Unit Ii Anatomy Lecture 5 And 6

Front 1

What are the positions of the forearm and thumb in anatomical position?

Back 1

Forearm is supinated, thumb is lateral

Front 2

How many carpal bones are there and how many rows are they arranged in to?

Back 2

8 bones, 2 rows

Front 3

What bones are in the proximal row of the carpals?

Back 3

Scaphoid, lunate, triquetrum, and pisiform

Front 4

What bones are in the distal row of the carpals?

Back 4

Hamate, capitate, trapezoid, trapezium

Front 5

What is the joint between the two rows of carpals called?

Back 5

Midcarpal joint

Front 6

What do the four distal carpals articulate with?

Back 6

5 metacarpals

Front 7

Describe the five metacarpals

Back 7

Referred to by Roman numerals, thumb (pollex) is one, pinkie (digiti minimi) is five
Each has head at distal end, shaft in middle, and base at proximal end
Tubercle on flexor (palmar) side

Front 8

Describe the phalanges of the metacarpals

Back 8

The thumb has two
Every other has three- proximal, middle, distal

Front 9

Describe a sesamoid bone

Back 9

Develops within tendons
Example: pisiform, develops in tendon of flexor carpi ulnaris
Also develop at head of first metacarpal which are in tendons of flexor pollicis brevis and adductor pollicis

Front 10

Describe growth of the hands

Back 10

Babies are born with bones formed in cartilage but not ossified
Epiphysis form in heads of metacarpals, base of thumb, bases of phalanges 2-3 years after birth

Front 11

In what order do the carpals ossify?

Back 11

Trapezium, scaphoid, trapezoid
Pisiform is last, between ages 8-12 years

Front 12

What are the five joints of the hand?

Back 12

1) Radiocarpal joint
2) Carpal joints
3) Carpometacarpal joints
4) Intermetacarpal joints
5) Metacarpo-phalangeal joints and interphalangeal joints

Front 13

Describe the radiocarpal joint

Back 13

Formed of distal end of radius and an articular disc of fibrocartilage at distal end of ulna articulating with scaphoid and lunate
When hand is adducted, triquetrum also articulates
Articular disc degenerates with age, sometimes almost completely
Synovium is usually separate from that of distal radio-ulnar joint where pronation and supinatioin occur

Front 14

Describe the carpal joints and ligaments

Back 14

Synovial joints between carpas tightly attached to each other by dorsal, palmar, and interosseus ligaments
Motion occurs at midcarpal joint including extension and some adduction and abduction
Abduction from natural position occurs solely on midcarpal joint

Front 15

Describe the carpometacarpal joints

Back 15

Simple hinges except for one at base of thumb which is saddle-shaped and allows movement in any plane
These joints on digits 2 and 3 don't move appreciably

Front 16

Describe the intermetacarpal joints

Back 16

Occur between metacarpals of digits 2-5 and don't move appreciably except between IV and V, which moves in cupping the hand, gripping a door handle, and opposing digiti minimi

Front 17

Describe metacarpo-phalangeal joint and interphalangeal joints

Back 17

Motions include flexion, extension, abduction, adduction, and circumduction
IP joints are hinges with limited extension

Front 18

What are the four ligaments of the wrist joint?

Back 18

1) Ulnar collateral
2) Radial collateral
3) Palmar radiocarpal
4) Dorsal radiocarpal

Front 19

Describe the ulnar collateral ligament

Back 19

Styloid process of ulna to triquetrum and pisiform

Front 20

Describe the radial collateral ligament

Back 20

From styloid process of radius to scaphoid and trapezium

Front 21

Describe the palmar radiocarpal ligament

Back 21

Between anterior distal radius and scaphoid, lunate, triquetrum, and capitate

Front 22

Describe the dorsal radiocarpal ligament

Back 22

From posterior distal radius and scaphoid, lunate, and triquetrum

Front 23

Describe the extensor retinaculum

Back 23

Crosses the back of the wrist and holds the extensor tendons in place
Attachments are anterior border of radius to the triquetrum and pisiform
Creates six tunnels which house extensor tendons in synovial sheaths
Dorsal branches of radial and ulnar nerves are superficial and dorsal

