intrinsic muscles.The EIP and extensor digiti minimi provide independentextension of the index and small finger. EDQ, Extensor digitiquinti. (From Trumble TE, editor: Principles of hand surgery andtherapy. Philadelphia, 2000,WB Saunders Company.)

from rheumatoid arthritis of the joint or can rupturebecause of attritional wear resulting from a dorsallydislocated ulnar head.

● Pathologic Condition—Rheumatoid synovitis, attritionalrupture

Sixth Dorsal Compartment● The sixth dorsal compartment contains the extensor carpi

ulnaris (ECU), which lies in a groove between the ulnarstyloid process and the ulnar head.With the wristextended and ulnarly deviated, the ECU tendon can bepalpated before its insertion onto the ulnar side of thefifth metacarpal base.A traumatic event can rupture thedorsal carpal ligament, which normally preventssubluxation of the tendon during pronation. Subluxationof the tendon usually is accompanied by pain and anaudible snap. Patients with rheumatoid arthritis cansimilarly have displacement of the tendon or evenrupture.

● Pathologic Condition—Posttraumatic dislocation, attritionalrupture in rheumatoid patients

Anatomy of the Extrinsic FlexorTendons

Wrist Flexor Tendons● The two major extrinsic flexor tendons of the wrist are

the flexor carpi radialis (FCR) and the FCU.To examinethe FCR, wrist flexion and radial deviation make thetendon prominent, as it lies radial to the palmarislongus tendon.The FCR (innervated by the mediannerve) originates at the medial epicondyle and crosses thescaphoid before inserting distally on the base of thesecond metacarpal and trapezium. Localized tenosynovitisof the FCR at the wrist level can become severe,necessitating release of the distal extent of the tendonfrom its sheath.The FCU lies ulnar to the palmarislongus and can be palpated when the wrist is flexedagainst resistance.The FCU (innervated by the ulnarnerve) also originates from the medial epicondyle andencloses the pisiform at its insertion. Occasionally, theinsertion of the FCU can be the site of severe pain whencalcific deposits form.

● The palmaris longus tendon bisects the volar aspect ofthe wrist.The palmaris tendon also originates from themedial epicondyle and inserts distally on the palmarfascia.The palmaris longus is one of the mostcommonly used tendons for a variety of upperextremity reconstructions. However, it is crucial toexamine for the presence of a palmaris longus tendonprior to surgery because this tendon is absent in 7% to20% of the population.To examine for the presence ofa palmaris longus tendon, the patient should flex thewrist and oppose the tips of the thumb and smallfinger.

Digital Flexor Tendons● The flexor digitorum superficialis (FDS) and the flexor

digitorum profundus (FDP) are the major extrinsicflexors of the digits, as the fingers themselves do notpossess any muscle bellies.The FDS originates from themedial epicondyle and the radial shaft and inserts on theon the palmar middle phalanx to produce flexion of thePIP joint. Proximal to the insertion onto the middlephalanx, the FDS divides into two slips to form Camper’schiasma (Figure 1–13).Anatomically, Camper’s chiasma isa long area located over most of the proximal phalanxand is not just a discrete point.The FDP tendon passesbetween these two slips before attaching on the distalphalanx.As the FDS tendons pass through the carpaltunnel, they are organized in two reproducible layers.TheFDSs to the ring and middle fingers are always locatedpalmar to the FDS of the index and small fingers.Thisanatomic relationship is of particular importance whenperforming flexor tendon repairs located at this level.A commonly taught way of remembering thisrelationship is that “34” in reference to the third andfourth digits is greater than “25” corresponding to thesecond and fifth digits (Figure 1–14). Each muscle of theFDS can function independently. However, absence of theFDS to small finger, seen in up to 30% of the population,prevents isolated flexion of the PIP joint of the smallfinger. Because the FDP shares a common muscle belly,only the FDS can cause active flexion of the middle, ring,and small fingers while the adjacent digits are held inextension (Figure 1–15).

