Unit 3 Study Guide
purpose of extensor retinaculum
It holds down the long extensor tendons, keeping them from bowstringing.
what is the midcarpal joint comprised of?
It is comprised of a series of gliding synovial intercarpal joints all within the same joint cavity;
functions of interosseous membrane
It serves to (a) resist the separation of the 2 bones when loading the hand and radius, and (b) distribute forces from the hand and radius into the ulna and humerus during compression or traction of the radius.
what two directions do the fibers run in the interosseous membrane?
Its fibers run in 2 directions: distally towards the radius (including the oblique cord), and distally towards the ulna (the bulk of the 'membrane').
which way do the palmar carpal ligament fibers run? what does it connect and what does this create?
Its fibers run transversely and connect the tendon and palmar aponeurosis to the pisiform and hook of the hamate, creating the ulnar (Guyon's) tunnel between its underside and the flexor retinaculum.
what direction are the flexor retinaculum's fibers? what do they attach to and what do they form?
Its transversely-oriented fibers attach to 4 points on the palmar sides of the carpals, forming the roof of the carpal tunnel and maintaining the carpal arch.
what are most of the fibers designed to do in the interosseous membrane? why?
Most of the fibers of the 'membrane' are designed to resist compression, since we commonly use our hands and arms to press against surfaces or objects.
what movements are permitted at the radiocarpal and ulnocarpal joints?
Motion at the radiocarpal + ulnocarpal joint occurs primarily in the anterior-posterior plane (flexion and extension of the wrist), but unlike most hinge joints, some lateral motions (ulnar and radial deviation) are permitted, especially ulnarly, as is limited circumduction.
motion at CMC joints?
Motion at these joints is generally limited for digits 2 to 4 but more significant for digits 1 and 5.
motion is largely restricted to what planes at the elbow?
Motion is largely restricted to the anterior-posterior plane
what type of joints are the IP?
double-condylar (hinge) that restrict motion to the anterior/posterior plane.
what does the proximal row of carpal bones form?
radiocarpal joint with the radius (although the pisiform does not participate directly in this joint)
the forearm (antebrachium) is comprised of what two bones?
radius and ulna
the head of the ulna is _____ relative to the distal radius
retracted
proximal row of carpal bones
scaphoid, lunate, triangular, pisiform
how are the shafts of the metacarpals slightly curved?
slightly longitudinally curved (concave) on their palmar side
what is the pneumonic to remember the carpal bones
some lions tackle prey that they can't handle
why are the central MCs elevated compared to MC1 and MC5
to protect the nerves and vessels that run the length of the palm when you press your hand on a hard surface or tightly grasp an object
what do the heads of the metacarpals form?
promiment "knuckles" on the dorsum of the hand.
the forearm attaches proximally to the _______ and distally to the _______
proximally to the distal humerus and distally to the carpals
where does the thumb's single IP joint lie?
(The thumb's single IP joint falls between its proximal and distal phalanges.)
what 3 joints intersect at the elbow?
(a) between the trochlea of the humerus and the trochlear surface of the ulna (the ulnohumeral joint); (b) between the capitulum and the radial head (the radiohumeral joint); and (c) between the radial head and radial notch of the ulna (the proximal radioulnar joint).
the joints formed by the radius and ulna on the capitulum and trochlea of the humerus create what type of joint?
-bicondylar (hinge) joint with the capitulum and trochlea becoming the paired condyles (similar to the knee joint) this is why the humeral prominences located immediately proximal to these condyles are called the medial and lateral *epicondyles*
what are the structures of the ulna?
-*trochlear articular surface (for ulnohumeral joint)* -*olecranon process* -*coronoid process* -*ulnar tuberosity* -*radial notch* -shaft -interosseous crest -neck -head -styloid process
what are the structures of the radius?
-head, neck, *tuberosity*, shaft, interosseous crest, *lister's (dorsal) tubercle*, *ulnar notch*, styloid process, *carpal articular surface (fore scaphoid and lunate)*
intrinsic stabilizing features of radioulnar joint
-joint capsule -palmar and dorsal radioulnar ligaments -interosseous membrane (oblique cord)
intrinsic stabilizing features of the radiocarpal and ulnocarpal joints
-joint capsule -triangular fibrocartilage (TFC) -palmar radioulnar ligament -dorsal radioulnar ligament
extrinsic stabilizing features of radiocarpal and ulnocarpal joints
-palmar radiocarpal ligament -palmar ulnocarpal ligamnet -dorsal radiocarpal ligament -dorsal ulnocarpal ligament -radial collateral ligament -ulnar collateral ligament -muscles
how are the proximal and distal radioulnar joints positioned?
