Forearm/hand Flashcards
Anatomy
What’s the difference between the extrinsic and intrinsic muscles of the hand?
Extrinsic - the muscle originates from outside of the hand and inserts in the hand.
Intrinsic - the muscle originates inside the hand and insert in the hand
What are the 8 Carpal bone?
Lateral to medial -
“Some Lovers Try Positions…
That They Cannot Handle”
Scaphoid, Lunate, Triquetrum, Pisiform
Trapezium, Trapezoid, Capitate, Hamate
What are the wrist joints?
Radiocarpal joint Intercarpal joints Metacarpophalangeal Carpometacarpal joint Interphalangeal joints
How many phalanges in the hand?
- 2 phalanges in thumb (distal and proximal)
- 3 phalanges in digit 2-5 (proximal, intermediate, and distal)
What are the fascial compartments of the forearm?
1) interosseous membrane
- Anterior (flexors)
- Posterior
2) Antebrachial fascia - prevents bowstringing
What is the function of the flexor retinaculum (transverse carpal ligament)?
Prevents bowstringing of tendons. The Flexor retinaculum converts the concavity formed by the carpal bones into the carpal tunnel.
What are the contents of the carpal tunnel?
Median Nerve!!!! Flexor digitorum superficialis/profundus, Flexor pollicis longus
What is the palmar aponeurosis
Strong covering of the soft tissue and overlies the long tendons. Contributes to the flexor tendon sheaths distally.
Which four superficial muscles attach to the common flexor tendon (attached to the medial epicondyle of humerus)?
1) Pronator teres
2) Flexor Carpi radialis (FCR)
3) Palmaris longus
4) Flexor carpi ulnaris (FCU) - ulnar nerve !!!
What is the intermediate flexor muscle of the forearm?
Flexor Digitorum Superficialis
What are the deep flexor muscles of the forearm?
1) Flexor Pollicis longus (FPL)
2) Flexor digitorum profundus (FDP) - digit 4-5 ulnar nerve, digit 2-3 ant. Interosseous
3) Pronator quadratus
* * Innervated by anterior interosseus nerve (a branch of the median nerve)
What muscles from the posterior compartment of the forearm originates from the lateral epicondyle ?
1) Extensor Carpi radialis brevis
2) extensor digitorum
3) extensor digiti minimi
4) extensor carpi ulnaris
5) supinator
** all are innervated by the deep branch of the radial nerve
What muscles from the posterior compartment of the forearm originates form the supracondylar ridge of humerus?
1) Brachioradialis
2) Extensor carpi radialis longus
* *innervated by radial nerve
Which 4 muscles from the posterior compartment of the forearm originates from the interosseous membrane and innervated by the posterior interosseous nerve?
Abductor pollicis longus (origin: proximal 1/2 of ulna, radius)
Extensor pollicis brevis (Distal 1/3 posterior radius)
Extensor pollicis longus (Mid 1/3 of posterior ulna)
Extensor indicis (Distal 1/3 posterior ulna)
What are the 3 thenar muscles?
1) Abductor pollicis brevis
2) Flexor pollicis brevis
3) Opponens pollicis
- *origin: flexor retinaculum and tubercles of scaphoid/trapezium
- innervations: recurrent branch of median nerve
What are the 3 hypothenar muscles that are innervated by the deep branch of the ulnar nerve?
1) abductor digiti minimi (from pisiform)
2) flexor digiti minimi brevis (hamate/flexor retinac..)
3) opponens digiti minimi (hamate/flexor retinac..)
what are the interosseous muscles, which are innervated by the deep branch of ulnar nerve?
1) Palmar Interossei (adduct digit 2, 4, 5) P..Ad
2) Dorsal Interossei (abduct digit 2-4) D..Ab
Origin, insertion, innervation, action of the Lumbricals.
Origin: tendons of flexor digitorum profundus
insert: lateral sides of extensor expansions, digits 2-5.
Nerves: Lumbrical 1-2 - branch of median
Lumbrical 3-4 branch of ulnar
What are the compartments of the hand?
thenar, hypthenar, adductor, central, and inteosseous
what are the 3 digitorum muscles (muscles that goes to the digits)?
1) Flexor digitorum superficialis
2) flexor digitorum profundus
3) extensor digitorum
What are the 3 supination or pronation muscles?
1) supinator
2) pronator teres
3) Pronator quadratus
What are the 4 extrinsic “Pollicis” muscles?
1) extensor pollicis longus
2) abductor pollicis
3) Extensor pollicis brevis
4) flexor pollicis longus
What is the only pollicis muscle innervated by the ulnar nerve? what are the Origin, insertion, innervation, action?
