Module 32: Upper Extremity IV – Wrist and Hand

Learning Objectives:

By the end of this class, students will be able to:

  • List the bones of the arm and elbow joint.
  • Identify the bony and ligamentous structures of the elbow joint.
  • Establish relationships between bony landmarks and attachments of muscles/tendons or neurovascular structures in the upper extremities.
  • Describe the wrist joint, MP, and IP joints, and infer how the muscle actions will create movement about the joints.
  • Review the innervation of muscles of the arm

Terms to Know

 


Bones

  • Ulna
    • Radial notch
    • Head
    • Styloid process
  • Radius
    • Styloid process
    • Ulnar notch
  • Carpals
    • Scaphoid
    • Lunate
    • Triquetrum
    • Pisiform
    • Trapezium
    • Trapezoid
    • Capitate
    • Hamate
  • Metacarpals
    • I-V
  • Phalanges
    • Proximal
    • Middle
    • Distal
 

Joints

  • Distal radioulnar joint
  • Radiocarpal joint
  • Midcarpal joints
  • Intercarpal joints
  • Carpometacarpal joints
  • Metacarpophalangeal joints
  • Proximal interphalangeal joints
  • Distal interphalangeal joints
  • Interphalangeal joint (thumb)

Muscles of the Hand

  • Hand
    • Flexor pollicis brevis
    • Abductor pollicis brevis
    • Opponens pollicis
    • Flexor digiti minimi brevis
    • Abductor digiti minimi
    • Opponens digiti minimi
    • Lumbricals
    • Dorsal Interossei
    • Palmar Interossei
    • Adductor pollicis
*NOTE – The table below contains the same information from M30. However, now the only bones presented are the radius, ulna, carpals, metacarpals, and phalanges.
BONES AND BONY MARKINGS OF THE FOREARM WRIST AND HAND
Ulna Trochlear notch Articulates with the trochlea of the humerus
Olecranon process Attachment for the triceps brachii
Coronoid process Attachment for ligaments of the elbow
Radial notch Distal articulation with the head of the radius
Head Articulates distally with the radius and with carpal bones
Styloid process Attachment for a ligament of the wrist
 
Radius Head Articulates with the ulna and humerus
Radial tuberosity Attachment for the biceps brachii tendon
Styloid process Attachment site for the brachioradialis muscle
Ulnar notch Distal articulation with the ulna
 
Carpals Scaphoid
Proximal row – most lateral (most common carpal bone fractured)
  Lunate Proximal row
  Triquetrum Proximal row
  Pisiform Proximal row – most medial
  Trapezium Distal row – most lateral
  Trapezoid Distal row
  Capitate Distal row
  Hamate Distal row – most medial
   
Metacarpals I-V I = metacarpal of the first ray (thumb), V = metacarpal of fifth ray (pinky)
   
Phalanges Proximal Digits I-V have one = 5 total
  Middle Digits II-V have one = 4 total
  Distal Digits I-V have one = 5 total

Joints of the wrist, hand, and fingers

Joints of the Wrist, Hand, and Fingers
Joint Bones Articulating Classification Motions Available
Radiocarpal (Wrist) Joint Radius and proximal row of carpals Condyloid (Ellipsoid) Joint Flexion/Extension
Abduction/Adduction
Circumduction
Carpometacarpal Joint (1st ray only) Metacarpal I and trapezium Saddle Joint Flexion/Extension
Abduction/Adduction
Circumduction
Metacarpophalangeal Joint Metacarpals and proximal phalanges Condyloid (Ellipsoid) Joint Flexion/Extension
Abdcution/Adduction
Circumduction
Interphalangeal Joint Digit I – proximal and distal phalanges (IP)
Digits II-V – proximal and middle phalanges (PIP)
Digits II-V – middle and distal phalanges (DIP)
Hinge Joint Flexion/Extension

Wrist, Hand, and Finger Joints

The radiocarpal (wrist) joint is a condyloid joint comprised of the distal radius and the first row of carpal bones. Similar motions to a ball-and-socket joint are available in the wrist. The first metacarpal and trapezium articulate to form the first carpometacarpal joint. The first carpometacarpal joint is a saddle joint. The carpometacarpal joints of digits II-V are more similar to plane joints where only gliding motion occurs. The metacarpophalangeal joints between the proximal phalanges and the distal end of the metacarpals are condyloid joints with similar motions to those seen in the wrists. The interphalangeal joints are hinge joints allowing only flexion and extension to occur between the phalanges. Note the thumb only has an interphalangeal joint, whereas there are proximal and distal interphalangeal joints in digits II-V.

 

Muscles That Move the Wrist, Hand, and Fingers

Wrist, hand, and finger movements are facilitated by two groups of muscles. The forearm is the origin of the extrinsic muscles of the hand. The palm is the origin of the intrinsic muscles of the hand.

Muscles of the Forearm That Move the Wrists, Hands, and Fingers

See Module 31 for a discussion of the muscles of the forearm.

Use the image/table below to understand the actions, origins, insertions, and innervation of the muscles that move the elbow and forearm.

*Note: Any box shaded in blue on the muscle chart requires you to know all the information (e.g., action, origin, insertion, and innervation) provided. Areas shaded in green require muscle identification and a general sense of the location of the origin or insertion. (e.g., knowing that the rhomboids originate on the vertebrae, as opposed to the specific numbered vertebrae).
Muscles That Move the Wrist, Hands, and Forearm

Intrinsic Muscles of the Hand

The intrinsic muscles of the hand both originate and insert within it. These muscles allow your fingers to make precise movements for actions, such as typing or writing. These muscles are divided into three groups. The thenar muscles are on the radial aspect of the palm. The hypothenar muscles are on the medial aspect of the palm. And the intermediate muscles are midpalmar.

The thenar muscles include the abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis. These muscles form the thenar eminence, the rounded contour of the base of the thumb, and all act on the thumb. The movements of the thumb play an integral role in the most precise movements of the hand. The thenar muscles are innervated by the median nerve. The hypothenar muscles include the abductor digiti minimi, flexor digiti minimi brevis, and the opponens digiti minimi. These muscles form the hypothenar eminence, the rounded contour of the little finger, and as such, they all act on the little finger. Finally, the midpalmar muscles act on all the fingers and include the adductor pollicis, the lumbricals, the palmar interossei, and the dorsal interossei. The hypothenar and midpalmar muscles are innervated by the ulnar nerve (**EXCEPT the lateral two lumbricals – they are innervated by the median nerve).

Intrinsic Muscles of the Hand

This multipart figure shows the intrinsic muscles of the hand with the major muscle groups labeled.
The intrinsic muscles of the hand both originate and insert within the hand. These muscles provide fine motor control of the fingers by flexing, extending, abducting, and adducting the more distal finger and thumb segments.

 

Use the image/table below to understand the actions, origins, insertions, and innervation of the intrinsic muscles of the hand.

*Note: Any box shaded in blue on the muscle chart requires you to know all the information (e.g., action, origin, insertion, and innervation) provided. You do not need to know the origins or insertions for the intrinsic muscle of the hand.

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