Lecture 16 - Musculoskeletal 5 Flashcards by Jaimee bingley

what the groups of the forearm flexor compartment and how many muscles are in each?

4 x superficial muscles,
1 intermediate muscle
3 x deep muscles

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what are the superficial muscles of the flexor compartment of the forearm?

pronator teres
flexor carpi radialis
palmaris longus
flexor capri ulnaris

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what is the origin of most of the superficial and intermediate forearm flexor muscles?

the common flexor tendon, originating at the medial epicondyle of the humerus

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what is the only muscle in the superficial flexor comparement of the forearm with a different origin, and what is the origin?

the pronator teres, which originates at the supracondylar ridge (just above the common flexor tendon)

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what is the insertion and primary function of the pronator teres?

lateral radius in the middle of the long bone
pronation of the forearm
- teres so is circular in cross section

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what is the insertion and primary function of the flexor carpi radialis?

insert at the base of the second metacarpal
primary function: flex the wrist and stabilise the wrist

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what is the insertion and primary function of the palmaris longus?

missing in 15% of population (you don’t have one jaimee)
inserts at the palmar aponeurosis (tendon on palmaris longus fans out into palmar aponeurosis)

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what is the palmar aponeurosis?

a thickened part of the deep fascia

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does the flexor carpi radialis tendon pass through the carpal tunnel? (e.g does it go under the flexor retinaculum)

yes

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does the flexor carpi ulnaris tendon pass through the carpal tunnel? (e.g does it go under the flexor retinaculum)

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does the palmaris longus tendon pass through the carpal tunnel? (e.g does it go under the flexor retinaculum)

no, it goes over

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what is the insertion of the flexor carpi ulnaris?

attaches to pisiform
insertion is at the base of metacarpals 4 and 5

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what muscles make up the intermediate flexor compartment of the forearm?

only the flexor digitorum superficialis
- has a radial and humero-ulnar head

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what is the sibling of the flexor digitorum superficialis?

the flexor digitorum profundus

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do the flexor digitorum flex the thumb?

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what is the insertion and primary movement of the flexor digitorum superficialis?

divides into four tendons and attaches to the base of the middle phalanx

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what is the insertion and primary function of the flexor digitorum profundus?

splits into four tendons, through carpal tunnel and inserts at the base of the distal phalanx

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what is the issue with the insertions of the two digitorum muscles?

the superficial one attaches more proximally, and so should be in the way of the profundus tendons attaching distally

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how does our body cope with the digitorum issue?

the FDS tendon splits, and creates an opening for the FDP to carry on and attach at the distal phalanx

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is FDS or FDP the muscle responsible when we flex one finger, and how do we know this?

FDS is responsible, and we know this because when we flex it, our distal phalanx is floppy/unsupported

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what kind of movement is FDP best for?

strong grip, ‘all or nothing’ so flexes all fingers when activated

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what are the three muscles of the deep flexor compartment of the forearm?

Flexor digitorum profundus
flexor pollicis longus
pronator quadratus

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what is the origin, insertion and primary function of the flexor pollicus longus?

goes from the anterior radius and partially the interosseous membrane, through carpal tunnel and to distal phalanx of the thumb
- flexes the thumb

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what is the origin, insertion and primary function of the pronator quadratus?

goes from the medial ulna, under all other tendons and inserts at lateral radius
- pronator of the forearm

what are the two pronator muscles of the forearm?

pronator teres pronator quadratus

how many extensor muscles are there of the forearm?

what three extensor muscles act upon the wrist, and what are their insertions?

- ECRL (base of 2nd metacarpal) - ECRB (base of 3rd metacarpal) - ECU (base of 5th metacarpal)

what three extensor muscles act upon the thumb, and what are their insertions?

- APL (base of 1st metacarpal) - EPB (base of proximal phalanx) - EPL (base of distal phalanx)

what three extensor muscles extend the fingers, and what are their insertions?

