BRACHIAL PLEXUS
BRACHIAL PLEXUS
uthe
nerve fibers derived from different segments of the spinal cord to be arranged
and distributed efficiently in different nerve trunks to the various parts of
the upper limb.
uThe
brachial plexus is formed in the posterior triangle of the neck by the
union of the anterior rami of the 5th, 6th, 7th, and 8th cervical and the
1st thoracic spinal nerve.
COMPONENTS
uRoots
– C5 – T1
uTrunks
– Upper – C5 and C6, Middle – C7, Lower – C8 and T1
uDivisions
– Anterior and Posterior
uCords
–in relation to the AXILLARY ARTERY
u–
Lateral Cord - anterior divisions of the upper and middle trunk
u-
Medial Cord - the anterior division of the lower trunk
u-
Posterior Cord - the posterior divisions of all three trunks
CORD
ulie
above and lateral to the first part of the axillary artery
uMEDIAL
CORD - crosses behind the artery to reach the medial side of the second
part of the artery.
uPOSTERIOR
CORD - lies behind the second part of the artery
uLATERAL
CORD - on the lateral side of the second part of the artery
uform
the main nerve trunks of the upper limb continue this relationship to the
artery in its third part.
LATERAL
CORD
uLateral
pectoral nerve
uMusculocutaneous
nerve
uLateral
root of median nerve
MEDIAL
CORD
uMedial
pectoral nerve
uMedial
cutaneous nerve of arm and
uMedial
cutaneous nerve of forearm
uUlnar
nerve
uMedial
root of median nerve
POSTERIOR
CORD
uUpper
and lower subscapular nerves
uThoracodorsal
nerve
uAxillary
nerve
uRadial
nerve
BRANCHES
FOUND IN THE AXILLA
uThe
nerve to the subclavius (C5 and 6)
usupplies
the subclavius muscle
ugive
a contribution (C5) to the phrenic nerve; this branch, when present, is
referred to as the accessory phrenic nerve.
uLong
thoracic nerve (C5, 6, and 7)
uarises
from the roots of the brachial plexus in the neck and enters the axilla by
passing down over the lateral border of the 1st rib behind the axillary vessels
and brachial plexus
uSupplies
the serratus anterior muscle
BRANCHES
FOUND IN THE AXILLA
uThe lateral pectoral nerve
uarises from the lateral cord of the brachial plexus
and supplies the pectoralis major muscle.
uThe musculocutaneous nerve
u from the lateral cord of the brachial plexus, supplies
the coracobrachialis muscle, and leaves the axilla by piercing that muscle.
uThe lateral root of the median nerve is the direct continuation of the lateral cord of the
brachial plexus.
BRANCHES
FOUND IN THE AXILLA
uThe medial pectoral nerve
ufrom the medial cord of the brachial plexus,
usupplies and pierces the pectoralis minor muscle,
and supplies the pectoralis major muscle.
uThe medial cutaneous nerve of the arm (T1)
uarises from the medial cord of the brachial plexus
ujoined by the intercostobrachial nerve (lateral
cutaneous branch of the 2nd intercostal nerve).
BRANCHES
FOUND IN THE AXILLA
uThe medial cutaneous nerve of the forearm
ufrom the medial cord of the brachial plexus and
descends in front of the axillary artery.
uThe ulnar nerve (C8 and T1)
u from the medial cord of the brachial plexus and
descends in the interval between the axillary artery and vein.
BRANCHES
FOUND IN THE AXILLA
uThe medial root of the median nerve
ufrom the medial cord of the brachial plexus
uCrosses in front of the third part of the axillary
artery to join the lateral root of the median nerve.
uThe upper and lower subscapular nerves
ufrom the posterior cord of the brachial plexus and
supply the upper and lower parts of the subscapularis muscle.
uthe
lower subscapular nerve supplies the teres muscle.
BRANCHES
FOUND IN THE AXILLA
uThe thoracodorsal nerve
uarises from the posterior cord of the brachial plexus
and runs downward to supply the latissimus dorsi muscle.
uThe axillary nerve is one of the terminal branches of the posterior cord of the brachial
plexus.
uIt turns backward and passes through the quadrangular
space
BRANCHES
FOUND IN THE AXILLA
uThe radial nerve
uLargest branch of the brachial plexus and lies behind
the axillary artery.
uGives off branches to the long and the medial heads of
the triceps muscle and the posterior cutaneous nerve of the arm.