Adductor pollicis
Origin: oblique head bases of 2-3 metacarpals, capitate and adjacent carpals. Transverse head is in the anterior surgace of 3rd metacarpal.
Insert: medial site of base of digit 1’s proximal phalanx.
Nerve: deep branch of ulna
Action: adduct thumb, duh!!!
What is Guyon’s canal
AKA ulnar canal. It’s a a band of tissue the ulnar nerve passes through.
What are the borders of the anatomical snuff box?
anterior - abductor pollicis longus/extensor pollicis brevis tendons
posterior - extensor pollicis
floor - scaphoid and radial artery
roof - superficial branch of radial nerve and cephalic vein
What is smith fracture?
Fracture of distal radius caused by falling on flexed wrist (impact on dorsum of hand). Presents as a complete transverse fracture of distal radius. Distal radial fragment is displaced ventrally. Ulnar styloid process avulsed. Associated injuries: Carpal tunnel syndrome, neuropathy, ischemia.
What is colles fracture?
Fracture of distal radius caused by falling on an extended pronated wrist (force dorsiflexion). Presents as a “dinner fork” deformity - transverse fracture of distal radius, radial fragment displaced dorsally, ulnar styloid avulsed. Associated injuries: median and ulnar nerve injury/carpal fractures/dislocation of radioulnar joint
What is the most common fractured carpal?
Scaphoid bone. Present with pain/tender anatomical snuff box. Complications: avascular necrosis - damage to the palmar carpal branch of the radial artery
what is a complication of a hamate fracture?
Compression of ulnar nerve as it pass through the Guyon’s canal. symptoms: loss of sensation in the medial half of digit 4 and whole digit 5
What is a Mallet Finger?
AKA Baseball finger. An avulsion of long extensor tendon. s/s: hyperflexion and inability to extend the distal interphalangeal joint
Give 2 examples of repetitive stress injuries of the elbow.
Lateral epicondylitis - tennis elbow
Medial Epicondylitis - golfer’s elbow
What is the Dupuytren Contracture?
Disease of palmar fascia and aponeurosis. Fascial thickening causes shortening on the medial side of hand. Genetic?
What is a claw hand?
An example of an ulnar nerve neuropathy (C8-T1 damage).
what are the five carpi muscles?
1) Flexor Carpi ulnaris
2) Flexor carpi radialis
3) Extensor carpi ulnaris
4) extensor carpi radialis longus
5) exterson carpi radialis brevis
what are the 3 specialist muscles?
1) brachioradialis - beer drinkers hand
2) extensor indicis - point your index finger
3) extensor digiti minimi - to pick your nose =)
what are the 3 “sock puppet” muscles?
4 lumbricals, 3 palmar interossei, 4 dorsal interossei
What would an avulsion fracture of the medial epicondyle cause?
“Claw Hand” deformity, paresthes in forearm and 4th and 5th digit from ulnar nerve injury
What are the clinical implications of supracondylar fracture of humerus caused by fall onto outstretched hand?
1) Limb shortening from the distal shaft fragment displaced
2) Risk of brachial artery laceration (Volkmann’s contracture)
3) “Hand of benediction” when making a fist- median nerve damage cause motor and sensory loss
What is the pronator syndrome?
Median nerve entrapment caused by compression between head of pronator teres. S/s pain and tenderness in proximal anterior forearm and hypoesthesia/hypesthesia in palmar part of lateral 3 1/2 digits
what causes “Ape hand”?
Damage to median nerve at the wrist will lose innervation to abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and lateral two lumbricals. Presents with loss of opposition from digit 1 and weakened digit 1 flexion and abduction.
What is carpal tunnel syndrome?
Damage to median nerve due to compression of the carpal tunnel. S/s: sensory and motor deficit
What causes wrist drop?
Damage to radian nerve, usually at the radial groove. s/s inability to extend wrist and fingers, wrist flexed d/t unopposed flexor tone and gravity
What are sign and symptoms of injury to the deep branch of the radial nerve cause by deep penetrating wounds of the posterior forearm?
- inability to extend thumb and fingers (mcp joint)
- no loss of sensation
Name the forearm and hand arteries
Ulnar, common interosseous, posterior interosseous, recurrent interosseous, anterior interosseous, Palmar carpal branch of radialulnar, Dorsal carpal branch of radial ulnar
proper palmar artery 3 common palmar digital arteries superficial branch of radial artery princeps pollicis artery 3-4 palmar metacarpal arteries deer palmar branch of ulnar artery
Where does the superficial lymphatic vessels and lymphatic plexus of the palm drain to?
The dorsum of the hand, which eventually drains to the lymph nodes in the axilla.
