Wrist, Palmar Hand Flashcards
What is the most commonly injured carpal bone?
scaphoid
Palmar Arches
distal transverse arch
proximal transverse arch
longitudinal arch
Wrist Creases
- proximal, middle, distal
- roughly correspond w/ carpal bones
Abduction of Thumb
occurs at CMC joint … trapezium + 1st metacarpal
Extension/Flexion of Thumb
occurs at CMC, MCP, and IP joints
CMC Joint Osteoarthritis
common wear-and-tear of CMC joint of thumb from manual, hands-on work
Extrinsic Muscles
- originate proximal to the wrist
- generate greater force
Intrinsic Muscles
- contained entirely w/in the hand
- precise control
Superficial Extrinsic Flexor Muscles
flexor carpi radialis
flexor carpi ulnaris
*palmaris longus
Intermediate Extrinsic Flexor Muscles
flexor digitorum superficialis
Deep Extrinsic Flexor Muscles
flexor digitorum profundus
flexor pollicis longus
pronator quadratus
Bifurication of Flexor Digitorum Superficialis
- tendon of FDS splits at proximal phalanx and inserts on middle phalanx
- tendon of flexor digitorum profundus (FDP) emerges through FDS bifurication at middle phalanx and attaches to distal phalanx
- FDS only extends fingers at PIP, while FDP extends at both the PIP and DIP
Which muscles are innervated by two different nerves?
- flexor digitorum profundus
- flexor pollicis brevis
- lumbricals
Flexor Tendon Zones (Injuries)
- 5 distinct zones
- zone 2 (where FDS bifurication occurs, proximal/middle phalanx) is “no man’s zone” due to complex repair and rehab when injured
Digital Pulley System
- annular pulleys (5)
- cruciate pulleys (4)
- keeps tendon of palmar muscles of digits in place to prevent “bowstringing”
- A2 (distal phalanx) and A4 (middle phalanx) = most important
Vincula of Extensor Hood
- vincula brevia, vinculum longum
- tendinous strands of extensor hood that keeps FDS in place
Extensor Tendon Pathways in Fingers
- extensor expansion/hood
- splits into a central slip and two lateral bands, then reconnects at terminal tendon
- sagittal band and lateral band keep extensor tendon in place
Trigger Finger
- stenosing tenosynovitis
- inflammation/nodule of A1 pulley
- leads to locking of finger in flexed position (can be extended again passively/with assistance)
Arterial Supply of Hand
- radial artery runs posteriorly to thumb and forms floor of anatomical snuffbox
- superficial palmar arch
- deep palmar arch
- digital branches around digits
Mallet Finger Deformity
- ruptured long extensor tendon (runs to distal phalanx)
- DIP in flexed position
- no active extension, but can passively extend DIP
Boxer’s Fracture
fracture of neck of 5th metacarpal commonly resulting from end-on blow of fist
Gamekeeper’s/Skier’s Thumb
injury of ulnar collateral ligament of thumb
Thenar Compartment/Eminence
flexor pollicis brevis
abductor pollicis brevis
opponens pollicis
Hypothenar Compartment
flexor digiti minimi
abductor digiti minimi
opponens digiti minimi
Adductor Compartment
adductor pollicis, which has two heads (oblique, transverse)
Short Muscles
lumbricals
palmar interossei
dorsal interossei
Lumbricals of Hand
1-4
- 1 and 2: unipennate, innervated by median nerve
- 3 and 4: bipennate, innervated by ulnar nerve
PAD vs DAP
PAD: 1-3, unipennate
DAB: 1-4, bipennate
Transverse Carpal Ligament
- in flexor retinaculum, covering ventral surface of carpals and carpal tunnel
Guyon’s Canal
- walls formed by pisiform and hook of hamate
- superficial and medial to carpal tunnel
- contains ulnar artery and ulnar nerve
Palmar Aponeurosis
- thick layer of fascia over palm that protects neurovascular structures
- synovial sheaths lubricate tendons and reduce friction during movement
Dupuytren’s Contracture
- abnormal thickening of palmar aponeurosis
- contracture of ring and small fingers (digits 4 and 5)
- cannot extend/straighten fingers, even w/ force