● The FDP originates from the ulna and inserts on thedistal phalanx, promoting flexion of the DIP joint. Incontrast to the FDS, the FDP possesses only a singlemuscle to the long, ring, and small fingers, which preventsindependent flexion.The index finger FDP usually hasindependent function.To test for FDP function, the PIPjoint should be held in extension while active flexion ofthe DIP joint is attempted (Figure 1–16).


Figure 1–13:The flexor digitorum profundus (FDP) passes through theCamper’s chiasma.The vincula provide the blood supply tothe flexor tendons. FDS, Flexor digitorum superficialis. (FromTrumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

FDS

Proximal Distal

FDP FDSCamper's Chiasma

● The FPL originates from the volar surface of the radiusand inserts into the base of the distal phalanx of thethumb, allowing for IP joint flexion (Figure 1–17).Between the FPL and the pronator quadratus at the levelof the distal radius is the space of Parona.This is the areawhere infection can spread from the thumb flexor tendonsheath to the small finger, causing a horseshoe abscess.

Flexor Tendon Sheath● At the level of the MCP joints, the digital flexors enter a

fibroosseous tunnel also referred to as the flexor tendonsheath.The flexor tendon sheath keeps the flexor tendonsclose to bone, improving the biomechanics of digitalflexion and preventing the tendons from bowstringing.The tendon sheath is composed of annular (A) and


Figure 1–14:The median nerve, all the digital flexor tendons, and the flexor pollicis longus (FPL) pass through the carpaltunnel. FCR, Flexor carpi radialis; FCU, flexor carpi ulnaris; FDP, flexor digitorum profundus; FDS, flexor dig-itorum superficialis. (From Trumble TE, editor: Principles of hand surgery and therapy. Philadelphia, 2000,WBSaunders Company.)

Flexor Retinaculum

Transverse Carpal Ligament

Palmaris Longus

Median Nerve

Flexor Carpi Ulnaris

Flexor Digitorum Superficialis

Ulnar Artery

Ulnar Nerve

FDS

Ulnar Artery

FCU

Pisiform

Triquetrum

Ulnar NerveFDP

FPL

Radial Artery

FCR

Palmaris Longus Median Nerve

Hamate

Capitate

Trapezium

Trapezoid

Flexor Digitorum Profundus

Flexor Pollicis Longus

Radial Artery

Flexor Carpi Radialis

cruciate (C) pulleys.There are five annular pulleys:A1 toA5 (Figure 1–18).The two most important of the fiveannular pulleys are A2 and A4, which are located over theproximal and middles phalanges, respectively. Injury tothese pulleys are responsible for bowstringing of theflexor tendons.The A1 pulley is frequently implicated inthe pathology of flexor tendon stenosing tenosynovitis ortrigger finger. Except in the case of rheumatoid arthritis,the A1 pulley can be released with little biomechanicalcompromise. In addition to the annular pulleys are threecruciate pulleys: C1 to C3, which are collapsible pulleysthat allow finger flexion without impingement of theadjacent pulleys.

Anatomy of the Extensor Hood andthe Intrinsic Muscles of the HandExtensor Hood Mechanism

● The extensor mechanism of the finger is much morecomplex than the flexor mechanism.The extensor hoodmechanism is where the extrinsic tendons and intrinsictendons merge to control PIP and MCP motion (Figures1–19 and 1–20).3 For each digit, the extensor hood hasattachments from the interosseous muscles and alumbrical muscle.These intrinsic muscles make up thelateral bands, which join distally and insert at the distalphalanx to allow DIP joint extension. Spanning betweenthe two conjoined lateral bands is the triangular ligament,which prevents their volar subluxation.Also stabilizingthe lateral bands is the transverse retinacular ligament(located at the level of the PIP joint), which preventsdorsal subluxation.The central slip is the part of theextensor tendon that inserts on the base of the middlephalanx, allowing PIP joint extension.

