Hand

arthrokinematics of MCP joint

concave-on-convex articulation, in that the concave base of the proximal phalanges will move in the same direction as the distal end of the proximal phalanges during movement. Therefore, the base of the proximal phalanx glides anteriorly during flexion and posteriorly during extension, medially (toward the midline of the hand) during adduction, and laterally (away from the midline of the hand) during abduction, while the distal end of the proximal phalanx moves in the same direction with all of these motions.

MCP joints (digits 2-5) joint classification and motions

condyloid flexion/extension abduction/adduction

A ___ joint surface glides in the opposite direction of the body segment's movement.

convex

the heads of all phalanges and metacarpals are

convex

has all the fingers flexed around the object, which usually lies at a right angle to the forearm. The thumb is wrapped around the object in the opposite direction, often overlapping the fingers. Examples of a cylindrical grip would be holding a hammer, a racquet, or a wheelbarrow handle.

cylindrical grip

Posterior extrinsic muscles of the hand

Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor digitorum Extensor indicis Extensor digiti minimi

The second, third, fourth, and fifth digits, commonly known as the index, middle, ring, and little fingers, respectively, have four joints each. These joints are the

CMC joint, MCP joint, proximal interphalangeal (PIP) joint, and distal interphalangeal (DIP) joint

caused by an inflammation and thickening of the sheath containing the extensor pollicis brevis and abductor pollicis longus, resulting in pain on the radial side of the wrist.

De Quervain's disease

prime movers for finger abduction at MCP joint

Dorsal interossei, abductor digiti minimi

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.

Dupuytren's contracture

prime movers for finger extension at MCP joint

Extensor digitorum, extensor indicis, extensor digiti minimi

prime movers for finger flexion at DIP joint

Flexor digitorum profundus

Anterior extrinsic muscles of the hand

Flexor digitorum superficialis Flexor digitorum profundus Flexor pollicis longus

prime movers for finger flexion at PIP joint

Flexor digitorum superficialis, flexor digitorum profundus

refers to the necrosis of the lunate, which may develop after trauma.

Kienböck's disease

prime movers for finger extension at DIP and PIP

Lumbricals, extensor digitorum, extensor digiti minimi, extensor indicis

prime movers for finger flexion at MCP joint

Lumbricals, flexor digitorum superficialis, flexor digitorum profundus

prime movers for opposition (fifth) at CMC joint

Opponens digiti minimi

grips that are used for precision hand movements.

Pad-to-pad, pinch, tripod grasp, tip-to-tip, pad-to-side, side-to-side, and lumbrical grips

common hand injury among athletes, involves an acute tear of the ulnar collateral ligament of the thumb.

Skier's thumb

two interphlangeal joints in each finger

The PIP joint is the articulation between the base of the middle phalanx and the head of the proximal phalanx. The DIP joint is formed by the base of the distal phalanx articulating with the head of the middle phalanx. Both the PIP and DIP joints are uniaxial hinge joints allowing only flexion and extension, which occurs in the sagittal plane.

Given that the hinge joint structure yields a concave-on-convex articulation at the majority of finger and thumb joints (see Table 13-1), the arthrokinematic movement is the same for all of these joints.

The base of the more distal segment must glide anteriorly during flexion, and posteriorly during extension, moving with the distal end of the bony segment. When joint mobilizations are performed to restore motion that is limited, an anterior glide is performed to increase flexion, and a posterior glide is used to increase extension.

what CMC joint is most mobile

The fifth CMC joint is the most mobile of the fingers because of its more condyloid shape, which allows for a small amount of fifth finger opposition. It does not, however, allow as much opposition as the thumb (the first CMC joint).

motions of the CMC joint of the thumb

The joint allows flexion and extension, abduction and adduction, and opposition and reposition

accessory movement

The rotation at the CMC joint is a passive, not voluntary, motion. This rotation occurs as a result of the joint's shape and not by any muscle action. This type of motion is commonly referred to as an accessory movement (a movement that accompanies the active movement and is essential to normal motion).

