3.5 Flashcards

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1
Q

Movements of the forearm

A
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2
Q

Movements of fingers

A

The fingers can undergo flex/ext at MCP and IP joints
They can undergo abd/add at MCP joints
- Midline is 3rd digit

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3
Q

Movements of the thumb

A
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4
Q

Muscles of forearm

A

The interosseous membrane and deep fascia separate into 2 compartments.

Posterior (extensor) compartment
- extensor muscle
- supinator mucsle
- innervated by radial nerve from posterior cord

Anterior (flexor) compartment
- flexor muscles
- pronator muscles
- innervated by median and ulnar nerves from median and lateral cords
- radial and ulnar arteries

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5
Q

Anterior forearm muscles

A

Superficial - 4 muscles
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris

Intermediate - 1 muscle
- flexor digitorum superficialis

Deep - 3 muscles
- flexor digitorum profundus
- flexor pollicis longus
- pronator quadratus

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6
Q

Muscles of the hand

A

Hypothenar
- abductor digiti minimi
- flexor digiti minimi
- opponens digiti minimi

Thenar
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis

Central
- lumbricals

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7
Q

Palmar aponeurosis

A
  • Thick, triangular shaped fascia covering central palm
  • Protects underlying tendons and neurovasculature
  • Palmaris longus inserts into the fascia as its apex
  • The distal end splits into 4 slips that are continuous with digital sheaths of digits 2-5
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8
Q

Dupuyten’s contracture

A
  • Progressive thickening and shortening of the palmar aponeurosis on the medial side of the hand which pulls the 4th and 5th digits into partial flexion at MP and PIP joints
  • Contracture is often bilateral and occurs in men over 50
  • Cause is unknown, but evidence points to a hereditary predisposition
  • treatment usually involves surgical excision of all fibrotic parts of the aponeurosis to free the fingers
  • similar to ulnar claw but MCP is flexed
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9
Q

Median nerve

A
  • Exits cubital fossa passing between 2 heads of pronator teres
  • Gives off anterior interosseous nerve which innervates deep muscle layer
  • Courses in plane between FDP and FDS
  • Becomes more superficial near wrist as it approaches carpal tunnel
  • Innervates all muscles of forearm except: FCU and medial half of FDP
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10
Q

Innervation of median nerve

A

Motor to lumbricals 1-2

Sensory branches:
- common and proper palmar digital branch
- nail beds of digits 1-4
- all of palmar hand except ulnar area

Recurrent branch:
- motor to thenar muscles
- very superficial making it vulnerable to cut injuries of the hand

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11
Q

Ulnar nerve

A
  • enters forearm after passing posterior to medial epicondyle
  • courses in plane between FCU and FDP, which it innervates
  • joins ulnar artery midway down forearm
  • crosses wrist through Guyon’s tunnel
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12
Q

Ulnar nerve innervation

A

Motor branches to:
- 3 hypothenar muscles
- adductor pollicis
- all interosei
- lumbricals 3-4

Sensory branches to:
- common and proper palmar digital branch
- pinky and medial finger
- medial side of hand

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13
Q

Crossing the wrist

A

Radial artery passes posterior to CMC joint of thumb to cross anatomical snuff box; superficial branch joins superficial palmar arch
Ulnar artery and nerve pass through Guyon’s tunnel
Median nerve passes through carpal tunnel
FDP, FDS, and FPL tendons - 9 tendons pass through carpal tunnel
FCP tendon passes lateral to carpal tunnel.
Palmaris longus passes superficial to carpal tunnel.

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14
Q

Carpal tunnel syndrome

A

Flexor retinaculum stretches between tubercles of trapezium/scaphoid and pisiform/hook of hamate
Carpal tunnel - passageway deep to the flexor retinaculum
Contains:
- median nerve
- 4 FDS tendons
- 4 FDP tendons
- FPL tendon
Tendon sheaths
Synovial sheaths around each tendon
Reduces friction as tendons slide with muscle action
Compression of medial nerve as it passes through carpal tunnel
Cause: swelling of synovial sheaths due to repetitive motion of flexor tendons
Symptoms:
- weakness/atrophy of thenar mm.
- inability to oppose thumbs
- parasthesia in palmar skin over lateral 3.5 digits
Treatment:
- overnight wrist brace to immobilize joint
- carpal tunnel release - surgical cut of flexor retinaculum to relieve pressure in tunnel

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15
Q

Guyon’s Canal

A

Ulnar nerve and artery pass through ulnar tunnel.
Ulnar canal syndrom - compression
Symptoms:
- parasthesia of medial 1.5 digits
- weakness of most intrinsic hand muscles

The paralysis of the interossei and 3rd and 4th lumbricals leading to “claw hand” deformity
- In “claw hand” the MCP joints are hyperextended due to unopposed action of the extensors; IP joint extension isn’t possible.

The other major site for ulnar damage is the medial epicondyle. Lesions there will affect both hand and forearm mm.

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