The radial artery lies lateral to the tendon of
the flexor carpi radialis

A patient who is unable to flex the arm and
forearm is likely to have a lesion in the ventral
rami of C5, C6, and C7. The biceps brachii and
brachialis receive fibers from C5 and C6, and the
coracobrachialis receives fibers from C5, C6, and
C7. C6 is the main source of fibers for each

The hand is abducted at the wrist joint by the
flexor carpi radialis, abductor pollicis longus,
extensor carpi radialis longus, and extensor carpi
radialis brevis

The extensor carpi radialis longus tendon
is crossed by the abductor pollicis longus and
extensor pollicis brevis

The deep artery of the arm accompanies
the radial nerve through the radial groove and
passes around the body of the humerus

The supinator, which forms the floor of the
cubital fossa along with the brachioradialis, is
innervated by the deep branch of the radial
nerve. It supinates the forearm by rotating the
radius. The biceps brachii also supinates the
forearm when the forearm is already flexed

The axillary artery gives rise to the superior
thoracic, thoracoacromial, lateral thoracic, subscapular, and anterior and posterior circumflex
humeral arteries. The brachial artery gives rise to
the deep artery of the arm, the nutrient humeral
artery, and the superior and inferior collateral
arteries. The ulnar artery gives rise to the anterior
and posterior ulnar recurrent, common interosseous, anterior and posterior interosseous, and
dorsal and palmar carpal branch arteries

The flexor pollicis longus is innervated by
the anterior interosseous nerve from the median
nerve

The median and ulnar nerves supply no
branches to the arm

The palmaris longus tendon is a guide for
locating the median nerve at the wrist

The median nerve assists in the innervation
of the elbow joint and gives muscular branches
to pronator teres, flexor carpi radialis, palmaris
longus, and flexor digitorum superficialis. The
median nerve also has an anterior interosseous
branch that innervates the lateral part of the
flexor digitorum profundus, flexor pollicis
longus, and pronator quadratus. The recurrent
branch of the median nerve innervates the
thenar muscles, and the palmar cutaneous
branch innervates the skin of the lateral part of
the palm

The radial artery gives rise to the radial
recurrent artery as well as dorsal and palmar
carpal branches. The ulnar artery gives rise to the
common interosseous artery, anterior and posterior interosseous arteries, anterior and posterior
ulnar recurrent arteries, and dorsal and palmar
carpal branches

The snuff box is bounded anteriorly by the
tendons of the abductor pollicis longus and extensor pollicis brevis. Posteriorly it is bounded
by the tendon of the extensor pollicis longus. The
radial artery can be felt in the floor, along with
the radial styloid process, first metacarpal,
scaphoid, and trapezium

The brachioradialis is a flexor of the forearm,
but it is located in the extensor compartment and
is innervated by the radial nerve

The abductor pollicis longus originates from
the posterior surfaces of the ulna, radius, and
interosseous membrane. The following muscles
take at least one of their origins from the lateral
epicondyle of the humerus: extensor carpi radialis brevis, extensor digitorum, extensor digiti
minimi, extensor carpi ulnaris, and supinator

The cubital fossa contains the terminal part
of the brachial artery (and the beginning of the
ulnar and radial arteries), deep accompanying
veins, the median nerve, and the biceps brachii
tendon. In the tissue superficial to the fossa are
the median cubital vein and medial and lateral
antebrachial cutaneous nerve. The deep and
superficial branches of the radial nerve are
within the floor of the fossa

The posterior cord gives rise to the upper and
lower subscapular nerves, thoracodorsal nerve,
axillary nerve, and radial nerve. The long thoracic nerve originates from C5–C6–C7

All muscles in the anterior compartment
of the forearm are innervated by the median
nerve, except for the flexor carpi ulnaris and the
medial part of the flexor digitorum profundus,
which are innervated by the ulnar nerve

The superficial muscles (pronator teres,
flexor carpi radialis, palmaris longus, flexor
carpi ulnaris, and flexor digitorum superficialis)
cross the elbow joint. The deep muscles (flexor
digitorum profundus, flexor pollicis longus, and
pronator quadratus) do not

The suprascapular nerve innervates the
supraspinatus, infraspinatus, and glenohumeral
(shoulder) joint

The brachialis originates from the distal half
of the anterior surface of the humerus and inserts
on the coronoid process and tuberosity of the
ulna. It crosses one joint, flexing the forearm in
all positions. While it is primarily innervated by
the musculocutaneous nerve, some of its lateral
part is innervated by a branch of the radial nerve

The anconeus assists in extension of the forearm, resists abduction of the ulna during pronation of the forearm, and tenses the capsule of the
elbow joint so that it is not pinched when the
joint is extended

To test the triceps brachii, the arm is abducted
90 degrees and then the flexed forearm is extended
against resistance

The median nerve gives rise to a palmar
cutaneous branch; the ulnar nerve as well has a
palmar cutaneous branch. The radial nerve gives
rise to the posterior brachial cutaneous nerve,
the posterior antebrachial cutaneous nerve, the
inferior lateral brachial cutaneous nerve, and a
superficial branch that innervates the dorsum of
the hand and the digits. The musculocutaneous
nerve continues as the lateral antebrachial cutaneous nerve. The axillary nerve gives rise to the
superior lateral brachial cutaneous nerve. The
medial cord of the brachial plexus gives rise to
the medial brachial cutaneous nerve and the
medial antebrachial cutaneous nerve. The supraclavicular nerves (from C3–C4) and the intercostobrachial nerve (from T2) also contribute
to the cutaneous innervation of the arm

To pronate the forearm, the pronator quadratus initiates pronation, assisted later by the
pronator teres