MCP joint type

They are biaxial condyloid joints with two degrees of freedom, allowing flexion, extension, and hyperextension, plus abduction and adduction

arthrokinematics of thumb for abduction and adduction

When abduction and adduction (sagittal plane motion) occur, the convex base of the first metacarpal glides on the concave trapezium in the opposite direction from the distal end of the metacarpal (convex-on-concave articulation). During abduction, the distal end of the metacarpal moves anteriorly while the base of the metacarpal glides posteriorly, whereas adduction causes posterior movement of the distal end of the metacarpal with an anterior glide of the base.

occurs when the second, fourth, and fifth fingers move away from the middle (third) finger for MCP joints

abduction Adduction is the return from abduction and occurs with the second, fourth, and fifth fingers

prim movers of thumb abduction

abductor pollicis brevis, abductor pollicis longus,

prime movers of thumb adduction

adductor pollicis

prime movers of thumb reposition

adductor pollicis, extensor pollicis longus, extensor pollicis brevis

The proximal end of the metacarpals and phalanges is called the and the distal end is called the

base head

The trapezoid articulates with

base of the 2nd metacarpal

the hamate articulates with the

base of the 4th and 5th metacarpals

the capitate articulates with the

base of the third metacarpal

arthrokinematics of MCP and IP joints

both the MCP and IP joints have a concave-on-convex articulation where the concave base on the proximal end of the distal segment articulates with the convex head on the distal end of the proximal segment. This causes the concave joint surface to glide in the same direction as the distal end of the bony segment during movement.

the deformity is in the opposite direction—extension of the MCP joint, flexion of the PIP joint, and extension of the DIP joint.

boutonnière deformity

extremely common condition caused by compression of the median nerve within the carpal tunnel. Symptoms include numbness and tingling in the hand, which often begins at night. Patients often complain of tingling, pain, and weakness in the hand, particularly in the thumb, index, and middle fingers.

carpal tunnel syndrome

A ____ joint surface glides in the same direction as the body segment's movement.

concave

the base of all phalanges are

concave

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. These muscles are the adductor pollicis, the interossei (of which there are four dorsal and three palmar), and the lumbricals (of which there are also four muscles).

deep palm muscles

arthrokinematics of thumb for flexion and extension

during flexion and extension (frontal plane motion), the concave base of the first metacarpal glides in the same direction as the distal end of the metacarpal (concave-on-convex articulation). When flexion occurs, the base of the metacarpal glides medially while the distal end of the metacarpal also glides medially. During extension, the base glides laterally, along with lateral movement of the distal metacarpal

reposition uses a combo of

extension, adduction and "rotation," is the return to anatomical position.

prime movers of thumb extension

extensor pollicis longus and brevis

In addition to the wrist muscles previously described, there are several other muscles that span the wrist and cross the joints in the hand. These muscles are called ___ of the hand because their proximal attachment is above, or proximal to, the wrist joint.

extrinsic muscles

Opposition is a combination o

flexion and abduction in which the tips of the first and fifth digits move toward one another, with the "built-in" accessory motion of rotation

prime movers of thumb flexion

flexor pollicis brevis & longus

Flexion and extension occur in what plane for the thumb

frontal plane

an old term referring to a stretching injury of this same ligament developed over time by English gamekeepers as they twisted the necks of small game. Most injuries to the ulnar collateral ligament occur with a fall on an outstretched hand.

gamekeepers thumb

uniaxial joint classification

hinge, flexion/extension MCP joint (digit 1) IP joint (digit 1) PIP joints (digits 2-5) DIP joints (digits 2-5)

involves the second through fifth fingers flexed around an object in a hooklike manner (Fig. 13-38). The MCP joints are extended, and the PIP and DIP joints are in some degree of flexion. The thumb is usually not involved. Therefore, this is the only power grip possible if a person has a median nerve injury and loses the ability to oppose the thumb. Examples of this grip are seen when holding on to a handle, such as on a suitcase, a wagon, or a bucket.

hook grip

forming the hypothenar eminence, act primarily on the little finger.

hypothenar muscles

have their proximal attachment at or distal to the carpal bones and have a function on the thumb or fingers. These muscles are responsible for the hand's fine motor control and precision movement.

intrinsic muscles

sometimes referred to as the plate grip, has the MCP flexed and the PIP and DIP joints extended. The thumb opposes the fingers holding an object horizontal (Fig. 13-43). This grip is usually used when something needs to be kept horizontal, such as a plate or a tray.

lumbrical grip It is called a lumbrical grip because the action of the lumbrical muscles is to flex the MCP joints while extending the IP joints.

caused by disruption of the extensor mechanism of the DIP joint, either because the tendon was severed or because the portion of bone where the tendon attached has avulsed from the distal phalanx.

mallet finger In either case, the distal phalanx remains in a flexed position and cannot be extended. The scaphoid is the most frequently injured carpal bone.