-so that the radius can rotate around the shaft of the ulna during supination and pronation of the forearm.
how are the heads of the metacarpals, and proximal phalanges shaped? what type of joint does this create and what does this allow movement wise?
-the heads of the metacarpals are condylar and bulbous -proximal phalanges are concave -this forms a semi-balla nd socket joint that allows the MP joints to move 3 directions (circumduction)
MC1 attached to ______ MC2 _____ MC3______ MC4 and 5 _____
1-trapezium 2-trapezoid 3-capitate 4 and 5-hamate
_____ separate synovial joints intersect at the elbow
3
what are the longest bones of the hand and form the bulk of the palm and dorsum? what is the structure of the bone?
5 metacarpals typical long bone-central shaft and 2 ends (proximal base and distal head)
the hand (manus) is comprised of ____ metacarpals, ____ manual phalanges, arranged in ____ rows
5 metacarpals 14 manual phalanges 4 rows
14 manual phalanges _____ proximal ______middle _____ distal
5 proximal, 4 middle, 5 distal
what is the number order for the carpal bones? (left hand palm up)
5678 (distal) 1234 (proximal) 1-some (scaphoid) 2-lions (lunate) 3-tackle (triangular-3rd one, triangle) 4-prey (pisiform) 5-that (trapezium-trapeziUM, thUMB) 6-they (trapezoid) 7-can't (capitate) 8-handle (hamate)
the wrist (carpus) is comprised of ____ carpals arranged in ___ rows of ____.
8 carpals arranged in 2 rows of 4
when can dislocation injuries happen with the ulnocarpal or radiocarpal joints? what strcutres are impacted?
Dislocation injuries can occur during heavy falls onto the hand, with the lunate being especially prone to moving out of position ventrally (where it can compress the median nerve); alternatively, the scaphoid and/or distal radial shaft can fracture.
dislocation injuries of the elbow occur during ___________. what happens to the radius and ulna during these injuries?
Dislocation injuries of the elbow occur during heavy falls onto the hand, with the proximal ulna and radius generally forcing their way posteriorly under the distal humerus; bone fractures (tip of coronoid process, neck or head of radius) are common in this scenario.
dislocation of the radioulnar joints-when can it occur and what does it result in?
Dislocation of the radioulnar joints can occur when the radius is put into extreme traction or compression relative to the ulnar shaft, or when something drives the 2 bone shafts apart at either end, resulting in a tear to the interosseous 'membrane'.
so the IP joints have collateral ligaments that are tightest during _______, but the MP joints have collateral ligaments that are tightest during _____
IP=extension MP=flexion
where does rotation of the radius occur? when does it occcur?
In addition, rotation of the radius during pronation and supination of the forearm occurs at the proximal radioulnar and radiohumeral joints (as well as at other more distal joints of the forearm; see below).
what happens to the interosseous membrane during full pronation or supination? what about midway between pron/sup?
In full pronation or full supination, the shafts come closer together and the membrane is a bit looser. midway-it gets really tight and is in close packed position
what motion occurs at the midcarpal joint
Motion occurs primarily in the anterior-posterior plane during flexion and extension of the wrist and mediolaterally during deviation of the wrist.
does the pisiform participate in the radiocarpal or ulnarcarpal joints?
Note that the pisiform rides atop the triangular bone and does not participate in either the radiocarpal or ulnocarpal joints.
taken together, the elbow is classified as a _______ joint in which ______ is more important than ________
Taken together, the elbow is classified as a double-condylar (hinge) joint in which stability is more important than flexibility
closed packed position of midcarpal joint
The "close-packed" position of the joint occurs when the wrist is fully extended, which is the position that is most likely to accompany heavy loading.
closed packed position of radiocarpal and ulnocarpal joints
The "close-packed" position of the joint occurs when the wrist is fully extended, which is the position that is most likely to accompany heavy loading.
what two bones does the TFC come into contact with?
The TFC comes into contact with the lunate and/or triangular bone, depending on the deviation status (ulnar or radial) of the wrist.
what muscles stabilize the elbow joint extrinsicly?
The brachial flexors and extensors and forearm flexors and extensors, when tensed, resist traction of the radius and ulna at the elbow.
where do the carpometacarpal (CM or CMC) joints lie? what kind of joint are they?
The carpometacarpal joints lie between the distal row of carpals and the bases of the 5 metacarpals. They are synovial gliding joints.
extensor retinaculum
The extensor retinaculum is an extension of the antebrachial fascia over the dorsum of the wrist. Its fibers run transversely, being continuous with the palmar carpal ligament on the palmar side.
what do the transverse metacarpal ligaments hold together, and what does it prevent?
