UMICH Brachial plexus Questions

Man riding motor cycle hits a wet spot in road, looses control and thrown from bike. Lands of right side of head and tip of shoulder, bendinghis head sharply to the left and stretching the right side of hisneck. Neuro exam revealed that the roots of the 5th and 6th cervical nerves had been torn away from spinal cord. What movements of arm at shoulder would you expect to be totally lost? A. Adduction B. Abduction C. Flexion D. Extension E. medial rotation

B. Abduction upper brachial injury (c5-c6) most common. Affects suprascapular, axilaary, musculocutaneous nerves causing paralysis of rotator cuff muscles, biceps, brachialis, coracobrachialis, deltoid. Lateral pec nerve and subscapular nerves. limb is adducted and medially rotated

a first year resident attemps a central venous catheter into heart by subclavicular approach to subclavian vein. Following attemp, its noted that the pt has difficulty breathing. What nerve lying immediately deep to subclavian vein as it crosses anterior scalene muscles may have been injured A> EXTERNAL BRANCH OF SUPERIOR LARYNGEAL N B. PHRENIC N. C. RECURRENT LARYNGEAL N D. SYMPATHETIC TRUNK E. VAGUS N

B. PHRENIC N.

Which structure lies immediately anterior to the right anterior scalene muscle at costal attachment A. subclavian artery B. Subclavian v. C. Thoracic duct D. Thyrocervical trunk E. Vagus n.

B. Subclavian vein

a 27 year old man who lifts wieght has recent weakness in left arm and tingling in hand/ fingers during exercise which subsides with rest. Has vascular insufficiency due to scalenus anticus syndrome and remedy is to transect anterior scalene muscle where it inserts on 1st rib. During surgery, what structures in contact w/ anterior surface of the muscle must the surgeon be careful of sparing A. Inferior trunk of brachial plexus B. Long thoracic nerve C. Phrenic nerve D. Sympathetic trunk E. Vagus n

C. Phrenic nerve

Erb's palsy, where roots C5 and C6 of brachial plexus are avulsed, which muscle is paralyzed? A. Latissimus Dorsi B. Pectoralis minor C. Supraspinatus D. Trapezius E triceps BRachii

C. Supraspinatus

Following above injury there would most likely be diminished cutaneous sensation over what part of the upper limb? A. Back of shoulder B. Pectoral region C. Top of shoulder and lateral side of arm D> Medial side of arm and forearm E. Tip of little finger

C. Top of shoulder and lateral side of arm c5-c6 dermatome covers top of shoulder and lateral sid eof arm.

Panel on roof falls off and hits man below across the anterior surface of right arm at midlength and severs all tissue to bone. When examined its noted that the patient can only weakly flex his elbow and lateral side of his forearm is numb. What nerve is injured? A. axillary B. Median C. musculocutaneous D. Radial E. Ulnar

C. musculocuntanous n.

axillary nerve arises directly from which part of the brachial plexus A. inferior trunk B. lateral cord C. Medial cord D. Middle trunk E. posterior cord F. Superior cord

C. posterior cord Axillary nerve and radial nerve both terminal branches from posterior cord.

phrenic nerve is formed from

C3, 4, 5 ventral primary rami. It lies on anterior scalene muscle

Phrenic nerve is formed by

C3,C4,C5 ventral primary rami. Lies on anterior scalene muscle deep to subclavian vein. innervates diaphragm - difficulty breathing.

long thoracic nerve comes off

C5, C6, C7 roots of BP and pierce middle scalene muscle, lies on surface of serratus anterior in thorax

back of shoulder is covered by

C6,C7,C8, T1

a weight lifter presents with pain and weakness in right upper limb that has developed over time. His limb is cool and there is obvious vascular insufficiency in upper extremity. He has large vessel passing b/t anterior and middle scalene muscles being occluded by hypertropy o muscles due to exercise. The artery involved is A. Axillar B. Brachial C. Brachiocephalic D. Subclavian E. Suprascapular.