● Swan-neck deformity is characterized by hyperextensionof the PIP joint and flexion of the DIP joint. Commoncauses of swan-neck deformity include rheumatoidarthritis, mallet finger, laceration of the FDS, and intrinsiccontracture. Except in the case of mallet finger (wherethe terminal extensor tendon is disrupted), thepathophysiology of swan-neck deformity arises from


Figure 1–16:Testing of the flexor digitorum profundus (FDP) is performedby blocking the proximal interphalangeal joint in full exten-sion. (From Trumble TE, editor: Principles of hand surgery andtherapy. Philadelphia, 2000,WB Saunders Company.)

Figure 1–15:Testing the flexor digitorum sublimus (FDS) is performed byasking the patient to flex the digits while holding the adjacentdigits in extension to block the action of the flexor digitorumprofundus. (From Trumble TE, editor: Principles of hand surgeryand therapy. Philadelphia, 2000,WB Saunders Company.)

Figure 1–17:Testing of the flexor pollicis longus (FPL) is performed byblocking the metacarpophalangeal joint in extension. (FromTrumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)


Figure 1–18:The flexor tendon sheath is composed of annularpulleys and cruciate pulleys. (From Trumble TE,editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

TransverseRetinacularLigament

Extensor toMiddle Phlanx

Lateral ConjoinedBand of Extensor

Oblique RetinacularLigament (ORL)

TerminalTendon ofExtensor

Flexor ProfundusTermination

A5 C3 C2 C1A4 A2 A1A3

FlexorProfundus

Flexor Pulleys

FlexorSuperficialis

LumbricalMuscle

InterosseousMuscle

Lateral Tendon ofDeep Head of DorsalInterosseous Muscle

Sagittal Band

Transverse Fibers

Oblique Fibers

Figure 1–19:Lateral view of digital exten-sor tendons and intrinsics.(From Trumble TE, editor:Principles of hand surgery andtherapy. Philadelphia, 2000,WB Saunders Company.)

Central SlipSagittal Band

Extrinsic Contribution

LateralConjoinedTendon

Dorsal View

Terminal Tendon

TriangularLigament

Dorsal View

Intrinsic Contribution

Oblique Fibersof DorsalAponeurosis Transverse

Fibers of DorsalAponeurosis

Lumbrical Muscleand Tendon

Dorsal and GalmarInterosseous Tendons

Extensor

Figure 1–20:Dorsal view of the digital extensor tendon andintrinsics. (From Trumble TE, editor: Principles ofhand surgery and therapy. Philadelphia, 2000,WBSaunders Company.)

stretching of the transverse retinacular ligaments, whichallows the lateral bands to sublux dorsal to the axis of thePIP joint.When combined with laxity of the volar plate,hyperextension of the PIP joint and subsequent swan-neck deformity occur.

● Boutonnière deformity is the opposite posture of swan-neck deformity, exhibiting PIP flexion and DIPextension. Rheumatoid arthritis, laceration, or traumaticinjury can cause a problem with central slip andsubsequent volar subluxation (in contrast to the dorsalsubluxation seen in swan-neck deformity) of the lateralbands as a result of incompetence or injury to thetriangular ligament.As the lateral bands translate in apalmar direction, they become a flexor at the PIP jointand an extensor at the DIP joint.

● The sagittal band is the most proximal portion of theextensor hood and centralizes the extensor mechanismover the metacarpal head. It is a unique structure in thatit encircles the proximal phalanx and attaches to theflexor tendon sheath, which allows extension of theproximal phalanx on the metacarpal head. MCP jointflexion and extension is a complex motion because thereare no attachments of either flexor or extensor tendons atthe proximal phalanx. Primary extension of the MCPjoint is accomplished when the extensor tendon pulls onthe sagittal bands, lifting the proximal phalanx frombelow (Figures 1–21 and 1–22). Located distal to thesagittal band are the transverse and oblique bands of thedorsal hood (see Figure 1–20).

Intrinsic Muscles● The intrinsic muscles assist with MCP joint flexion via

their attachments to the extensor mechanism.Thelumbrical muscles cross the MCP joint palmar to its axisand dorsal to the axis of the PIP joint before attaching onthe middle phalanx.This line of force allows the intrinsicmuscles to cause MCP joint flexion and PIP jointextension.