The heads of MC2 to 5 are held together by transverse metacarpal ligaments, which keep them from separating during grasping and therefore maintain the shape of the palm.
types of interphalangeal joints (IP) and where they lie?
The interphalangeal joints lie between (a) the heads of the proximal phalanges and bases of the middle phalanges (proximal interphalangeal, or PIP joints), and (b) the heads of the middle phalanges and bases of the distal phalanges (distal interphalangeal, or DIP joints
muscles that help stabilize the midcarpal joints
The long forearm flexor and extensor tendons crossing the wrist help to stabilize the midcarpal joint.
what muscles help to stabilize the radiocarpal and ulnocarpal joints?
The long forearm flexor and extensor tendons crossing the wrist help to stabilize the radiocarpal and ulnocarpal joints.
where do the metacarpophalangeal(MP) joints lie? what kind of joint are they? what kind of movement do they permit?
The metacarpophalangeal joints lie between the heads of the metacarpals and the bases of the proximal phalanges. They are synovial condylar joints that permit motion in all directions (flexion / extension, abduction / adduction, and limited circumduction).
joint capsule of radioulnar joint
The proximal and distal radioulnar joints are each surrounded by a fibrous blanket; the proximal's capsule also surrounds the entire elbow joint. The distal's capsule also surrounds the radiocarpal and ulnocarpal joints (see below), but its synovial cavity is separated from the cavity of the others by the triangular fibrocartilage.
radiocarpal joint is classified as a ______ in which stability and flexibility are _____ balanced than the elbow
The radiocarpal joint is classified as a modified double-condylar (hinge) synovial joint in which stability and flexibility are more evenly balanced than in the elbow.
what structurs run through the ulnar (Guyon's) tunnel?
The ulnar nerve and artery run through the tunnel.
palmar and dorsal radioulnar ligaments-purpose
These stabilize the distal radioulnar joint by keeping the head of the ulna in contact with the ulnar notch of the radius; see section
how are the IP joints strengthened? when are their ligaments the tighest?
They are strengthened by extrinsic collateral ligaments on their radial and ulnar sides, which are tightest in *extension* of those joints. In addition, each joint contains a palmar ligament (plate) on the palmar side, which protects the joint when grasping hard objects.
extrinsic collateral ligaments on MP joints (where are they located and when are they tightest)
They are strengthened by extrinsic collateral ligaments on their radial and ulnar sides, which are tightest in flexion of those joints.
how are the CMC joints strengthened?
They are strengthened by extrinsic palmar and dorsal carpometacarpal ligaments.
what kind of joints are the interphalangeal (IP) joints, what kind of motion do they permit?
They are synovial bicondylar joints that permit motion primarily in the anterior-posterior plane (flexion and extension).
what three joints link the radius to the ulna?
Three separate joints link the radius with the ulna: (a) the synovial proximal and distal radioulnar joints, and (b) a fibrous 'middle' radioulnar syndesmosis that extends for most of the length of the forearm.
intercarpal ligaments
Various small ligaments bind the carpals that participate in this joint.
annular ligament-what is it and what is its purpose?
a band of fibers surrounding the greatest circumference of the radial head, keeping it in close contact with the radial notch of the ulna (at the proximal radioulnar joint) but still allowing the radius to rotate along its long axis in any position of the elbow.
lateral (radial) collateral ligament=what is it, when is it tightest, and what does it prevent?
a fan-shaped ligament connecting the lateral epicondyle to the proximal radius via the annular ligament. It is tightest in full extension of the elbow and resists ulnar (medial) deviation of the forearm.
medial (ulnar) collateral ligament-what is it, when is it tightest, and what does it prevent?
a fan-shaped ligament connecting the medial epicondyle to the proximal ulna. It is tightest in full extension of the elbow and resists radial (lateral) deviation of the forearm.
palmar surfaces of the phalanges are flat transversely but curved longitudinally providing
a nice surface for grasping objects
what fills the gap between the head of the ulna and the triangular bone?
a pad of fibrocartilage (triangular fibrocartilage)
joint capsule of midcarpal joint
a single fibrous blanket surrounds the entire midcarpal joint and all carpals that participate in it.
together the 3 joints around the radius and ulna allow
allow the radius to rotate around the ulna during pronation and supination while simultaneously ensuring that the 2 bones do not pull apart.
flexor retinaculum (transverse carpal ligamnet)
an extension of the antebrachial fascia over the palmar side of the wrist, deep to the palmar carpal ligament.
palmar carpal ligmanet
an extension of the antebrachial fascia over the palmar side of the wrist, superficial to the palmaris longus tendon and flexor retinaculum.
