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.
