4.2 Wrist and hand joints Flashcards
What are the joints of the hand?
*Carpometacarpal - b/w carpals and metacarpals
*Intermetacarpal - b/w metacarpals themselves
Metacarpophalangeal - metacarpals and phalanges
Interphalangeal - b/w phalanges themselves
**synovial joints
What are the joints of the wrist?
Radiocarpal*
Intercarpal* - between carpal bones
Midcarpal - between the distal and proximal rows of carpal bones, physiological/functional
*synovial joints
Describe the wrist complex.
Radiocarpal joint
-b/w distal radius and scaphoid, lunate, triquetrum
Intercarpal joint
-b/w proximal and distal carpals
Midcarpal
-b/w proximal and distal carpal rows
What are the features of the wrist joint? (ie. ligaments, type of joint, presence of disc)
- Radiocarpal joint is a condyloid joint (concave/convex surface)
- *biaxial joint, slight amount of F/E, condyloid joint due to concave/convex shapes of carpal bones
Ligaments:
- medial collateral
- lateral collateral
- palmar and dorsal radiocarpal
- palmar and dorsal radioulnar
-Triangular fibrocartilaginous disc
What is the blood and nerve supply to the wrist joint?
Blood: branches of palmar and dorsal carpal arches
Nerve: anterior/posterior interosseous, deep branch of ulnar
What are the movements at the wrist joint?
Flexion:
FCR, FCU, FDS, FDP, FPL, PL, APL
Extension:
ECRL, ECRB, ECU, ED, EI, ECM, EPL, EPB
Radial deviation (abduction) APL, FCR, ECRL
Ulnar deviation (adduction) ECU, FCU *more ulnar deviation than radial deviation due to condyloid nature of joint, and orientation of carpals
Intercarpal joints
- B/w carpal bones in proximal and distal row
- Joint capsule same as carpometacarpal (CMC) joints
- Ligaments: anterior, posterior, IO
- Movement: gliding between carpals (plane type of joints, ie. making a fist, or extension of wrist where carpal bones rub together)
- Fall on outstretched hand
Blood and nerve supply of intercarpal joints?
BS: palmar and dorsal carpal arches (radial and ulnar arteries)
NS: anterior interosseous, deep branch of ulna
Midcarpal joint features
- functional joint
- convex-concave
- condyloid type
- movement: F/E, radial deviation > ulnar deviation
- *flexion = scrunching up hand, extension is returning to non scrunched position
What type of joint is it between capitate and index/middle fingers in CMC joint?
Capitate projects into and holds the joint with the 2nd and 3rd metacarpals in place. Fairly tight joint, immobile, stable, limiting the movement in this joint, which is a plane joint with slight gliding.
What type of joint is CMC of the 4th and 5th metacarpals?
Here the hamate meets up with capitate, 4th and 5th metacarpals are much more mobile, allows F/E.
Hinge joint
Type of joint of CMC 1st metacarpal?
Saddle joint:
- Trapezium itself has that concave/convex shape, has 2 curvatures in sagittal and coronal plane that sits against the 1st metacarpal
- Allows movements of F/E, Ab/Ad, rotation, opposition
What connects the CMC and IMC?
Ligaments
- interosseous
- collateral ligaments
Blood and n’ supply of CMC & IMC joints
BS: palmar arterial arches, dorsal & palmar metacarpal arteries
NS: anterior and posterior IO, deep ulnar
Features of MCP
Fibrous capsule surround joints
- b/w head of metacarpal (distal; proximal = base, mid = body of metacarpal), base of proximal phalanx
- condyloid
- F/E, Ab/Ad
-connected with each other
Features of IP
- b/w head of proximally placed phalanx and base of distal
- hinge: F/E
What are the ligaments of the MCP and IP?
- Collateral ligaments (med/lat)
- Transverse metacarpal ligaments (fibrous ligament that connects heads of metacarpals together and in place)
- Palmar (volar) plate (fibrous and ligamentous plate: deep to extensor expansions, increase SA of ligaments going through that area)
- Dorsal plate
- Modified hinge (movement is restricted by deep transverse ligaments, but are able to do a little bit of F/E, Ab/Ad)
What are the BS & NS of MCP & IP?
BS: palmar arterial arch
NS: median and ulnar nerves
What is the Skier’s thumb?
Rupture of medial collateral ligament from forced abduction and extension.
Finger injuries: Swan-neck deformity
Ventral IP injury
- palmar plate breaks off and subsequent dislocation posteriorly, ventral tendons have broken away, but dorsal expansion tendons are working
- hyperextension at proximal IP joint
- compensatory flexion at distal IP joint (profunda tendons are working)
Finger injuries: Boutonniere deformity
Dorsal IP injury: extensor expansion ruptures off
- flexion at proximal IP
- compensatory hyperextension at distal IP
*lumbricals responsible for flexion/comp. hyperext above
‘Mallet finger’ injury
Distal IP injury
ie. ball hits end of finger
What movements are the digits capable of?
Ab/Ad, F/E, Opposition/reposition
Wrist: F/E
Features of synovial sheaths
- Common flexor sheath: tendons of FDS (2 rows), FDP (1 row), FPL
*tendons travel through confined spaces to work on distal end of digits, require lubrication to work, therefore synovial membrane envelopes all flexor tendons of hand
*FDS & FDP synovial enclosure of ulnar bursa (medial side)
FPL - radial bursa - Digital synovial sheaths
- Fibrous digital sheaths
*Note: sheath for little finger is continuous with ulnar and radial bursa, absence of sheath where lumbrical muscles attach
What are the origin and insertion of the lumbricals?
Origin: tendon of FDP
Insertion: extensor expansion on either side
Fibrous flexor sheaths
Fibrous covering that holds the synovial sheaths in place:
- Annular (A) fibres
- Cruciform (C) fibres: during flexion, produces continuous tunnel for tendon with lubrication
- connect volar plates
Clinical implications:
- spread of infection in synovial sheath (ie. little finger and ulna bursa)
- De Quervain’s tenosynovitis (tendon sheaths get inflammed, particularly laterally - in thumb EPL & AbPL tendons)
- digital tenovaginitis stenosans (tendons inflammed, flexion produces snapping sound)
Median nerve (C5-T1)
Muscle: supplies most muscles of anterior compartment of forearm and most muscles of thumb
-passes through carpal tunnel
Skin: lateral 3.5 digits and nail beds
*susceptible to compression injury (or to associated blood supply) in carpal tunnel
Potential motor & sensory loss if to skin if injured - Tinel’s test
Consequences of a cut median nerve?
‘Hand of Benediction’
- opponens wasting/wasting of thenar elements
- pins and needles
- won’t be able to form fist due to intrinsic muscles on lateral side are affected
Ulnar nerve (C8, T1)
Muscles: supplies remaining muscles in anterior compartment of forearm and hand, except for thumb
Skin: medial 1.5 digits (both palmar & dorsal)
- susc. to compressino and/or stretch across back of medial epicondyle
- passes superficial to flexor retinaculum
- at wrist, susc. to compression against bike handlebars
Radial nerve (C5-T1)
Muscles: extrinsic muscles of arm & forearm
Skin: skin of arm, forearm, back of hand
-Runs across shaft of humerus (between med/lat heads of triceps)
*Susc to damage in humeral shaft fracture, compression (Saturday night palsy)
