Chapter 12 Wrist Joint Kinesiology

Joint Capsule

encloses the radiocarpal joint, is reinforced by radial and ulnar collateral ligamentsand by the palmar and dorsal radiocarpal ligaments

When using a longer lever arm:

less force is needed.

Articular Disk

located on distal end of the ulna and articulates with the triquetrium and lunate bones, acts as shock absorber and as filler btw distal ulna and adjacent carpal bones the triq and lunate. Disk fills gap created, bc the ulna and its styloid process do not extend as far distally as radius and styloid process

Working against gravity requires more work than

working with gravity or with gravity eliminated.

7. Which muscles cross the wrist on the radial side?

- Flexor carpi radialis - Extensor carpi radialis longus

8. Which muscles cross the wrist on the ulnar side?

- Flexor carpi ulnaris - Extensor carpi ulnaris

1. Name the bones of the wrist joint, starting laterally on the proximal row and going medially. Use the same order for the distal row.

- Proximal row: scaphoid, lunate, triquetrum, pisiform - Distal row: trapezium, trapezoid, capitate, hamate

Muscle Action of the Wrist

-Flexion = Flexor Carpi Radialis, Flexor Carpi Ulnaris -Extension = Ext Carpi Radialis Longus/Brevis, Ext Carpi Ulnaris -Radial Dev = Flex Carpi Radialis, Ext Carpi Radialis Longus - Ulnar Dev = Flex Carpi Ulnaris, Ext Carpi Ulnaris

Hook of Hamate (also bony landmark)

-Hook of the Hamate: projection on anterior surface of the hamate, providing attachment for transverse carpal ligament

3. Standing with your arm at your side, elbow flexed, palm down, hold on to a loop of elastic tubing that has the other end anchored under your foot. Curl your wrist up. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. What muscles are being strengthened? D. What muscle group is also acting at the elbow? E. What type of contraction is occurring at the elbow?

A - Wrist Extension B - Concentric contraction C - Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor carpi ulnaris (wrist extensors) D - Elbow flexors E - Isometric contraction

2. With you wrist bent up, slowly lower the weight to the position of your forearm resting on your thigh, with the palm up. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. What muscles are being strengthened?

A - Wrist extension B - Eccentric C - Flexor carpi radialis - Flexor carpi ulnaris (wrist flexors)

4. Standing with your arm at your side, elbow flexed, palm down, hold on to a loop of elastic tubing that has the other end anchored under your foot. Curl your wrist up. Slowly lower your wrist. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. What muscles are being strengthened?

A - Wrist extension B - Eccentric contraction C - Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor carpi ulnaris (wrist extensors)

1. Sit with your forearm resting on your thigh, palm up, and holding a weight in your hand. Bend your wrist up. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. What muscles are being strengthened?

A - Wrist flexion B - Concentric contraction C - Flexor carpi ulnaris - Flexor carpi radialis (wrist flexors)

5. Holding a box from the bottom a. wrist position b. wrist muscle group

A - Wrist position: neutral B - Wrist muscle group: flexors

2. Typing on a conventional computer keyboard a. wrist position b. wrist muscle group

A - Wrist position: neutral or slight extension B - Wrist muscle group: extensors

3. Pushing down on a stapler a. wrist position b. wrist muscle group

A - Wrist position: neutral/slight extension B - Wrist muscle group: flexors

2. Which wrist motions occur: A. In the sagittal plane around the frontal axis? B. In the frontal plane around the sagittal axis? C. In the transverse plane around the vertical axis?

A wrist flexion and extension B wrist radial and ulnar deviation C no wrist motions occur in transverse plane around the vertical axis

3. Describe the Wrist joint. A. Number of Axes Radiocarpal ____ Intercarpal _____ B. Shape of Joint Radiocarpal ____ Intercarpal _____ C. Joint Motion Allowed Radiocarpal ____ Intercarpal _____

A. Radiocarpal: 2 Intercarpals: 0 B. Radiocarpal: Condyloid Intercarpals: Plane or Irregular C. Radiocarpal: Flexion, Extension, radial/ulnar deviation Intercarpals: gliding

Muscles of the Wrist

Anterior -Flexor Carpi Ulnaris -Flexor Carpi Radialis -Palmaris Longus Posterior -Extensor Carpi Radialis Longus -Extensor Carpi Radialis Brevis -Extensor Carpi Ulnaris The distal attachment (insertion) for all of these is a metacarpal, except the palmaris longus muscle

6. If you were shown a drawing of only a wrist joint, what landmarks could tell you if the drawing were a posterior or anterior view?

