Bony Things
How do the bones move
ligaments!
ROM values
miscellaneous
suns out guns out
TFCC
100
what muscle tendon runs around Lister's tubercle?
extensor pollicis longus as it runs towards it's distal attachment on the distal phalanx of the thumb
100
what is the central column made up of and what is convex/concave at each layer
central column consists of distal radius, lunate, capitate, and the third metacarpal
the radio-lunate joint is concave-convex respectively
the luno-capitate joint is concave-convex respectively
the capitate-metacarpal joint is very stable and doesn't really matter for this purpose
100
what is the function of the short ligaments of the intrinsic wrist ligaments
connect the distal row of carpal bones; helps to firmly stabilize and unite them
100
what is the typical ROM values for wrist flexion
70-85 degrees
100
what is the close packed position of the wrist
full extension
100
what muscles (2) have the biggest potential for ulnar deviation based on moment arm
extensor carpi ulnaris and flexor carpi ulnaris
100
what is the TFCC stand for and what is it made up of
triangular fibrocartilage complex
made up of fibrocartilage
200
explain each row of carpals and their respective mobility and stability
the proximal row of carpals is joined very loosely and allows motion
the distal row of carpals is bound tightly by strong ligaments, because of this tight binding, it is more rigid and a stable base for the articulation with the metacarpal bones
200
explain kinematics of the radiocarpal and midcarpal joints during flexion, extension, radial deviation, and ulnar deviation
convex on concave motion at each joint for each motion:
flexion is a roll palmar, slide dorsal
extension is a roll dorsal, slide palmar
radial deviation is a roll radially, slide ulnarly
ulnar deviation is a roll ulnarly, slide radially
200
what reinforces the ulnar side of the wrist
ulnar collateral ligament
200
what is the typical ROM values for wrist extension and what is it limited by
60-75 degrees; limited by stiffness in the palmar radiocarpal ligaments
200
what makes up the sides of the carpal tunnel and what are the bony attachments
carpal tunnel is formed by the palmar sides of the carpal bones and the transverse carpal ligament
the transverse carpal ligament attaches to the pisiform, hook of the hamate, and the tubercles of the scaphoid and trapezium
200
what is stronger for each pair of movements based on torque potential: flexion or extension, ulnar deviation or radial deviation
flexors are able to produce about 70% greater isometric torque compared to wrist extensors
radial deviators are able to produce about 15% greater isometric torque compared to ulnar deviators
200
what is the primary component of the TFCC
the triangular fibrocartilage (articular disc)
300
how does a scaphoid fracture normally occur and why is it important to make sure this gets treated properly if it does occur
fracture normally occurs via a FOOSH type MOI
the proximal pole of the scaphoid is avascular, thus if left untreated it could lead to avascular necrosis which is bad. fractures of the proximal pole typically require surgery while fractures of the distal pole often just require immobilization
300
what is the axis of rotation of the wrist and what axes are each motion occurring in (flexion/extension and ulnar/radial)
axis of rotation is the capitate
flexion/extension occurs on the medial-lateral axis
radial/ulnar deviation occurs on the anterior-posterior axis
300
the palmar radiocarpal ligament provides mechanical stability to the wrist, at what wrist position is it most taut in
full wrist extension
300
what are the typical ROM values for ulnar and radial deviation
ulnar: 35-40 degrees
radial: 15-20 degrees
300
how much compression force passes through each of the forearm bones
about 20% of the total compression force that crosses the radiocarpal joint passes through the articular disc to the ulna; the remaining 80% passes directly through the scaphoid and lunate to the radius
300
all the digitorum muscles (flexor digitorum profundus, flexor digitorum superficialis, extensor digitorum) are all more likely to produce the same motion in the frontal plane, what motion is this?
ulnar deviation!
