Wrist Joint & Hand

Anatomical Description of Wrist Joint and Hand Skeleton

1. WRIST JOINT & HAND Dr. Mushfiqul Hoque  Lecturer  Dhaka National Medical College

2. Wrist Joint

3. Wrist Joint Type of joint: Wrist joint is a synovial joint of the ellipsoid variety Lower end of radius and articular disc of inferior radioulnar joint proximally  three lateral bones of proximal row of carpus, i.e. scaphoid, lunate and triquetral distally . The pisiform does not play a role in the radiocarpal articulation. It is a sesamoid bone acting as a pulley for flexor carpi ulnaris.

4. Wrist Joint Articular Surfaces Upper: Inferior surface of the lower end of the radius Articular disc of the inferior radioulnar joint Lower: Scaphoid  Lunate  Triquetral bones. 

5. Wrist Joint Ligaments: Articular Capsule Palmar radiocarpal ligament Palmar ulnocarpal ligament Dorsal radiocarpal ligament Radial collateral ligament Ulnar collateral ligament

6. Wrist Joint Blood supply : Anterior and posterior carpal arches Nerve supply : Anterior and posterior interosseous nerves

7. Wrist Joint Movements : Flexion ( Flexor carpi radialis, Flexor carpi ulnaris, Palmaris longus) Extension ( Extensor carpi radialis longus, Extensor carpi radialis brevis,  Extensor carpi ulnaris) Abduction (Radial Deviation) ( Flexor carpi radialis, Extensor carpi radialis longus and extensor carpi radialis brevis, Abductor pollicis longus and extensor pollicis brevis) Adduction (ulnar Deviation) ( Flexor carpi ulnaris, Extensor carpi ulnaris) circumduction

8. Hand

9. Bones of the Hand There are 3 groups of bones in the skeleton of the hand: Carpal bones at the wrists Metacarpal bones at the palm Phalangeal bones in the digits

10. Bones of the Hand Carpal bones: Short bones  8 in number Arranged in proximal and distal rows Proximal row: (From lateral to medial) scaphoid, lunate, triquetral, pisiform Distal row: (from lateral to medial) trapezium, trapezoid, capitate, hamate

11. Bones of the Hand Metacarpal bones: Miniature long bones 5 in number Numbered from lateral to medial Each metacarpal possesses a diaphysis and a single epiphysis The epiphysis of all metacarpal directed towards  the head except the first where it is located towards the base

12. Bones of the Hand Phalangeal bones: Total number 14 3 for each finger, 2 for the thumb Referred to as proximal middle and distal Possesses one diaphysis Single epiphysis directed towards the base Miniature long bones

13. Joints of the Hand Intercarpal joints: Plane type of synovial joint Carpometacarpal joints of thumb: Saddle type of synovial joint Other carpometacarpal joints: Plane type of synovial joints Intermetacarpal joints: Plane type of synovial joints Metacarpophalangeal joints: ellipsoid type of synovial joints Interphalangeal joints: Hinge type of synovial joints

14. Hand The human hand is designed: For grasping, For precise movements, For serving as a tactile organ.

15. Steps of dissection A horizontal incision at the distal crease of front of the wrist. Make a vertical incision from the centre of the above incision through the palm to the centre of the middle finger. Make one horizontal incision along the distal palmar crease. Make an oblique incision starting 3 cm distal to incision no. 2 and extend it till the tip of the distal phalanx of the thumb. 

16. Steps of dissection Thus the skin of the palm gets divided into 3 areas. Reflect the skin of lateral and medial flaps on their respective sides. The skin of the intermediate flap is reflected distally towards the distal palmar crease. Further the skin of middle finger is to be reflected on either side.

17. Palm of the Hand Layers: Skin Superficial fascia Deep fascia Muscles, tendons, nerves and vessels

18. Palm of the Hand The skin of the palm is:  Thick for protection of underlying tissues.  Immobile because of its firm attachment to the underlying palmar aponeurosis.  Creased.  All of these characters increase the efficiency of the grip.  The skin is supplied by spinal nerves C6, C7, C8 through the median and ulnar nerve.

19. Palm of the Hand The deep fascia is specialised to form:  The flexor retinaculum at the wrist.  The palmar aponeurosis in the palm.  The fibrous flexor sheaths in the fingers.  All three form a continuous structure which holds the tendons in position and thus increase the efficiency of the grip

20. Flexor Retinaculum  Flexor (Latin to hold back) retinaculum is a strong fibrous band which bridges the anterior concavity of the carpus and converts it into a tunnel, the carpal tunnel 

21. Attachment of the flexor retinaculum Medially, to The pisiform bone.  To the hook of the hamate.  Laterally, to The tubercle of the scaphoid, and  The crest of the trapezium.

