Hand Exam: Motor 6/13 – Hypothenar Muscles

Hypothenar Muscles: Instruct the patient “Bring your little finger away from the others”
All supplied by deep branch of ulnar nerve 

Abductor Digiti Minimi (ADM)

  • Origin: pisiform
  • Insertion: medial side of base of proximal phalanx of small finger
  • Action: abducts small finger, extends IP joints when MCP joint is stabilized
  • Innervation: deep branch of ulnar nerve

Flexor Digiti Minimi (FDM)

  • Origin: Flexor retinaculum and hook of the hamate
  • Insertion: medial side of base of proximal phalanx of small finger
  • Action: flexes MCP joint
  • Innervation: deep branch of ulnar nerve

Opponens Digiti Minimi (ODM) 

  • Origin: Flexor retinaculum and hook of the hamate
  • Insertion: medial border of 5th metacarpal
  • Action: rolls 5th metacarpal toward thumb, flexes 4th and 5th MCP joints for better thumb opposition
  • Innervation: deep branch of ulnar nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis


Hand Exam: Motor 5/13 – Interosseous Muscles

 

Interosseous Muscles: Instruct the patient “Spread your fingers apart”

Palmar Interossei (3) – PAD (Palmars ADduct, bring fingers together)

  • Action: adduction of index, ring and small fingers
  • Innervation: deep branch of ulnar nerve

Dorsal Interossei (4) – DAB (Dorsals ABduct, bring fingers apart)

  • Action: abduction of index, long, ring and small fingers
  • Innervation: deep branch of ulnar nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis

Hand Exam: Motor 4/13 – Thenar Muscles

Thenar Muscles (radial group): Instruct the patient “Touch the thumb to the small finger”
All supplied by recurrent branch of median nerve 

Abductor Pollicis Brevis (APD)

  • Origin: flexor retinaculum and tubercles of scaphoid and trapezium
  • Insertion: lateral side of base of the proximal phalanx of the thumb
  • Action: palmar abduction, tiny bit MP flexion and IP extension
  • Innervation: recurrent branch of median nerve

Opponens Pollicis (OP)

  • Origin: Flexor retinaculum and tubercle of trapezium
  • Insertion: lateral side of first metacarpal bone
  • Action: rotates thumb pinch with index finger
  • Innervation: recurrent branch of median nerve

Flexor Pollicis Brevis (FPB)

  • Origin: Flexor retinaculum and tubercle of trapezium
  • Insertion: medial side of base of proximal phalanx of the thumb
  • Action: flexes and stabilizes MPJ
  • Innervation: recurrent branch of median nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis


Hand Exam: Motor 3/13 – Flexor Digitorum Superficialis (FDS)

Flexor Digitorum Superficialis (FDS)

  • Instruct the patient “Bend your finger at the middle joint” while stabilizing their other fingers (otherwise FDP tries to help out)
  • Insertion: middle phalanxes of fingers
  • Action: flexion of proximal interphalangeal joints
  • Innervation: Median nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis


Hand Exam: Motor 2/13 – Flexor Digitorum Profundus (FDP)

Flexor Digitorum Profundus (FDP)

  • Instruct the patient “Bend the tip of your finger” while stabilizing their PIP joint
  • Insertion: distal phalanxes of fingers
  • Action: flexion of distal interphalangeal joints
  • Innervation: Median nerve (radial half), Ulnar nerve (ulnar half)

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis

Hand Exam: Motor 1/13 – Flexor Pollicis Longus (FPL)

Flexor Pollicis Longus (FPL)

  • Instruct the patient “Bend the tip of your thumb”
  • Insertion: distal phalanx of thumb
  • Action: flexion of thumb IP joint
  • Innervation: Median nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis


Holding Hands (the hand exam)

This wasn’t even going to be an education post, but I got guilted into it. The original is 18×24″, oil on canvas.

The hand exam

  • Inspection: You can use the acronym SEADS: swelling, erythema, atrophy, deformity, skin changes. Remember: you should be able to see their whole arm up to the elbows
  • Palpation: You can use the acronym TEST CA: tenderness, effusion, swelling, temperature, crepitations, atrophy
  • Range of Motion and Power: Do active, if it’s not full you can then check passive.
  • Special Tests: fancy things for carpal tunnel like Phalen’s and Tinel’s

The anatomical snuff box and deQuervain’s tenosynovitis

The anatomical snuff box is among one of the most fun-named anatomic structures, it’s called the snuff box because people used to put snuff (tobacco) in it.

If you have dinky little hands like me, the snuff box is pretty prominent (as you can see in the doodle since that’s my left hand). The borders are the extensor pollicis longus posteriorly, extensor pollicis brevis and abductor pollicis longus anteriorly and the radial stylus process proximally. If you poke around the snuff box you can feel both the scaphoid and the trapezium as well as the radial artery. Like the rest of the forearm and hand, the snuff box is chock full of way too many structures. The radial nerve is deep in the box while the dorsal cutaneous branch of the radial nerve lies superficially to the extensor pollicis longus. The cephalic vein also originates in the snuff box.

DeQuervain’s Tenosynovitis
This is when the tendons of the extensor pollicis brevis and abductor pollicis longus get inflamed (usually due to overuse, particularly gripping/grasping). Any maneuver that causes these tendons to activate (ie extending the thumb against resistance) causes pain along the lateral side of the wrist and forearm. The classic test is Finkelstein’s maneuver, in which a fist is made over the thumb and the wrist is ulnarly deviated. This stretches the tendons over the radial styloid causing significant pain.

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