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K Hand
book
Term | Definition |
---|---|
CMC joint of the thumb | made up of the trapezium bone, which articulates with the base of the 1st metacarpal. It is biaxial, saddle joint. |
The CMC joint of the thumb allows... | flexion & extension, abduction and adduction, and opposition and reposition. |
Flexion and extension occur in a plane... | parallel to the palm |
Abduction and adduction occur in a plane... | perpendicular to the palm |
Opposition is a combination of... | flexion and abduction with "built-in" accessory motion of rotation |
Reposition is... | the return to anatomical position. It is bc of this accessory rotation that the CMC jt is usually considered a "modified" biaxial jt |
The MCP joint of the thumb is ... | a hinge jt that allows only flexion and ext and is therefore a uniaxial jt |
The IP joint is... | the only phalangeal joint in the thumb, also allows only flexion and ext |
The carpometacarpal jts of the fingers are classified as... | nonaxial plane (irregular) synovial joints that provide more stability than mobility |
The trapezium articulates with | the base of the first metacarpal |
the capitate articulates with | the third metacarpal |
the hamate articulates with | the 4th and 5th metacarpals |
the 5th CMC joint is the most... | mobile of the fingers and allows for a small amount of fifth finger opposition |
the metacarpophalangeal joints (MCP) of the fingers are... | biaxial condyloid jts |
the motions allowed at the MCP are... | flexion, ext, and hyperext, plus abduction and adduction |
the middle finger is... | the point of reference for abduction and adduction |
there are 2 interphalangeal jts... | PIP & DIP |
major difference between the bones in thumb and fingers... | thumb has 2 phalanges, whereas the fingers each have 3 |
the proximal end of the metacarpals and phalanges is called... | the base |
distal end of metacarpals and phalanges is called | the head |
oblique line | located on the anterior surface of the radius from below the tuberosity, running diagonally to approximately midradius |
flexor retinaculum ligament | is a fibrous band that spans the anterior surface of the wrist in a mediolateral (horizontal) direction. |
main function of flexor retinaculum ligament | hold tendons close to the wrist, thus preventing the tendons from pulling away from the wrist (bow-stringing) when the wrist flexes. also prevents the two sides of carpal bones from spreading apart or separating |
flexor retinaculum is made up of | two parts that formerly were known as palmar carpal ligament and the transverse carpal ligament. |
palmar carpal ligament is more | proximal and superficial. attaches to the styloid processes of the radius and ulna and crosses over the flexor muscles |
transverse carpal ligament | lies deeper and more distal. it attaches to the pisiform and hook of the hamate on the medial side and to the scaphoid and trapezium bones laterally. arches over carpal bones forming a tunnel thru which the median nerve & 9 extrinsic flexor tendons pass |
extensor retinaculum ligament | fibrous band traversing the posterior side of the wrist in a horizontal mediolateral direction. attaches medially to the styloid process of the ulna and to the triquetrum, pisiform, and lateral side of the radius. holds extensor tendons close to wrist |
extensor expansion ligament | also called extensor hood- small triangular flat aponeurosis covering the dorsum and sides of the proximal phalanx of the fingers.extensor digitorum tendon blends into the expansion |
extensor hood area formed by extensor expansion proximally | covers the head of the metacarpal and keeps the extensor tendon in the midline |
proximal carpal arch | formed by the proximal end of the metacarpals (base) and carpal bones and is maintained by the flexor reticulum |
distal carpal arch | shallower, made up of the metacarpal heads |
longitudinal arch | begins at the wrist and runs the length of the metacarpal and phalanges for each digit. it is perpendicular to the other two arches |
extrinsic muscles | start in the forearm and end in the hand and have an assistive role in the wrist function but their primary function is at the thumb or finger |
pollicis | thumb |
anterior extrinsic muscles | flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus |
posterior extrinsic muscles | abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor digitorum, extensor indicis, extensor digiti minimi |
the borders of the anatomical snuffbox are defined by | the tendon of the extensor pollicis longus muscle on one side and the tendons of the abductor pollicis longus and brevis muscles on the other side |
intrinsic muscles | start in the hand and end in the hand- responsible for the hand's fine motor control and precision movement |
thenar muscles | are those that function to move the thumb- flexor pollicis brevis, abductor pollicis brevis, opponens pollicis |
deep palm muscles | are located deep in the palm of the hand between the thenar and hypothenar muscles. they perform some of the more intricate motions that usually involve multiple muscles -adductor pollicis, interossei, lumbricales |
hypothenar muscles | forming the hypothenar eminence, act primarily on the little finger- flexor digiti minimi, abductor digiti minimi, opponens digiti minimi |
DAB | Dorsal Interossei-abducts fingers at MCP jt |
PAD | Palmer Interossei-adducts fingers at the MCP jt |
Colles' fracture | common injury of elderly people, resulting from a fall on the outstretched hand. this transverse fracture of the distal radius includes a posterior displacement of the distal fragment |
Smith's fracture | the distal fragment is displaced anteriorly (reverse Colles) and is caused by a fall on the back of the hand |
greenstick fracture | refers to an incomplete fracture, usually of the radius and more proximal than a Colles' fracture. more common in children |
ganglion cyst | is a benign tumor mass commonly seen as a bump on the dorsal surface of the wrist |