22. Relations of the flexor retinaculum The structures passing superficial to the flexor retinaculum are:  The palmar cutaneous branch of the median nerve.  The tendon of the palmaris longus.  The palmar cutaneous branch of the ulnar nerve.  The ulnar vessels.  The ulnar nerve. The thenar and hypothenar muscles arise from the retinaculum 

23. Relations of the flexor retinaculum The structures passing deep to the flexor retinaculum are:  The median nerve. Four tendons of the flexor digitorum superficialis. Four tendons of the flexor digitorum profundus .  The tendon of the flexor pollicis longus. The ulnar bursa. The radial bursa.  The tendon of the flexor carpi radialis lies between the retinaculum and its deep slip, in the groove on the trapezium 

24. Palmar Aponeurosis This term is often used for the entire deep fascia of the palm. However, it is better to restrict this term to the central part of the deep fascia of the palm which covers the superficial palmar arch, the long flexor tendons, the terminal part of the median nerve, and the superficial branch of the ulnar nerve

25. Palmar Aponeurosis Palmar aponeurosis is triangular in shape. The apex which is proximal, blends with the flexor retinaculum and is continuous with the tendon of the palmaris longus. The base is directed distally. 

26. Palmar Aponeurosis Functions: Palmar aponeurosis fixes the skin of the palm and thus improves the grip. It also protects the underlying tendons, vessels and nerves.

27. Fibrous Flexor Sheaths of the Fingers The fibrous flexor sheaths are made up of the deep fascia of the fingers. The fascia is thick and arched. It is attached to the sides of the phalanges and across the base of the distal phalanx. Proximally, it is continuous with a slip of the palmar aponeurosis.

28. Fibrous Flexor Sheaths of the Fingers A blind osseofascial tunnel is formed which contains the long flexor tendons enclosed in the digital synovial sheath. The fibrous sheath is thick opposite the phalanges and thin opposite the joints to permit flexion. The sheath holds the tendons in position during flexion of the digits. 

29. Intrinsic muscles of Hand The intrinsic muscles of the hand serve the function of adjusting the hand during gripping and also for carrying out fine skilled movements. The origin and insertion of these muscles is within the territory of the hand. There are 20 muscles in the hand.  The muscles are divided into 4 layers

30. Intrinsic muscles of Hand 1st layer of muscles a. Three muscles of thenar eminence  Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis. b. One adductor of thumb:  Adductor pollicis.

31. Intrinsic muscles of Hand Second layer of muscles Four Hypothenar muscles Palmaris brevis Abductor digiti minimi Flexor digiti minimi Opponens digiti minimi

32. 3rd Layer: Lumbricals

33. 4th Layer: Palmar and Dorsal Interossei

34. Nerves of Hand Ulnar nerve Median nerve

35. Nerves of Hand Ulnar nerve: Main nerve of hand. Ulnar nerve lies superficial to flexor retinaculum, covered only by the superficial slip of the retinaculum. It terminates by dividing into a superficial and a deep branch.

36. Nerves of Hand Median nerve: The median nerve is important because of its role in controlling the movements of the thumb which are crucial in the mechanism of gripping by the hand.

37. Nerves of Hand Median nerve: Median nerve lies deep to flexor retinaculum in the carpal tunnel and enters the palm. Soon it terminates by dividing into muscular and cutaneous branches.

38. Spaces of Hand The arrangement of fasciae and the fascial septa in the hand is such that many spaces are formed. These spaces are of surgical importance because they may become infected and distended with pus. The important spaces are as follows.

39. Spaces of Hand The important spaces are as follows: A. Palmar spaces  Pulp space of the fingers  Mid palmar space  Thenar space  B. Dorsal spaces  Dorsal subcutaneous space  Dorsal subaponeurotic space  C. The forearm space of Parona .

40. Pulp spaces of the fingers The tips of the fingers and thumb contain subcutaneous fat arranged in tight compartments formed by fibrous septa which pass from the skin to the periosteum of the terminal phalanx. Infection of this space is known as whitlow . The rising tension in the space gives rise to severe throbbing pain.

41. Synovial Sheaths in the Hand Many of the tendons entering the hand are surrounded by synovial sheaths. The extent of these sheaths is of surgical importance as they can be infected These are: Digital synovial sheaths Ulnar bursa Radial bursa

42. Synovial Sheaths in the Hand Ulnar bursa: Infection of this bursa is usually secondary to the infection of the little finger, and this in turn may spread to the forearm space of the Parona . It results in an hourglass swelling. Pricking in the little finger might cause spread of infection in the ulnar bursa because the synovial sheath of little finger is connected with ulnar bursa.  

43. END OF CLASS QUESTIONS?