The hand part 2 Flashcards
List the joints of the hand region
Distal radio-ulnar joint Wrist joint Intercarpal joints Carpo-metacarpal and inter-metacarpal joints Metacarpo-phalangeal joints Interphalangeal joints
Describe the muscles involved in the different movements of the wrist joints
Flexion
FCR and FCU – important
Long flexors of thumb and fingers
(PL, APL)
Extension
ECRL, ECRB, ECU – important
Long extensors of the thumb and fingers
Radial deviation
APL, FCR, ECRL, ECRB
Ulnar deviation
ECU, FCU
Summarise the intercarpal joints
Joints between the proximal row
scaphoid, lunate, triquetral, pisiform
Joints between the distal row
trapezium, trapezoid, capitate, hamate
Joints between the proximal and distal rows
the midcarpal joint
“gliding occurs at these joints”
Describe the structure of the carpal joints and the movements that they facilitate
The synovial joints between the carpal bones share a common articular cavity. The joint capsule of the joints is reinforced by numerous ligaments.
Although movement at the carpal joints (intercarpal joints) is limited, the joints do contribute to the positioning of the hand in abduction, adduction, flexion, and, particularly, extension.
Summarise the carpometacarpal joints
CMC of the thumb – clinically important (trapezium to thumb metacarpal) CMC of digits Movements are; flexion and extension radial deviation and ulnar deviation circumduction
Describe the carpometacarpal joint of the thumb and its clinical importance
The saddle joint, between metacarpal I and the trapezium, imparts a wide range of mobility to the thumb that is not a feature of the rest of the digits. Movements at this carpometacarpal joint are flexion, extension, abduction, adduction, rotation, and circumduction.
The carpometacarpal joint of the thumb (pollex), also known as the first carpometacarpal joint, or the trapeziometacarpal joint (TMC) because it connects the trapezium to the first metacarpal bone, plays an irreplaceable role in the normal functioning of the thumb. The most important joint connecting the wrist to the metacarpus, osteoarthritis of the TMC is a severely disabling condition; up to twenty times more common among elderly women than in average.[1]
Pronation-supination of the first metacarpal is especially important for the action of opposition.[1] The movements of the first CMC are limited by the shape of the joint, by the capsulo-ligamentous complex surrounding the joint, and by the balance among involved muscles. If the first metacarpal fails to sit well ‘on the saddle’, for example because of hypoplasia, the first CMC joint tends to be subluxated (i.e. slightly displaced) towards the radius
Describe the carpometacarpal joints of the digits
There are five carpometacarpal joints between the metacarpals and the related distal row of carpal bones
The carpometacarpal joints between metacarpals II to V and the carpal bones are much less mobile than the carpometacarpal joint of the thumb, allowing only limited gliding movements. Movement of the joints increases medially, so metacarpal V slides to the greatest degree. This can be best observed on the dorsal surface of the hand as it makes a fist.
What joints are found between the metacarpals
Intermetacarpal joints
What are the metacarpophalangeal joints
The joints between the distal heads of the metacarpals and the proximal phalanges of the digits are condylar joints, which allow flexion, extension, abduction, adduction, circumduction, and limited rotation (Fig. 7.92). The capsule of each joint is reinforced by the palmar ligament and by medial and lateral collateral ligaments.
Describe the two parts of the lateral collateral ligaments of the MCP joints
Cord like part
Fan like part
Summarise the interphalangeal joints
Flexion and extension only Proximal Interphalangeal PIP Distal Interphalangeal DIP IP (thumb) volar plate
Summarise the interphalangeal joints of the hand
The interphalangeal joints of the hand are hinge joints that allow mainly flexion and extension. They are reinforced by medial and lateral collateral ligaments and palmar ligaments.
Explain why we don’t see abduction and adduction of the interphalangeal joints
The collateral ligaments are in place to prevent abduction or adduction of the interphalangeal joins as they are not stable on there own.
