Trauma and orthopaedics (7): The hand Flashcards
hand can be split up into the
phalanges
metacarpals
carpals
Carpal bones
- 8 irregularly shaped bones ‘Some Lovers Try Positions That They Can’t Handle’
- Organised into two rows
metacarpal bones
- Articulates proximally with the carpals and distally with the proximal phalanges
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Numbered and associated with a digit:
- Metacarpal I – Thumb.
- Metacarpal II – Index finger.
- Metacarpal III – Middle finger.
- Metacarpal IV – Ring finger.
- Metacarpal V – Little finger.
phalanges
- Thumb has a proximal and distal phalanx
- Rest of digits have proximal, middle and distal phalanges
the wrist joint also known as
- Radiocarpal joint
- Synovial joint
- Ellipsoidal- allowing movement along two axes
- Flexion
- Extension
- Adduction
- Abduction
- Articulating surfaces
- Distally- proximal row of the carap bones
- Proximally- distal end of the radius and
the ……. is not part of radiocarpal (wrist joint)
-
Ulnar is not part of the wrist joint
- Articulates with the radius just proximal to the wrist joint at the distal radioulnar joint
- Prevented from articulating with carpal bones by fibrocartilaginous ligament called the articular disc
stabilising factors of the wrist joint
Stabilising factors
- Joint capsule
- Ligaments
joint capsule
Dual layered capsule
- Fibrous outer layer attaches to the radius, ulnar and the proximal row of the carpal bones
- Internal layer comprises a synovial membrane secretes synovial fluid which lubricates the joint
innervation of the wrist
- Median nerve- anterior interosseous branch
- Radial nerve- posterior interosseous branch
- Ulnar nerve- deep and dorsal branches
muscle compartment
Can be divided into extrinsic and intrinsic muscles:
-
Extrinsic
- Located in anterior and posterior compartments of the forearm
- Responsible for crude movements and produce a forceful grip
-
Intrinsic
- Located within the hand itself
- Responsible for fine motor functions of the hand
- No muscles on the dorsal (only palmar) part of the hand
intrinsic muscles of the hand
thenar (median nerve)- thumb
hypothenar (little finger)
a number of muscles within these but dont worry about them
Lumbrical muscles
- 4 lumbricals in the hand
- Each associated with a finger
- Link the extensor tendons to the flexor tendons
- Denervation of theses muscles is the basis for the ulnar claw and hand of benediction
interosseus muscles
Located between the metacarpals- divided into two groups: Dorsal and Palmar
- Dorsal interossei X4
Most superficial of all dorsal muscles
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Action
- Abduct the fingers at the MCP joint
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Attachment
- Originates – each come from the lateral and medial surfaces of the metacarpals.
- Inserts- into the extensor hood and proximal phalnx of each finger
- Blood supply
-
Innervation
- Ulnar
-
Palmar interossei X3
-
Action
- Adducts the fingers at the MCP joint
-
Attachment
- Originates from a medial or lateral surface of a metacarpal
- Inserts into the extensor hood and proximal phalanz of same finger
- Blood supply
-
Innervation
- Ulnar nerve
-
Action
areas in the hand
anatomical snuffbox
Triangular depression found on the lateral aspect of the dorsum of the hand, located at the level of carpal bones best seen when thumb is extended
- In past the depression was used to hold snuff (ground tobacco) before inhaling via the nose
borders of the anatomical snuffbox
Snuffbox has 3 borders, a floor and a roof:
- Ulnar (medial) border: tendon of the extensor pollicis longus
- Radial (lateral) border: tendons for the extensor pollicis brevis and abductor pollicis longus
- Proximal border: styloid process of the radius
- Floor: scaphoid
- Roof: skin
Contents of the anatomical snuffbox
-
Radial artery
- Crosses the floor of the anatomical snuffbox, then turns medially and travels between the head of the adductor pollicis muscle
- Radial pulse can be palpated
-
Superficial branch of the radial nerve
- Found in the skin and subcutaneous tissue of the anatomical snuff box- innervates the dorsal surface of the lateral three and half digits, and the associated area on the back of the hand
- Cephalic vein
innervation of the hand
trigger finger
Trigger finger is a condition causing pain and difficulty moving a finger. It is also known as stenosing tenosynovitis.
- finger or thumbs gets lock when in flexion, prevnting a return to extension
pathophysiology of trigger finger
Most cases of trigger finger are preceded by flexor tenosynovitis, often from repetitive movements, leading to inflammation of the tendon and sheath.
Superficial and deep flexor tendons with local tenosynovitis at the metacarpal head subsequently develop localised nodal formation on the tendon, distal to the pulley . The A1 pulley is the most frequently involved ligament in trigger finger.
When the fingers are flexed, the node moves proximal to the pulley, however when the patient attempts to extend the digit this node fails to pass back under the pulley. Consequently, the digit becomes locked in a flexed position.
dupuytrens contracture
Dupuytren’s contracture is a condition where the fascia of the hand becomes thickened and tight, leading to finger contractures.
-the finger is tightened into a flexed position and cannot fully extend.
special test fo dupuytens
The table-top test is a straightforward test for Dupuytren’s contracture. The patient tries to position their hands flat on a table. If the hand cannot rest completely flat, the test is positive, indicating Dupuytren’s contracture.
types of fasciectomy for dupuytrens
- Regional fasciectomy, whereby the entire cord is removed (the most common approach)
- Segmental fasciectomy, whereby only short segments of the cord are removed
- Dermofasciectomy, whereby the cord and overlying skin are removed, to be followed by a skin graft
types of fasciectomy for dupuytrens
- Regional fasciectomy, whereby the entire cord is removed (the most common approach)
- Segmental fasciectomy, whereby only short segments of the cord are removed
- Dermofasciectomy, whereby the cord and overlying skin are removed, to be followed by a skin graft
scaphoid fracture
The scaphoid is ‘boat’-shaped* bone and is the most common carpus to be fractured.
- diagnostic uncertainty therefore often referred to orthopaedics
blood supply to the scaphoid
radial artery
The scaphoid is anatomically divided into three parts: the proximal pole, waist, and distal pole.
- dorsal branch supplies 80% of the scaphoid, entering via the distal pol and travels in a retrograde fashion towards the proximal pole
- volar branch supplies the rest
scaphoid at risk of
AVN
fractures can compromise the blood supply, leading to avascular necrosis (AVN) and subsequent degenerative wrist disease.
The more proximal the scaphoid fracture, the higher the risk of AVN.
investigations for scaphoid fracture
‘scaphoid series’ of x-ray (AP, lateral and oblique views)
BEWARE
not always detected by initial x-ray- may need to repeat in 10-14 days (immobilise wrist and thumb splint in mean time)
