Wrist and Hand

Damage to ulnar nerve at wrist (in Guyon's canal)

"ulnar claw hand" at rest but preservation of flexion of DIP joints of digits 4 and 5 when making a fist. Paralysis of finger abduction and adduction. Loss of sensation on dorsal and palmar surface of digit 5 and half of 4.

2 sets of interosseous muscles

Arise from bodies of metacarpals and attach distally to extensor hood and bases of proximal phalanges. Produce opposite actions on abduction and adduction of digits 205. Through attachment of all interossei on extensor hood, these muscles also produce flexion of MP joints and extension of IP joints.

Opponens pollicis

Attaches distally along lateral margin of body of thumb. Pulls thumb toward longitudinal midline of hand and rotates it medially.

Proximal bases of metacarpal bones

Bound together with ligaments and joint capsules while heads of metacarpals held in position by superficial and deep transverse metacarpal ligaments.

Dermatomes and hand

C6 dermatome = innervates thumb C7 dermatome = innervates middle finger C8 dermatome = innervates pinky

Carpal tunnel

Contains flexor digitorum and flexor pollicis longus tendons as well as median nerve

Palmar carpal ligament

Continuation of deep antebrachial fascia on anterior surface of wrist

Deep fascia of hand

Covers hand and digits. Extension of antebrachial deep fascia. Deep fascia of dorsum is thin and covers dorsal interossei and bones. Palmar deep fascia is thin over thenar and hypothenar muscles. Deep fascia of rest of palm is thickened and called palmar aponeurosis.

Cartilaginous disc attachments

Disc is also called triangular ligament. It attaches between distal ends of radius and ulnar, thereby reinforcing distal radioulnar joint.

Wrist joint

Distal radius and ulna and proximal row of carpal bones form this joint

Fascial septa extend from deep fascia to metacarpals

Divide hand into compartments and spaces. Thenar compartment contains thumb muscles. Adductor pollicis compartment is recognized as separate space deep to thenar compartment. Hypothenar contains pinky muscles. Central (midpalmar) compartment is between thenar/hypothenar and contains flexor tendons, lumbricals, and superficial palmar arterial arch. Metacarpal bones and interosseous muscles contained in space bounded by deep fascia covering palmar/dorsal interosseous muscles.

DAB

Dorsal interosseous muscles ABduct fingers

Damage to ulnar nerve at elbow or above

Extension of MP joint and flexion of IP joints of digits 4 and 5 when hand is at rest (producing "ulnar claw"). Paralysis of flexion of DIP of digits 4 and 5 when making a fist. Paralysis of finger abduction and adduction. Loss of sensation over palmar and dorsal surfaces of medial hand and palmar surface of digit 5 and half of 4.

Which two flexor tendons pass through separate fibrous tunnels superficial to carpal tunnel as they cross the wrist?

Flexor carpi radialis tendon Flexor carpi ulnaris tendon

Nerves, vessels and tendons are ordered on anterior surface of wrist I

Flexor carpi ulnaris tendon is most medial (attaches to pisiform and through pisometacarpal ligaments to base of 5th metacarpal) Ulnar nerve is next to ulnaris tendon. Ulnar artery lies lateral to nerve (and both pass in a CT tunnel called Guyon's canal between palmar carpal ligament and flexor retinaculum). Palmaris longus tendon and flexor carpi radialis tendon also pass between palmar carpal ligament and flexor retinaculum

Radial bursa

Flexor pollicis longus tendon lies laterally in separate synovial sheath.

Flexor retinaculum attaches to these bones

Hook of Hamate bone Tubercle of Trapezium Tubercle of Scaphoid

Extended distal end of radius

Makes direct articulation with scaphoid and lunate bones (this is the radiocarpal joint)

What is the only nerve to pass through carpal tunnel?

Median nerve

Ulnar nerve for hand I

Motor to intrinsic muscles of hand but has significant sensory compartment as well. Palmar branch arises proximal to wrist and provides sensory innervation to medial palm. Dorsal branch provides sensation to posterior lateral dorsum of hand and dorsum of digits 4 and 5.

Ulnar bursa

One continuous synovial sheath encases all the flexor digitorum tendons at wrist. Usually continuous with sheath that surrounds 5th digit flexor tendons in finger.