Describe the transverse metacarpal ligaments
The three deep transverse metacarpal ligaments (Fig. 7.93) are thick bands of connective tissue connecting the palmar ligaments of the metacarpophalangeal joints of the fingers to each other. They are important because, by linking the heads of the metacarpal bones together, they restrict the movement of these bones relative to each other. As a result, they help form a unified skeletal framework for the palm of the hand.
Where does a deep transverse metacarpal ligament not occur
Significantly, a deep transverse metacarpal ligament does not occur between the palmar ligament of the metacarpophalangeal joint of the thumb and the palmar ligament of the index finger. The absence of this ligament, and the presence of a saddle joint between metacarpal I and the trapezium, are responsible for the increased mobility of the thumb relative to the rest of the digits of the hand.
What ligament prevents hyperextension of the interphalangeal joints?
Palmar plates (AKA volar plates)
What happens to the dorsal extensor expansion as it approaches the distal phalanx
It narrows out- allowing us to extend the digit
Summarise the arterial supply of the hand
The blood supply to the hand is by the radial and ulnar arteries, which form two interconnected vascular arches (superficial and deep) in the palm (Fig. 7.105). Vessels to the digits, muscles, and joints originate from the two arches and the parent arteries:
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The radial artery contributes substantially to the supply of the thumb and the lateral side of the index finger.
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The remaining digits and the medial side of the index finger are supplied mainly by the ulnar artery.
Describe the passage of the ulnar artery and its contribution to the superficial palmar arch
Lateral to FCU at wrist
The ulnar artery and ulnar nerve enter the hand on the medial side of the wrist (Fig. 7.106). The vessel lies between the palmaris brevis and the flexor retinaculum and is lateral to the ulnar nerve and the pisiform bone. Distally, the ulnar artery is medial to the hook of the hamate bone and then swings laterally across the palm, forming the superficial palmar arch, which is superficial to the long flexor tendons of the digits and just deep to the palmar aponeurosis. On the lateral side of the palm, the arch communicates with a palmar branch of the radial artery.
Describe the contribution of the ulnar artery to the deep palmar arch
One branch of the ulnar artery in the hand is the deep palmar branch (Figs. 7.105 and 7.106), which arises from the medial aspect of the ulnar artery, just distal to the pisiform, and penetrates the origin of the hypothenar muscles. It curves medially around the hook of the hamate to access the deep plane of the palm and to anastomose with the deep palmar arch derived from the radial artery.
Describe the branches from the superficial palmar arch
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a palmar digital artery to the medial side of the little finger, and
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three large, common palmar digital arteries, which ultimately provide the principal blood supply to the lateral side of the little finger, both sides of the ring and middle fingers, and the medial side of the index finger (Fig. 7.106); they are joined by palmar metacarpal arteries from the deep palmar arch before bifurcating into the proper palmar digital arteries, which enter the fingers.
Describe the passage of the radial artery
Under brachioradialis and medial to FCR at the wrist
The radial artery curves around the lateral side of the wrist and passes over the floor of the anatomical snuffbox and into the deep plane of the palm by penetrating anteriorly through the back of the hand (Figs. 7.105 and 7.107). It passes between the two heads of the first dorsal interosseous muscle and then between the two heads of the adductor pollicis to access the deep plane of the palm and form the deep palmar arch.
The deep palmar arch passes medially through the palm between the metacarpal bones and the long flexor tendons of the digits. On the medial side of the palm, it communicates with the deep palmar branch of the ulnar artery
Before penetrating the back of the hand- what vessels does the radial artery give off
Before penetrating the back of the hand, the radial artery gives rise to two vessels:
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a dorsal carpal branch, which passes medially as the dorsal carpal arch, across the wrist and gives rise to three dorsal metacarpal arteries, which subsequently divide to become small dorsal digital arteries, which enter the fingers; and
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the first dorsal metacarpal artery, which supplies adjacent sides of the index finger and thumb.
Which vessels arise form the radial artery in the plane between the first interosseous and the adductor pollciis
Two vessels, the princeps pollicis artery and the radialis indicis artery, arise from the radial artery in the plane between the first dorsal interosseous and adductor pollicis. The princeps pollicis artery is the major blood supply to the thumb, and the radialis indicis artery supplies the lateral side of the index finger.
