Wrist - Synovial Joints

#1

Synovial Joints

- The Wrist Joint

What Is A Wrist Joint?

#2

• also known as the radiocarpal joint
• a distal upper limb condyloid (allows for motions of flexion, extension, abduction, and adduction) synovial joint
• connects and acts as a transition point between forearm and hand

Physical Characteristics

• dual layered
• fibrous outer layer binds radius, ulna and proximal row of carpal bones
• in synovial membrane, inner layer secretes synovial fluid to lubricate the joint

#3

• joint formed through the articulations of the different bones;

distal radius and the scaphoid, lunate, triquetrum

• concave shape formed by proximal articulation;

consisting of a combination between distal end of radius and articular disc

• distal articulation is convex and composed of proximal hand's:

scaphoid, lunate, and triquetrum bones

4 ligaments ensuring stability of joint;

• palmar radiocarpal ligaments
• dorsal radiocarpal ligaments ulnar collateral ligaments
• radial collateral ligaments

#4

Muscles Surrounding the Joint

* Muscles monitor wrist movement in the forearm. * Each muscle's body is situated in the forearm proximally * Tendons extend distally across the joint of the wrist * Muscles associated may be grouped by function

Flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus and palmaris longus to a lesser degree

Flexion

Extension

Extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum and to a lesser extent extensor indicis

Abduction

Abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis

Adduction

Flexor carpi ulnaris, extensor carpi ulnaris

Movements of the Wrist Joint

#5

* Allows for movement along two axes; biaxial* Implies that at the wrist joint, flexion, extension, adduction and abduction can all occur* Radiocarpal joint allows movements (transverse and sagittal) across two axes

Palmar aspect of the hand moves towards the forearm (saggital plane); Range of motion: around 50°scaphoid and lunate bones glide along the concave articular surface of the distal radius in a posterosuperior direction

Flexion

Enables the palmar part of the hand to shift away from the forearm; Range of motion: around 35°occurs when the same bones shift in the opposite direction with the added rotation of the scaphoid along the longitudinal axis

Extension

Abduction

The lunate and the triquetral move medially and while the triquetral moves farther away from the radius, the lunate stops in the same plane with the lower radioulnar joint; Range of motion: about 7°

Motion ranges of 30°; rotation of the scaphoid bone makes it possible for the lunate to shift laterally and to place itself entirely distal to the inferior surface of radius

Adduction

#6

Carpal Tunnel Syndrome & Release

• a clinical complication that affects the median nerve
• travels from the forearm to the hand through the carpal tunnel
• in refractory cases, a carpal tunnel release is conducted
• most carpal tunnel releases are conducted using an open surgical technique

#6

Technique - Carpal Tunnel Release

1. Landmarks detected and labelled with a marker on the skin
2. Longitudinal incision made with distal extent; marked by the intersection of Kaplin's cardinal line & radial border of fourth digit
3. Extend incision proximally and distally to the wrist crease
4. Dissect to expose transverse carpal ligament (TCL); through subcutaneous tissue & palmar fascia
5. incise and feather the muscle of the palmaris brevis
6. Open TCL to meticulous incision using self-retaining and manual blunt elevators
7. Ulnar part of TCL (scarcely radial to hamate hook) is firmly incised both proximally as well as distally
8. Consideration for protection of median nerve.
9. Proximally, release distal forearm fascia as it may be a secondary compression site. Assess median nerve prior to closing
10. Using 3-0 nylon to close the skin and dress the wound with soft dressing
11. Following the operation, patient is advised to elevate the wrist to minimise swelling.

#7

Blood Supply & Lymphatics

* Blood flow to the forearm and the hand- produced by ulnar and radial arteries

* Lymphatic drainage arises through lymphatic vessels; attach to epitrochlear nodes and ultimatel the axillary nodes

* They provide vasculature to radiocarpal joint via penetrating branches of dorsal and palm carpal arches

video

References

Erwin, J., & Varacallo, M. (2018). Anatomy, Shoulder and Upper Limb, Wrist Joint. In StatPearls Jones, O. (2019). The Wrist Joint. Retrieved November 16, 2020, from https://teachmeanatomy.info/upper-limb/joints/wrist-joint/MD, R. (2020, October 29). Radiocarpal joint. Retrieved November 16, 2020, from https://www.kenhub.com/en/library/anatomy/the-wrist-jointTheAnatomyZone. (2015, April 05). Upper Limb Arteries - Hand and Wrist - 3D Anatomy Tutorial. Retrieved November 16, 2020, from https://www.youtube.com/watch?v=lRjF5wI_IqU