● There are four dorsal interosseous muscles and threepalmar interossei (Figure 1–23).The dorsal interossei areresponsible for abduction of the digits.The insertions ofthe dorsal interossei are on both the radial and ulnar sidesof the index, long, and ring fingers.The palmar interosseiadduct the index, ring, and small fingers.A way toremember the function of the interossei are the wordsDAB and PAD, which represent dorsal-abduction andpalmar-adduction, respectively.

● The lumbrical muscles originate on each of the FDPtendons and insert on the radial lateral band of theextensor expansion.The lumbrical muscle is the onlymuscle in the body that originates and inserts on atendon (Figure 1–24).Another unique attribute of thelumbrical muscle is its ability to relax its own antagonist,the FDP. Innervation of the lumbrical muscles is the ulnarnerve for the ulnar two lumbricals and the median nervefor the radial two lumbricals.

● The intrinsic tightness test is used to examine forcontracture of the intrinsic muscles.4 To perform theintrinsic tightness test, the amount of passive PIP jointflexion is tested with the MCP joints held in extension.Next, the MCP joints are flexed (relaxing the intrinsicmuscles) and amount of passive PIP flexion reevaluated.Theintrinsic tightness test is positive when there is less passivePIP flexion when the MCP joint is extended (Figure1–25). Clinically, intrinsic tightness hampers the grasp oflarge objects, in contrast to extrinsic tightness, whichprevents closure of the fist and the grasp of small objects.


Figure 1–22:The transverse band of the extensor mechanism provides forflexion of the metacarpophalangeal joint. (From Trumble TE,editor: Principles of hand surgery and therapy. Philadelphia, 2000,WB Saunders Company.)

Figure 1–21:Sagittal bands of the extensor mechanism provide for exten-sion of the metacarpophalangeal joint. FDP, Flexor digitorumprofundus; FDS, flexor digitorum superficialis. (From TrumbleTE, editor: Principles of hand surgery and therapy. Philadelphia,2000,WB Saunders Company.)

Oblique Retinacular Ligament(of Landsmeer)

● The oblique retinacular ligament (ORL) links the PIPjoint and DIP joint extension. Its line of force is analogousto the intrinsic muscles but is applied more distally in thefinger.The ORL originates from the periosteum of theproximal phalanx and the A1 and C1 pulleys and insertson the terminal tendon.With extension of the PIP joint,the ORL, which is palmar at this level, tightens.Thistension is transmitted distally, pulling on the terminaltendon as the ORL travels dorsally at the level of the DIP

joint.The ORL becomes contracted in chronicboutonnière deformity. Because of the ORL, Fowlerterminal tendon tenotomy can be performed to correctthis deformity, with preservation of DIP extension.

Thenar Muscles● The muscles of the thenar eminence are the abductor

pollicis brevis (APB), flexor pollicis brevis (FPB),opponens pollicis, and adductor pollicis. Muscles located


Fourth DorsalInterosseous

Third DorsalInterosseous

Second DorsalInterosseous

First DorsalInterosseous

First PalmarInterosseous

Second PalmarInterosseous

Third PalmarInterosseous

AdductorPollicis

Figure 1–23:Four dorsal interossei provide abduction and threevolar interossei provide adduction of the fingers.(From Trumble TE, editor: Principles of hand surgeryand therapy. Philadelphia, 2000,WB SaundersCompany.)

