Upper Limb - Wrist Notes

Learning Objectives

  • Recognize the osteology of the upper limb, focusing on the wrist, along with common injuries.
  • Identify muscles of the forearm and be able to describe the associated movement and note the innervation.

Osteology - Hand

  • Phalanges:
    • Distal
    • Middle
    • Proximal
  • Metacarpals: 5
  • Carpals:
    • Hamate
    • Triquetrum
    • Pisiform
    • Lunate
    • Trapezoid
    • Trapezium
    • Capitate
    • Scaphoid (navicular)
  • Bones of the Forearm:
    • Ulna
    • Radius
  • Joints:
    • Interphalangeal joints
    • Metacarpophalangeal joints

Retinaculum

  • Top of the tunnel creating the Carpal Tunnel.
  • Ligament-like, thick fascia.
  • Contains vessels/nerves and tendons/muscles.

Carpal Tunnel

  • Carpal tunnel: Opening in the wrist formed by the carpal bones and the flexor retinaculum.
    • Nerves, vasculature, tendons, and muscles transverse through it.
  • Carpal tunnel syndrome: Compression of the median nerve as it passes through the carpal tunnel.

Fundamental Movements - Wrist

  • Flexion
  • Extension
  • Hyperextension
  • Ulnar deviation
  • Radial deviation

Important Notes on Muscles

  • Be able to identify/draw the muscle AND describe its action
  • Do NOT need to memorize the EXACT origin and insertion, despite these facts being listed on the slides
  • Note the innervation

Anterior Forearm Muscles

  • Innervation:
    • Median Nerve
    • Ulnar Nerve

Superficial Group:

  • Pronator Teres
    *Innervation: Median Nerve
  • Flexor Carpi Radialis
    *Innervation: Median Nerve
  • Palmaris Longus *Innervation: Median Nerve
    • 14% of humans do not have this muscle.
  • Flexor Carpi Ulnaris
    *Innervation: Ulnar Nerve

Intermediate Group:

  • Flexor Digitorum Superficialis
    *Innervation: Median Nerve

Deep Group:

  • Flexor Digitorum Profundus
    *Innervation: Median Nerve AND Ulnar Nerve
  • Flexor Pollicis Longus
    *Innervation: Anterior Interosseus of Median Nerve
  • Pronator Quadratus
    *Innervation: Anterior Interosseus of Median Nerve

Medial Epicondyle of Humerus = Common Flexor Origin (CFO)

1. Pronator Teres

  • Origin (Proximal Attachment): Coronoid process of ulna; CFO
  • Insertion (Distal Attachment): Middle lateral surface of radius
  • Innervation: Median nerve
  • Action: Pronates and flexes forearm

2. Flexor Carpi Radialis

  • Origin (Proximal Attachment): CFO
  • Insertion (Distal Attachment): Base of 2nd and 3rd metacarpal
  • Innervation: Median nerve
  • Action: Flexes at wrist and radial deviation

3. Palmaris Longus

  • Origin (Proximal Attachment): CFO
  • Insertion (Distal Attachment): Distal half of flexor retinaculum and palmar aponeurosis
  • Innervation: Median nerve
  • Action: Flexes hand at wrist and tenses palmar aponeurosis

4. Flexor Carpi Ulnaris

  • Origin (Proximal Attachment): CFO, Ulna (posterior border), Olecranon process
  • Insertion (Distal Attachment): Pisiform bone, Hook of Hamate, Base of 5th metacarpal
  • Innervation: Ulnar nerve
  • Action: Flexes at wrist and Ulnar deviation

Flexor Digitorum Superficialis

  • Origin (proximal): CFO, Coronoid Process of Ulna, Oblique Line of Radius
  • Insertion (distal): Shafts (bodies) of middle phalanges of medial four digits
  • Innervation: Median Nerve
  • Action: Flexes wrist joint, Flexes proximal interphalangeal joints of middle four digits, Flexes proximal phalanges at metacarpophalangeal joints

Anterior Forearm Muscles – Deep Group

  • Does NOT cross the elbow joint

Flexor Digitorum Profundus

  • Origin (proximal): Proximal ¾ of coronoid process of ulna and interosseous membrane
  • Insertion (distal): Bases of distal phalanges of 2nd, 3rd, 4th, and 5th digits
  • Innervation: Median Nerve (Lateral part – digits 2 and 3); Ulnar Nerve (Medial part – digits 4 and 5)
  • Action: Flexes wrist joint, Flexes distal interphalangeal joints, proximal interphalangeal joints, and metacarpophalangeal joints of digits 2, 3, 4, 5

Flexor Pollicis Longus

  • Origin (proximal): Anterior surface of the radius and adjacent interosseous membrane
  • Insertion (distal): Base of distal phalanx of thumb
  • Innervation: Anterior Interosseous nerve of Median nerve
  • Action: Flexes wrist joint, Flexes metacarpophalangeal and interphalangeal joints of thumb

Pronator Quadratus

  • Origin (proximal): Distal quarter of anterior surface of Ulna
  • Insertion (distal): Distal quarter of anterior surface of Radius
  • Innervation: Anterior Interosseous nerve of Median nerve
  • Action: Pronates forearm, deep fibers bind radius and ulna together

Posterior Forearm Muscles

  • Innervated by Radial Nerve

Hand Muscles

  • Median Nerve
    • Lateral 3.5 digits (cutaneous) – Thumb, pointer finger, middle finger, and half of ring finger
  • Ulnar Nerve
    • Medial 1.5 digits (cutaneous) – Pinky and half of ring finger

Summary of Forearm / Wrist MUSCLES

ANTERIOR MUSCLES

Superficial Group:
  • Pronator Teres (Median Nerve)
  • Flexor Carpi Radialis (Median Nerve)
  • Palmaris Longus (Median Nerve)
  • Flexor Carpi Ulnaris (Ulnar Nerve)
Intermediate Group:
  • Flexor Digitorum Superficialis (Median Nerve)
Deep Group:
  • Flexor Digitorum Profundus (Median Nerve AND Ulnar Nerve)
  • Flexor Pollicis Longus (Anterior Interosseus of Median Nerve)
  • Pronator Quadratus (Anterior Interosseus of Median Nerve)

POSTERIOR MUSCLES

  • Radial Nerve

ANTERIOR HAND MUSCLES

  • Median Nerve – Lateral 3.5 digits
  • Ulnar Nerve – Medial 1.5 digits