Anterior side: hook of the hamate & pisiform visible

11. Why is the ulna not considered part of the wrist joint?

Because the articular disk is located between the ulna and the proximal row of carpals

Innervation of Wrist Muscles

Extensor Carpi Radialis Longus = Radial C6, C7 Extensor Carpi Radialis Brevis = Radial C6, C7 Extensor Carpi Ulnaris = Radial C6, C7 Flexor Carpi Radialis = Median C6, C7 Palmaris Longus = Median C6, C7 Flexor Carpi Ulnaris = Ulnaris C8, T1

10. Starting on the anterior surface of the ulnar side and moving in the direction of the radial side, name the wrist muscles that cross the wrist. Go completely around the wrist and only use wrist muscles.

Flexor carpi ulnaris; palmaris longus; flexor carpi radialis; extensor carpi radialis longus and brevis, extensor carpi ulnaris (basically goes in a circle from anterior ulnar side to posterior ulnar side)

15. What is the name of the bony landmark just proximal to the lateral epicondyle?

Lateral supracondylar ridge

Wrist

One of most complex joints, made up of 2: radiocarpal joint & midcarpal joint

Joint Motions

Wrist Flexion, Palmar Flexion, Extension, Hyperextension -occur in sagittal plane around frontal axis -90 degrees of flexion 70 degrees in extension Dorsiflexion Neutral Position - straight out from forearm Radial & Ulnar Deviation - 25 degrees of radial dev, 35 degrees of ulnar deviation

12. Generally speaking, you use wrist muscles when hammering. However, when extra force is needed, you may use elbow or even shoulder muscles. Why does that create greater force?

You are using a longer lever arm and larger muscles

13. When hammering overhead, why are your wrist ulnar deviators working harder that when hammering at waist level?

You are working against gravity when hammering overhead and with gravity when hammering at waist level

Palmar Fascia

aka palmar aponeurosis - Located superficially - Distal attachment of the palmaris longus muscle - Covers tendons of the extrinstic wrist muscles - provides some protection to structures in the palm

Carpometacarpal (CMC) joints

- Appear between the distal row of carpal (wrist) bones and the proximal end of the metacarpal bones - They have more direct function in the movement of the hand

Palmar radiocarpal ligament

- Attaches from the anterior surface of the distal radius and ulna to the same (anterior) surface of the scaphoid, lunate, and triquetrum , pisiform (proximal row) carpal bones & to the capitate in the distal row - Limits wrist extension - Prevents injury from flexion forces

Dorsal radiocarpal ligament

- Attaches from the posterior surface of the distal radius to the same (posterior) surface of the scaphoid, lunate, and triquetrum - Limits amount of wrist flexion - Prevents injury from excessive extension forces - not as strong as PRCL

Ulnar collateral ligament (see above pic)

- Attaches to styloid process of the ulna & to the pisiform and triquetrum bones - Provides medial stability (support) for the wrist joint - Prevents injury from lateral forces

Radial Collateral Ligament

- Attaches to the styloid process of the radius & to the scaphoid and trapezium bones - Provides lateral stability (support) for the wrist joint - Prevents injury from medial forces

Radiocarpal Joint

- Consists of the distal end of the radius and the radioulnar disk proximally - Consists of the scaphoid, lunate, and triquetrum bones distally - The ulna is not part of this joint - pisiform is located in proximal row but does not articulate w/the disc bc it is more anterior to triquetrium - Synovial Condyloid joint - the concave distal end of the radius and the articular disk articulating with the convex scaphoid, lunate, & triquetrum -Convex shaped proximal row of carpal bones moves in a direction opposite the hand - Biaxial joint (flexion/extension, radial deviation/ulnar deviation) Combo of all 4 is circumduction but there is no rotation at the wrist

5. Which muscles attach on or close to the lateral epicondyle of the humerus?

- Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor carpi ulnaris

4. Which muscles attach on the medial epicondyle of the humerus?

- Flexor carpi ulnaris - Flexor carpi radialis - Palmaris longus

Midcarpal aka Intercarpal Joints

- Located between the two rows of carpal (wrist) bones --> (proximal row: scaphoid, lunate, triquetrum & distal row: trapezium, trapezoid, capitate, hamate) - Contribute to wrist motion - Irregular shape - Plane joints - Nonaxial (only allow gliding motions, which collectively allow radiocarpal joint motions)

Flexor Carpi Ulnaris Muscle

- Superficial muscle, runs along the ulnar, slightly anterior, side of the forearm - Only wrist muscle attaching to a carpal bone O - Medial Epicondyle of Humerus I - Pisiform & base of 5th metacarpal A - Prime mover in wrist flexion and ulnar deviation N - Ulnar Nerve (C8, T1)

