Carpal Tunnel (lecture 11) Flashcards
Bones of the Hand
- Scaphoid - boat shaped
- Lunate - cresent shaped
- Triquetrum - 3 sides
- Pisiform - pea shaped (seamoid bone in tendon of FCU)
- Trapezium - irregularly shaped
- Trapezium - 4 sided
- Capitate - largest
- Hamate - prominent hook
Carpal Tunnel
- Arch is formed by carpals
- Base is formed by the flexor retinaculum (which prevents bowing)
- Contents: 4 tendons of flexor digitorum profundus
4 tendons of flexor digitorum superficialis
tendon of flexor pollicis longus
and median nerve
synovial sheaths (FDP and FDS - single synovial sheath)
FDP has its own synovial sheath
After existing the carpal tunnel, the tendons of the FDS and FDP enter fibrous sheath on the palmar aspect of the digits and these are formed by curciating ligaments and they hold the tendon in the boney plane to prevent bowing
What are the contents that DO NOT go through the carpal tunnel
- Tendon of the FCR - it runs through a tubular compartment which is actually formed by the attachment of the flexor retinaculum to a groove on the side of the trapezium and it does not count as passing through the tunnnel
- Ulnar nerve, ulnar artery, tendon of palmaris longus - it is not surrounded by synovial sheath, and these three things pass into the hand anterior to the flexor retinaculum (over top of it)
- Radial artery - passes dorsally around the lateral side of the wrist and it lies adjacent to the external surface of the scaphoid
- Extensor tendons - passes into the hand on the medial lateral and posterior surfaces of the wrist, they pass in 6 compartments, which are defined by extensor retinaculum and also lined by synovial sheaths
Carpal Tunnel Syndrome
- Entrapment Syndrome
- Pressure on median nerve within the carpal tunnel
- Causes: overuse of wrist and fingers, swelling of tendons and tendon sheaths, cysts
- Signs: tinels sign (pain and pin-and-needles, weakness) and loss of muscle bulk of thernar muscles
- Treatment: Reduce inflammation, remove repetitive insults, surgery
Palmar Aponeurosis
- Deep Fascia
- Apex - continuous with palmaris longus tendon (or attached to flexor retinaculum)
- Fibers radiate and project into each finger and thumb (to a lesser extent)
- Transverse fibers connect longitudinal bundles
Palmaris Brevis
- Small intrinsic muscle of hand
- Overlies hypothenar msucles, ulnar artery, and superficial branch of ulnarl nerve
- Originate from aponeurosis and flexor retinaculum
- Inserts into dermis of skin on medial margin of hand
- Deepens cup of palm - improving grip
- Innervated by superficial branch of ulnar nerve
Anatomical Snuffbox
-tendons of the muscles formed the borders of the snuffbox
Trinagular. Depression
The lateral border is the tendonos of the Abductor policies longus and extensor policis breviws, medial border is the tendons of the extensor pollicius longus and then the floor is the scaphioid and trapezium (all of these formed a trignalge) - if you adduct the arm as far as it can go, you will see a traignalge depression
The radial artery passes obliquely through the anatomical snuffbox (crosses the box) and the terminal parts of the superficial branch of the radial nerve but then also the origin of the cephalic vein which then goes into the doral venous arch of the hand so you can see it passes over top of the box
Radial artery is passing deep to the tendons and the cephalic vein is passing superifcl to the tendons
You can palplate the schapoid bone and the radialartery pulse
The tendons of the ED and EPL pass onto the doral aspects of the digits and then they expand over the proximal phalanges and extensor hoods
The tendons of the digiti minimi, extensor indicis and extensor policis brevis, the muscles join these hoods
Each enstensor hood is triangluarl
The apex is attached to the distal phalanx, central is attached to the distal phalanx, and in the thumb it is attached to the proximal phalanx
Many of the intrinsic muscles of the hand insert into the free margin of the hood on each side and so by doing this, they contribute to the complex and delicate movements of the digits
Intrinsic muscles of the hand
- Palmaris Brevis
- Interossei
- Adductor Pollicis
- Thenar
- Hypothenar
- Lumbrical
Interossei (Dorsal)
Dorsal:
- 4 bipennate: two rows of muscle fibers
- Attached to shafts of adjacent metacarpal bones
- Tendons pass deep to transverse metacarpal ligaments
- Flexion and extension of fingers, major abductors of index, middle, and ring fingers (little and thumb have their own abductors)
- Radial artery passes between two heads of 1st dorsal interosseous muscle
Interossei (Palmar)
Palmar:
- Three (or four) unipennate muscles
- Originate from metacarpals of digits
- Tendons pass deep to transverse metacarpal ligaments
- Adduct thumb, index, ring and little fingers; also produce complex flexion and extension movements of the digits
Adductor Pollicis
- Originate as two heads (transverse and oblique)
- Radial artery passes anteriorly and medially between two heads (forms the deep palmar arch)
- Powerful adductor of the thumb and opposes the thumb to the rest of the digits in gripping
Thenar Muscles
- Associated with opposition and delicate movements of thumb
- Thenar eminence
- Opponens pollicis (pad of thumb facing pads of fingers)
- Abductor Pollicis breviews (action most apparent when thumb is maximally abducted)
- Flexor pollicis brevis
- Innervated by recurrent branch of median nerve
Hypothenar Muscles
- Hypothenar eminence
- Opponens digit minimi
- Penetrated by deep branches of ulnar nerve and ulnar artery
- rotates metacarpal 5 towards palm; movement less dramatic than thumb
- Abductor digiti minimi (principle abductor of little finger)
- Flexor digiti minimi brevis
- Deep branch of ulnar nerve
Lumbrical Muscles
- 4 worm-like muscles
- Originate from the tendons of FDP in the palm
- Medial 2 - bipennate
- -Middle and ring, ring and little
- deep branch of ulnar nerve
- Lateral 2 - unipennate
- Index and middle
- Digital branches of median nerve
- Pass dorsally around lateral side of each finger
- Link flexor tendons with extensor tendons
Arterial Supply
Two interconnected vascular arches (superficial and deep)
- Radial artery; thumb and lateral side of the index finger
- Ulnar artery; remaining digits and medial side of index finger
