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Cubital Fossa, Anterior Forearm and Wrist
I.
Landmarks
A. cubital fossa – a triangular shaped space in front of elbow
1. boundaries
a. medial – lateral border of the pronator teres muscle
b. lateral – medial border of the brachioradialis muscle
c. base – line between the epicondyles of the humerus
d. floor – brachialis muscle
e. roof – skin
2. contents
a. tendon of biceps brachii muscle
b. brachial vessels and its terminal branches
(1) radial artery
(a) radial recurrent artery
(2) ulnar artery
(a) common interosseous artery
i. anterior interosseous artery
ii. posterior interosseous artery
† interosseous recurrent artery
(b) anterior and posterior ulnar recurrent arteries
c. median nerve
d. radial nerve and its branches in the lateral wall of the cubital fossa
B. forearm and wrist
1. ulnar is subcutaneous throughout the forearm
2. styloid processes of the radius and ulna
3. distal skin – corresponds to the proximal border of the flexor retinaculum
4. tendon of the flexor carpi radialis muscle
5. tendon of the palmaris longus muscle, if present
6. tendon of the flexor carpi ulnaris muscle
7. pulses of the radial and ulnar arteries
8. pisiform bone
9. hook of the hamate bone
10. tubercle of the scaphoid bone
11. crest of the trapezium bone
II.
Osteology
A. radius –in the lateral side of the forearm
1. head
2. neck
3. radial tuberosity
4. ulnar notch
5. styloid process
5. dorsal tubercle
B. ulna – in the medial side of the forearm
1. olecranon process
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2. trochlear notch
3. coronoid process
4. radial notch
5. ulnar tuberosity
6. styloid process
C. carpal bones – from lateral to medial
1. proximal row
a. scaphoid or navicular (boat-like)
b. lunate (moon-shaped)
c. triquetrum (triangular)
d. pisiform (pea-sized sesamoid bone in tendon of the flexor carpi ulnaris)
2. distal row
a. trapezium (greater multangular)
b. trapezoid (lesser multangular, wedge-shaped)
c. capitate (head shaped)
d. hamate (has a hook or hamulus)
III.
Fascia
A. antebrachial fascia – surrounds muscles
B. palmar carpal ligament – thickening of the antebrachial fascia just above wrist
C. flexor retinaculum (transverse carpal ligament)
1. attached laterally to the tubercle of the scaphoid and crest of the trapezium and
medially to the pisiform and hamulus if the hamate
2. prevents the flexor tendons from bowing
3. serves as a boundary of the carpal tunnel which contains the following
a. tendons of flexor digitorum superficialis muscle
b. tendons of flexor digitorum profundus muscle
c. tendon of flexor pollicis longus muscle
d. median nerve
D. thenar fascia – deep fascia of the thenar muscles
E. hypothenar fascia –deep fascia of the hypothenar muscles
F. palmar aponeurosis – a very thick, stout fascia covering the central compartment
of the hand, continuous with the tendon of the palmaris longus
IV.
Muscles
A. eight muscles are found in the anterior compartment of the forearm:
five of these have an origin off the medial epicondyle of the humerus and
names of them are synonymous with their action. There are four layers
1. first layer – all have an origin off the medial epicondyle of the humerus
a. pronator teres muscle #1 - has a second head of origin from the ulna
(1) inserts into the middle of the lateral surface of the radius
(2) pronates the hand
(3) innervation – branch of the median nerve (C6 & 7)
b. flexor carpi radialis muscle #2 – goes through a split in the flexor
retinaculum
(1) inserts into the base of the 2nd and 3rd metacarpal bones
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(2) flexes the hand and helps abduct (radial flex) it
(3) innervation – branch of the median nerve (C6 & 7)
c. palmaris longus muscle #3 – absent in about 10% of subjects
(1) inserts into the central part of the flexor retinaculum and palmar
aponeurosis
(2) flexes the hand
(3) innervation – branch of the median nerve (C6 & 7)
d. flexor carpi ulnaris muscle #4 – has a second head of origin from ulna
(1) inserts into the pisiform bone
(2) flexes and adducts (ulnar flexes) the hand
(3) innervation – branch of the ulnar nerve (C8 & T1)
2. second layer – has origin from the medial epicondyle of the humerus
a. flexor digitorum superficialis muscle #5 – it also has a origins from the
ulna (lateral to coracoid process) and radius (from radial tuberosity to
the insertion of the pronator teres muscle)
(1) inserts on the bases of the middle phalanges of the four fingers
(2) flexes the middle phalanx of each finger; further action flexes the hand
(3) innervation – branches of the median nerve (C7, 8, & T1)