300
what are the functions of the TFCC
securely binds the distal ends of the radius and ulnar while simultaneously permitting the radius (with attached carpus) to freely rotate around a fixed ulna
helps transfer compression forces
primary stabilizer of the distal radioulnar joint
400
what is the ulnar tilt and palmar tilt of the wrist
ulnar tilt is the 25 degree angle of the distal radius towards the ulnar direction (allows for more ulnar deviation vs radial)
palmar tilt is the 10 degree tilt of the distal articular surface of the radius in the palmar direction
400
during ulnar deviation, what happens at the carpal bones (and more specifically the scaphoid) to allow for more motion
the proximal row of carpal bones are said to extend slightly and the scaphoid "stands up" or lengthens to project its tubercle more distally
400
what is the primary stabilizer of the lunate
scapholunate ligament
400
what are the typical values needed for ADLs for all wrist motions
40 degrees wrist flexion
40 degrees wrist extension
10 degrees radial deviation
30 degrees ulnar deviation
400
what nerve roots does the radiocarpal joint get sensory information from
C6 and C7 carried by the median and radial nerves
400
at what ROM value does peak wrist flexion torque occur
about 40 degrees of flexion
400
what reinforces the sides of the triangular fibrocartilage
connections to the deeper fibers of the palmar and dorsal capsular ligaments of the distal radioulnar joint
500
what is the most unstable carpal bone and why
the lunate is the most unstable carpal bone due to:
shape
lack of muscular attachments
lack of strong ligamentous attachments to the rigid capitate
500
during radial deviation, what happens at the carpal bones (and more specifically the scaphoid)
during radial deviation, the proximal row of carpal bones are said to flex slightly and the scaphoid takes on a shortened statue which allows for a few more degrees of radial deviation before complete blockage against the radial styloid process
500
what are the two long ligaments (of the intrinsic wrist ligaments)
palmar intercarpal ligament: attaches the capitate to the scaphoid (lateral leg) and to the triquetrum (medial leg)
dorsal intercarpal ligament: interconnects the trapezium, scaphoid, triquetrum, and occasionally a small part of the lunate
500
what is the dart throwing motion and why does it occur
refers to the fact that extension naturally occurs with radial deviation and flexion occurs with ulnar deviation
this occurs because it is the path of least passive resistance to wrist motion and maximizes joint contact with the major joints of the wrist; it also helps to limit unwanted rotations of the scaphoid and lunate bones; finally it reflects the dominant actions of the wrist muscles
500
what nerve roots does the midcarpal joint get its sensory information from
C6 and C7 (carried by the median and radial nerves) AND C8 (carried by the deep branch of the ulnar nerve
500
what 2 muscles are able to produce the highest radial deviation torque and why
extensor carpi radialis longus and abductor pollicis longus because of their combined cross sectional area and moment arm
500
why is it dangerous to damage the triangular fibrocartilage
because the central 80% is avascular with poor or no healing potential
600
what is a DISI and a VISI
DISI: when the lunate dislocates so that its distal articular surface faces dorsally; often due to injury of the scapholunate ligament
VISI: when the lunate dislocates so that its distal articular surface faces volarly; often due to injury to the lunotriquetral ligament
600
explain the medial and lateral compartments of the midcarpal joint and their osteokinematics
the medial compartment is made up of the convex head of the capitate and apex of hamate fitting into the concave recess of the distal scaphoid, lunate, and triquetrum
the lateral compartment is made up of the slightly convex distal pole of the scaphoid fitting into the slightly concave proximal surfaces of the trapezium and trapezoid
600
explain the double V system of ligaments
distal inverted V: formed by medial and lateral legs of the palmar intercarpal ligament
proximal inverted V: formed by the lunate attachments of the palmar ulnocarpal and palmar radiocarpal ligaments
600
what are the ROM values for the functional grip and why is this the functional grip
30-35 degrees extension
5-15 degrees ulnar deviation
this optimizes the length tension relationship of the extrinsic finger flexors
600
which muscle has the greatest wrist flexion torque potential of all the primary wrist flexors
flexor carpi ulnaris
600
what is the main function(s) of the wrist extensor muscles
position and stabilize the wrist during activities involving active flexion of the digits; counterbalance the wrist flexion torque produced by the finger flexor muscles
600
what are the signs of TFCC damage
pain
joint instability
weakened grip
crepitus
reduced ROM at wrist and forearm