14. The wrist motions have what types of end feels?

- Wrist flexion/extension & ulnar deviation: firm end feel (soft tissue stretch) - Wrist radial deviation: hard end feel (bony)

Bony Landmarks of the Wrist Con't

-Medial Epicondyle: located on the distal side of humerus, attaches common flexor tendon -Lateral Epicondyle: located on distal side of humerus, attaches common extensor tendon -Supracondylar Ridge: located just proximally to lateral epicondyle, attachment for extensor carpi radialis longus muscle

Bony Landmarks of the Wrist

-Styloid Process: distal projection on lateral side of the radius and distal medial posterior side of the ulna, providing attachment for collateral ligaments

Extensor Carpi Ulnaris Muscle

-Superficial arising from common extensor tendon O - Lateral Epicondyle of humerus I - base of 5th metacarpal A - prime mover in wrist extension and ulnar deviation, assists in elbow extension N - Radial Nerve (C6, C7, C8)

Extensor Carpi Radialis Brevis Muscle

-lies next to longus, like longus passes under 2 tendons that go to thumb, then under extensor retinaculum -bc attachment is close to axis of motion for radial and ulnar deviation, it is only assistive in radial deviation O - Lateral Epicondyle of humerus I - base of 3rd metacarpal A - Prime mover in wrist extension, assists with elbow extension N - Radial Nerve (C6, C7)

Extensor Carpi Radialis Longus Muscle

-mostly superficial, attaching proximally just above the lateral epicondyle on the lateral supracondylar ridge, then runs down posterior side of forearm, under 2 tendons that go to thumb, then under extensor retinaculum O - Supracondylar ridge of humerus I - base of 2nd metacarpal A - prime mover in wrist extension and radial deviation, assisting in elbow extension N - Radial Nerve (C6, C7)

Palmaris Longus Muscle

-superficial muscle running down anterior surface of the forearm from common flexor attachment attaching in midline at base of the wrist. -has only one bony attachment at proximal end and missing in approx 21% of ppl, but bc of small size, this does not result in any real loss of strength O - Medial epicondyle of humerus I - Palmar Fascia A - Assistive in Wrist Flexion N - Median Nerve (C6, C7)

Flexor Carpi Radialis Muscle

-superficial muscle, running diagonally across anterior forearm to attach laterally at the base of 2nd & 3rd metacarpals O - Medial Epicondyle of Humerus I - Base of 2nd & 3rd metacarpals A - Prime mover in wrist flexion and radial deviation N - Median Nerve (C6, C7)

Carpal Bones

2 rows of 4 Bones Each: Starting Thumb Side Proximally (closer to the arm bones first) -Scaphoid, Lunate, Triquetrium, Pisiform -Trapezium, Trapezoid, Capitate, Hamate Some Lovers Try Positions That They Cant Handle -arranged in an arch w/concavity on the anterior (palmar surface) side and the convexity on the posterior side, this arrangement contributes greatly to thumbs opposition

4. Brushing long hair with a comb (with right hand brushing on the left side) a. wrist position b. wrist muscle group

A - Wrist position: neutral or slight flexion B - Wrist muscle group: flexors

Identify the wrist joint position and the muscle group contracting isometrically. 1. Holding a cup of coffee a. wrist position b. wrist muscle group

A - Wrist position: neutral or slightly extended B - Wrist muscle group: radial deviators

6. Standing with your arm at your side, elbow flexed, forearm in a neutral position, hold to a loop of elastic tubing that has the other end anchored above your head to some stationary object. Bend your wrist down. Now, slowly return to the starting position. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. Explain why is this type of contraction. D. What muscles are being strengthened?

A - Wrist radial deviation B - Eccentric contraction C - elasticity of tubing would bring wrist back to neutral if ulnar deviators were not slowing down the motion D - Wrist Ulnar Deviators

5. Standing with your arm at your side, elbow flexed, forearm in a neutral position, hold to a loop of elastic tubing that has the other end anchored above your head to some stationary object. Bend your wrist down. A. What joint motion is occurring in the wrist? B. What type of contraction (isometric, concentric, or eccentric) is occurring? C. What muscles are being strengthened?

A - Wrist ulnar deviation B - Concentric contraction C - Flexor carpi ulnaris - Extensor carpi ulnaris (wrist ulnar deviators)

9. Which muscle, if present, is very easy to identify but has little functional importance?

Palmaris longus located on anterior surface in middle of wrist

Innervation of wrist muscles is straight forward:

radial nerve innervates posterior, median innervates anterior muscles on thumb side, and ulnar nerve innervates ulnar side muscles.