Lecture 8: cubital fossa and forearm

Recognise the major features of the radius and ulna and appreciate how they articulate with the humerus. Describe the elbow joint, the range of movements that can occur at it, and the structures that stabilise it. Identify the cubital fossa, recognising its boundaries and contents. Identify the major muscles in the forearm, and describe their actions on the elbow, wrist, and fingers. Identify the major nerves that supply the muscles of the forearm and appreciate their segmental distribution. Describe the pattern of blood supply and venous drainage in the forearm.

what are the boundaries of the forearm?

elbow to wrist

what do the muscles of the forearm act on?

elbow, wrist and digital joints

what are the joints of the forearm?

Elbow joint, Proximal and distal radioulnar joints

what are the bones of the forearm?

Radius and ulna

what is the action of the muscles in the anterior compartment of the forearm and how many?

flexor – 8 muscles

what is the role of the muscles in the posterior forearm and how many are there?

extensor – 12 muscles

where is the radius found?

On lateral side

where’s the ulnar found?

On medial side

label structure 1-5?

radial notch, head, neck, radial tuberosity, radius

label structures 6-10?

styloid process of radius, olecranon process, trochlear notch, coronoid process, proximal radioulnar joint

label structures 11-15

interosseous membrane, ulna, ulnar notch, head of ulna, styloid process of ulna

label structures 16-20

distal radioulnar joint, head of radius, neck of radius, radius, styloid process of radius

The elbow is a compound joint what does this mean?

A single capsule housing multiple individual joints working together

what two joints make up the elbow?

humeroulnar joint, proximal radioulnar joint

what does the humeroulnar joint do?

The hinge connection between the upper arm and inner forearm bone responsible for flexion and extension

what does the radioulnar joint do?

The pivot connection between the two forearm bones near the elbow, pronation and supination

fill in the blanks

radial deviation, ulnar deviation

fill in the blanks

extension, flexion

label structures 1-4

flexor capi radialis, palmaris longus, flexor carpi ulnaris, pronator teres

what is the blood supply to the posterior compartment of the forearm?

radial and ulnar aa.

what is the innervation of the forearm?

median n.

what muscles are in the superficial area of the forearm anterior compartment?

pronator teres, flexor carpi radialis, palmaris longus, flexor carpi lunaris

whats the action of the pronator teres?

pronation of forearm, flexes elbow

what is the action of the flexor carpi radialis?

flexion and abduction at wrist

what is the action of the palmaris longus?

flexes wrist

whats the action of the flexor carpi ulnaris?

flexion and adduction of wrist

whats in the intermediate forearm anterior compartment?

Flexor digitorum superficialis

what is the action of the flexor digitorum superficialis?

flexor of digits 2-5 (primarily at proximal interphalangeal joints)

what muscle is this?

flexor digitorum superficialis

whats the blood supply to the Flexor digitorum superficialis?

radial and ulnar aa.

whats the innervation of the Flexor digitorum superficialis

median n.

what muscles are in the deep area of the forearm anterior compartment

flexor pollicis longus, pronator quadratura, flexor digitorum profundus

what is the action of the flexor pollicis longus?

flexion of thumb

what is the action of the pronator quadratus?

pronates the forearm

what is the action of the flexor digitorum profundus?

: flex hand and both interphalangeal joints

what is the blood supply to the deep area of the anterior compartment of the forearm?

radial and ulnar aa

what is the innervation to the deep area of the anterior compartment of the forearm?

median n

label structures 1-3

flexor digitorum profundus, flexor pollicis longus, pronator quadratus

what muscle is this?

flexor digitorum profundus

what is this muscle?

flexor pollicis longus

What’s this muscle?

pronator quadratus

whats in the mobile wad of the forearm posterior compartment?

Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis

what muscle is this?

Brachioradialis

what muscle is this?

Extensor carpi radialis longus

what muscle is this?

Extensor carpi radialis brevis

what is the action of the Extensor carpi radialis brevis?

extension and abduction of wrist, weak elbow flexor

what is the action of the Brachioradialis?

flexion of elbow, supination and pronation to 90°

what is the action of the Extensor carpi radialis longus?

extension and abduction of wrist, weak elbow flexor

what is the blood supply to the mobile wad?

ulnar a.

what is the innervation to the mobile wad?

radial n.

What muscles are in the superficial posterior compartment of the forearm?

