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Flashcards in Palmar hand Deck (24):

Osteology of the wrist

-Wrist composed of 8 carpal bones
-2 rows, both w/ 4 bones
-Proximal row of bones, lateral->medial: Scaphoid, Lunate, Triquetrum, Pisiform (So Long To Pinky)
-Distal row, medial->lateral): Hamate, Capitate, Trapezoid, Trapezium (Here Comes The Thumb)
-The last word in each pneumonic is the digit that pneumonic ends on


Osteology of the hand

-5 metacarpals (1st= thumb, 5th= pinky)
-5 proximal phalanges
-4 intermediate phalanges (no intermediate phalange on thumb)
-5 distal phalanges
-MCP (metacarpal phalangeal) joint (knuckles): first joints of the fingers
-PIP (proximal interphalangeal) joint: second joint of the fingers
-DIP (distal interphalangeal) joint: third joint of the fingers
-Thumb only has MCP and IP (interphalangeal) joints


Carpal tunnel

-Tunnel at the ventral wrist created by the distal row of carpal bones (Hamate, Capitate, Trapezoid, Trapezium) deeply and the flexor retinaculum superficially
-10 structures run w/in the carpal tunnel: 4 tendons of flexor digitorum superficialis, 4 tendons of flexor digitorum profundus, tendon of flexor pollicis longus, and the median nerve
-Flexor carpi radialis, ulnar artery, and ulnar nerve are NOT in the tunnel


Carpal tunnel syndrome (CTS)

-Clinical Sx: tingling or loss of sensation in the lateral 3 1/2 digits (median nerve compression), reduced capacity to oppose the thumb (weakness of thenar muscles)


Scaphoid fracture

-To determine if scaphoid is fractured (due to putting heavy weight on wrist), put pressure on snuffbox. Tenderness indicates scaphoid fracture
-Since the radial artery and superficial branch of the radial nerve are within the box, must consider damage to them based on extent of fracture


Movements of the thumb

-W/ thumb in resting position next to the fingers (all closed), abduction is bringing the thumb anteriorly 90 degrees
-Adduction of the thumb is bringing the thumb back into resting position
-Extension of the thumb is moving the thumb laterally 90 degrees
-Flexion of the thumb is bringing it across the hand (medially) to touch the 5th proximal phalange
-Opposition of the thumb is bringing it medial to touch the tip of the pinky


Movements of the digits

-Flexion of the digits is closing them (anteriorly), and extension is opening the hand up (posteriorly)
-Abduction is moving the fingers away from the 3rd digit (spreading the fingers)
-Adduction is moving the fingers toward the 3rd digit (closing the fingers)
-The middle finger (3rd digit) cannot be adducted or abducted


Joints involved in thumb movements

-Carpometacarpal joint: in all movements of thumb (adduction, abduction, extension, flexion, opposition and reposition)
-This joint is btwn the trapezium and 1st metacarpal
-Interphalangeal joint (IP) is involved only in flexion and extension
-Joint is btwn proximal and distal phalanges of the thumb


Joints involved in hand movements

-Radiocarpal (btwn ulna/radius and proximal carpal bones) and midcarpal (btwn proximal and distal carpal bones): flexion, extension, abduction, and adduction of fingers (more mobility for midcarpal joints)
-Carpometacarpal joint of the digits: variable amount of flexion, extension, abduction and adduction (more on ulnar side)
-Metacarpophalangeal (MCP) joints: flexion, extension, limited abduction and adduction
-PIP and DIP: flexion and extension


Intrinsic hand muscles

-Thenar (thumb) muscles (3): flexor pollicis brevis, abductor pollicis brevis, opponens pollicis
-Hypothenar (pinky) muscles (3): flexor digiti minimi, abductor minimi, opponens digiti minimi
-Lumbricals (4) attach from flexor digitorum profundus tendons to extensor aponeurosis (hood)
-Interosseous muscles (4 dorsal ones and 3 palmar ones): attach from the metacarpal bones to the extensor aponeurosis
-Adductor pollicis (part of the webbing btwn 1st and 2nd digit)


Thenar muscles

-Flexor pollicis brevis (FPB, more medial): flexes the thumb
-Abductor pollicis brevis (APB, more lateral): abducts the thumb
-Opponens pollicis (OP, deep to APB): opposes (rotates) the thumb
-All are innervated by the recurrent branch of the median nerve


Hypothenar muscles muscles

-Flexor digiti minimi (FDM, more lateral): flexes the pinky
-Abductor digiti minimi (ADM, more medial): abducts the pinky
-Opponens digiti minimi (ODM, deep to FDM): opposes the pinky
-All innervated by ulnar nerve


Lumbrical muscles

-4 limbricals on the 4 digits, all insert radially on the extensor aponeurosis distal to the MCP
-They all originate from the flexor digitorum profundus tendons
-They are extensors of the DIP and PIP joints and flexors at the MCP joints (along w/ interossei muscles)
-Medial 2 innervated by ulnar nerve (5th and 4th digits)
-Lateral 2 innervated by median nerve (3rd and 2nd digits)
-Flexor digitorum profundus inserts onto distal phalanges (flexes both the PIP and DIP, crosses both joints)
-Flexor digitorum superficialis inserts onto proximal phalanges (flexes only PIP since it does not cross the DIP)