Front 24

Describe injury to the extensor retinaculum

Back 24

Position of extensor tendons put them at risk if radius is broken
Possible complication of Colles' fracture is malunion of radius, creating a rough edge, which can cut through tendon of extensor pollicis longus

Front 25

Describe cysts of the extensor retinaculum

Back 25

Synovial or ganglion cysts may form in the sheaths of extensor tendons distal to extensor retinaculum
Common in extensor carpi radialis brevis
May or may not be painful
May or may not be caused by overuse
If in flexor sheath, can compress median nerve, causes symptoms of carpal tunnel syndrome

Front 26

Describe the flexor retinaculum

Back 26

Heavy, thick band attached on radial side to tubercles of scaphoid and trapezium, and on ulnar side to pisiform and hook of hamate
Converts carpal sulcus to carpal tunnel, which occurs between tubercles of scaphoid and trapezoid laterally and hook of hamate and pisiform medially
Proximal border is about distal skin crease of wrist, distal border is at distal margin of base of abducted thumb
Structures deep include: median nerve, tendon of flexor pollicis longus, and tendons of flexors digitorum superficialis and profundus
Ulnar artery and nerve are superficial to flexor retinaculum

Front 27

Describe carpal tunnel syndrome

Back 27

Median nerve entrapment
Caused by any lesion reducing space in tunnel
Symptoms: pain, paraesthesias or loss of sensation in thumb, index finger, middle finger, and lateral side of ring finger
May also include weakness and clumsiness of thenar muscles, pain with use of thenar muscles, and may progress to pain up limb to axilla

Front 28

What is often injured in suicide attempts involving cutting the wrist?

Back 28

Median nerve

Front 29

Describe flexion of the wrist

Back 29

Primarily produces by flexor carpi radialis and flexor carpi ulnaris muscles which are assisted by digital flexors and palmaris longus

Front 30

Describe extension of the wrist

Back 30

Primarily affected by extensor carpi radialis longus and brevis and by extensor carpi ulnaris
Assisted by digital extensors

Front 31

Describe abduction of the wrist

Back 31

Primarily produced by simultaneous contraction of flexor carpi radialis and extensor carpi radilis longus and brevis
Limited to about 15 degrees because of styloid process of radius

Front 32

Describe adduction of the wrist

Back 32

Effected by simultaneous contraction of extensor carpi ulnaris and flexor carpi ulnaris

Front 33

Describe the muscles of the anterior wrist and palm

Back 33

Functional extension of antebrachial flexor compartment
Superficial muscles of flexor compartment are wrist flexors
Distal attachment of flexor carpi radialis crosses not just wrist but midcarpal joint
Deep to that in forearm is flexor digitorum superficialis, inserts on middle phalanx of each finger
Deepest is flexor pollicis longus and flexor digitorum profundus which breaks rule that muscles that cross more joints are superficial; its tendons split tendons of flexor digitorum superficialis on way to distal phalanges

Front 34

Describe the synovial sheaths of the wrist

Back 34

Tendons and digital flexors run in them
Digital fibrous tendonous sheaths attach to lateral edges of phalanges
In front of joints sheaths are thin and pliable (cruciform portion) but anterior to phalanges, fibers are curved (annular portion) and thick
Area within digital fibrous tendinous sheaths, particularly where deep flexor tendon slides through superficial flexor tendon, is sometimes referred to as "surgical no man's land" because scarring within sheath can result in loss of function, especially ability to flex and extend at distal joint

Front 35

Describe the posterior wrist and hand

Back 35

Functional extension of antebrachial extensor compartment
Extensors originate in forearm and have synovial sheaths as they run under extensor retinaculum
Single extensor digitorum with four tendons (no profundus and superficialis) but deeper layer is present for some fingers as separate muscles (extensor digiti minimi, extensor indicis)
Thumb has long and short extensors

Front 36

Describe the anatomical snuffbox

Back 36

Tendons of extensor pollicis longus and abductor pollicis longus create it on dorsoradial side of wrist
Contents include radial artery and superficial branches of radial nerve
Floor of snuffbox is scaphoid bone

Front 37

Describe the extensors of the fingers

Back 37

Single tendon of extensor digitorum which may be joined by extensor digiti minimi or extensor indicus, spreads into aponeurosis called dorsal digital expansion or "extensor hood"
Tendons of lumbrical and dorsal palmar interosseous muscles also contribute to aponeurosis with abductor digit minimi on little finger
Hood then has separate insertions in middle and distal phalanges

