Hand Flashcards
where does APL insert?
base of 1st metacarpal
where does ECRL insert?
bases of 2nd metacarpal
where does ECRB insert?
base of 3rd metacarpal
where does ECU insert?
base of 5th metacarpal
6 dorsal compartments of the wrist?
- EPB, APL
- ECRB, ECRL
- EPL
- EDC, EIP
- EDM
- ECU
2-2-1-2-1-1
1st dorsal compartment
APL, EPB
- 50% have separate compartments (must release all of them!)
- APL has multiple slips (must release all of them!)
- site of DeQuervain’s
2nd dorsal compartment
ECRL, ECRB
- site of INTERSECTION SYNDROME
- RADIAL to lister’s tubercle
3rd dorsal compartment
EPL
- ULNAR to lister’s tubercle
- watershed zone in this area can lead to attritional rupture after DRF or RA pts
4th dorsal compartment
EDC, EIP
- EIP is ULNAR to index EDC and has the more DISTAL MUSCLE BELLY
- EDC to small finger present in <25% of people
5th dorsal compartment
EDM
-EDM is ULNAR to EDC to small finger
6th dorsal compartment
ECU
- fibro-osseous tunnel at distal ulna
- subsheath part of TFCC (if ECU disorder make sure to check TFCC)
Juncturae tendinum
- tendon interconnections which may mask tendon lacerations
- examine against resistance!
sagittal bands
- center EDC at MCP joint
- ATTACH TO VOLAR PLATE
- RADIAL band prevents ulnar subluxation of tendon (flea flicker injury)
Interossei muscles
- ulnar nerve innervated
- flex MCPs and extend IPs
- 3 palmar (PADs)
- 4 dorsal (DABs)
Lumbricals
- arise from RADIAL side of FDP tendon
- pass VOLAR to transverse METACARPAL ligament
- contribute to EXTENSOR mechanism thru the LATERAL BANDS (radial side)
- EXTEND IP joints both directly (lateral bands) and indirectly (contraction relaxes flexor pull on the DIP)
- coordinates flexor and extensor systems
- MEDIAN (IF, MF) and ULNAR (RF, SF) nerve innervated
Central slip
- EDC (contributions from lumbricals and interossei)
- inserts on base of P2
- extends PIP joint
- DIP extended thru lateral bands
Lateral bands
- contributions from extrinsic and intrinsic systems
- forms terminal extensor tendon that inserts on base of P3
Triangular ligament
- prevents VOLAR subluxation of LATERAL BANDS
- BOUTONNIERE DEFORMITY
Transverse retinacular ligament
- prevents DORSAL subluxation of LATERAL BANDS
- SWAN NECK deformity
Oblique retinacular ligament (Landsmeer)
- most distal structure of extensor mechanism
- coordinates DIP and PIP motion
- resistance to DIP flexion w/ PIP extended
extensor tendon zones of injury
9 total
-odds over joints, even over shaft
FDS
- origin: humerus/coronoid process/radius
- insertion: base of P2
- VOLAR to FDP in forearm
- position in carpal tunnel: 34/25 (RF and MF volar to IF and SF; important in spaghetti wrist lacerations)
- MEDIAN nerve innervated
- INDEPENDENT muscle bellies
- small finger FDS ABSENT in 20% of people
FDP
- origin: coronoid/ulna/IOM
- insertion: base of P3
- decussation w/ FDS at Camper’s Chiasma
- ULNAR and AIN innervated
- MF, RF, SF all arise from SINGLE muscle belly (important in tendon advancement procedures, if one of of the MF/RF/SF tendons are over-advanced this will result in slack in the other two tendons, known as QUADRIGIA)
There is no direct muscle attachment to P1, flexion at MCP is controlled by lumbricals and interossei
.
Flexor pulley system
- 5 annular (A1, A3, A5 centered over joints)
- 3 cruciform
- A1, A2, C1, A3, C2, A4, C3, A5
- prevent bowstringing
- A2 and A4 are most important to prevent bowstringing!!