D. Subclavian

Stab wound just above the left clavicle lateral to sternocleidomastoid muscle maybe life threatening b/c of possibly injry to the A. Brachial plexus B. Internal jugular vein C. Axillary artery D> Subclavian artery E. Thoracic duct

D. Subclavian artery.

A WOMAN RIding bike hits rut and thrown from bike. Her upper arm hits a tree, fractures her humerus just above insertion of teres major muscles. Later axm notes she cannot extend her forearm at elbow or hand at wrist. Which nerve is injured A. Axillary B. Medain C. Musculocutanoeus D. Radial E. Ulnar

D. radial nerve

following gunshot wound to shoulder, pt is unable to abduct the arm between 0 and 15 degrees, with reduced lateral rotation of humerus. What nerve is injured? A. Accessory (CNXI) B. Axillary C. Median D. Suprascapular E. Ulnar

D. suprascapular supraspinatus mm initiates abduction of arm through first 15 degrees. SS nerve also innervates infraspinatus, lateral rotator of the arm so weakness in lateral rotation.

there is no _____ cord of brachial plexus only ____

No superior cord only superior trunk

axiliarry artery is ocntinuation of

Subclaian a. beneath the 1st rib.

Trapezius innervated by

accessory nerve NOT BRACHIAL PLEXUS nerve.

subclavian aretery runs b/t

anterior and middle scalene muscles- supplying upper limb

subclavian vein lies

anterior to right and left anterior scnalene . Courses over anterior scalene muscle on both right and left sides

Radial nerves path

around posterior surface of shaft of humerus in radial grove. Innervates exetnsors.

subclavian artery crosses

b/t anterior and middle scalene, posterior to sternocleiodomastoid. Lateral to SCM the subclavian runs just above clavicle .

roots of brachial plexus come out

b/t anterior and middle scalenes and trunks are lateral to anterior scalene

musculocuntanous n innervates

biceps brachii and coracobrachialis m which flex the arm.

Vagus n. runs within the

carotid sheath superficial to anterior scalene muscles. It passes b/t subclavian artery and v.

sympathetic trunk is

deep to scalene muscles on prevertebral fascia along the front of vertebral column

axillary n innervateds

deltoid and teres minor- injury = no abduction of arm

median nerve injury

distal end of humerus trouble flexing wrist

radial nerve innervates

extensors of arm, elbow, wrist, and hand.

thyrocervical trunk is branch of

first part of subclavian artery, medial to anterior scalene. NOT in contact with anterior scalene.

ulnar nerve innervates

hand primarily.

axillary nerve is injured in

humeral fractures at surgical neck- cannot abduct arm.

Vagus nerve lies

in carotid sheath . Anterior to anterior scalene but not immediate contact with the muscle.

loss of senstaion over lateral part of forearm indicates

lateral antebrachial cutaneous n has been damaged = musculocutanoues n.

ulnar nerve

located near medial epicondyl of humerus muscular deficits in hand

Pectoralis minor innervated by

medial pectoral nerve off medial cord C8, T1

T1 and C8 dermatome cover

medial side of arm C8 extends to tip of little finger

juggular vein located

medial to posterior SCM muscle.

ulnar nerve innervates

muscles of hand.

median nerve innervates

muscles that flex wrist and muscles of thumb

median nerve innervates

muscles that permit flexion at wrist, muscles of hand - thumb.

lateral cord gives off

musculocuntanous n. and part of median n

middle trunk gives off

no direct branches

musculocutanous nerve

not involved in humeral fractures

flexion of arm is

not totally lost. Biceps brachii and coracobrachialis denervated b/c pec major is not completly lost.

thoracic duct lies

on left side only NOT RIGHT SIDE OF NECK. enters left brachiocephalic vein where its formed by union of subclavian and internal jugular v. ITs DOES contact anterior scalene but only on left side of neck!!!

T1, T2, T3 Dermatome covers

pectoral region

subclavian arters lie

posterior to anterior scnalene muscles and travel b/t anterior and middle scalenes on both sides of neck

Triceps brachii innervatd by

radial nerve - terminal branch of posterior cord of brachial plexus C5,C6,C7,C8,T1.

axillary nerve innervates

teres minor deltoid

Latissimjs dorsi innervated by

thoracodorsal n. coming of posterior cord C6, C7, C8

Accessory n CN XI innervates

traps sternocleidomastoid

extension occurs through actions of

triceps which is innervated by radial nerve and should be intact

medial cord

ulnar n. and branch of median n. and medial pectoral n medial cutaneous n arm. medial cutaneous n. forearm.