Front 38

Describe flexion and extension of fingers

Back 38

Occur mostly at metacarpal phalangeal joints and at interphalangeal joints
Flexion is produced by flexor digitorum profundus and flexor digitorum superficialis
Extension is produced by extensor digitorum, extensor indicis, extensor digiti minimi, interosseous muscles, and lumbrical muscles

Front 39

Describe abdcution and adduction of fingers

Back 39

Relative to axis drawn through middle finger
Abduction by dorsal interossei
Adduction produced by palmar interossei

Front 40

Describe the movements of the thumb

Back 40

Oriented at almost 90 degrees from plane of orientation of digits 2-5
Flexion/extension and abduction/adduction occur in different direction
When you spread your hand out, you are abducting your fingers but extending your thumb
Thumb and little finger oppose each other
Flexion/extension of thumb occur at carpometacarpal joint, metacarpophalangeal joint, and single interphalangeal joint

Front 41

What are the intrinsic muscles of the hand?

Back 41

1) Dorsal and palmar interossei
2) Lumbricals
3) Thenar and hypothenar

Front 42

Describe the dorsal and palmar interossei

Back 42

All innervated by deep branch of ulnar nerve
Dorsal abduct fingers away from center axis of hand, are bipinnate, and there are four of them- radial side of index finger, ulnar side of digit 4, and one on each side of digit 3; numbered 1-4 in radial-to-ular order
Palmar interossei adduct fingers toward median axis of hand, none are attached to middle finger, there are three, numbered 1-3 in radial-to-ulnar order, attaching to digits 2, 4, and 5
Originate on sides of metacarpals and have double insertion, into base of proximal phalanges and extensor hood of each finger

Front 43

Describe the lumbricals

Back 43

Four, originate on tendon of flexor digitorum profundus that goes to each finger, insert on and contribute to extensor hood distal to MP joint
Flex MP and extend proximal and distal interphalangeal joints (PIP and DIP)
Key to pinching with or appressing pads of fingers with pad of thumb, as in writing or picking up a playing card
Innervated primarily through ventral ramus of spinal nerve T1 with some from C8
Lateral (radial) two are innervated by median nerve and median (ulnar) two by the ulnar nerve
Common for second lumbrical to be innervated by both, and less commonly, all four innervated by ulnar nerve

Front 44

Describe the thenar and hypothenar muscles

Back 44

Thenar muscles move thumb and create thenar eminence of palm
Hypothenar move fifth digit and create hypothenar eminence
Thenar are opponens pollicis, flexor pollicis brevis, abdcutor pollicis brevis, and adductor pollicis; all innervated by recurrent branch of median nerve
Adductor pollicis does not lie in thenar muscle compartment, but is included b/c its fxn is movement of first digit; innervated by ulnar nerve
Hypothenar are abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi; innervated by ulnar nerve

Front 45

What is the proximal attachment of the abductor pollicis brevis?

Back 45

Flexor retinaculum and tubercle of scaphoid and trapezium

Front 46

What is the distal attachment of the abductor pollicis brevis?

Back 46

Lateral side of base of proximal phalanx of thumb

Front 47

What is the innervation of abductor pollicis brevis?

Back 47

Recurrent branch of median nerve (C8 and T1)

Front 48

What is the main action of abductor pollicis brevis?

Back 48

Abdcuts thumb and helps oppose it

Front 49

What is the proximal attachment of flexor pollicis brevis?

Back 49

Flexor retinaculum and tubercle of scaphoid and trapezium

Front 50

What is the distal attachment of flexor pollicis brevis?

Back 50

Lateral side of base of proximal phalanx of thumb

Front 51

What is the innervation of flexor pollicis brevis?

Back 51

Recurrent branch of median nerve (C8 and T1)

Front 52

What is the main action of flexor pollicis brevis?

Back 52

Flexes thumb

Front 53

What is the proximal attachment of opponens pollicis?

Back 53

Flexor retinaculum and tubercle of scaphoid and trapezium

Front 54

What is the distal attachment of opponens pollicis?

