Session 4: The Hand (14.01.2020) Flashcards
Names of the digits
Thumb (I) Index finger Middle finger Ring finger Little finger (V)
(1->5 in anatomical position)
What are the bones of the wrist and hand?
- The Radius
- The Ulna
- The Carpus (carpal bones);
- Proximal row – scaphoid, lunate, triquetrum, pisiform
- Distal row – trapezium, trapezoid, capitate, hamate
- The metacarpal bones
- The phalanges
Bones of the wrist and articulation
The distal ends of the radius and ulna articulate with the proximal row of carpal bones, with the exception of pisiform (a sesamoid bone) and with the articular disk.
How is the skin of the hand different? Why?
- Skin in palm of the hand and foor is different (thick skin)
- no hair
- histologically outer layer much thicker than in the rest of the skin of the body
- palms and soles of feet exposed to much more
Fascia of the palm
Palmar fascia
Palmar aponeurosis
- overlies the long flexor tendons of the hand
- proximally continuous with the flexor retinaculum
- distally continuous with the fibrous digital sheaths
Fibrous digital sheaths
- contain the flexor tendons and their synovial sheaths
Flexor retinaculum
= transverse carpal ligament
-> forms the roof of the carpal tunnel
Compartments of the hand
- Septa – medial and lateral
- Septa ; from palmar apponeurosis to
- medially : to little finger metacarpal
- laterally : to middle finger metacarpal - Hypothenar compartment
- Central compartment
- Thenar compartment
- Adductor compartment
Connective tissue and septae of the hand
x
Muscles of the region (summary)
Anterior compartment of the forearm (revision)
- Superficial compartment
- Deep compartment
Posterior compartment of the forearm (revision)
Intrinsic muscles of the hand
- thenar compartment
- adductor compartment
- hypothenar compartment
- interossei and lumbricals
Forearm muscles in terms of hand
- The hand and wrist are operated by “remote control” by the forearm muscles
- The forearm muscles attach at the distal humerus as well as the radius and ulna
- Flexors (and pronators) anteriorly
- Extensors (and supinators) posteriorly
- in the upper forearm - you don’t want muscle bulk in the wrist area
What are forearm muscles acting across the wrist called?
- carpi
but not to the digits
Carpi muscles
Muscles acting across the wrist - the “carpi” muscles.
Digitorum muscles
Muscles acting on the digits – the “digitorum” muscles and long muscles of thumb, index finger (extensor) and little finger
What are muscles acting on the digits called?
Muscles acting on the digits – the “digitorum” muscles and long muscles of thumb, index finger (extensor) and little finger
-> thumbs: pollicis
Which muscles are in the deep anterior compartment of the forearm?
Flexor digitorum profundus (FDP) Flexor pollicis longus (FCP) Pronator quadratus (PQ)
x
x
Intrinsic muscles of the hand
Thenar muscles
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
Adductor muscle
- adductor pollicis
Hypothenar muscles
- abductor digiti minimi
- flexor digiti minimi
- opponens digiti minimi
Interossei and lumbricals
- lumbricals – flex the MCP’s, extend the IPJs
- palmar interossei – adduct the digits (“PAD”)
- dorsal interossei – abduct the digits (“DAB”)
=> very precise movements of the hand, the small muscles are involved in precise movements of the hand (e.g. picking up something small of the table)
Muscles that move the thumb - which muscles do it?
Abduction
-> APL, APB
Adduction
-> Adductor pollicis, first dorsal interosseous
Extension
->EPL, EPB, APL
Flexion
-> FPL, FPB
Opposition
->Opponens pollicis
What is the hand subdivided into?
- wrist (carpus)
- metacarpus
- the digits (five fingers incl. thumb)
anterior and posterior surface of the hand
anterior: palm
dorsal: dorsum of hand
Carpals mnemonic
Some - scaphoid Lovers - lunate Try - triquetrum Position - pisiform That - trapezium They - trapezoid Cannot - capitate Handle - hamate
How many metacarpals and phalanges are there?
metacarpals - 1 in each digit
- 3 phalanges in each digit except thumb (proximal (middle) distal)
What is the palmar aponeurosis?
- it is a triangular condensation of deep fascia that covers the palm and is anchored to the skin in distal regions.
- the apex of the tendon is continuous with the palmaris longus tendon, when present.
- from there, fibers radiate to extensions at the bases of the digits that project into each of the index, middle, ring and little fingers and to a lesser extent the thumb.
- transverse fibers interconnect the more longitudinally arranged bundles that continue into the digits.
- vessles, nerves and long flexor tendon lie deep to the palmar aponeurosis.