FPL
- origin: radius/coronoid process/IOM
- insertion: base of P2 of thumb
- MOST RADIAL STRUCTURE IN CARPAL TUNNEL
- AIN innervated
- 2 annular pulleys
- 1 OBLIQUE PULLEY (most important to prevent bowstringing)
Flexor tendon zones of injury
- 1: distal to FDS insertion
- 2: prox edge of pulleys (distal palmar crease) to FDS insertion; NO MAN’S LAND
- 3: Distal transverse carpal ligament to pulley system
- 4: Carpal tunnel
5: musculotendinous junction to proximal edge of transverse carpal ligament
Hand spaces and infection spread
- many potential spaces (radial/ulnar bursae, dorsal, midpalmar, thenar/hypothenar, parona’s, interdigital)
- RADIAL BURSA and flexor sheath thumb contiguous
- ULNAR BURSA and flexor sheath small finger contiguous
- 50-80% OF ULNAR AND RADIAL BURSAE COMMUNICATION (this is the reason why you can get a horseshoe abscess w/ flexor tendon sheath injury via communication thru Parona’s (quadrilateral) space
Parona’s (quadrilateral) space borders
dorsal: pronator quadratus
palmar: digital flexor tendons
ulnar: flexor carpi ulnaris
radial: flexor pollicis longus
- infections here can lead to acute carpal tunnel syndrome because of compression
Thenar muscles
- ABDuctor pollicis brevis (APB) (median)
- Opponens pollicis (median)
- ADDuctor pollicis (ulnar)
- FPB (2 heads)(deep head–> ulnar innervated; superficial head –> median innervated)
Hypothenar muscles
- ABDuctor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi
- all ULNAR nerve innervated
Arterial supply to hand
- RaDial artery- Deep palmar arch
- Ulnar artery- sUperficial palmar arch
- 80% of people have anastamosis between deep and superficial arches
- ARTERY is DEEP to the nerve on VOLAR side, and SUPERFICIAL to nerve on DORSAL SIDE. Think of increased sensation on volar side of hand, making a more superficial nerve make sense, the other side is opposite
Ligaments in digits
- Grayson’s (VOLAR/ground)
- Cleland (Dorsal/ceiling)
- Artery dorsal to nerve
- Grayson’s involved in Dupuytren’s disease, Cleland is NOT
Carpal tunnel
- 10 structures total
- 4 FDS, 4 FDP, median nerve, FPL
- FDS/FDP orientation is 34/25
- FPL is most RADIAL STRUCTURE in carpal tunnel
- Recurrent motor branch of median nerve is OUTSIDE the carpal tunnel, but can have variable course. If median nerve laceration present, important to line up the most VOLAR-RADIAL fascicles during repair as this represents the portion that becomes the recurrent motor branch
Guyon’s canal
- ulnar artery
- ulnar nerve
- MOTOR BRANCH FASCICLES = DORSAL AND ULNAR
- pisiform and hamata (ulnar and radial borders), transverse carpal ligament (FLOOR of guyon’s canal)
Martin-Gruber anastomosis
- motor and sensory crossover between median and ulnar nerve at forearm level
- 15-20% of people
- important because if you have laceration of median nerve at wrist PROXIMAL to recurrent motor branch, you can still have median nerve function because the fibers from the recurrent branch can anastomose w/ ulnar nerve fibers and distal median nerve fibers
blood supply to scaphoid
direct branch from radial artery, entering distally along the dorsal ridge
-RETROGRADE BLOOD SUPPLY
Which nerve supplies the serratus anterior muscles and dysfunction causes scapular winging? which cervical roots does it branch from?
- Long thoracic nerve
- branches from C5-7 (leach w/ a key opening the scapula)
AIN syndrome
- weakness of the muscles innervated by the AIN, which include the flexor pollicis longus, index flexor digitorum profundus, and pronator quadratus.
- can be present following blunt or penetrating trauma. It can also be seen in the absence of trauma, in which case there may be a prodrome of upper extremity discomfort, generalized fatigue, and/or fever. Clinical findings include weakness of the thumb interphalangeal (IP) joint and index DIP joint flexion, sometimes referred to as the “Playboy bunny sign.” Pronator quadratus weakness is also present; however, there is uncertainty as to the validity of manual muscle testing in determining pronator quadratus weakness. Electrodiagnostic studies demonstrate evidence of denervation (fibrillations and positive sharp waves) of the muscles supplied by the AIN.