Anteriorly, muscles on the thumb side are supplied primarily by the

median nerve

The thenar muscles are those that function to

move the thumb

The CMC joints of the fingers (digits 2 to 5) are classified as

nonaxial, plane-shaped synovial joints that provide slight gliding motion. Actually, they provide more stability than mobility.

prime movers of thumb opposition

opponens pollicis

MCP and PIP joints of the finger(s) are flexed, the thumb is abducted and opposed, and the distal joints of both are extended, bringing the pads of the finger(s) and thumb together.

pad-to-pad grip

has the pad of the extended thumb pressing an object against the radial side of the index finger (Fig. 13-41). This is a strong grip, but it allows less fine movements than the other two types. The terminal device of upper extremity prostheses adapts this type of grip. Also, because this grip does not require an opposed thumb, a person who has lost opposition but has retained thumb adduction can grasp and hold small objects.

pad-to-side grip

The flexor retinaculum is made up of the

palmar and transverse carpal ligaments (anterior view).

prime movers for finger adduction at MCP joint

palmar interossei

nonaxial joint classification

plane, gliding/sliding CMC joints (digits 2-5)

used when an object must be held forcefully while being moved about by more proximal joint muscles (holding a hammer or doorknob)

power Often a power grip involves an isometric contraction with no movement occurring between the hand and the object being held.

There are basically two types of prehension (grasps)

power and precision

used when an object must be manipulated in a finer type movement, such as holding a pen or threading a needle

precision grip

Similar to the wrist, muscles on the posterior surface of the hand are innervated mostly by the

radial nerve

CMC joint (digit 1) classification

saddle motions- flexion/extension abduction/adduction

Abduction and adduction occur in the

sagittal plane

usually results from a fall on the outstretched hand of a younger person. Because of a poor vascular supply, it has a high incidence of avascular necrosis.

scaphoid fracture

somewhat similar to pad-to-side grip, requires adduction of the index finger and abduction of the middle finger (Fig. 13-42). It is a weak grip and does not permit much precision. It is perhaps most frequently used to hold a cigarette. It is also used to hold an object, like a pencil, between two fingers while using another pencil or pen. Because the thumb is not involved, this grip could be used in the absence of the thumb.

side-to-side grip

has all the fingers and thumb abducted around an object, and, unlike the cylindrical grip, the fingers are more spread apart. The palm of the hand is often not involved (Fig. 13-37). Activities involving this grip include holding an apple or a doorknob or picking up a glass by its top.

spherical grip

characterized by flexion of the MCP joint, (hyper)extension of the PIP joint, and flexion of the DIP joint.

swan neck deformity

inflammation of tendons and their surrounding sheaths

tenosynovitis

The MCP joints of the fingers are formed by

the concave-shaped bases of the proximal phalanges articulating with the convex, rounded heads of the metacarpals. These are commonly referred to as the "knuckles."

IP joint type

the only phalangeal joint of the thumb, also allows only flexion and extension

bone structure of phalanges

the thumb has two phalanges, where the fingers each have 3

CMC joint is made up of

the trapezium bone, which articulates with the base of the first metacarpal. Its classification is debated by some, but it is most commonly described as a modified biaxial saddle joint. With both joint surfaces being concave and convex, the shape and relationship of these joint surfaces can be compared with two Pringles potato chips stacked one on top of the other.

The intrinsic muscles can be further divided into the

thenar, hypothenar, and deep palm muscles.

adductor pollicis muscle attaches in the middle of the palm to the

third metacarpal

joints of the thumb

three joints: the carpometacarpal (CMC) joint metacarpophalangeal (MCP) joint interphalangeal (IP) joint

involves bringing the tip of the thumb up against the tip of another digit, usually the index finger, to pick up a small object such as a coin or a pin

tip-to-tip grip It is also called pincer grip. This type of grip becomes difficult, if not impossible, with very long fingernails.

problem with the sliding mechanism of a tendon in its sheath. When a nodule or swelling of the sheath lining or the tendon develops, the tendon can no longer slide in and out smoothly. It may pass into the sheath when the finger flexes, but it becomes stuck as the finger attempts to extend.

trigger finger The flexor tendons of the middle and ring fingers are most commonly involved.

involve the thumb and two fingers, usually the index and middle fingers. ex holding a pencil

tripod grasp or three-jaw chuck.

results in ulnar deviation of the fingers at the MCP joints.

ulnar drift

muscles on the little finger side are supplied primarily by the

ulnar nerve

The adductor pollicis muscle appears to be the exception; it is innervated by the

ulnar nerve rather than the median nerve like all the other thumb (pollicis) muscles.

ligaments of the hand

- annular ligaments - cruciate ligaments - extensor retinaculum - flexor retinaculum - palmar carpal ligament - transverse carpal ligament

joints of the hand

- carpometacarpal joint - distal interphalangeal joint (digit 2-5) - interphalangeal joint (digit 1) - metacarpophalangeal joint - proximal interphalangeal joint (digit 2-5)