3. third layer
a. flexor pollicis longus muscle #6 – originates from the anterior surface of the
radius and interosseous membrane
(1) interosseous membrane – a fibrous tissue connecting almost the whole
length of the interosseous (border) crest of the radius to that of the ulna
(1) inserts on the base of the distal phalanx of the thumb
(2) flexes the distal phalanx of the thumb
(3) innervation – a branch of the anterior interosseous nerve from the
median nerve (C8 & T1)
b. flexor digitorum profundus muscle #7 –
(1) origin – from the proximal ¾ of the volar (palmar) and medial surface
of the ulna plus part of the upper the posterior ¾ of the ulna
(2) insertion – into the bases of the distal phalanges of the four fingers
(3) flexes the terminal phalanges; further action flexes the other phalanges
(4) innervation – 2 sources: a branch of the anterior interosseous nerve
from the median nerve and a branch from the ulnar nerve (C8 & T1)
4. fourth layer
a. pronator quadratus muscle #8
(1) origin – the distal part of the palmar surface of the ulna
(2) inserts – into the distal fourth of the lateral border and palmar surface of
the radius
(3) pronates the hand
(4) innervation – a branch of the anterior interosseous nerve from the
median nerve (C8 & T1)
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V.
Blood vessels
A. brachial artery
1. in the cubital fossa it lies between the biceps brachii tendon and median nerve,
deep to the bicipital aponeurosis
2. begins at the lower margin of tendon of the teres major muscle
3. bifurcates into radial & ulnar branches about 1 cm distal to the bend of the
elbow
B. radial artery – smaller in calibur that the ulnar artery
1. proximally - crosses superficial to the pronator teres muscle but under cover
of brachioradialis muscle in the radial side of the forearm
2. distally – it lays between the brachioradialis and flexor carpi radialis tendons
3. at the wrist – reaches the back of the carpal bones by passing between the
radial collateral ligament of the wrist and tendons of the abductor pollicis
longus and extensor pollicis brevis muscles; then it is crossed by the tendon
of the extensor pollicis longus muscle before it disappears between the heads
of the 1st dorsal interosseous muscle
4. branches given off in the forearm
a. radial recurrent artery – arises immediately distal to the elbow to supply
the parts of the supinator, brachioradialis and brachialis muscles plus elbow
joint
(1) anatomoses with radial collateral artery (off deep brachial artery)
b. muscular arteries – distributed to muscles on radial side of forearm
c. palmar carpal artery – small vessel arising distal to pronator quadratus
muscle supplying the articulations of the wrist
d. superficial palmar artery – arises where the radial artery is about to
wind around the lateral side of the wrist
(1) then passes through the muscles of the thenar eminence forming
an anastomoses with the terminal portion of the ulnar artery creating
the superficial palmar arch
(2) size - mostly ends in thenar muscles or can be as large as radial artery
5. branches given off at the wrist
a. dorsal carpal artery – small vessel arising deep to the extensor tendons
of the thumb and anastomoses with dorsal carpal artery (off ulnar artery)
b. 1st dorsal metacarpal artery – arises just before the radial artery passes
between the two heads of the 1st dorsal interosseous muscles to supply the
adjacent sides of the thumb and index finger
C. ulnar artery – the larger of the brachial artery's two terminal branches
1. begins a little distal to the bend of the elbow going to the ulnar side of forearm
2. proximally – deep to the pronator teres (ulnar head), flexor carpi radialis,
palmaris longus, and flexor digitorum superficialis muscles; it lies upon the
brachialis and flexor digitorum profundus muscles
a. the median nerve is medial to about the first 2 ½ cm of the ulnar artery
but then the nerve passes over the ulnar head of the pronator teres muscle,
which separates the two (nerve & artery)
3. distally – the artery lies on the flexor digitorum profundus muscle being
covered by the skin, subcutaneous tissue, and deep fascia; it is also placed
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between the flexor carpi ulnaris and flexor digitorum superficialis muscles
a. the ulnar nerve is medial to the distal 2/3rds of the ulnar artery
4. branches given off in the forearm
a. anterior ulnar recurrent artery – arises immediately distal to the elbow
joint; runs proximally between the brachialis and pronator teres muscles,
supplying parts of those muscles; anterior to the medial humeral epicondyle