- In the setting of acute trauma exploration, decompression and repair of the AIN is indicated early. In the case of a spontaneous and sudden onset of symptoms, especially when associated with other indications of an inflammatory process, a viral or inflammatory neuritis is much more likely. In these cases, multiple studies demonstrate a high incidence of spontaneous resolution over 6 to 12 months. Although systemic corticosteroids may be of benefit in the case of inflammatory neuritis, there are no data to support their use and no data to support the use of AIN corticosteroid injection. Although surgical exploration is supported in the literature for patients who do not show improvement within 3 months of onset, immediate surgical exploration at 6 weeks is not indicated. Tendon transfers are indicated only if recovery fails to occur spontaneously or after surgical exploration of the AIN.
Dupuytren disease etiology and complications from surgery
-The spiral cord seen in Dupuytren disease arises from the confluence of abnormal fascial thickening of the spiral bands, lateral digital sheet, and Grayson’s ligament. The orientation of these contributing structures results in a continuous band of fibrous tissue spiraling around the neurovascular bundle. As the developing spiral cord contractures from distal to proximal, the cord itself becomes increasingly linear and shorter, causing displacement of the neurovascular bundle both centrally and superficially. This displacement of the neurovascular bundle brings it closer to the skin and midline, making it more vulnerable to surgical trauma
-Studies have demonstrated a high association between a PIP joint flexion contracture and a spiral cord (Figure 1). Spiral cords are also seen in association with a soft, fleshy mass between the proximal digital flexion crease and distal palmar crease in the interdigital space referred to as an interdigital soft-tissue mass. This represents displacement of normal subcutaneous tissues by contracture of the diseased fascia associated with the spiral cord.
-A complication following surgical treatment of Dupuytren contracture is trauma to the neurovascular bundle. This can be a consequence of blunt or sharp trauma. In the case of traumatic stretch injury from retraction, vasospasm may develop. The treatment of vasospasm includes flexion, warming the digit, and application of topical medication to treat vasospasm. Allowing the newly extended digit to flex is an important first step, particularly in the case of chronic and severe PIP joint contractures. In these cases, the vessel may have shortened over time, and full extension may cause intimal trauma and secondary vasospasm. Cold is also a stimulus for reactive vasospasm, so warming the digit with warm saline irrigation can be helpful. Finally, topically applied lidocaine (without vasoconstrictive additives) can help diminish vasospasm and lead to digital reperfusion. Phentolamine is useful in cases of prolonged vasospasm secondary to administration of anesthetics containing epinephrine. Streptokinase is a thrombolytic agent that may be useful in treatment of embolic or thrombotic vascular disease. Systemic heparin is useful for digital vessel repair but should not be necessary to treat simple vasospasm.
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blood supply to scaphoid
provided by the dorsal carpal branch of the radial artery and the superficial palmar branch of the radial artery. Approximately 70% to 80% of the scaphoid vascularity is from the dorsal carpal branch, which enters the scaphoid dorsally and distally and provides all the blood supply to the proximal scaphoid. The superficial palmar branch enters the scaphoid volarly and distally, and provides blood supply to 20% to 30% of the bone in the region of the distal tuberosity. The radioscaphoid ligament is a minor contributor to the blood supply of the scaphoid through arterioles and venules. The anterior interosseous artery can provide collateral circulation to the scaphoid, but is not the primary blood supply.
fractures of the proximal pole of the scaphoid
Fractures of the proximal pole of the scaphoid are inherently unstable and at high risk for nonunion. As many as one-third of these fractures go on to nonunion even with appropriate immobilization. Additionally, healing of these proximal fractures is slow and can require immobilization for 12-24 weeks until union is achieved. As such, screw fixation via a dorsal approach is the current accepted preferred treatment to minimize the risk of nonunion. This can be performed either percutaneously or through an open approach, at the discretion of the surgeon. Further randomized studies are needed. Proximal row carpectomy) or scaphoid excision and partial wrist fusion is indicated for salvage of arthritic or scaphoid nonunion advanced collapse wrists, and would not be indicated in this acute injury in a young individual.
lunate and perilunate dislocations
Perilunate dislocations (Figure 3) are relatively rare but make up an important spectrum of carpal pathology. These injuries are typically associated with high-energy trauma such as a motor vehicle collision or a fall from height. Mayfield and associates described a series of injuries using 4 stages with predictable disruption to the scapholunate articulation (stage 1), lunocapitate articulation (stage 2), and lunotriquetral articulation (stage 3) prior to allowing for a lunate dislocation into the carpal tunnel (stage 4) through the space of Poirier. These authors distinguished these purely ligamentous “lesser arc injuries” from “greater arc injuries” in which the energy absorbed by the wrist leads to fractures of the radius, capitate, triquetrum, and ulnar styloid.
