Download Structure and Function of the Wrist

Structure and Function of the Wrist
8 small bones in 2 rows that articulate with the
distal radius, ulna and proximal metacarpals
The Wrist
 Articulations:
 The radiocarpal joint
 The midcarpal joint
 Motions:
 Flexion & Extension
 Radial & Ulnar Deviation
The Wrist
 Palmar = anterior aspect of the wrist and hand
 Dorsal = posterior aspect of the wrist and hand
Distal Ulna & Radius
Styloid Processes
Head
Styloid Process
Radius
Ulna
The Wrist with the Carpals
Carpal Tunnel Syndrome
 The Transverse Carpal Ligament
Arthrology of the Wrist
 Radiocarpal Joint
 Accepts approximately 80% of
the force that crosses the wrist
 Concave radial surface & articular
disc
 Convex carpals: scaphoid (7) & lunate
(8)
 Midcarpal
Intrinsic versus Extrinsic to the Wrist
 Intrinsic Originating within the area and
inserting in the area
 Extrinsic Originating outside of the area but
inserting in the area
Triangular fibrocartilage (TFC)
Lunotriquetral Ligament (L T Lig)
Scaphoid Lunate (S L Lig)
Innervations
 All muscles that extend the wrist: Radial Nerve
 All muscles that flex the wrist: Median (thumb side) and
Ulnar Nerve (ulna side)
Arthrokinematics
 Axis of rotation located at the capitate bone
 Extension and Flexion
 Medial-lateral axis of rotation
 Extensors will pass posterior
 Flexors will pass anterior
 Ulnar and Radial Deviation of the Wrist
 Anterior-Posterior axis of rotation
 Ulnar deviators pass medially
 Radial deviators pass laterally
Motions allowed at the Wrist
 Extension: 70 degrees
 Flexion: 80 degrees
 Rad Dev: 20 degrees
 Ulnar Dev: 40 degrees
 Amount of wrist extension
needed for functional activities
 Lift glass to mouth:
 Cut with knife:
 Lift fork to mouth:
 Use telephone:
 Rise from chair using arms to
push up:
Myology of the Wrist
Extensor Carpi Radialis Longus
Origin
Lateral epicondyle of the humerus,
common extensor tendon
Insertion
Base of the second metacarpaldorsal aspect
Innervation
Radial n.
Action
Wrist extension, radial deviation
“tidbit”
What’s in a name?
Common origin?
Myology of the Wrist
Extensor Carpi Radialis Brevis
Origin
Lateral epicondyle of the humeruscommon extensor tendon
Insertion
Base of the 3rd metacarpal-dorsal
aspect
Innervation
Radial n.
Action
Wrist extension, radial deviation
“tidbit”
What’s in a name?
Common origin?
Myology of the Wrist
Extensor Carpi Ulnaris
Origin
Lateral epicondyle of the humerus-common
extensor tendon and posterior border of the
middle 1/3 of the ulna
Insertion
Base of the 5th metacarpal-dorsal surface
Innervation
Radial n.
Action
Wrist extension, ulnar deviation
“tidbit”
What’s in a name?
Common origin?
Common Pathology
 “Tennis Elbow”, aka lateral epicondylitis
 Overuse of the wrist extensor muscles causing inflammation at
the origin site.
 Large force onto a small area
Myology of the Wrist
Flexor Carpi Radialis
Origin
Medial epicondyle of the humeruscommon flexor tendon
Insertion
Base of the 2nd metacarpal-palmar
aspect
Innervation
Median n.
Action
Wrist flexion, radial deviation
“tidbit”
What’s in a name?
Common origin?
Myology of the Wrist
Flexor Carpi Ulnaris
Origin
Medial epicondyle of the humeruscommon flexor tendon and
posterior border of the middle 1/3
of the ulna
Insertion
Base of the 5th metacarpal and
pisiform- palmar aspect
Innervation
Ulnar n.
Action
Wrist flexion, ulnar deviation
“tidbit”
What’s in a name?
Common origin?
Myology of the Wrist
Palmaris Longus
Origin
Medial epicondyle of the humerus- common flexor
tendon
Insertion
Transverse carpal ligament and the palmar fascia
Innervation
Median n.
Action
Wrist flexion
“tidbit”
Approximately 20% of the population will NOT
have this muscle; could be unilateral only
Common Pathology
 1. If wrist extensor overuse was called tennis elbow, then
flexor overuse is called ????
 2. Radial Nerve injury
 Common causes: using crutches incorrectly, and fracture of
humerus
 Pain, numbness, weakness in triceps and wrist extensors