Forearm II- Script Diogo Flashcards
What should be assessed when you are concerned for a scaphoid fracture?
the anatomical snuffbox
What are the five major nerves of the upper limb?
- axillary nerve
- musculocutaneous nerve
- median nerve
- ulnar nerve
- radial nerve
The musculocutaneous nerve transmits mainly what spinal nerve fibers to the anterior arm muscles?
C5 and C6
The radial nerve transmits mainly what spinal nerve fibers to the triceps brachii?
C7 and C8
What are the anterior forearm muscles that are involved in pronation of the forearm? What are they innervated by?
- pronator teres innervated by median nerve
- pronator quadratus is the chief pronator and innervated by the anterior interosseous nerve (distal to the supinator which marks the transition of name from median nerve to the anterior interosseous nerve)
What are the anterior forearm muscles that move the hand at the wrist and midcarpal joints?
- flexor carpi radialis: inserts into bases of metacarpals 2 and 3; innervated by median nerve
- flexor carpi ulnaris: inserts into base of metacarpal 5, pisiform, and hamate; innervated by the ulnar nerve
- palmaris longus: inserts into palmar aponeurosis (Deep fascia, not a bone); innervated by median nerve
all of their origins: medial epicondyle
The radial recurrent artery supplies blood to what muscles in the upper limb?
brachialis (anterior)
brachioradialis (posterior superifical)
supinator (posterior deep)
What are the anterior forearm muscles that flex the digits ?
- flexor pollicis longus is the sole flexor of the thumb’s distal phalanx; innervated by the anterior interosseous nerve
- flexor digitorum superficialis has the chief action of flexion of the middle phalanges of the fingers; innervated by the median nerve
- flexor digitorum profundus has the chief action of flexion of the distal phalanges of the fingers; lateral part (digits 4,5 )of the muscle is innervated by anterior interosseous nerve and the medial part (digits 2,3) is innervated by the ulnar nerve
What is another name for the wrist joint?
radiocarpal joint
What occurs with the tendon of the flexor digitorum superficialis in relation to the flexor digitorum profundus?
flexor digitorum superificalis: tendon splits into two slips that inserts into the base of the middle phalanx
flexor digitorum profundus: tendons travel beneath the spliting of the flexor superficialis tendons and inserts into the base of the distal phalanx
What forms the roof of the carpal tunnel?
flexor retinaculum
What major structures pass through the carpal tunnel?
- median nerve
- tendons of the anterior muscles that flex the digits (flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus)
What is the purpose of the synovial sheaths that surrounds the flexor digitorum superificalis and flexor digitorum profundus?
it allows tendons to slide back and forth underneath the flexor retinaculum in an almost frictionless-fashion
What is the function of the flexor retinaculum?
retains the insertion tendons of the flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus in close association with the underlying carpals
What is the function of the deep fascia that lies in the palmar side of the thumb and each of the fingers called fibrous sheath?
keeps the flexor pollicis longus tendon, abd the flexor digitorum (superficialis and profundus) tendons close to the digit’s phalanges when the digit is flexed at its metacarpophalangeal and interphalangeal joints
What spinal nerve provides most of the nerve fibers that control flexion of the thumb and fingers at their interphalangeal joints?
C8
The anterior and posterior groups of forearm muscles are each surrounded by a compartment composed of what?
forearm’s deep fascia, an intermuscular septum, the shafts of the radius and ulna, and the interosseous membrane of the forearm
Why can the compartment enclosure of the anterior and posterior groups of muscles put these muscles at risk of ischemia?
- it puts these muscles in a fixed volume
- should injury or disease occur, pressure within this space or compartment can increase resulting in compression of nerves, blood vessels, and muscles in the compartment
How does a supracondylar fracture of the humerus cause Volkmann’s ischemic contracture, where the thumbs and fingers are drawn into marked flexion?
- a supracondylar humeral fracture can be at risk of untreated swelling of the anterior forearm muscle compartment which will cause ischemic necrosis
- the necrotic muscle tissue is replaced by fibrous scar tissue that permanently shortens the affected forearm muscles and draws the thumb and fingers into marked flexion
What are the posterior forearm muscles that move the forearm?