Anconeus, Extensor digitorum, Extensor carpi ulnaris, Extensor digiti minimi

What is the action of the Anconeus?

prevents the elbow joint capsule being pinched in the olecranon fossa during extension of the elbow

whats the innervation to the anconeus?

radial n

whats the blood supply to the anconeus?

deep brachial a.

what muscles highlighted in green?

anconeus

what muscle is the line pointing to?

anconeus

what happens when the extensor is expanded in the superficial posterior forearm?

flattened tendons (aponeurosis) of extensor muscles on phalanges. Also known as extensor hood, dorsal expansion, dorsal hood, dorsal aponeurosis.

Whats the action of the extensor digitorum?

extension of wrist and digits 2-5

Whats the action of the Extensor carpi ulnaris?

extension and adduction of wrist

what is the action of the Extensor digiti minimi?

extension of wrist and digit 5

what are the missing structures NB purple muscles missing?

extensor digitorum, extensor digitorum minimi, extensor carpi ulnaris

what is the blood supply of the superficial posterior compartment of the forearm?

ulnar a.

What is the innervation of the superficial posterior compartment of the forearm?

radial n.

what labels are missing?

supinator, extensor indices

what muscles are in the deep posterior compartment of the forearm?

supinator, extensor indicies, abductor pollices longus, extensor pollices brevis, extensor pollices longus

what supplies the deep posterior forearm?

ulnar artery

what is the innervation of the deep posterior forearm?

radial nerve

what is the action of the supinator?

supinates forearm

what is the action of the extensor indices?

extension of wrist and digit 2

what muscle is this

supinator

what muscle is this?

extensor indicies

what is the action of the abductor pollices longus?

abduction of digit 1

what is the action of the extensor policis brevis?

extension of digit 1 at metacarpophalangeal joint

what is the action of the extensor policis longus?

extension of digit 1 at MCP/interphalangeal joints

what muscles are highlighted in red orange and more medial orange?

red: abductor pollicis longus orange: extensor pollicis brevis medial orange: extensor pollicis longus

what are the blood vessels of the forearm form the arch of the aorta?

L/R subclavian artery → axillary artery → brachial artery → radial and ulnar arteries

what are the blood vessels of the forearm from the wrist?

cephalic and basilic veins (superficial) + radial and ulnar veins (deep) → brachial vein (deep)  ⇉ axillary vein → L/R subclavian vein → L/R brachiocephalic vein → SVC

label BV 1-5

subclavian artery, axillary artery, anterior circumflex humeral artery, branchial artery, radial collateral artery

label BV 6-11

radial artery, carotid artery, aorta, ulnar collateral artery (superior), ulnar collateral artery (inferior), ulnar artery

what is the cubital fossa?

Triangular space/depression on anterior elbow

Transition between arm and forearm

how many boundaries does the cubital fossa have?

3 + floor + roof

how many things does the cubital fossa contain?

5 structures inside the space

3 structures on roof

what is the lateral border of the cubital fossa?

brachioradialis m.

what is the medial border of the cubital fossa?

pronator teres m.

What is the superior border of the cubital fossa?

epicondylar line

what is the floor of the cubital fossa?

brachialis m. proximally and supinator m. distally

what is the roof of the cubital fossa?

bicipital aponeurosis (from biceps brachii m.), fascia, subcutaneous fat, and skin

fill in blanks 1-6

epicondylar line, branchioradialis, radius, humerus, pronator teres, ulna

what are the contents of the cubital fossa from lateral to medial

Radial nerve, biceps tendon, branchial artery, branchial vein, medial nerve

label structures 1-5

superior border (epicondylar line), radial nerve, biceps tendon, superficial radial nerve, lateral border (branchioradialis)

label structures 6-10

deep radial nerve, radial artery, radial vein, branchial artery, branchial vein

label structures 11-15

median nerve, median border (pronator teres), ulnar vein, ulnar artery

label structures 1-5

epicondylar line, radial nerve, biceps tendon, cephalic vein, superficial radial nerve

label structures 6-10

branchioradialis muscle, deep radial nerve, radial artery, radial vein, radius, humerus

label structures 11-15

humerus, branchial artery, branchial vein, median nerve, pronator teres,

label structures 16-21

ulnar vein, ulnar artery, bicipital aponeurosis, median cubital vein, basilic vein, ulna

what does the median cubital vein do?

connects basilic and cephalic veins

what is significant about the vessels on the roof of the cubital fossa?

Easily accessible for venipuncture (taking blood)

where is the roof of the cubital fossa?

Between bicipital aponeurosis and fascia