Forearm Flexors & Nerves
Which muscle flexes digits 2–5 at the PIP joints?
Flexor digitorum superficialis (FDS).
What is the most commonly fractured carpal bone?
Scaphoid.
What are the five muscular compartments of the hand?
Thenar, hypothenar, central, adductor, and interosseous.
What nerve passes through the carpal tunnel?
Median nerve.
Who is married to the median nerve
Brachial artery
Which muscle flexes digits 2–5 at the DIP joints?
Flexor digitorum profundus (FDP).
What is the most commonly dislocated carpal bone?
Lunate.
What three muscles make up the thenar compartment?
Abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis.
What structures pass through the carpal tunnel in addition to the median nerve?
Nine long flexor tendons: 4 FDS + 4 FDP + 1 Flexor pollicus longus, and the median nerve
Who is married to the Deep brachial artery
Radial Nerve
Which portion of FDP is innervated by the ulnar nerve?
Medial half associated with digits 4 and 5.
What mechanism of injury commonly causes a scaphoid fracture?
FOOSH — fall on an outstretched hand.
What nerve branch innervates the thenar muscles?
Recurrent branch of the median nerve.
What nerve passes through the Canal of Guyon rather than the carpal tunnel?
Ulnar nerve.
Who is married to the ulnar nerve?
Superficial collateral ulnar artery
What branch of the median nerve provides motor innervation to most of the deep anterior forearm muscles?
Anterior interosseous nerve (AIN).
Why can a scaphoid fracture result in delayed healing or nonunion?
The fracture can disrupt the blood supply to the bone.
What are the actions of the palmar versus dorsal interossei?
PAD/DAB: Palmar ADduct; Dorsal ABduct.
Which arteries are the main contributors to the superficial and deep palmar arches?
Superficial = ulnar artery; deep = radial artery.
Who is married to the axillary nerve?
Posterior circumflex artery
A supracondylar fracture can cause compartment syndrome and ischemia of the forearm flexors, resulting in what condition?
Volkmann’s ischemic contracture.
What four carpal bones form the proximal row from lateral to medial?
Scaphoid, lunate, triquetrum, pisiform.
What two movements do the lumbricals produce through their relationship with the extensor hood?
Flex the MCP joints and extend the interphalangeal joints.
Compare the sensory distributions of the median and ulnar nerves in the digits.
Median nerve = 3½ digits; ulnar nerve = 1½ digits.
Who is going to pass this test?
EVERYONEEEEEEEEEEEEEE