What does the deep palmar arch give rise to
The deep palmar arch gives rise to:
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three palmar metacarpal arteries, which join the common palmar digital arteries from the superficial palmar arch; and
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three perforating branches, which pass posteriorly between the heads of origin of the dorsal interossei to anastomose with the dorsal metacarpal arteries from the dorsal carpal arch.
Describe Allen’s test
To test for adequate anastomoses between the radial and ulnar arteries, compress both the radial and ulnar arteries at the wrist, then release pressure from one or the other, and determine the filling pattern of the hand. If there is little connection between the deep and superficial palmar arteries, only the thumb and lateral side of the index finger will fill with blood (become red) when pressure on the radial artery alone is released.
Why are connections between the radial and ulnar arteries important
So when your are moving the hand (i.e grasping) and compressing the arteries- multiple other arteries can maintain an adequate supply of all parts of the hand.
Summarise the venous drainage of the hand
As generally found in the upper limb, the hand contains interconnected networks of deep and superficial veins. The deep veins follow the arteries; the superficial veins drain into a dorsal venous network on the back of the hand over the metacarpal bones
Describe the formation of the cephalic and basilic veins
The cephalic vein originates from the lateral side of the dorsal venous network and passes over the anatomical snuffbox into the forearm.
The basilic vein originates from the medial side of the dorsal venous network and passes into the dorsomedial aspect of the forearm.
Describe the superficial veins of the hand
Cephalic vein (superficial) runs up lateral border of arm
Basilic vein (superficial) runs up the medial border of arm
Basilic veins joins venae comitantes to form the axillary vein in the arm (just above the elbow)
Cephalic vein joins axillary vein in the axilla
Axillary vein becomes the subclavian vein at the level of the first rib
Describe the deep veins of the hand
Run with the arteries as venous comitantes- may be 3 or 4 of them
They pass in the opposite direction to the arterie
Radial vein
Ulnar vein
posterior and anterior interosseous veins
superifical and deep palmar arches
Describe venepuncture
In many patients, venous access is necessary for obtaining blood for laboratory testing and administering fluid and intravenous drugs. The ideal sites for venous access are typically in the cubital fossa and in the cephalic vein adjacent to the anatomical snuffbox. The veins are simply distended by use of a tourniquet. A tourniquet should be applied enough to allow the veins to become prominent. For straightforward blood tests the antecubital vein is usually the preferred site, and although it may not always be visible, it is easily palpated. The cephalic vein is generally the preferred site for a short-term intravenous cannula.
What is important to remember about the median cubital vein
Superficial veins in the region of the Cubital Fossa are commonly used for phlebotomy or insertion of a venous line. The median cubital vein, linking the basilic and cephalic veins, is not always present.
Which spinal nerve levels contribute to the median, radial and ulnar nerves
Ulnar nerve (C8T1) Median nerve (C678T1) Radial nerve (C5678T1)
Summarise the nerves in the hand
Median nerve
Main nerve of the anterior compartment of forearm
Some supply to hand intrinsic muscles
Ulnar nerve
Main nerve of the hand
Some of anterior compartment (FCU, half of FDP)
Radial nerve
Posterior compartment of the forearm
Some sensory component to the hand
What is important to remember about the digital arteries
Purely sensory (only tendons pass here- muscles housed in hand compartments or forearm compartments) Often damaged- can lead to great disability- apraxia
Describe the passage of the median nerve
At the wrist lies between FDS and FDP, deep to PL
Enters the carpal tunnel with FDP, FDS and FPL
Describe the innervation of the median nerve in the hand
The median nerve is the most important sensory nerve in the hand because it innervates (palmar) skin on the thumb, index and middle fingers, and lateral side of the ring finger (Fig. 7.111). The nervous system, using touch, gathers information about the environment from this area, particularly from the skin on the thumb and index finger. In addition, sensory information from the lateral three and one-half digits enables the fingers to be positioned with the appropriate amount of force when using precision grip.
