Hand anatomy Flashcards

extensor mechanism/ hood Retinaculum triangular ligament MC collaterals Oblique ligament

1
Q

Drawing and name a transverse section through the finger?

A

See diagram but name

  • terminal slip
  • Lateral band
  • Central band
  • Sagital Band
  • Lumbricals
  • Flexor digitorium profundus
  • Flexor digitorium superificialis
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2
Q

What causes MCP Flexion?

A
  • 70% Interosseous
    • 3 Palmar inerosseous- adductors
    • 4 Dorsal Interosseous-abduct
    • origin mc shaft to base of prox phalanx+ extensor expansion
    • supply deep branch of ulnar nerve
  • 30% Lumbricals- attach to FDP distal and extensor proximally
    • lumbricals 1/2 =2/3 rd digit= median nerve- unipennate, from radial side FDP2/FDP 3
    • lumbricals 3/4= 4/5 digit= ulna nerve- bipennate, from radial side fdp3/4 (lumbrical3 ) and fdp 4/5 (lumbrical 4)
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3
Q

What causes PIPJ and DIPJ extension?

A

PIPJ

  • Lumbricals ( via lateral band)
  • EDC Central slip
  • Dorsal interossei

DIPJ

  • EDC terminal tendon
  • Lumbricals via lateral bands
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4
Q

What causes extension at MCPJ?

A

Extensor digitorium communis (sagittal band)

  • Origin- lat epicondyle of humerus
  • Inserts- extensor expansions 4 digits- index-ring
  • also extends hand at wrist joint + MCPJ extension
  • innervation: PIN ( radial N)
  • blood s= Interosseous arteries
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5
Q

What flexes the PIPJ and DIPJ?

Describe their origin/insertion/Nerve and blood supplyDI?

A

PIPJ

Flexor digitorium superificalis (FDS)

Flexor digitorium profundus (FDP)

DIPJ

Flexor digitorium profundus (FDP)

FDP

origin- ant 3/4 proximal ulna, interosseous membrane,deep fascia of forearm. Thru carpal tunnel with FDS

Inserts: thru fds inserts distal phalanx

innervation: 4/5 th digitis ulna, 2/3rd AIN ( medial)

FDS
origin- medial epicondyle humerus(common flexor origin)

inserts:ant margins of base of middle phalanges 2-4 fingers

Innervation : Median Nerve

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6
Q

What does the retinacular ligament do ?

A
  • Retain and position the extensor mechanism during DIPj adn PIPJ flexion
  • Similar to sagittal band function
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7
Q

Describe the components of retinacular ligament and their function?

A
  • Oblique Band- links motion of DIPJ and PIPJ from lateral volar proximal phalanx->dorsal terminal phalanx. when PIPJ flexes-> DIPJ flexes vis versa
    • Contracture-> volar displacment of lateral band-> Bountonniere
  • Transverse Band- with pipj flexion pulls lateral bands volarly over pip
    • attenuation lead to dorsal translation of lateral bands-> swan neck deformity
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8
Q

Name the digital cutaneous ligaments?

A
  • Cleland’s- ‘Ceiling’
    • Dorsal to digital nerves, NOT involved in Dupytren’s
  • Grayson’s- ‘Ground’-
    • Volar to digital nerves, involved in Dupytrens
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9
Q

What is the funciton of digitial cutaneous ligaments?

A
  • Tether skin to deeper layers of fascia and bone to prevent excess movement of skin and improve grip
  • It also stabilses the NV bundle during flexion and extension
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10
Q

What is the function of the extension hood?

A

Allow extension of the PIPJ and DIPJ

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11
Q

What are the components of the extension hood?

A
  • Central slip- extends PIPJ- inserts base of middle phalanx
  • Lateral band- extends DIPJ-inserts distal phalanx formed from deep head of dorsal interossei and volar interossei combining
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12
Q

What inserts into the lateral band?

A
  • Interossei- dorsal /palmar
  • lumbricals
  • Extensor incidis
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13
Q

What is the function of MCPJ collaterals?

A
  • Stabilise MCPJ during motion
  • Collaterals tight in flexion, loose in extension- as MCP flexes PIPJ further away so tightening ligaments
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14
Q

Describe the MCPJ collaterals?

A
  • Radial Collateral ligaments more horizontal than Ulnar Collateral ligaments
  • Each collateral has an accessory and proper ligaments
  • Accessory - more volar, tight in extension- add/abduction stress in extension
  • Proper- more dorsal, tight in 30o of flexion- add/abduction stress in 30o flexion
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15
Q

What is the function of deep transverse metacarpal ligaments?

Where does it insert?

A
  • Prevents MC heads from splaying apart
  • Connects 2-5th MC heads together at volar plate
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16
Q

What is the role of the Natatory ligament?

A
  • Resists abduction
  • Most superifical MC ligaments
  • origin- MC/MCPJ
  • inserts- prox phalanx of all 5 fingers
  • Involved in Dupytrens
17
Q

What is the function of the sagittal bands?

What is its orgin/ insertions?

A
  • Keep extensor mechanism tracking in midline during flexion of MCPJ
  • Origin- Palmar plate
  • inserts- dorsal extensor mechanism
18
Q

What is the traingular ligament’s function?

A
  • counteracts pull of oblique ligament-preventing lateral subluxation of common extensor mechanism
  • located on dorsal side of extensor mechanism, distal to PIPJ
  • Triangular in shape
19
Q

what is the functon of the volar plate?

A
  • Prevent hyperextension
  • thickening of joint caspule at MC head and inserts into proximal phlanax via checkrein ligaments
  • tight in extension, loose in flexion