TENDON
REFLEXES
uBiceps brachii tendon reflex: C5 and 6 (flexion of the
elbow joint by tapping the biceps tendon).
uTriceps tendon reflex: C6, 7, and 8 (extension of the
elbow joint by tapping the triceps tendon).
uBrachioradialis
tendon reflex: C5, 6, and 7 (supination of the radioulnar joints by tapping the
insertion of the brachioradialis tendon).
UPPER
LESIONS OF THE BRACHIAL PLEXUS
ufrom excessive displacement of the head to the
opposite side and depression of the shoulder on the same side.
ucauses excessive traction or even tearing of C5 and 6
roots of the plexus.
uIt
occurs in infants during a difficult delivery or in adults after a blow to or
fall on the shoulder (usually trauma)
ERB'S PARALYSIS:
Erb's point
Causes
Nerve roots involved
Muscles Paralysed
Deformity
Disability
ERB'S PARALYSIS:
Erb's point
Causes
Nerve roots involved
Muscles Paralysed
Deformity
Disability
UPPER
LESIONS OF THE BRACHIAL PLEXUS
uPARALYSIS
uthe supraspinatus (abductor of the shoulder)
uinfraspinatus (lateral rotator of the shoulder)
uthe subclavius (depresses the clavicle)
uthe biceps brachii (supinator of the forearm, flexor
of the elbow, weak flexor of the shoulder)
uthe greater part of the brachialis (flexor of the
elbow) and
ucoracobrachialis (flexes the shoulder);
udeltoid (abductor of the shoulder)
uteres
minor (lateral rotator of the shoulder
UPPER
LESIONS OF THE BRACHIAL PLEXUS
uERB-DUCHENNE PALSY
uUpper limb hang limply by the side
umedially rotated (due to the the unopposed
sternocostal part of the pectoralis major);
uthe forearm will be pronated (because of loss of the
action of the biceps)
uThe position of the upper limb in this condition has
been likened to that of a porter or waiter hinting for a tip (WAITER’S TIP
APPEARANCE)
LOWER
LESIONS OF THE BRACHIAL PLEXUS
uusually traction injuries caused by excessive
abduction of the arm - a person falling from a height
uThe 1st thoracic nerve is usually torn.
uThe
nerve fibers from this segment run in the ulnar and median nerves to supply all
the small muscles of the hand
LOWER
LESIONS OF THE BRACHIAL PLEXUS
uThe hand has a clawed appearance (hyperextension of
the metacarpophalangeal joints and flexion of the interphalangeal joints)
uThe extensor digitorum is extends the
metacarpophalangeal joints (unopposed by the lumbricals and interossei);
uThe flexor digitorum superficialis and profundus and
flex the middle and terminal phalanges, respectively (unopposed by the lumbricals and interossei) – KLUMPKE’S PALSY
uloss of sensation will occur along the medial side
of the arm
NERVES
uAXILLARY NERVE – ABDUCTORS
uMUSCULOCUTANEOUS NERVE – FLEXORS OF THE ARM
uRADIAL NERVE – EXTENSORS OF THE ARM, FOREARM AND HAND
uMEDIAN NERVE – FLEXORS OF THE MEDIAL 2/3s of FOREARM
AND HAND
uULNAR
NERVE – FLEXORS OF THE MEDIAL 1/3s of FOREARM AND HAND
LESIONS
OF NERVES
uLONG THORACIC NERVE
-Blows to the posterior triangle of the neck or
mastectomy
-Paralysis of Serratus anterior – “Winged Scapula”
uAXILLARY NERVE
ushoulder dislocations or fractures of the surgical
neck of the humerus.
LESIONS
OF NERVES
uRADIAL
NERVE - commonly damaged in the axilla and in the spiral groove.
AXILLA
-badly fitting crutch pressing up into the armpit or by
a drunkard falling asleep with one arm over the back of a chair – SATURDAY
NIGHT PARALYSIS
-badly damaged in the axilla by fractures and
dislocations of the proximal end of the humerus
-
The patient is unable to extend the elbow
joint, the wrist joint, and the fingers.