Figure 1–24:The lumbrical muscles function to flex the metacarpopha-langeal joint and extend the proximal interphalangeal joint.(From Trumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

Figure 1–25:When the intrinsic tightness test is positive, the proximalinterphalangeal joint has less passive flexion with meta-carpophalangeal extension because the contracted intrinsicmuscles are under greater stretch. (From Trumble TE, editor:Principles of hand surgery and therapy. Philadelphia, 2000,WB Saunders Company.)

on the radial side of the FPL are innervated by themedian nerve; muscles on the ulnar side are innervated bythe ulnar nerve (Figure 1–26).The APB (innervated bythe median nerve) originates from the transverse carpalligament and the trapezium and inserts on the radialaspect of the proximal phalanx.Thumb flexion,pronation, and palmar abduction all are caused by actionof the APB.The FPB originates from the transverse carpalligament and trapezium and inserts on the radialsesamoid.There is a dual innervation of the FPB: themedian nerve innervates the superficial head and theulnar nerve innervates the deep head.The APB and FPBobtain opposition and thumb rotation by a combinationof action. Located deep to the APB and FPB is theopponens pollicis brevis (OPB). It also arises from thetransverse carpal ligament and inserts on the radial aspectof the thumb metacarpal, causing flexion of the thumbmetacarpal at the CMC joint.The adductor pollicis(innervated by the ulnar nerve) originates from the thirdmetacarpal and capitate and inserts onto both sesamoids,providing major strength during pinch.

Hypothenar Muscles● All of the hypothenar muscles are innervated by the ulnar

nerve.These muscles are the abductor digiti quinti(ADQ), flexor digiti quinti (FDQ), and opponens digitiquinti (ODQ).The ADQ originates on the pisiform andinserts on the ulnar aspect of the proximal phalanx of thesmall finger, providing for abduction of the small finger(see Figure 1–26).The FDQ originates on the hook ofthe hamate and inserts on the palmar base of the smallfinger proximal phalanx, causing flexion at the smallfinger CMC joint.The ODQ is deep to the ADQ andFDQ, originates from the hamate, and inserts on the fifthmetacarpal.

Innervation of the Hand● Although it is beyond the scope of this chapter to

describe the brachial plexus in its entirety, understandingthe contributions of the cervical spine to each nerveof the hand is crucial. Sensation and motor innervation in


AdductorPollicis

FPB

APB

Opponens Pollicis

Median Nerve with Motor Branch

Transverse Carpal Ligament

Radial Artery

FCR

FPL

FDS

Ulnar Artey

Ulnar Nerve

Paimar LongusTendon

FCU

FlexorDigitiMinimi

AbductorDigitiMinimi

SuperficialPalmarArch

Palmar Aponeurosiswith Palimar LongusTendon

Lumbricals Figure 1–26:The muscles of the thenar emi-nence include the abductorpollicis brevis (APB), flexorpollicis brevis (FPB), opponens,and adductor pollicis. FCR,Flexor carpi radialis; FCU,flexor carpi ulnaris; FDS, flexordigitorum superficialis; FPL,flexor pollicis longus. (FromTrumble TE, editor: Principles ofhand surgery and therapy.Philadelphia, 2000,WBSaunders Company.)

the hand are mediated through the median, radial, andulnar nerves and their branches.When assessing an injuryto one or more of the nerves of the hand, key aspects ofthe physical examination are indicative of the area ofinjury (Table 1–2).

Radial Nerve● The radial nerve originates from the posterior cord of the

brachial plexus (receiving innervation from C5 throughT1) and then spirals distally from medial to lateral beforeemerging between the brachialis and brachioradialisanterior to the lateral epicondyle. Proximal to the elbowthe nerve innervates, in order, the anconeus,brachioradialis, and ECRL, before dividing into itsposterior interosseous and sensory branch.The radialsensory nerve proceeds distally deep to the brachioradialisuntil approximately 4 cm proximal to the tip of the radialstyloid, where the nerve becomes superficial and passesbetween the ECRL and the brachioradialis.At this level,the nerve can be injured during placement of an externalfixator.As the sensory nerve proceeds distally, it providesfor sensation on the dorsum of the thumb and dorsalradial web space (Figures 1–27 and 1–28).At the radialaspect of the wrist, the superficial branch of the radialsensory nerve and the lateral antebrachial cutaneousnerve (the terminal branch of the musculocutaneousnerve) overlap the same sensory territories in 75% of thepopulation. Because of this overlap, treatment of injury orneuroma at this level is fraught with mediocre results.