Back 54

Lateral side of first metacarpal

Front 55

What is the innervation of opponens pollicis?

Back 55

Recurrent branch of median nerve (C8 and T1)

Front 56

What is the main action of the opponens pollicis?

Back 56

Draws 1st metacarpal bone laterally to oppose thumb toward center of palm and rotates it medially

Front 57

What is the origin of the palmaris brevis?

Back 57

Palmar aponeurosis and flexor retinaculum

Front 58

What is the insertion of the palmaris brevis?

Back 58

Into dermis on ulnar side of hand

Front 59

What is the innervation of palmaris brevis?

Back 59

Superficial branch of ulnar nerve (C8 and T1)

Front 60

What is the main action of the palmaris brevis?

Back 60

Helps tense skin over hypothenar muscles

Front 61

What is the origin of abductor digiti minimi?

Back 61

Pisiform bone and tendon of flexor carpi ulnaris

Front 62

What is the insertion of abductor digiti minimi?

Back 62

Base of proximal phalanx and dorsal aponeurosis of little finger

Front 63

What is the innervation of abdcutor digiti minimi?

Back 63

Deep branch of ulnar nerve (C8 and T1)

Front 64

What is the main action of abductor digiti minimi?

Back 64

Abducts little finger

Front 65

What is the origin of flexor digiti minimi?

Back 65

Hamulus of hamate bone and flexor retinaculum

Front 66

What is the insertion of flexor digiti minimi?

Back 66

Bone of proximal phalanx of little finger

Front 67

What is the innervation of flexor digiti minimi?

Back 67

Deep branch of ulnar nerve (C8 and T1)

Front 68

What is the main action of flexor digiti minimi?

Back 68

Flexes little finger at metacarpophalangeal joint

Front 69

What is the origin of opponens digiti minimi?

Back 69

Hamulus of hamate bone and flexor retinaculum

Front 70

What is the insertion of opponens digiti minimi?

Back 70

Ulnar side of 5th metacarpal bone

Front 71

What is the innervation of opponens digit minimi?

Back 71

Deep branch of ulnar nerve (C8 and T1)

Front 72

What is the main action of opponens digiti minimi?

Back 72

Brings little finger into opposition with thumb

Front 73

Describe the branches of the ulnar nerve in the wrist and hand

Back 73

Branches include:
1) Palmar cutaneous- to skin on medial palm
2) Superficial branch- to palmaris brevis
3) Deep branch- to hypothenar, lumbricals 4 and 5, all interossei, and deep head of flexor pollicis brevis
4) Common palmar digital- to proper palmar digital nerves
5) Proper palmar digital nerves- to palmar surface of digit 5 and half of digit 4, dorsal surface of distal segments of digits 4 and 5

Front 74

Describe the dorsal branch of the ulnar nerve in relation to the wrist and hand

Back 74

Branches in forearm and passes deep to flexor carpi ulnaris
Then divides into 2 or 3 dorsal digital nerves on dorsum of hand
Supply only proximal parts of backs of digits 4 and 5, distal parts supplied by proper palmar digital branches

Front 75

Describe ulnar canal syndrome

Back 75

Ulnar nerve passes under pisohamate ligament connecting pisiform bone and hook of hamate bone (ulnar canal)
If compressed, most common symptom is weakness of hand, particularly first dorsal interosseus muscle, and numbness in little finger
Dorsal ulnar cutaneous sensation not affected
Causes of compression may be cyst, tumor, abberant ulnar artery, fracture of hammate, or occupational such as using a jackhammer

Front 76

Describe "Cyclist's Palsy"

Back 76

Also called "Handlebar Palsy"
Rest body weight on handelbars with wrist extended, can compress ulnar nerve
Not the same as ulnar canal syndrome because ulnar nerve is not trapped in canal

Front 77

What are the branches of the median nerve in the wrist?

Back 77

1) Palmar cutaneous- to skin of central palm
2) Medial branch- 2nd lumbrical, palmar and distal dorsal digits 2-4
3) Recurrent branch- abdcutor pollicis brevis, opponens pollicis, superficial head of flexor pollicis brevis
4) Lateral branch- 1st lumbrical, palmar and distal dorsal skin of thumb, radial side index finger
5) Common palmar digital- to proper palmar digital
6) Proper palmar digital- to digits, from medial and lateral branches via common palmar digital, to lumbricals

Front 78

Describe the radial nerve in relation to the hand

Back 78

Superficial branch innervated skin of dorsum of hand

Front 79

What are the two anastomoses of the radial and ulnar arteries in the wrist?