the CM joints at the bases of digits 2-4 are rather
boxy and interlock tightly
transverse arch
can be seen at the carpals (forming carpal tunnel) and at the heads of the metacarpals
what carpal bone lies at the very center of the wrist
capitate
longitudinal arch
carpals to fingertips runs the length of the hand
distal row of carpal bones forms the
carpo-metacarpal (CM or CMC) joints
each metacarpal is attached to a distal row carpal at a ____ joint
carpometacarpal (CM)
what are the MP joints strengthened by?
extrinsic collateral ligaments palmar plate (ligament) transverse metacarpal ligaments
intercarpal joints
fall between various carpals all contained in one large synovial capsule
the majority of the interosseous membrane is made of
fibers running distally towards the ulna
radial collateral ligament
fibers running from the radial styloid to the scaphoid and trapezium bones. They prevent excess ulnar deviation and hyperextension of the wrist.
ulnar collateral ligament
fibers running from the ulnar styloid to the triangular and pisiform bones. They prevent excess radial deviation and hyperextension of the wrist.
dorsal radioulnar ligament
fibers running transversely from the radius to the ulnar styloid, holding the dorsal edge of the TFC in place and stabilizing the distal radioulnar joint.
palmar radioulnar ligament
fibers running transversely from the radius to the ulnar styloid, holding the palmar edge of the TFC in place and stabilizing the distal radioulnar joint.
what happens to the ulna and radius during flexion and extension of the elbow?
flexion and extension occurs when the ulna rotates around the trochlea at the ulnohumeral joint, and the radius glides on the capitulum at the radiohumeral joint.
how are the digits numbered? what number is the thumB
from radial to ulnar, making the thumb (pollux) digit 1, and the pinky digit 5 regardless of the position of the hand or forearm
what does the retraction of the ulnar head relative to the distal radius allow?
gives us greater motion in ulnar deviation of the wrist than radial deviation more motion at ulnar deviation than radial
when are the ulnar and radial collateral ligaments the tightest?
in close packed position of the elbow-extension
what does the radioulnar syndesmosis include?
includes the interosseous 'membrane' (a ligament) that falls between the shafts of the radius and ulna.
extrinsic stabilizing features of midcarpal joint
intercarpal ligaments muscles
the articular surfaces at the sides of the adjacent metacarpals form the
intermetacarpal joints
how is the CM joint of MC1 unusual?
it is *saddle-shaped* and allows the thumb to be much more mobile than the other fingers.
intrinsic stabilizers of midcarpal joint
joint capsule
intrinsic stabilizing features of the elbow joint
joint capsule
interphalangeal (IP) joints
joints between phalanges
PIP joints
joints between proximal and middle phalanges (proximal interphalangeal joints)
DIP joints
joints between the middle and distal phalanges (distal interphalangeal joints)
extrinsic stabilizing features of the elbow joint
lateral (radial) collateral ligament median (ulnar) collateral ligament annular ligament muscles
the 14 manual phalanges are also classified as
long bones. have same basic features as metacarpals
the proximal head of the capitate looks a bit like a ______ when viewed from the palmar side, and the carpals in the proximal row encircle it.
marble
the joint between the proximal and distal rows of carpal bones is the
midcarpal joint
what joint lies between the proximal and distal rows of carpals?
midcarpal joint
what does the thumb not have? why?
middle phalanx. not sure
extrinsic stabilizers of radioulnar joint
muscles-The forearm flexors and extensors crossing between the radius and ulna (supinator, pronator teres & quadratus) stabilize all 3 radioulnar joints by resisting separation of the 2 bones.
so does the ulna articulate with the carpals at the radiocarpal joints?
no
why are the shafts of the metacarpals slightly concaved on their palmar side?
not sure ask
close-packed position of the radioulnar syndesmosis
occurs when the 'membrane' is tightest, which occurs when the forearm is midway between pronation and supination. In this 'neutral' position of the forearm, the bowed shafts of the 2 bones are farthest apart.
the TFC can be treated as an extension of
of, or a shelf projecting from, the radius' carpal articular surface.
what kind of joint does the thumb have?
only a single interphalangeal joint
palmar plate (ligament) in MP joit
palmar plate (ligament) on the palmar side, which protects the joint when grasping hard objects.
the CM joint of the ______ is slightly more flexible than those of digits 2-4 which allow
pinky allows the pinky to come across the distance of the palm to fully oppose the thumb
the capitate is known as the
structural center of the wrist
the apex of the TFC is loosely attached to the
styloid process of the ulna by the palmar and dorsal radioulnar ligaments.