● After branching from the radial nerve, the posteriorinterosseous nerve (PIN) dives deep to the fascia of theproximal edge of the supinator (also known as the arcadeof Froshe), one of the potential sites of compression inradial tunnel syndrome.The PIN innervates thesupinator at this level and then all of the extensormuscles of the forearm (see Table 1–3 for the order ofinnervation).


Table 1–2: Physical Examination Points Indicativeof Nerve Injury5

Sensory ExaminationRadial nerve: Dorsal radial hand near the first web spaceMedian nerve: Pulp of the thumb and index fingerUlnar nerve: Pulp of the small finger

Motor ExaminationMedian nerve

Intrinsic: Thumb palmar abductionExtrinsic: All flexor digitorum superficialis tendonsFlexor digitorum profundus to indexFlexor pollicis longusFlexor carpi radialis

Ulnar nerveIntrinsic: Hypothenar muscles, first dorsal interosseous (FDIO)Extrinsic: Flexor digitorum profundus to the small fingerFlexor carpi ulnaris

Radial nerveExtrinsic: Wrist extensionFinger extension at the metacarpophalangeal jointThumb extension

Radial Median Ulnar

PalmarBranches

PalmarDigitalBranches

Ulnar NervePalmar DigitalBranches

Median NerveProper PaimarDigital Branches Ulnar Nerve

ProperPalmarDigitalBranches

DorsalBranchand DorsalDigitalBranches

SuperficialBranch

PosteriorAntebrachialCutaneousNerve

Radial Nerve

Figure 1–27:Sensory patterns of the median ulnar andradial nerves for the palm (left view) and dor-sum (right view) of the hand. (From TrumbleTE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

Median Nerve● The median nerve originates from both the medial and

lateral cords of the brachial plexus (receiving fibers fromC6, C7, C8, and T1 and sometimes C5) and travels withthe brachial artery before entering the forearm medial tothe biceps tendon.The nerve then passes between the twoheads of the pronator teres.At the level of the pronatorteres, the median nerve gives off its anterior interosseousnerve (AIN) branch, providing innervation to the FDPmuscle of the index and middle fingers, the FPL, andpronator quadratus.To test for function of the AIN, askthe patient to make the “OK” sign with the index fingerand thumb. Because of the location of the AIN in thedeep flexor compartment of the forearm, the AIN canbecome injured in compartment syndrome and/orfractures of the forearm or elbow. In the volar forearm, allof the forearm flexor muscles are innervated by the

median nerve, except for the FDP to the ring and smallfingers and the FCU, which are innervated by the ulnarnerve.The nerve continues distally between the FDS andFDP (innervating the entire FDS).Approximately 5 cmproximal to the wrist flexion crease, the palmar cutaneousbranch splits off of the radial side of the nerve and runsbetween the palmaris longus and the FCR, innervatingthe skin at the base of the thenar eminence.

● Beneath the transverse carpal ligament, the median nerveenters the hand and gives off its motor branch from theradial side.The motor branch provides innervation to theAPB, opponens pollicis, and superficial head of the FPB.There are three variations of the motor branch.The mostcommon (occurring in approximately 50% of thepopulation) is the extraligamentous and recurrent, wherethe motor branch comes off of the median nerve distal tothe transverse carpal ligament before innervating the thenarmusculature. In 30% of the population the nerve branchesbeneath the transverse carpal ligament (subligamentous),and in 20% the nerve is transligamentous, piercingtransverse carpal ligament after branching below.Toexamine the motor branch of the median nerve, ask thepatient to oppose the thumb to the small finger while theAPB muscle is palpated for contraction.

● The median nerve provides sensation to the palmaraspects of the radial 31⁄2 digits and the dorsum of thesedigits from the DIP joint to the fingertips (see Figures1–27 and 1–28).The four sensory nerves begin deep tothe superficial palmar arch but become superficial to thearteries in the distal palm.The nerve always lies superficialto the artery within the finger. Innervation of the radialtwo lumbricals is provided by the common digital nerves.


