BRACHIAL PLEXUS

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

uBranches

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.

ujoined by the medial root to form the median nerve trunk, but       no branches in axilla

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).

uIt supplies the skin on the medial side of the arm.

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.

u gives off no branches in the axilla

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

uHaving given off a branch to the shoulder joint, it divides into anterior and posterior branches

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.

uThe latter branch is distributed to the skin on the middle of the back 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

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)

uthere will be a loss of sensation down the lateral side of the arm.

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

uC8 damage - loss of sensation in the medial side of the forearm,       hand, and medial two fingers.

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.

uParalysis of the deltoid and teres minor muscles result and there      is inability to ABDUCT

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.