forearm and cubital fossa Flashcards
what articulations do the radius and ulna make?
The two long bones lie vertically in the forearm, with the radius lateral to the ulna (so the radius is in line with thumb, and the ulna with the pinky)
● The proximal ends of the radius and ulna articulate with the distal end of the humerus to form the elbow joint
● The distal ends of the radius and ulna articulate with the carpal bones to form the wrist joint
what are 5 landmarks of the radius?
Head of the radius
● A disk shaped structure
● It articulates with the capitulum of the distal humerus
Neck of radius
● A narrow area of bone between the radial head and radial tuberosity
Radial tuberosity
● A bony projection, where the biceps brachii attaches
Styloid process
● The lateral side projection of the distal end of the shaft
Ulnar notch
● A concavity found on the medial surface of the distal end of the shaft which articulates with the head of the ulna
which of the carpals does the radius articulate with?
scaphoid and lunate
what are 6 landmarks of the ulna (including their purpose)?
hint - start with olecranon…
Olecranon
● A large projection which extends proximally (up) forming part of the trochlear notch.
● It can be palpated as the ‘tip’ of the elbow
● The triceps brachii muscle attaches to it
Coronoid process
● This ridge of bone projects outwards anteriorly, forming part of the trochlear notch
Trochlear notch
● A wrench shape formed by the olecranon and coronoid process
● It articulates with the trochlea of the humerus
Radial notch
● Located on the lateral surface of the trochlear notch
● This area articulates with the head of the radius to form the proximal radioulnar joint
Tuberosity of ulna
● A roughening immediately distal to the coronoid process
● It is where the brachialis muscle attaches
- styloid process at the distal end, quite small
what kind of joint is the elbow, and what is it comprised of?
what movements does it allow?
synovial hinge joint
an articulation between the distal end of the humerus and proximal ends of radius and ulna
flexion and extension of the forearm
what kind of joint is the proximal radioulnar joint and what is is comprised of?
what movement does it allow?
synovial pivot joint
under the elbow, it is where the head of the radius and the radial notch of the ulna meet
allows for pronation and supination (along with the distal RU joint)
what kind of joint is the distal radioulnar joint and what is it comprised of?
what movement does it allow?
synovial pivot joint, between head of ulna and ulnar notch of the radius (ulna head = at bottom, radius head = at top)
allows for the distal (bottom) end of the radius to move anteromedially over the ulna during pronation. also contributes to allowing supination
what is the general role of the muscles of the anterior compartment of the forearm?
where do these muscles originate from?
also known as the flexor compartment, comprised of 8 muscles that flex the wrist and digits
the superficial and intermediate muscles all originate from the medial epicondyle (not the deep muscles)
which nerves innervate the anterior compartment of the forearm?
mostly innervated by the median nerve,
except for flexor carpi ulnaris and the medial half of flexor digitorum profundus,
which are innervated by the ulnar nerve
what blood vessels supply the anterior compartment of the forearm?
the radial and ulnar artery
name the 8 muscles of the anterior compartment of the forearm including ehat layer they are in
superficial -
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
intermediate -
flexor digitorum superficialis
deep -
flexor pollicis longus
flexor digitorum profundus
pronator quadratus
TABLE
what is the role of the muscles in the posterior compartment of the forearm?
innervation?
common origin?
the extensor muscles, typically extend the wrist and the digits
all innervated by the radial nerve
most originate from the lateral epicondyle or the supracondylar ridge
name the 12 extensor muscles of the posterior compartment of the forearm, and what layer they belong to
superficial -
brachioradialis
extensor carpi radialis longus
extensor carpi radialis brevis
extensor digitorum
extensor digit minimi
extensor carpi ulnaris
anconeus
deep -
supinator
abductor pollicis longus
extensor pollicis brevis
extensor pollicis longus
extensor indicis
define the boundaries of the cubital fossa
triangular shaped depression over anterior aspect of the elbow
lateral border = brachioradialis muscle
medial border = pronator teres muscle
superior border = an imaginary line going between the two epicondyles of the humerus
roof = bicipital aponeurosis fascia fat and skin
floor = brachialis proximally and supinator distally
from lateral to medial, what are the contents of the cubital fossa?