Table 1–3: Radial Nerve Order of Innervation

1. Triceps2. Anconeus3. Brachioradialis4. Extensor carpi radialis longus5. Extensor carpi radialis brevis6. Supinator7. Extensor digitorum communis8. Extensor digiti quinti9. Extensor carpi ulnaris

10. Abductor pollicis longus11. Extensor pollicis longus12. Extensor pollicis brevis13. Extensor indicis proprius

UlnarNerve

UlnarNerve

MedianNerve

RadialNerve

RadialNerve

Figure 1–28:Anatomy of the dorsal sensory nerves of thehand on the palm (left view) and dorsum (rightview). (From Trumble TE, editor: Principles of handsurgery and therapy. Philadelphia, 2000,WBSaunders Company.)

Ulnar Nerve● The ulnar nerve is composed of fibers from the C8 and

T1 nerve roots and sometimes a minor contribution fromC7. Nearly all of the fibers arise from the lower trunk ofthe brachial plexus and pass through the medial cordbefore forming the ulnar nerve. It is important toremember that a large portion of the median nerve andmedial antebrachial cutaneous nerve also originate fromthe medial cord. From the brachial plexus, the ulnarnerve runs along the medial aspect of the arm.At theelbow, the nerve passes in the groove between the medialepicondyle and olecranon process, the cubital tunnel.Theulnar nerve continues distally, enters the forearm betweenthe two heads of the FCU, which it supplies, and thenruns between the FCU and the FDP.At this level, thenerve gives off motor branches to the FDP to the ringand small fingers. In the distal third of the forearm, theulnar nerve gives off the ulnar sensory nerve.Approximately 4 cm proximal to the wrist crease, theulnar sensory branch exits dorsal to the FCU, providingsensation to the dorsum of the ring and small fingers.

● The ulnar nerve enters the wrist via Guyon’s canal.Themotor branch of the ulnar nerve innervates thehypothenar muscles (ADQ, FDQ, ODQ) and all of theinterossei.The motor branch to the interossei takes anacute turn just distal to the hook of the hamate andusually is visualized during removal of the hook for afracture (see Figure 1–7).The sensory portion of theulnar nerve supplies the palmar small finger and the ulnarhalf of the ring finger (see Figures 1–27 and 1–28).Sensory abnormalities on the dorsum of the hand helpdistinguish between a lesion of the nerve locatedproximal versus distal to the branch of the ulnar sensorynerve.Testing for motor function of the ulnar nerve isaccomplished through pinch strength. Froment’s sign ishyperflexion of the thumb IP joint as a patient withdeficient ulnar innervation applies a firm key pinch.When the adductor pollicis is paralyzed, the patientcompensates by using the FPL, which causes hyperflexionof the IP joint (Figure 1–29). Other tests of ulnar nervefunction include examination of digital abduction to testthe interossei.

Arterial Anatomy● The arterial anatomy of the hand is one of the greatest

areas of variability among patients.There are three mainarches for blood supply to the hand: the superficial palmararch, the deep palmar arch, and the dorsal carpal arch.These three arches are formed by the radial and ulnararteries and provide a rich collateral circulation to thehand.The main blood supply to the superficial palmararch is the ulnar artery.This arch is located at Kaplan’scardinal line at the distal extent of the transverse carpal

ligament and is superficial to the median nerve and thelong finger flexors.The common digital arteries to thesecond, third, and fourth web spaces arise from thesuperficial palmar arch.

● Deep to the median nerve and the long finger flexors isthe deep palmar arch.The main blood supply of the deeppalmar arch is the radial artery, which also gives a branchto the dorsal carpal arch.The princeps pollicis is a branchof the radial artery just distal to the deep palmar arch. Itruns on the palmar aspect of the adductor pollicis beforeemerging into the subcutaneous tissue at the MCPflexion crease of the thumb. It then branches into the twocollateral palmar arteries of the thumb, which run alongthe flexor sheath, before anastomosing at the fingertip.Other branches, given off while still at the level of theadductor pollicis, include the radialis indicis artery, whichsupplies the radial digital artery to the index finger, and abranch to the deep palmar arch.