carpal tunnel syndrome | is an extremely common condition caused by compression of the median nerve within the carpal tunnel. |
carpal tunnel syndrome symptoms | numbness and tingling in the hand, which often begins at night. Patients often c/o tingling pn and weakness in the hand, particularly in the thumb, index and middle fingers. tapping over the carpal tunnel often produces symptoms. |
DeQuervain's disease | caused by inflammation and thickening of the sheath containing the extensor pollicis brevis and abductor pollicis longus, resulting in pn on the radial side of the wrist. |
tenosynovitis | inflammation of tendons and their surrounding sheaths |
dupuytren's contracture | occurs when the palmar aponeurosis undergoes a nodular thickening. it is most common in the area of the palm in line with the ring and little fingers. often those fingers will develop flexion contractures |
stenosing tenosynovitis | commonly known as trigger finger, is a problem with the sliding mechanism of a tendon in its sheath. flexor tendons of the middle and ring fingers are most commonly involved |
skier's thumb | a common hand injury among athletes, involves an acute tear of the ulnar collateral ligament of the thumb |
gamekeeper's thumb | old term referring to a stretching injury of this ligament developed over time by English gamekeepers as they twisted the necks of small game |
swan neck deformity | characterized by flexion of the MCP jt, (hyper)extension of the PIP jt and flexion of the DIP jt |
boutonniere deformity | the deformity is in the opposite direction-ext of the MCP jt, flexion of the PIP jt, and ext of the DIP jt |
ulnar drift | results in ulnar deviation of the fingers at the MCP jts |
mallet finger | is caused by the disruption of the extensor mechanism of the DIP jt, either b/c the tendon was severed or b/c the portion of bone where the tendon attached has avulsed from the distal phlanax. distal phalanx remains in flexed position and cant be ext |
scaphoid fracture | scaphoid is most frequently injured carpal bone. usually results from a fall on the outstretched hand of a younger person. b/c of poor vascular supply, it has a high incidence of avascular necrosis |
Kienbock's disease | refers to the necrosis of the lunate, which may develop after trauma |
prehension | main function of hand is grasp |
the shoulder girdle and shd jt position the hand | in space |
the elbow allows the hand to | move closer or farther away from the body, especially the face |
the wrist provides | stability while the hand is manipulating objects |
release is the role of | the MP (on pg 189), PIP, and DIP extensors |
hand sensation is provided by the | radial, ulnar and median nerves |
functional position of the wrist and hand | wrist is in slight ext, the MCP and PIP jts are in some degree of flex, and the thumb is in opposition |
basically 2 types of prehension | power grips & precision grips |
power grip | used when an object must be held forcefully while being moved about by more proximal jt muscles (holding hammer or doorknob) |
precision grip | precision prehension, is used when an object must be manipulated in a finer type movement, such as holding a pen or threading a needle |
3 commonly described power grips | cylindrical, spherical and hook |
cylindrical grip | all the fingers flexed around the object, which usually lies at a right angle to the forearm. thumb is wrapped around the object in opposite direction overlapping fingers ex holding a hammer, racquet, wheelbarrow handle |
variation of the cylindrical grip | fingers flexed around a handle in a graded fashion. 5th finger joints are flexed the most, and the second finger jts are only partly flexed. thumb lies parallel and against the handle and wrist is in slight ulnar deviation, ex golf club, screwdriver |
spherical grip | all the fingers and thumb abducted around an object, unlike the cylindrical grip, the fingers are more spread out. palm often not involved. ex holding apple or doorknob or picking up a glass by its top |
hook grip | involves the 2nd-5th fingers flexed around an object in a hooklike manner. Thumb usually not involved. only power grip available if median nerve injury. ex holding on to handle, such as suitcase, wagon or bucket |
4 commonly recognized types of precision grip | pad-to-pad, tip-to-tip, pad-to-side, side-to-side |
pad-to-pad grip | MCP & PIP jts of finger(s) are flexed, thumb abducted & opposed, distal jts of both ext, bringing the pads of the finger(s)& thumb together |
pinch grip | when pad-to-pad involves the thumb & 1 finger, usually the index |
three-jaw chuck | when pad-to-pad involves the thumb and 2 fingers, usually index & middle. ex holding a pen or pencil. most common precision grip |
tip-to-tip grip | involves bringing the tip of the thumb up against the tip of another digit, usually index, to pick up small object like coin or pin- also called pincer grip. hard with long nails |
pad-to-side grip | lateral prehension- pad of the ext thumb pressing an object against the radial side of the index finger. strong grip, less fine movements. Doesn't require opposed thumb. ex car key |
side-to-side grip | somewhat similar to pad-to-side grip, requires adduction of 2 fingers, usually the index or middle fingers. weak grip & does not permit much precision. it is perhaps most freq used to hold a cigarette. doesn't involve thumb |
lumbrical grip | sometimes referred to as the plate grip, has the MCP flexed and the PIP and DIP jts extended. thumb opposed the fingers holding an object horizontal. usually when something needs to be horizontal like plate or tray, named after the lumbrical muscles |
isometric contractions are used | to stabilize or hold a body part in position |
convex jt surface moves | in the opposite direction of the body segment's movement |
concave jt surface moves | in the same direction of the body segment's movement |
the sagittal plane divides the body | into right and left parts |
the frontal plane divides the body | into front and back parts |
the transverse plane divides the body | into top and bottom parts |