The median nerve also innervates the thenar muscles ( (APB, FPB, OP) that are responsible for opposition of the thumb to the other digits.
Also motor to lumbrical I and II
Describe the recurrent branch of the median nerve
The median nerve enters the hand by passing through the carpal tunnel and divides into a recurrent branch and palmar digital branches (Fig. 7.111).
The recurrent branch of the median nerve innervates the three thenar muscles. Originating from the lateral side of the median nerve near the distal margin of the flexor retinaculum, it curves around the margin of the retinaculum and passes proximally over the flexor pollicis brevis muscle. The recurrent branch then passes between the flexor pollicis brevis and abductor pollicis brevis to end in the opponens pollicis.
Describe the palmar digitial nerves of the median nerve
The palmar digital nerves cross the palm deep to the palmar aponeurosis and the superficial palmar arch and enter the digits. They innervate skin on the palmar surfaces of the lateral three and one-half digits and cutaneous regions over the dorsal aspects of the distal phalanges (nail beds) of the same digits. In addition to skin, the digital nerves supply the lateral two lumbrical muscles.
Summarise the passage of the ulnar nerve
The ulnar nerve enters the hand lateral to the pisiform and posteromedially to the ulnar artery (Fig. 7.109). Immediately distal to the pisiform, it divides into a deep branch, which is mainly motor, and a superficial branch, which is mainly sensory.
Also lateral to FCU
Runs over (not under) the flexor retinaculum, lateral to the pisiform
Describe the deep branch of the ulnar nerve
The deep branch of the ulnar nerve passes with the deep branch of the ulnar artery (Fig. 7.109). It penetrates and supplies the hypothenar muscles to reach the deep aspect of the palm, arches laterally across the palm, deep to the long flexors of the digits, and supplies the interossei, the adductor pollicis, and the two medial lumbricals (III and IV) and the hypothenar muscles. In addition, the deep branch of the ulnar nerve contributes small articular branches to the wrist joint.
What structure does the deep branch of the ulnar nerve pass through
As the deep branch of the ulnar nerve passes across the palm, it lies in a fibro-osseous tunnel (Guyon’s canal) between the hook of the hamate and the flexor tendons. Occasionally, small outpouchings of synovial membrane (ganglia) from the joints of the carpus compress the nerve within this canal, producing sensory and motor symptoms.
Describe the superficial branch of the ulnar nerve
The superficial branch of the ulnar nerve innervates the palmaris brevis muscle and continues across the palm to supply skin on the palmar surface of the little finger and the medial half of the ring finger
Summarise the radial nerve
Divides just above the level of the elbow into;
Deep branch – the posterior interosseous nerve (motor)
Superficial branch – the superficial radial nerve (sensory)
No motor supply in the hand
Sensory supply to the dorsum of the hand
How does the branch of the superfical radial nerve enter the hand
The only part of the radial nerve that enters the hand is the superficial branch (Fig. 7.112). It enters the hand by passing over the anatomical snuffbox on the dorsolateral side of the wrist. Terminal branches of the nerve can be palpated or “rolled” against the tendon of the extensor pollicis longus as they cross the anatomical snuffbox.
What does the superficial radial nerve innervate
The superficial branch of the radial nerve innervates skin over the dorsolateral aspect of the palm and the dorsal aspects of the lateral three and one-half digits distally to approximately the terminal interphalangeal joints.
Summarise innervation of the intrinsic hand muscles
Intrinsic hand muscle innervation:
Median supplies thenar muscles and the lateral 2 lumbricals
Ulnar supplies all of the other intrinsic hand muscles
What is the key difference between the ulnar and radial artery in terms of the arches
Ulnar:
Superficial palmar arch – palmar digital arteries
Deep palmar arch
Radial:
Deep palmar arch
Summarise the structure of the flexor retinaculum
The carpal tunnel is formed anteriorly at the wrist by a deep arch formed by the carpal bones (forms a gutter) and the flexor retinaculum (see Fig. 7.92).
The base of the carpal arch is formed medially by the pisiform and the hook of the hamate and laterally by the tubercles of the scaphoid and trapezium.
