14. Dissection of the Anterior Forearm and Hand Practical Flashcards
Can you find:
The pisiform bone
The trapezium
The flexor pollicis longus tendon
The flexor digitorum profundus tendon
Name the structures
1 = palmar aponeurosis
X = muscles of thenar eminence
Y = adductor pollicis
Name the structures
5 = Flexor digitorum superficialis tendons
6 = Flexor digitorum profundus tendons
Name the structures
2 = lumbricals (originateattendonsofflexordigitorumprofundusandinsertatthelateral sides of the extensor expansions of 2nd-5thdigits)
3 = palmar interossei muscles (origin is metacarpals, insertion is the proximal phalanges)
4 = dorsal interossei muscles (origin is the metacarpals, insertadjacent sides of metacarpals to the bases of proximal phalanges & extensor expansions of digits 2-4)
Y = adductor pollicis (originbases of metacarpals 2 and 3, insert base of 2/3rdmetacarpals and proximal phalanx of thumb)
Where do the following insert:
flexor pollicis longus
flexor digitorum profundus
FDP - M. flexor digitorum profundus
FDS - M. flexor digitorum superficialis
FPL - M. flexor pollicis longus
FPB - M. flexor pollicis brevis
LL - Mm. lumbricales
FCR - M. flexor carpi radialis
FCU - M. flexor carpi ulnaris
What does the carpal tunnel contain?
Which tendons and which nerve?
The carpal tunnel contains the following structures, from superficial to deep:
Four flexor digitorum superficialis tendons
Median nerve (laterally)
Flexor pollicis longus tendon (laterally)
Four flexor digitorum profundus tendons
Where are the flexor muscles?
What bones can be seen?
Find the brachial, the radial, the ulnar and common interosseous arteries…
Brach A = brachial
RadA = radial
UlnA = ulnar
CommInterossA = common interosseous
Which vein passes superficially over the roof of the cubical fossa and is a bridging vein between the cephalic vein and basilic vein?
Median cubital vein
Which side is
(a) cephalic vein
(b) basilic vein
on in the anterior forearm?
Cephalic vein = lateral
Basilic vein = medial
What are the boundaries of the cubital fossa?
Medially = pronator teres
Laterally = brachioradialis
Superiorly = imaginary line between the epicondyles of the humerus
Floor = brachial and supinator
Roof = bicipital aponeurosis and antebrachial fascia
What is the content of the cubital fossa?
Where are they found within?
Biceps brachii tendon
Brachial artery - found medial to biceps brachii tendon
Median nerve - found medial to the brachial artery
TAN
Venae comitantes - veins which accompany the brachial artery (aka brachial veins)
Which compartment does the brachioradialis muscle lie within and why do you think it belongs there?
- Brachioradialis – lies in extensor compartment, embryological origin
What is the action of brachioradialis?
Flexion of forearm at elbow joint in mid-pronation
What is the innervation of brachioradialis?
Radial nerve
What accompanies the radial nerve in the arm?
Radial artery
What does the radial artery bifurcate into?
Where do the branches go?
Superficial and deep branches.
Superficial - continues distally underneath brachioradialis muscle.
Deep - pierces supinator muscle to pass to the posterior compartment of the forearm.
What does the deep radial artery become in the posterior compartment?
The posterior interosseous nerve
What do the basilic and cephalic veins arise from?
The dorsal venous arch
What muscle is immediately lateral to the brachioradialis muscle?
Extensor carpi radialis longus muscle (ECRL)
What is lateral and more superficial to the extensor carpi radialis longus muscle?
Extensor carpi radialis brevis (ECRB)
What muscles arise from the common extensor tendon?
ECRB
Extensor digitorum
Extensor digit minimi
Extensor carpi ulnaris
What is the origin of there common extensor tendon?
Lateral epicondyle of the elbow
Why does the extensor digitorum muscle give off?
4 tendons which attach to the digits (not thumb) and assists in extension of the fingers.
Which is the most medial muscle of the posterior compartment?
Extensor carpi ulnaris
What does the posterior interossous nerve arise from, and what does it travel with?
Arises from the deep radial nerve.
Travels with the posterior interosseous artery
What are the boundaries of the anatomical snuffbox?
Medial - Extensor Pollicis Longus tendon
Laterally (radial aspect) - Extensor Pollicis Brevis & Abductor Pollicis Longus tendons
What important structures lie in the floor of the anatomical snuffbox?
Radial artery, superficial branch of radial nerve, cephalic
vein
Which of the forearm muscles are not present in 100% of the population?
Palmaris longus
What does the radial artery lie lateral to in the forearm?
The flexor carpi radialis
Which two tendons are used as landmarks when palpating the radial arterial pulse?
Flexor carpi radialis and brachioradialis
What does lies medial to palmaris longus at the wrist?
Median nerve
Which is the only muscle of the intermediate layer of the anterior compartment of the forearm?
Flexor digitorum superficialis (FDS)
What is the purpose of the tendinous arch of the flexor digitorum superficialis?
Allows the ulnar artery and median nerve to pass deep to it.
What lies between the median nerve and the ulnar artery at the wrist?
flexor digitorum superficialis
What does the ulnar nerve branch into?
The common interossoeous artery (which further divides into anterior and posterior interosseous arteries)
Why is the anatomical snuffbox clinically relevant?
Carpal fracture (scaphoid) may
result in vascular injury and can lead to avascular necrosis of the carpal bones
What is the function of the dorsal interosseous muscles?
Abduction of the digits
The middle layer of the muscles in the anterior compartment of the forearm contain a single muscle - which one is it?
Flexor digitorum superficialis
The cubital fossa is bound by which muscle on the lateral border?
Brachioradialis
Which nerve passes through the carpal tunnel and when compressed results in symptoms distributed over the hand?
Median nerve
Which muscle acts on the thumb and is not innervated by the recurrent branch of the median nerve?
Adductor pollicis
Which nerve lies in the cubital fossa and may be damaged during venipuncture if the needle is inserted in the wrong location?
Median nerve
The common flexor origin is located on the medial epicondyle of the humerus? True or False.
Yes
The ulnar nerve passes posteriorly to the lateral humeral epicondyle at the elbow joint. True or False?
False
The palmaris longus is not always present in each individual, but it is normally located in the superficial muscle layer of the anterior compartment of the forearm. True or False?
True
The roof of the carpal tunnel is formed by the extensor retinaculum. True or False?
False - the roof of the carpal tunnel is formed by the flexor retinaculum.
The lumbricals act to flex the digits at the metacarpophalangeal joints whilst maintaining extension in the interphalangeal joints. True or False?
True