(1) anastomoses with inferior ulnar collateral artery (off brachial artery)
b. posterior ulnar recurrent artery – arises just distal to the previous artery
and is larger; passes dorsally and medially over the flexor digitorum
profundus muscle and behind the medial epicondyle of the humerus
(1) anastomoses with superior ulnar collateral artery (off brachial artery)
c. common interosseous artery – about 1 cm in length: arises immediately
distal to the radial tuberosity and passes to the upper border of the
interosseous membrane, giving off two branches
(1) palmar interosseous artery – passes down forearm on the palmar
surface of the interosseous membrane accompanied by the palmar
interosseous branch of the median nerve
(a) at the proximal border of the pronator quadratus it pierces the
interosseous membrane, enters the dorsal forearm where it
anastomoses with the dorsal interosseous artery
(2) dorsal interosseous artery – given off at the upper border of the
interosseous membrane to pass down its dorsal side; at its distal
end it anastomoses with the above palmar interosseous artery
(a) interosseous recurrent artery – arises near the origin of the
dorsal interosseous artery but ascends to the interval between the
lateral epicondyle and the olecranon, deep to the anconeus muscle
(b) anastomoses with middle collateral artery (off deep brachial
artery)
d. muscular branches - distributed to the muscles on the ulnar side of the
forearm
5. branches given off at the wrist
a. palmar carpal artery – a small vessel deep to the tendons of the flexor
digitorum profundus; anastomoses with the palmar carpal artery off the
radial artery
b. dorsal carpal artery – arises immediately proximal to the pisiform bone,
goes to dorsal wrist and anastomoses with the corresponding artery from
radial artery
VI.
Nerves
A. median nerve – typically, gives off no branches above the elbow joint
1. passes between the humeral and ulnar heads of the pronator teres muscle,
then deep to the flexor digitorum superficialis muscle where it descends to
the wrist
2. at the wrist it can be located between the tendons of the flexor carpi radialis
and palmaris longus tendons
3. supplies the following muscles in the forearm
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a. pronator teres
b flexor carpi radialis
c. palmaris longus
d. flexor digitorum superficialis
4. passes under the flexor retinaculum or carpal tunnel
5. gives off the anterior (palmar) interosseous nerve in the cubital fossa
a. accompanies anterior interosseous artery on the interosseous membrane
b. supplies the following muscles
(1) radial half of the flexor digitorum profundus
(2) flexor pollicis longus
(3) pronator quadratus
6. palmar branch of the median nerve – pierces the antebrachial fascia distal
to the wrist and divides into medial and lateral branches (C6, 7, & 8)
a. medial branch – supplies skin in proximal palm
b. lateral branch – supplies skin over the thenar eminence
6. nerve to pronator teres muscle – may arise from above the elbow, rarely
B. ulnar nerve
1. enters the forearm from behind the medial epicondyle of the humerus (funny
bone) by passing between the heads of the humeral an ulnar heads of the
flexor carpi ulnaris muscle
2. travels upon the flexor digitorum profundus muscle being medial to the ulnar
artery in the distal half of the forearm
3. enters the hand by passing superficial to the flexor retinaculum (carpal
tunnel) otherwise called the transverse carpal ligament
4. grooves the lateral side of the pisiform bone being held down by the palmar
carpal ligament
5. supplies the following muscles in the forearm
a. ulnar half of the flexor digitorum profundus
b. flexor carpi ulnaris
6. palmar cutaneous branch of the ulnar nerve – arises near the middle of
the forearm and accompanies the ulnar artery into the hand (C8 & T1)
a. penetrates the flexor retinaculum then supplies the palm superficial to the
palmaris brevis muscle
7. dorsal branch – arises in the distal half of the forearm to reach the dorsum
of the wrist; divides into two dorsal digital nerves and metacarpal branch
a. more medial digital nerve – supplies skin on the ulnar side of little finger
b. next more lateral digital nerve – supplies the adjacent skin of the little
finger and ring fingers
c. metacarpal branch – supplies the skin of that area and web between the
ring and middle fingers
8. palmar branch – the terminal portion of the ulnar nerve; crosses the wrist in
company of the artery superficial to the flexor retinaculum and under cover
of the palmaris brevis muscle
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