Superficial branch of radial nerve

Only sensory. Supplies sensation to dorsum of lateral hand and digits 1, 2, and 3.

PAD

Palmar interosseous muscles ADduct fingers

Damage to radial nerve at or above elbow

Paralysis of wrist and finger extension thus producing "wrist drop" with inability to extend fingers. Loss of sensation to dorsum of lateral hand and dorsum of thumb and digits 2 and 3 to the nail bed. Damage to superficial branch of radial nerve in forearm would result in only sensory deficits in hand.

Radial artery

Passes latearlly around radius, crosses floor of anatomical snuffbox, and passes through 1st dorsal interosseous, then between the 2 heads of adductor pollicis. Gives rise to superficial palmar brach that anastomoses with superficial palmar arterial arch.

Veins of hand

Prominent in superficial space of dorsum. These form the dorsal venous arch; cephalic and basilic veins are derived from this plexus.

Anatomical snuff box

Shorthand for space between extensor pollicis longus and brevis tendons at wrist. Scaphoid and trapezium lie in bottom of snuff box and radial artery crosses snuffbox as it winds around wrist.

Extensor expansion (hood)

Specialized CT structure. Found on posterior surface of digits 2-5. Extensors of digits and most of intrinsic hand muscles have attachments to extensor hood.

Ulnar nerve for hand II

Superficial branch in hand supplies sensation to palmar surface of medial half of digit 4 and 5. Deep branch of ulnar innervates hypothenar muscles, adductor pollicis, lumbricals 3 and 4, and all interossei.

Dorsal surface of hand

Supplied by small branches from both radial and ulnar arteries. These contribute to a dorsal carpal arterial arch. From this arch will arise dorsal metacarpal arteries that pass distally toward fingers. Dorsal metacarpal arteries branch into dorsal digital arteries. Penetrating arteries from deep palmar arterial arch pass between metacarpal bones to anastomose with this dorsal arterial system.

Median nerve for hand I

Supplies both sensory and motor function to hand. Superior palmar branch arises from median proximal to carpal tunnel and supplies palm sensation. Median divides into 3 common palmar digital nerves which each divides into proper palmar digital branches that pass along side of digits 1 to half of 4. Median supplies sensation to palmar surfaces of digits 1 to half of 4 as well as to dorsum of tips of same fingers.

Distal branches of median, ulnar, and radial nerves

Supply cutaneous sensation to hand. These pass in superficial space.

Skin of dorsum of hand

Thin and pliable. But, skin of palmar surface is specialized. Superficial fascia of dorsum is also quite thin and free of fat.

Flexor retinaculum

Transverse carpal ligament. Not a component of deep fascia. It spans the anterior arch of carpal bones and forms CT roof of carpal tunnel.

Cartilaginous disc between ulna and wrist

Ulna doesnt articulate directly with carpal bones. Cartilaginous disc is located between ulna head and pisiform and triquetrum.

Damage to median nerve at or above elbow

Will compromise all sensory and motor functions supplied by the nerve. Relative to hand function: complete paralysis of flexion of digits 1-3 (producing "hand of benediction" when attempting to make a fist), paralysis of lumbricals 1 and 2, paralysis of thenar muscles (inability to oppose thumb), and loss of sensation over lateral palm and palmar surface of digits 1-3 and half of 4.

Anastomosis between common palmar digital arteries and palmar metacarpal arteries

Will give rise to proper palmar digital arteries that pass on either side of most fingers

Ulnar artery

enters hand lateral to pisiform bone. Gives rise to superficial palmar arch. From this arch will arise common palmar digital arteries that pass toward fingers. Superficial palmar branch anastomoses with deep palmar arch from radial artery.

Lumbrical muscles

Arise proximally from tendons of flexor digitorum profundus. Attach distally to lateral sides of extensor hood of digits 2-5. Contraction pulls on extensor hood; this produces flexion of MP joints and extension of IP joints.