● The dorsal carpal arch is formed by the radial and ulnardorsal carpal branches.This arch is an important bloodsupply to the carpal bones, especially the scaphoid.Thescaphoid receives its blood supply proximally along thedorsal carpal ridge via the dorsal carpal branch of the radialartery and distally from the volar tuberosity.The dorsalcarpal arch extends distally with the dorsodigital arteries,which are important for performing local dorsal hand flaps.


Figure 1–29:Positive Froment’s sign with thumb interphalangeal joint flex-ion to compensate for paralysis of adductor pollicis muscleindicates a low ulnar nerve palsy. FPL, Flexor pollicis longus.(From Trumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

● The patency of the palmar arch can be determined bythe Allen test (Figure 1–30).To perform the test, theradial and ulnar arteries are occluded with manualpressure while the patient makes a fist several times.Pressure is released from one artery, and capillary refillshould be noted in the fingertips within 5 seconds.Failure to provide rapid capillary refill to all the digitsafter releasing pressure from one of the arteries indicatesthe patient has a vessel occlusion or an incomplete arch.Similarly, a digital Allen test can be performed at thefinger level to assess the digital arteries.

References1. Berger RA, Landsmeer JM:The palmar radiocarpal ligaments: a

study of adult and fetal human wrist joints. J Hand Surg Am15:847-854, 1990.

Three palmar radiocarpal ligaments are described: radioscapho-capitate, long radiolunate, and short radiolunate.

2. Viegas SF,Yamaguchi S, Boyd NL, Patterson RM:The dorsal lig-aments of the wrist: anatomy, mechanical properties, and func-tion. J Hand Surg Am 24:456-468, 1999.This study examined the anatomy and mechanical propertiesof the dorsal radiocarpal and dorsal intercarpal ligaments of thewrist.

3. Smith RJ: Balance and kinematics of the hand under normal andpathologic conditions. Clin Orthop 104:92-111, 1974.A classic description of the intrinsic mechanism.

4. Zancolli E: In Structural and dynamic bases of hand surgery.Philadelphia, 1969, JB Lippincott.A detailed discussion, with drawings, of the anatomy and func-tion of the hand.

5. Mackinnon SE, Dellon AL: Surgery of the peripheral nerve. NewYork, 1988,Thieme Medical Publishers.


Figure 1–30:The Allen test to evaluate patency of theradial and ulnar arteries. (From Trumble TE,editor: Principles of hand surgery and therapy.Philadelphia, 2000,WB Saunders Company.)

6. Weaver L, Tencer AF, Trumble TE: Tensions in the palmar liga-ments of the wrist. I.The normal wrist. J Hand Surg Am 19:464-474, 1994.A discussion of the tensions of the palmar radiocarpal ligaments.

7. Hoppenfeld S: Physical examination of the spine and extremi-ties. 1976,Appleton & Lange.A classic textbook on the physical examination of the entiremusculoskeletal system and the provocative maneuvers forcommon pathologic conditions.

8. Miller MD, Brinker MR: Review of orthopaedics, ed 3,Philadelphia, 2000,WB Saunders.

9. Peimer CA, editors: Surgery of the hand and upper extremity. NewYork, 1996, McGraw-Hill Companies.

10. Green DP, Hotchkiss RN, Pederson WG, editors: Greens operativehand surgery, ed 4, New York, 1998, Churchill Livingstone.

11. Trumble TE, editor: Principles of hand surgery and therapy.Philadelphia, 2001,WB Saunders.


Anatomy and Physical Examination of the Hand · 2 Hand, Elbow & Shoulder: Core Knowledge in...

Documents

Transcript of Anatomy and Physical Examination of the Hand · 2 Hand, Elbow & Shoulder: Core Knowledge in...