The flexor retinaculum is a thick connective tissue ligament that bridges the space between the medial and lateral sides of the base of the arch and converts the carpal arch into the carpal tunnel
Which structures pass through the carpal tunnel
The four tendons of the flexor digitorum profundus, the four tendons of the flexor digitorum superficialis, and the tendon of the flexor pollicis longus pass through the carpal tunnel, as does the median nerve
What structure permits free movement of the tendons in the carpal tunnel
Free movement of the tendons in the carpal tunnel is facilitated by synovial sheaths, which surround the tendons. All the tendons of the flexor digitorum profundus and flexor digitorum superficialis are surrounded by a single synovial sheath; a separate sheath surrounds the tendon of the flexor pollicis longus. The median nerve is anterior to the tendons in the carpal tunnel.
Where do the tendons of the flexor carpi radialis pass through
The tendon of the flexor carpi radialis is surrounded by a synovial sheath and passes through a tubular compartment formed by the attachment of the lateral aspect of the flexor retinaculum to the margins of a groove on the medial side of the tubercle of the trapezium.
Which structures do not pass through the carpal tunnel
The ulnar artery, ulnar nerve, and tendon of the palmaris longus pass into the hand anterior to the flexor retinaculum and therefore do not pass through the carpal tunnel (Fig. 7.95). The tendon of the palmaris longus is not surrounded by a synovial sheath.
The radial artery passes dorsally around the lateral side of the wrist and lies adjacent to the external surface of the scaphoid.
Where do the extensor tendons pass through
The extensor tendons pass into the hand on the medial, lateral, and posterior surfaces of the wrist in six compartments defined by an extensor retinaculum and lined by synovial sheaths (Fig. 7.95):
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The tendons of the extensor digitorum and extensor indicis share a compartment and synovial sheath on the posterior surface of the wrist.
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The tendons of the extensor carpi ulnaris and extensor digiti minimi have separate compartments and sheaths on the medial side of the wrist.
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The tendons of the abductor pollicis longus and extensor pollicis brevis muscles, the extensor carpi radialis longus and extensor carpi radialis brevis muscles, and the extensor pollicis longus muscle pass through three compartments on the lateral surface of the wrist.
What is carpal tunnel syndrome
Carpal tunnel syndrome is an entrapment syndrome caused by pressure on the median nerve within the carpal tunnel. The etiology of this condition is often obscure, though in some instances the nerve injury may be a direct effect of increased pressure on the median nerve caused by overuse, swelling of the tendons and tendon sheaths (e.g., rheumatoid arthritis), and cysts arising from the carpal joints. Increased pressure in the carpal tunnel is thought to cause venous congestion that produces nerve edema and anoxic damage to the capillary endothelium of the median nerve itself.
Describe the treatment and presentation of carpal tunnel syndrome
Patients typically report pain and pins-and-needles sensations in the distribution of the median nerve. Weakness and loss of muscle bulk of the thenar muscles may also occur. Gently tapping over the median nerve (in the region of the flexor retinaculum) readily produces these symptoms (Tinel’s sign).
Initial treatment is aimed at reducing the inflammation and removing any repetitive insults that produce the symptoms. If this does not lead to improvement, nerve conduction studies will be necessary to confirm nerve entrapment, which may require surgical decompression of the flexor retinaculum.
What wrist movement is needed to achieve full flexion of the fingers and why
The flexors have to be slightly longer than need be to allow the wrist and fingers to fully extend
This means that to get full flexion you need to extend the wrist to shorten the flexors so that they can fully flex
This is why you can more easily take something from someone’s grip if you flex the wrist to loosen the gri
Describe the power grip
long flexors of the fingers and thumb
intrinsic muscles of the palm
extensors of the wrist joint!
Describe precision grip
the wrist and fingers are held rigidly by the long flexors and extensors
the intrinsic muscles of the hand carry out the fine movements needed
Describe hook grip
consumes little energy, mainly involves long flexors of digits; e.g. carrying shopping bag or briefcase
