Forearm/Wrist/Hand Anatomy

Question 1

Anatomic Snuffbox

Answer 1

• Floor = scaphoid > trapezium, radial artery
• Proximal border = radial styloid process
• Lateral border = tendons of the abductor pollicis longus & extensor pollicis brevis
• Medial border = tendon of extensor pollicis longus
• APL + EPB + EPL*

–> painful w/ scaphoid fractures

Question 2

DeQuervain’s Tenosynovitis

Answer 2

Tendinopathy of 1st dorsal extensor compartment

• All peanut lovers eat peanut butter*
• Abductor pollicis longus tendon
• Extensor pollicis brevis tendon

–> painful snuffbox w/ resistance to extension of the thumb

Question 3

Radial Nerve

Answer 3

• Posterior branch of brachial plexus (C5-C8, T1)
• Radial n. -> deep radial n. -> posterior interosseous n.
• Innervates –> triceps, anconeous, brachioradialis, supinator (deep radial), & extensor (dorsal) hand muscles (PIN)
  
  • EXTENSOR/Pronator&supinator M.*

Question 4

Median Nerve

Answer 4

• Medial & lateral cord of brachial plexus (C6-C8, T1)
• Travels down forearm w/ brachial artery
• Branches –>
  1. anterior interosseous & palmar cutaneous n. (forearm)
  2. recurrent & digital cutaneous branches (hand)
• Innervates –> flexor muscles of forearm (except flexor carpi ulnaris) & the 1st/2nd lumbricals & thenar muscles (recurrent branch)
  
  • FLEXOR/Supinator&Pronator M.*

Question 5

Ulnar Nerve

Answer 5

• Medial cord of brachial plexus (C8, T1)
• No branches (superficial & deep)
• Innervations –> hycpothenar eminence, flexor carpi ulnaris, 3rd/4th lumbricals, & dorsal interossei

Question 6

Carpal Tunnel Syndrome

Answer 6

• Numbness in tips of fingers (MC in 4th/5th) b/c the median nerve is compressed
• Palm doesn’t get numb b/c it is fed by the palmar branch of the median nerve, which bypasses the carpal tunnel

Question 7

Carpal Tunnel

Answer 7

-Palmar aspect, connecting forearm to wrist
-10 structures:
` 4 deep tendons-flexor digitorum profundus
` 4 superficial tendons-flexor digitorum superficialis
` 1 extra tendon-flexor pollicis longus
` 1 nerve-median nerve (b/t the FDP & FDS)

Question 8

Median Nerve Forearm Innervation

Answer 8

= flexor forearm muscles & pronation

• pronator teres (C6-7)
• flexor carpi radialis (C6-8)
• palmeris longus (C7-8, T1)
• flexor digitorum superficialis (C7-8, T1)
• flexor digitorum profundus (radial) (C7-8, T1)
• flexor pollicis longus (C7-8, T1)
• pronator quadratus (C7-8, T1)
• thenar & 1st/2nd lumbrical muscles (1/2 LOAF) (C8, T1)

Question 9

Ulnar Innervated Muscles

Answer 9

= mostly in hand

• flexor carpi ulnaris (C7-8, T1)
• flexor digitorum profundus (ulnar) (C7-8, T1)
• hypothenar muscles (C8, T1)
• palmar brevis (C8, T1)
• interossei (dorsal & palmar)
• 3rd/4th lumbricals (C8, T1)
• adductor pollicis (C8, T1)
• flexor pollicis brevis (deep head) (C8, T1)

Question 10

Radial Innervated Muscles

Answer 10

• Triceps (radial) (C7-8)
• Anconeus (radial) (C7-8)
• Extensor carpi ulnaris (PIN) (C6-7)
• Extensor carpi radialis longus (PIN) (C6-7)
• Extensor carpi radialis brevis (PIN) (C7-8)
• Extensor digitorum (PIN) (C7-8)
• Extensor digiti minimi (PIN) (C7-8)
• Extensor indicis (PIN) (C7-8)
• Supinator (PIN) (C5-6)
• Extensor pollicis longus/brevis (PIN) (C7-8)
• Abductor pollicis longus (PIN) (C6-7)

Question 11

Vein Used for Peripheral Blood Draw

Answer 11

Median cubital vein

• branch of the basilic vein
• connects w/ the cephalic vein