- Wristdrop, or flexion of the wrist occurs as a result
of the action of the (unopposed flexors)
LESIONS
OF NERVES
uRADIAL NERVE -
uSPIRAL GROOVE - . The prolonged application of a
tourniquet to the arm in a person and fractures of the shaft of the radius
uMotor: The patient is unable to extend the wrist and
the fingers, and wristdrop occurs.
uSensory:
A variable small area of anesthesia is present over the dorsal surface of the
hand and the dorsal surface of the roots of the lateral three and a half
fingers.
LESIONS
OF NERVES
uMUSCULOCUTANEOUS NERVE
uthe biceps and coracobrachialis are paralyzed and the
brachialis muscle is weakened (the latter muscle is also supplied by the radial
nerve)
uThere
is also sensory loss along the lateral side of the forearm
LESIONS
OF NERVES
uMEDIAN NERVE - ELBOW
uinjured occasionally in the elbow region in
supracondylar fractures of the humerus.
uIt
is most commonly injured by stab wounds or broken glass just proximal to the
flexor retinaculum or suicidal attempts
LESIONS
OF NERVES
uMEDIAN NERVE
uMOTOR
uThe pronator muscles of the forearm and the long
flexor muscles of the wrist and fingers, with the exception of the flexor
carpi ulnaris and the medial half of the flexor digitorum profundus, will
be paralyzed.
uthe forearm is kept in the supine position; wrist
flexion is weak and is accompanied by adduction.
uSENSORY
ulost on the lateral half or less of the palm of the
hand and the palmar aspect of the lateral three and a half fingers.
ualso
occurs on the skin of the distal part of the dorsal surfaces of the lateral
three and a half fingers
LESION
OF NERVES
uMEDIAN NERVE – WRIST
uMOTOR:
uThe muscles of the thenar eminence are paralyzed and
wasted so that the eminence becomes flattened.
uThe thumb is laterally rotated and adducted. The hand
looks flattened and “apelike.” – APE HAND
uOpposition movement of the thumb is impossible.
uThe first two lumbricals are paralyzed.
uCARPAL
TUNNEL SYNDROME - a burning pain or “pins and needles” along the
distribution of the median nerve to the lateral three and a half fingers and
weakness of the thenar muscles.
LESIONS
OF NERVES
uULNAR NERVE
-commonly injured at the elbow, where it lies behind
the medial epicondyle, (fractures)
-the wrist, where it lies with the ulnar artery in front of the flexor
retinaculum. (Stab wounds)
LESIONS
OF NERVES
uULNAR NERVE – ELBOW
uMOTOR
uflexor carpi ulnaris and the medial half of the flexor
digitorum profundus muscles are paralyzed
uThe profundus tendons to the ring and little fingers
will be functionless, and the terminal phalanges of these fingers are therefore
not capable of being markedly flexed.
uFlexion of the wrist joint will result in abduction,
owing to paralysis of the flexor carpi ulnaris.
uSmall muscles of the hands – paralyzed
uSENSORY
- Loss of skin sensation will be observed over the anterior and posterior
surfaces of the medial third of the hand and the medial one and a half fingers.
LESIONS
OF NERVES
uULNAR NERVE – WRIST
u Motor:
uThe small muscles of the hand will be paralyzed and
show wasting, except for the muscles of the thenar eminence and the first two
lumbricals.
uThe clawhand is much more obvious in wrist
lesions because the flexor digitorum profundus muscle is not paralyzed, and marked flexion of the terminal phalanges occurs.
uFROMENT’S
SIGN
LESIONS
OF NERVES
uULNAR NERVE
uSensory:
uThe main ulnar nerve and its palmar cutaneous branch
are usually severed; the posterior cutaneous branch, which arises from the
ulnar nerve trunk about 2.5 in. (6.25 cm) above the pisiform bone, is usually
unaffected.
uconfined
to the palmar surface of the medial third of the hand and the medial one and a
half fingers and to the dorsal aspects of the middle and distal phalanges of
the same fingers.
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