Week 4 Flashcards
Name the superficial, intermediate, and deep muscles of the anterior compartment of the forearm
Superficial: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teresIntermediate: flexor digitorum superficialisDeep: flexor digitorum profundus, flexor pollicus longus, pronator quadratus
The superficial muscles in the anterior compartment of the forearm all originate from where?
They all originate from a common tendon, which originates from the medial epicondyle of the humerus (they hence all cross the elbow joint)
What is the action of the flexor carpi ulnaris? What is its innervation?
Flexion and adduction at the wrist; ulnar nerve
What is the action of the palmaris longus? What is its innervation?
Flexion at the wrist; median nerve
Which structure is just underneath the palmaris longus? In what percentage of the population is the palmaris longus absent?
Median nerve; 15%
What is the action of the flexor carpi radialis? What is its innervation?
Flexion and abduction at the wrist; median nerve
What is the significance of the pronator teres with regard to the cubital fossa?
The lateral border of the pronator teres forms the medial border of the cubital fossa
What is the action of the pronator teres? What is its innervation?
Pronates the forearm; median nerve
Which two structures can be found passing between the two heads of the flexor digitorum superficialis?
The median nerve and ulnar artery
To where do the four distal tendons of the flexor digitorum superficialis attach?
The middle phlanges of the four fingers
What are the actions of the flexor digitorum superficialis?
Flexes the metacarpophalangeal joints, and proximal interphalangeal joints at the 4 fingers, and flexes the wrist
What is the innervation of the flexor digitorum superficialis?
The median nerve
The tendons of which two muscles pass through the carpal tunnel?
Flexor digitorum superficialis and flexor digitorum profundus
To what do the tendons of the flexor digitorum profundus attach?
The distal phlanges of the four fingers
What are the actions of the flexor digitorum profundus?
It is the only muscle that can flex the distal interphalangeal joints at the wrist; it also flexes the metacarpophalangeal joints and at the wrist
What is the innervation of the flexor digitorum profundus?
Medial half is innervated by the ulnar nerve; the lateral half is innervated by the median nerve
Describe the position of the flexor pollicis longus relative to the flexor digitorum profundus
The flexor pollicis longus lies laterally to the flexor digitorum profundus
What are the actions of the flexor pollicis longus?
Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb
What is the innervation of the flexor pollicis longus?
Median nerve
Describe the shape and location of the pronator quadratus
Square shaped muscle, lies deep to the tendons of the flexor digitorum profundus and flexor pollicis longus
What is the action of the pronator quadratus? What is its innervation?
Acts to pronate the forearm; median nerve
Which bones and what else form the carpal tunnel?
Pisiform, triquetrum, lunate, capitate, trapezoid trapezium, flexor retinaculum
Which structures are of importance within the carpal tunnel?
Median nerve, tendons of the flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus (9 tendons)
What is carpal tunnel syndrome?
Compression of the median nerve within the carpal tunnel; thought to be due to increased pressure/thickening of tendon sheaths
What are the typical signs of carpal tunnel syndrome?
Pins and needles in the sensory distribution of the median nerve and weakness of thenar muscles
Why is some median nerve function retained in carpal tunnel syndrome?
The palmar cutaneous branch of the median nerve travels superficial to the flexor retinaculum
Where is there sensation loss for people with Erb’s palsy?
The sensory areas that are supplied by the axillary and musculotaneous nerves; down the lateral side of the arm
Does the musculotaneous nerve have any sensory function?
Lateral cutaneous nerve provides sensory function to the lateral side of the forearm
Where would there be loss of sensation with a lesion of the musculotaneous nerve?
Lateral side of the forearm
What sensory function does the axillary nerve contribute to?
Gives rise to lateral cutaneous nerve of arm; innervates the skin over the posterior deltoid, the ‘regimental badge’ area
What sensory loss will occur with an injury to the axillary nerve?
If the lateral cutaneous nerve supply is interrupted, there will be loss of sensation over the regimental badge area
Which to muscles does the median nerve travel in between as it passes through the forearm?
Flexor digitorum profundus and flexor digitorum superficialis
Describe two important branches of the median nerve as it passes through the forearm, and their functions
Anterior interosseous nerve, supplying deep flexor muscles, and palmar cutaneous nerve, which innervates skin on the palmar, lateral aspect of the hand
What are the respective areas supplied by the radial and ulnar arteries?
Radial: posterior aspect, Ulnar: anterior aspect
What are some common risk factors for carpal tunnel syndrome?
TRAMP; trauma, rheumatoid arthritis, acromegaly, myxoedema, pregnancy
Which myotome performs abduction of the arm at the glenohumeral joint?
C5
Which myotome performs flexion of the forearm at the elbow joint?
Primarily C6 (some C5)
Which myotome performs extension of the forearm at the elbow joint?
Mainly C7 (some 6/8)
Which myotome performs flexion of the forearm of the fingers?
C8
Which myotome performs abduction and adduction of the index, middle and ring fingers?
T1
What is the cubital tunnel?
Formed by tendinous arch joing humeral and ulnar heads of the attachment of flexor carpi ulnaris; the median nerve enters the forearm through it
Which myotome performs adduction at the shoulder?
C6, C7, (C8)
Which myotome performs pronation?
C7, C8
Which myotome performs supination?
C6
What are the medial and lateral attachments of the flexor retinaculum?
Medially attached to the pisiform and hook of hamate; laterally attached to the tubercle of the scaphoid and trapezium bones
Give causes of carpal tunnel syndrome
Tenosynovitis (thickening of synovium), repetitive trauma (compression forces and stretching), oedema, fractures, dislocations, inherited small bone fractures