radial nerve - travels along lateral side and divides into deep and superficial branches
biceps tendon - passes down the centre, attaching to the radial tuberosity (and gives rise to bicipital aponeurosis)
brachial artery - bifurcates into radial and ulnar artery @ apex of cubital fossa. pulse can be felt
median nerve - travels medially, exiting by passing between the 2 heads of the pronator teres
some superficial veins lie on top of the cubital fossa’s roof…
what superficial veins lie on top of the cubital fossa’s roof?
these can be accessed for taking blood (venepuncture)
the median cubital vein, which connects the cephalic and basilic veins
(think this might be in the cubital fossa but) the brachial vein is seen alongside the brachial artery and also branches into ulnar and radial veins
pronator teres?
superficial muscle in anterior comp. of forearm
origin = medial epicondyle
insertion = mid-shaft of radius
function = pronates and flexes forearm
flexor carpi radialis
superficial muscle in anterior comp. of forearm
O: medial epicondyle
I: base of metacarpals 2-5
F: flexes forearm, flexes hand, abducts hand
palmaris longus?
superficial muscle of the anterior comp. of forearm
O:medial epicondyle
I: palmar aponeurosis of the hand
F: flexes forearm and hand
flexor carpi ulnaris?
superficial ant. forearm
O:medial epicondyle
I: pisiform, base of metacarpal 5
F: flexes forearm, flexes hand, ADDucts hand
flexor digitorum superficialis
intermediate ant. forearm
O: medial epicondyle and radius
I: middle phalanges 2-5
F: flexes proximal interphalangeal joints (hand and forearm
flexor pollicis longus?
deep anterior forearm
O: anterior surface of radius and interosseous membrane
I: base of distal phalanx of the thumb
F: flexes thumb
flexor digitorum profundus?
deep anterior forearm
O: anterior surface of ulna and interosseous membrane
I: distal phalanges 2-5
F: flexes distal interphalangeal joints, and hand
pronator quadratus?
deep anterior forearm
O: distal anterior surface of ulna
I: distal anterior surface of radius
F: pronates forearm
brachioradialis?
posterior forearm - superficial
O: lateral supracondylar ridge
I: distal end of radius
F: flexes at the elbow
extensor carpi radialis longus?
posterior forearm - superficial
O: lateral supracondylar ridge
I: base of metacarpal 2 (index finger)
F: extends and abducts wrist
extensor carpi radialis brevis?
posterior forearm - superficial
O: lateral epicondyle
I: base of metacarpals 2-5
F: extends and abducts wrist
extensor digitorum?
posterior forearm - superficial
O: lateral epicondyle
I: base of middle and distal phalanges 2-5 via the extensor hoods
F: Extension of the digits at the interphalangeal and metacarpophalangeal joints
extensor digiti minimi?
posterior compartment of forearm - superficial
O: lateral epicondyle
I: dorsal hood of little finger
F: Extends the little finger, and contributes to extension at the wrist
extensor carpi ulnaris?
posterior forearm - superficial
O: lateral epicondyle
I: base of metacarpal 5
F: Extension and adduction of wrist
anconeus?
posterior forearm - superficial
O: lateral epicondyle
I: olecranon and posterior surface of ulna
F: Extends and stabilises the elbow joint. Abducts the ulna during pronation of the forearm
supinator?
deep posterior forearm
O: lateral epicondyle
I: radius
F: supinates the forearm
abductor pollicis longus?
posterior compartment of forearm - deep
O: posterior surface of ulna, radius and interosseous membrane
I: base of metacarpal 1
F: abducts the thumb
extensor pollicis brevis?
deep posterior forearm
O: posterior surface of radius and interosseous membrane
I: base of proximal phalanx of the thumb
F: extends thumb
extensor pollicis longus?
deep posterior forearm
O: posterior surface of ulna and interosseous membrane
I: base of distal phalanx of the thumb
F: extends thumb
extensor indicis?
deep posterior forearm
O: posterior surface of ulna and interosseous membrane
I: extensor hood of index finger
F: extends the index finger
blood supply of muscles of anterior compartment of forearm vs posterior?
anterior = radial and ulnar arteries
posterior = posterior interosseous artery, a branch of the common interosseus artery, which is a branch of the ulnar artery
fractures of the humerus often damage which nerve? why and what problem does this cause?
axillary nerve because it wraps around the surgical neck of the humerus
damage results in loss of shoulder abduction