- aconeous assists the triceps brachii in extension of the forearm; innervated by radial nerve and supplied by deep brachial artery and recurrent interosseous artery
- brachioradialis flexes the forearm ; innervated by radial nerve and supplied by radial recurrent artery
- supinator’s only action is the supination of the forearm; innervated by deep radial nerve and supplied by radial recurrent artery
What are the posterior forearm muscles that move the hand at the wrist and midcarpal joints?
extensor carpi radialis longus: extend and abduct hand; innervated by radial nerve and supplied by the radial artery
extensor carpi radialis brevis: extend and abduct the hand: innervated by radial nerve and deep radial nerve and supplied by the radial artery
extensor carpi ulnaris: extend and adduct the hand; innervated by radial nerve and supplied by ulnar artery
Supinator is innervated by what spinal nerves?
C5 and C6 nerve fibers
Marked weakness or paralysis of what muscles results in the inability to extend the hand at the wrist AKA wrist drop?
extensor carpi muscles
What is another term for Saturday night palsy?
wrist drop
- which is the result of an inebriated person falling asleep in a chair with his/her arm draped over the back of the chair
- the resulting pressure on the radial nerve in the axilla may lead to a temporary case of wrist drop
What are the three posterior forearm muscles that extend the thumb?
abductor pollicis longus: extend and abduct the thumb
extensor pollicis longus: extend the thumb
extensor pollicis brevis: extend the thumb
all are innervated by the posterior interosseous nerve and supplied by the posterior interossesous artery
The anatomical snuffbox, which is a hollowed out triangular area consisted of what borders?
laterally the tendons of abductos pollicis longus and extensor pollicis brevis and medially the extensor pollicis longus
What is the most commonly fractured carpal?
scaphoid
What is the most commonly dislocated carpal?
lunate
Why is the anatomical snuffbox a highly clinically relevant surface anatomy to help diagnose a fractured scaphoid?
the scaphoid forms part of the bony floor of the anatomical snuffbox
What are the posterior forearm muscles that extend one or all four fingers?
extensor digitorum: extend all four fingers at their metacarpophalangeal and interphalangeal joints; innervated by the radial nerve and supplied by posterior interosseous artery
extensor digiti minimi: extend the little finger at its metacarpophalangeal and interphalangeal joints; innervated by radial nerve and supplied by posterior interosseous artery
extensor indicis: extend the index finger at its metacarpophalangeal and interphalangeal joints; innervated by posterior interosseous nerve and supplied by the ulnar artery
What happens to the tendon of the extensor digitorum?
- the tendon broadens and thins out on each side to form a fascial hood called the extensor expansion
- the extensor expansion divides into three slips just proximal to the proximal interphalangeal joint
- the central slip extends across the proximal interphalangeal joint just before inserting onto the base of the middle phalanx
- the two side or collateral, slips merge as they extend distally and insert into the base of the distal phalanx interphalangeal joint
Which muscles originated from the lateral epicondyle via the common extensor tendon?
extensor carpi ulnaris
extensor digitorum
extensor digit minimi
What leads to lateral epicondylitis?
repetitive, strenuous exercise of the muscles that originate from the lateral epicondyle via the common extensor tendon
What is the purpose of the extensor retinaculum?
forms a tunnel like corrideor through which the insertion tendons of the posterior forearm muscles that move the hand at the wrist or extend the thumb and finger pass
the extensor retinaculum thus retains the insertion tendons of these muscles in constant close association with the underlying bones during movements of the hands and its digits
What arteries and nerves pass superficial and through the flexor retinaculum?
- median nerve pass through the carpel tunnel
- ulnar nerve and ulnar artery passes superficial to the flexor retinaculum
What spinal nerve provides most of the sensory innervation to skin on the lateral side of the forearm?
C6
What spinal nerve provides most of the sensory innervation to skin on the medial side of the forearm?
T1