Dorsal interosseous muscles (DIM)

-Radial artery passes thru the first dorsal interosseous muscle to reach deep palmar arch (1o supplier of DPA)
-4 DIMs: all are ABductors of the digits, along w/ flexing at MCP joint and extending at PIP/DIP joints (works w/ lumbricals and palmar interossei to achieve the latter two)
-Dorsal ABducts fingers: DAB
-All are innervated by ulnar nerve
-First one attaches to radial (lateral) side of index finger, allowing for abduction
-2 and 3 DIMs attach to the two (radial and ulnar) sides of the middle finger (thus middle finger can only be abducted, moving anyway is abduction)
-The 4th DIM attaches to the ulnar side of the ring finger, allowing for abduction


Palmar interossei muscles (PIMs)

-3 of them, they are ADductors of the digits, flexors at MCPs, and extensors at DIP/PIPs (along w/ DIMs and lumbrical muscles)
-Palmar ADducts fingers: PAD
-All innervated by ulnar nerve
-All come from the palmar metacarpal bones (of the 2nd, 4th, and 5th digits) and insert into extensor aponeurosis on the same side they arise from (none on the 3rd digit, thus middle finger cannot adduct)
-The one on the 2nd digit arises from and inserts onto the medial side of the index finger (allowing for adduction)
-The ones on the 4th and 5th digits arise from and insert onto the lateral side of the digits (allowing for adduction)


Adductor pollicis brevis muscle

-Deeply positioned triangular muscle of the thumb in the "webbing" btwn the thumb and index finger
-Adducts the thumb and is innervated by the ulnar nerve


Innervation to hand muscles (ulnar and median nerves)

-Ulnar nerve: innervates all interossei muscles, all hypothenar muscles, the ulnar 2 lumbrical muscles, the ulnar 2 flexor digitorum profundus muscles, and the adductor pollicis brevis
-The median nerve innervates all thenar muscles (recurrent branch), the radial 2 lumbrical muscles, the radial 2 flexor digitorum profundus muscles, and all of the flexor digitorum superficialis muscles


Innervation to hand muscles (radial nerve)

-The radial nerve innervates the extensor muscles (and abductor pollicis longus)
-Extensor digitorum: extends hands at wrist (2o), fingers 2-5 at MCP, PIP, and DIP
-Extensor indices: extends index finger at MCP, PIP, and DIP
-Extensor digiti minimi: extends pinky at MCP, PIP, and DIP
-Extensor pollicis longus: abducts hand at wrist (2o), extends 1st metacarpal, thumb at MCP, PIP, DIP
-Extensor pollicis brevis: abducts hand at wrist (2o), extends 1st metacarpal, thumb at MCP
-Abductor pollicis longus: abducts hand at wrist (2o), 1st metacarpal joint


Cutaneous innervation to hand 1

-Superficial radial nerve does the dorsal side of the radial half (including 1/2 of 4th digit) of the hand (except for finger tips of 1st, 2nd, 3rd digits)
-Finger tips of these digits is by median nerve
-The ulnar half (the rest) of the dorsal side of the hand is by the ulnar nerve


Cutaneous innervation to hand 2

-The anterior hand is broken up in half, w/ the 5th and 1/2 of the 4th digit being the ulnar nerve and the rest being the median nerve
-The superficial radial nerve does a small portion of the anterior surface near where the thumb and wrist come together
-To test the dermatomes, use the thumb for C6, the index or middle finger for C7, and the pinky for C8


Ulnar nerve lesion

-Usually occurs at the elbow (medial epicondyle fracture), or at the wrist
-Results in claw hand: hyperextended MCP joints of 4 and 5 and flexes DIP/PIP of 4 and 5 w/ abducted thumb
-Pts cannot adduct or abduct the fingers due to loss of interossei muscles, cannot grip something placed in palm or resist adduction force


Median nerve lesion

-Often occurs from suicide attempts, when the recurrent branch is severed
-Can also be compressed in carpal tunnel syndrome
-Deficits: thumb rests in plane of hand, pt cannot oppose thumb and pink, pt cannot grip an object (loss of flexor digitorum superficialis and radial part of profundus, along w/ loss of thenar muscles)


Radial nerve lesion

-Occurs when deep radial nerve is damaged adjacent to neck of the radius (or radial nerve damage in upper arm)
-Deficit: pt cannot extend wrist or MCP joints, hand is in wrist-drop position
-Loss of sensation to lateral side of dorsum of hand is lesion is above elbow joint (before superficial radial comes off)
-Pt can still extend digits (at PIP/DIPs) due to action of lumbricals and interossei (ulnar and median intact)


Blood supply to the hand

-Radial artery pierces the 1st dorsal interosseous muscle to provide the major supply to the deep palmar arch (DPA)
-The superficial palmar arch (SPA) is mostly provided by the ulnar artery, w/ some collateral from the radial artery
-The deep palmar arch is mostly provided by the radial artery w/ some collateral from the ulnar artery
-Common digital arteries made from branches of DPA and SPA seen on both sides of each digit
-The common digital arteries branch into proper digital arteries after the MCP to give one branch to each digit adjacent to the artery
-Proper digital arteries extend to the distal phalanges