the radiocarpal and carpo-metacarpal joints are all
synovial but many are reinforced by strong extrinsic ligaments
all three of the joints at the elbow fall within the same
synovial joint capsule
dorsal radiocarpal ligament
the combined fibers running from the distal radius to the various carpals on the dorsal side of the wrist; the fibers run ulnarly as they move distally. They resist hyperflexion of the radiocarpal joint and pull the hand with the radius during pronation.
palmar radiocarpal ligament
the combined fibers running from the distal radius to the various carpals on the palmar side of the wrist; the fibers run ulnarly as they move distally. They resist hyperextension of the radiocarpal joint and pull the hand with the radius during supination.
palmar ulnocarpal ligament
the combined fibers running from the distal ulna to the various Materials for the Upper Extremity -- page 3-24 carpals on the palmar side of the wrist; the fibers run radially as they move distally. They resist hyperextension of the ulnocarpal joint.
dorsal ulnocarpal ligament
the combined fibers running from the distal ulna to the various carpals on the dorsal side of the wrist; the fibers run radially as they move distally. They resist hyperflexion of the ulnocarpal joint.
The convex surfaces of the scaphoid, lunate, and triangular bones move on the concave surface formed by the
the distal radius and the triangular fibrocartilage at the head of the ulna; the latter portion is the ulnocarpal joint, which is indirect since the head of the ulna does not normally contact the carpals.
the midcarpal joint includes the contact point between the
the head of the capitate and the proximal carpals, which together form a semi- condylar arrangement.
how does the length of the head of the ulna (distal area) compare to the distal radius
the head of the ulna (at its distal end) does not extend as far or as prominently as the distal radius; *the ulna therefore does not articulate directly with the carpals at the wrist (radiocarpal) joint*
why do most people include the ulnocarpal joint as a part of the radiocarpal joint
the head of the ulna does not normally contact the carpals. Therefore, most people include the ulnocarpal joint as part of the radiocarpal joint.
interosseous membrane
the ligament that crosses the gap between the interosseous crests on the shafts of the ulna and radius
what does the olecranon process do when the arm is in full extension? what does this do?
the olecranon process of the ulna rotates into the olecranon fossa of the humerus during full extension of the elbow helping to lock it in place under a load
what forms the heel of the hand?
the shaft of MC5 and the overlying tissues of the hypothenar eminence
how is the ulnohumeral joint (trochlear) designed? what type of movement does it permit?
the structure is designed to direct motion antero-posteriorly and limit motion medio-laterally.
metacarpophalangeal (MP) joints
the synovial joints that fall between the heads of the metacarpals and the bases of the proximal phalanges
joint capsule radiocarpal and ulnocarpal joints
the tough, fibrous connective tissue blanket surrounding both the radiocarpal and ulnocarpal joints as well as the distal radioulnar joint.
joint capsule of elbow joint (what is it and what does it surround)_
the tough, fibrous connective tissue blanket surrounding the joint, encapsulating the radiohumeral, ulnohumeral, and proximal radioulnar joints.
where does the ulna articulate with the distal humerus?
the ulnohumeral (trochlear) joint at the trochlea of the humerus
two or 3 manual sesamoids typically form within the long flexor tendons on the palmar sides of the heads of the 1, 2 and sometimes 3 metacarpals. what is their function?
these tiny bones facilitate the movement of the tendons across the joints and protects them from crushing during strong grasping of hard objects
where do the interosseous crests onthe shafts of the radius and ulna face when the bones are in their proper anatomical positions? in life what would the crests be joined by?
they face each other -in life they would be joined by the interosseous membrane (actually a ligament), forming a *syndesmosis (fibrous)* joint along their entire length
what is the elbow joint comprised of?
three different joints: ulnohumeral (trochlear), radiohumeral (radiocapitate), and proximal radioulnar joints.
distal row of carpal bones
trapezium, trapezoid, capitate, hamate
each distal phalanx terminates in a flat, bulbous head that serves as a foundation for the surrounding fingerpads and fingernails. the _____ shape of the distals is the source of their name
triangular phalanx=wedge
stable, closed-packed position of the elbow
when the ulna is fully extended and its olecranon process becomes cradled in the olecranon fossa of the humerus.
what does the triangular fibrocartilage consist of? where is it attached and what is its function?
• triangular fibrocartilage (TFC): also known as the "TFCC" (triangular fibrocartilage complex). It consists of a triangular pad of fibrocartilage (an articular disk, or meniscus) that is attached to the ulnar side of the distal radius, dividing the joint space between the head of the ulna and the triangular bone and also separating the distal radioulnar joint cavity from the radiocarpal + ulnocarpal joint cavity.