Back 79

Palmar and dorsal carpal arteries

Front 80

What are the two anastomoses of the radial and ulnar arteries in the hand?

Back 80

Superficial and deep palmar arches

Front 81

What may need compression to stop bleeding in the hand?

Back 81

Brachial artery

Front 82

Describe the superficial palmar arch

Back 82

Principally supplied by ulnar artery, but also by one brach of radial artery

Front 83

Describe the deep palmar arch

Back 83

Separated from superficial by flexor tendons and running with deep branch of ulnar nerve
Principally supplied by radial artery, with some ulnar

Front 84

Describe the dorsal carpal arch

Back 84

Supplies dorsum of hand with branches of dorsal carpal radial and ulnar arteries

Front 85

Describe the radial pulse

Back 85

Radial artery usually lies very superficially on flexor surface of wrist, just above thenar eminence, can take pulse there
May also be found in anatomical snuffbox

Front 86

Describe the compartments of the hand

Back 86

The hand is divided by tough, fibrous septa which form compartments
Potential spaces for blood or infection to collect

Front 87

What are the four compartments of the hand?

Back 87

1) Central compartment
2) Thenar compartment
3) Hypothenar compartment
4) Adductor compartment

Front 88

Describe the central compartment

Back 88

Contains palmar aponeurosis, superficial palmar arch, palmar branch of median nerve, flexor tendons and their sheaths, lumbrical muscles, and superficial branch of ulnar nerve
Deepest part potentially called midpalmar space, runs proximally to wrist

Front 89

Describe the thenar compartment

Back 89

Contains abdcutor pollicis brevis, flexor pollicis brevis, and opponens pollicis, and nerves and arteries supplying them
Same plane as midpalmar space

Front 90

Describe the hypothenar compartment

Back 90

Contains abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi, and nerves and arteries supplying them

Front 91

Describe the adductor compartment

Back 91

Formed by adductor pollicis, which constitutes a barrier separating palmar compartments from dorsum of hand
Another potential space dorsal to adductor pollicis, posterior adductor space

Front 92

What are some consequences of non-treatment of a wrist injury?

Back 92

Avascular necrosis of scaphoid or lunate
Permanent loss of grip strength or wrist stability

Front 93

What is the common injury from dislocation resulting from fall on extended hand?

Back 93

Carpals of distal row usually displaced dorsally to carpals of proximal row

Front 94

Describe fracture of the scaphoid

Back 94

Most commonly fractured carpal
May be tender in anatomical snuffbox
Risk is avascular necrosis of proximal part, since blood supply is to the distal potion

Front 95

Describe dislocation of lunate

Back 95

Most commonly dislocated carpal
Dislplace in palmar direction
Can produce carpal tunnel symptoms

Front 96

Describe perilunate dislocation

Back 96

Lunate stays in articulation with forearm, but distal carpals are dislocated posteriorly relative to it

Front 97

What are some injuries associated with falling on an extended hand?

Back 97

1) Fracture of scaphoid
2) Dislocation of lunate
3) Perilunate dislocation

Front 98

What are some injuries associated with punching immovable objects?

Back 98

1) Boxer's fracture
2) Dorsal dislocation of 4th and 5th metacarpals

Front 99

Describe Boxer's fracture

Back 99

Head of 5th metacarpal
Most common injury

Front 100

Describe dorsal dislocation of 4th and 5th metacarpals

Back 100

With hamate fracture
less common
Often missed on first presentation

Front 101

Describe puncture wounds in the palm

Back 101

Can cause infection of synovial sheaths
When inflammation of tendon and sheath occurs (tensosynovitis), digit swells and movement painful
Infection usually confined
If left untreated, infection may rupture proximal ends of sheath and can spread to midpalmar space then wrist and forearm
May also lacerate one of palmar arches and cause bleeding (compress brachial artery)
Infection or bleeding may be compartmentalized, and because palmar aponeurosis is so thick, swelling may be more visible on dorsum of hand