On radiographic assessment, the posterior-anterior view typically shows disruption of “Gilula’s arcs,” which are formed by the proximal and distal articular surfaces of the proximal row and the proximal cortical margins of the distal row. On the lateral view, a perilunate dislocation will show a lunate that is in its normal position on the radius within the lunate fossa. The carpus will typically be displaced dorsally. A lunate dislocation (stage 4 injury) such as seen in this scenario will reveal the lunate displaced volarly into the carpal tunnel. The short radiolunate ligament remains intact in a lunate dislocation, which allows for the lunate to remain attached to the radius. The lunate typically causes direct compression of the median nerve in the carpal tunnel and is 1 reason why patients often have acute carpal tunnel syndrome. Although the bony and ligamentous injuries can be addressed electively within a few days of injury, acute carpal tunnel is a surgical emergency and should be addressed within the first few hours after diagnosis. An emergency department reduction of a lunate dislocation can be attempted and, if successful, may decrease carpal tunnel symptoms and obviate the need for emergent surgery. In cases in which the lunate is in the carpal tunnel, a combined dorsal and volar approach should be used. The volar approach allows for carpal tunnel release and direct reduction of the lunate. The dorsal approach allows for better visualization of the carpus and fixation of associated bony fractures and ligament injuries. Closed reduction and pinning can lead to worse outcomes following treatment.
volar thumb MCP dislocation
A volar thumb MP joint dislocation is an uncommon injury, occurring much less often than dorsal dislocation. Thumb volar MP dislocations often necessitate an open reduction because of interposed tissue including the EPL, extensor pollicis brevis (EPB), dorsal capsule, or volar plate. Several presurgical factors are associated with failure of a closed reduction. A closed reduction is less likely to be successful with no palpable EPL, displacement of the EPL or EPB, interposed sesamoids on radiographs, and paradoxical MP joint flexion and interphalangeal joint extension on attempting MP extension. The dorsal capsule is often noted to be disrupted following the injury, but this does not necessarily lead to an irreducible joint. The APL tendon inserts on the base of the thumb metacarpal and is not involved in the pathoanatomy of an irreducible MP dislocation. A collateral ligament injury is often associated with a volar thumb MP dislocation regardless of the ability to perform a closed reduction.
what is the only repeatedly validated factor predictive of fracture stability after closed reduction of a distal radius fracture?
Patient age
what is most critical factor in recovery from a nerve injury?
Patient age
what is the maximum sural nerve graft length you can use?
4cm
Brachial plexus roots
C5-T1 typically
- Occasionally C4 (prefixed) or T2 (postfixed)
- traverse between scalene anterior and scalene medius
- Dorsal scapular nerve (C5)
- Long thoracic nerve (C5,6,7)!!
Brachial plexus trunks
- Upper (C5 and C6; Suprascapular nerve)
- Middle (C7)
- Lower (C8 and T1)
Brachial plexus divisions
Split above the clavicle
Brachial plexus cords
- named from relationship to axillary artery
- Lateral (anterior divisions of upper and middle trunk)
- Medial (anterior division of lower trunk)
- Posterior (posterior divisions of all three trunks)
Lateral cord of brachial plexus
- superficial and lateral to axillary artery
- lateral pectoral nerve
- musculocutaneous nerve
- contribution to median nerve
Medial cord of brachial plexus
- Medial to axillary artery
- Medial pectoral nerve
- Medial brachial cutaneous nerve
- Medial antebrachial cutaneous nerve
- Ulnar nerve
- Contribution to median nerve (along w/ lateral cord)
Posterior cord of brachial plexus
- posterior to axillary artery
- upper and lower subscapular nerves (C5,6)
- thoracodorsal nerve (C6,7,8; innervates Lattisimus Dorsi; BETWEEN SUBSCAPULAR NERVES)
- axillary nerve (TERES MINOR, DELTOID)
- radial nerve