Tendons of flexor digitorum profundus

Arranged in 1 layer (not 2 like superficiales)

Tendons of flexor digitorum superficiales

Arranged with tendons 3 and 4 superficial (anterior) to tendons 2 and 5

Nerves, vessels and tendons are ordered on anterior surface of wrist II

Median nerve is located just lateral to palmaris longus tendon (if that tendon is missing, median nerve is located in middle of anterior wrist). Radial artery emerges from underneath brachioradialis just lateral to flexor carpi radialis tendon. Radial artery at wrist passes laterally around radius and deep to extensor/abductor pollicis tendons where it passes across floor of anatomical snuff box.

Extensor digitorum tendons (includes minimi and extensor indicis tendons)

Attach to extensor hood and to phalanges. Central band of each extensor tendon attaches to base of middle phalanx. Lateral bands pass on either side of PIP and reunite to attach to base of distal phalanx. Extensor tendon merges with extensor hood. Extensor tendons have interconnections with each other as they pass through dorsum. No synovial sheaths on extensor tendons distal to wrist.

Fibrous digital sheath

Located on anterior surface of each digit. Attached to phalangeal bones and retains flexor digitorum tendons.

Thenar muscles

Move thumbs. 3 muscles. All 3 have proximal attachment to flexor retinaculum and tubercles of scaphoid and trapezium. Abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis.

Flexor pollicis longus tendon attachments

Base of distal phalanx. Housed inside digital sheath and protected inside separate synovial sheath.

Median nerve for hand II

Just distal to carpal tunnel, median gives rise to recurrent (motor) branch that innervates thenar muscles. Median also innervates lateral 2 lumbrical muscles.

Hypothenar muscles

Moves pinky. Muscles have common proximal attachment to flexor retinaculum, hamate, and pisiform. Each attach distally so as to accomplish the function described as their name. Abductor digiti minimi, Flexor digiti minimi brevis, and Opponens digiti minimi.

Palmaris brevis

Superficial muscle spreading transversely across hypothenar muscles

What are the 3 posterior compartment muscles tendons that attach to the thumb?

Abductor pollicis longus (attaches on anterior surface of base of 1st metacarpal). Extensor pollicis brevis tendon lies immediately posterior to abductor tendon and attaches on lateral part of base of proximal phalanx of thumb. Extensor pollicis longus tendon passes medial to dorsal tubercle of radius, passes along posterior surface of thumb to attach to base of distal phalanx. Synovial sheaths of these tendons dont extend past extensor retinaculum

Lymph from hand

Accompany both superficial and deep venous drainage to cubital nodes, to lateral (humeral) axillary nodes, or to those found adj to cephalic vein where it empties into axillary vein.

Abductor pollicis brevis

Attaches distally to anterior surface of base of 1st metacarpal.

Flexor pollicis brevis

Attaches distally to base of proximal phalanx of thumb

Extensor retinaculum

Extension of deep antebrachial fascia; spans dorsum of wrist and forms 6 separate tunnels through which pass extensor/abductor tendons

Adductor pollicis

Fan shaped muscle with 2 heads. Adducts thumb. Oblique head arises from middle carpal bones and adj metacarpal bases. Transverse head arises from middle of body of 3rd metacarpal. Both heads converge to single tendon that attaches distally to medial side of base of proximal phalanx of thumb.

Radial artery at base of thumb

Gives rise to 3 arteries: princeps pollicis artery (supplies thumb) radiailis indicis artery (supplies lateral side of 2nd digit) deep palmar arterial arch (continues medially across midpalmar compartment and will give rise to palmar metacarpal arteries that pass toward fingers)

Extensor retinaculum

Immediately adj to wrist bones and helps retain extensor/abductors tendons in place. CT septa extending from extensor retinaculum to wrist bones divides out 6 separate compartments

Cephalic and basilic veins distal origin

In dorsal venous plexus of hand. Deep veins of hand will drain to deep veins that accompany the branches of radial and ulnar arteries.

Anastomosis between radial and ulnar arteries in hand

Integrity of this anastomosis can be assessed with Allen's test.

Flexor digitorum tendons attachments

Superficiales tendons pass within fibrous digital sheath of each finger, split and attach on either side of middle phalanx. Profundus tendons pass within fibrous digital sheath deep (posterior) to superficiales tendons and attach to base of distal phalanx. Both tendons for each finger are contained in a single synovial sheath inside fibrous digital sheath.