- ED - EI - EDM all insert on the dorsal digital exapansion hood of the appropriate digit

what three extensor muscles act upon the forearm but not the wrist or fingers, and what are their primary movements?

- anconeus (extend elbow) - brachioradialis (flex elbow) - supinator (supinates forearm along with biceps)

which forearm muscles all have their origin as the supracondylar ridge above the lateral epicondyle of the humerus?

- brachioradialis (then to base of the radial styloid process) - anconeus (then to posterior radius) - Extensor carpi radialis longus (then to base of 2nd metacarpal)

what is the origin of 9 of the 12 extensor forearm muscles?

common extensor tendon

what is the insertion and primary movement of brachioradialis?

insertion is the base of the radial styloid process flexor of the elbow

what makes brachioradialis unique?

it is part of the extensor compartment, even though it flexes the elbow. - might be because it is innervated by the same nerve as the others, radial nerve

how is brachioradialis a good shunt muscle?

prevents radial dislocation from the humerus due to its position

list the muscles of the posterior comparment of the forearm from lateral to medial in superficial view

ECRL, ECRB, ED, EDM, ECU

what is extensor digitorum?

the opposite of FDS and FDP, but there is only one muscle doing both jobs. like coen doing jobs for oscar

how is the extensor retinaculum different to the flexor digitorum, and what is its function?

not a big tunnel. strap with smaller tunnels underneath it. prevents bowstringing of extensor tendons

what is the dorsal digital expansion hood?

inserts at the distal phalanx via two lateral bands - ensures the ED or other tendons sta on the posterior side

what is the insertion of the ED?

the DDEH and the middle phalanx

what are intertendinous bands?

connect ED tendons between digits

what is extensor digiti minimi?

attaches to the DDEH of the pinky

what is unique about the carpi muscles?

oriented in the corners, and can cause flexion, extension, abduction adduction when two adjacent ones are flexed at once.

why do we have two ECR muscles?

resists the wrist being pulled into flexion when flexing the thumb, so we need two

what is a wrist drop?

caused by damage to the radial nerve, which effects flexor efficiency. so whenever they try to pick up things, the wrist flexes`

what are the 5 muscles of the deep posterior forearm?

EPL EPB EI APL supinator

describe the downfall of the fingers that don't have their own extensor tendon

ED tries to pull on all fingers at once, and if the index finger and the pinky are flexed while the other two arent, they can barely be picked up off the table due to the intertendinous bands connecting the tendons. with the two that have their own extensor tendon, the ED can go quiet and the EI and EDM can still lift the other two fingers

what is EI?

extensor indicis, comes from distal half of posterior ulna, attaches to index DDEH

what is the abduction and adduction of the fingers like?

the midline is through the centre of the middle finger, so spreading fingers is abduction.

what is abduction of the middle finger like

can abduct medially or laterally (medial abduction and lateral abduction)

where is abduction and adduction of the thumb?

in the frontal plane, it is out of phase with the fingers

what is the insertion of the extensor pollicis brevis?

base of the proximal phalanx (of the thumb - polliis)

where is the insertion of the extensor pollicis longus?

base of the distal phalanx

when do superficial muscles travel underneath deep muscles?

the ECRL and ECRB try to get to their insertions at the 2nd and 3rd metacarpals early, and dip below the tendons of EPB, EPL and APL

anatomical snuff box is where

between the EPB and the EPL - clinically useful strcuture for detemining fracture of the scaphoid carpal

describe supinator

- has two heads, superficial and deep - superficial head comes from lateral epicondyle - deep comes from ridge by radial notch

what kind of joint is the first carpometacarpal joint, and what is the benefit of this joint type at this digit?

saddle joint- they give us movement in the three planes (f/e and A/a) but not to the same degree as a ball and socket joint. - enables the thumb to oppose the fingers

what kind of joint are the metacarpophalangeal joints?

condyloid joints - they only have one condyle. metacarpals have the condyle, can f/e and A/a

what kind of a joint is at the interphalangeal joints?

hinge - permits flexion and extension only. Collateral ligaments prevent adduction and abduction.