PNS exam 3

Brachial plexus

supplies upper extremities, formed by anterior primary rami of C5-T1, travels laterally over rib 1 into axilla, travels medial to lateral

roots of brachial plexus

combine into trunks, each receives a gray ramus communicans from sympathetic trunk, pass between anterior and middle scalene muscles (in scalene triangle) into posterior triangle, posterior and superior run to subclavian artery

superior trunk of brachial plexus

combined C5 and C6

middle trunk of brachial plexus

C7

inferior trunk of brachial plexus

combined roots of C8 and T1

trunks of brachial plexus

pass over rib 1 into axilla

divisions of brachial plexus

relate to compartments of arm and forearm, each trunk splits into anterior and posterior division

anterior/posterior divisions of brachial plexus

anterior supplies anterior arm compartments while posterior supplies posterior arm compartments

lateral cord of brachial plexus

formed by anterior divisions of superior and middle trunks, contains fibers from C5-C7, lies lateral to second part of axillary artery

medial cord of brachial plexus

formed by anterior division of inferior trunk, contains fibers from C8 and T1, lies medial to second part of axillary artery

posterior cord of brachial plexus

formed by union of posterior division of all 3 trunks, contains fibers from C5-T1, lies posterior to second part of axillary artery

nerves formed from roots of brachial plexus

dorsal scapular nerve, long thoracic nerve

dorsal scapular nerve

branches off and only contains fiber from C5 root, supplies levator scapula, rhomboid major and minor

levator scapula

supplied by C3-C5

long thoracic nerve

formed and contains fibers from roots of C5-C7, supplies serratus anterior

nerves branching off superior trunk of brachial plexus

suprascapular nerve, nerve to subclavius

suprascapular nerve

fibers from C5 and C6, supplies supraspinatus and infraspinatus

nerve to subclavius

fibers from C5 and C6, supplies subclavius

nerves branching off lateral cord of brachial plexus

lateral pectoral nerve, musculocutaneous nerve

lateral pectoral nerve

fibers from C5-C7, supplies pectoralis major

musculocutaneous nerve

1 of 2 terminal branches of lateral cord, fibers from C5-C7, supplies muscles of anterior arm compartment- coracobrachialis, biceps brachii, brachialis and cutaneous distal to elbow,

course of musculocutaneous nerve

fibers from C5-C7 pierce belly of coracobrachialis → long and short heads of biceps brachii → continues between biceps brachii and brachialis into forearm to become lateral cutaneous nerve of the forearm

branches off medial cord of brachial plexus

all contain fibers from C8-T1, medial pectoral nerve, medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm, ulnar nerve, median nerve

medial pectoral nerve

fibers from C8-T1, supplies Pectoralis Minor and Major

medial cutaneous nerve of the arm

fibers from C8-T1, ramifies in axilla and supplies skin of the medial arm between axilla and elbow, receives some fibers from T2 through a communication with intercostobrachial nerve

medial cutaneous nerve of the forearm

fibers from C8-T1, leaves medial cord distal to medial cutaneous nerve of the arm, supplies skin over biceps brachii and skin over anterior and medial aspects of forearm proximal to wrist

ulnar nerve

1 of 2 terminal branches of medial cord, fibers from C8-T1 and sometimes C7, gives off no branches in arm, supplies flexor carpi ulnaris and medial half of flexor digitorum profundus, gives off sensory dorsal and palmar branches in forearm, divides into superficial and deep branches superficial to flexor retinaculum

cours of ulnar nerve

travels medial to brachial artery in medial bicipital sulcus → gives off no branches in arm → crosses elbow on posterior side of medial epicondyle in sulcus for ulnar nerve → continues in forearm between 2 heads of flexor carpi ulnaris → innervates 2 muscles of forearm → gives off 2 sensory branches in forearm → travels deep to flexor carpi ulnaris. to wrist and superficial to flexor retinaculum → divides into terminal superficial and deep branches

ulnar nerve innervates

flexor carpi ulnaris, medial half of flexor digitorum profundus

dorsal branch of ulnar nerve

supplies sensory info to skin on ulnar side of posterior hand

palmar branch of ulnar nerve

supplies sensory info to skin over hypothenar eminence

superficial branch of ulnar nerve

1 of 2 terminal branches, divides into 3 terminal branches that supply palmar aspect of little finger and medial half of the ring finger

deep branch of ulnar nerve

1 of 2 terminal branches, curves toward thenar eminence and gives off branches to supply most hand muscles __except__ thenar eminence and 1st/2nd lumbricals

claw hand/Ape hand

clinical consideration for ulnar nerve, flexion of 4th/5th digits while hyperextended at metacarpophalangeal joints, lumbricals are paralyzed

median nerve

contains contributions from lateral and median cords, fibers from C6-T1, innervates 7 muscles in forearm

7 muscles supplied by median nerve

pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, pronator quadratus, flexor pollicis longus, lateral bellies of flexor digitorum profundus

course of median nerve

travels through arm in medial bicipital sulcus → gives off no branches in arm → crosses elbow on anterior side → enters forearm after passing between 2 heads of pronator teres → passes through carpal tunnel and divides into 3 common palmar digital nerves

anterior interosseous nerve of the forearm

given off median nerve in elbow, supplies pronator quadratus, flexor pollicis longus, and lateral bellies of flexor digitorum profundus

palmar branch of median nerve

given off in distal third of forearm, supplies skin of thenar eminence, lateral wrist, and palm

common palmar digital nerves

supply first 2 lumbrical muscles, each nerve splits into 2 proper palmar digital nerves, branches off 1st nerve supply thenar muscles (abductor pollicis longus, flexor pollicis brevis, opponens pollicis)

proper palmar digital nerves

sensory function only, supply skin over lateral 3.5 digits anteriorly and lateral 2.5 digits posteriorly

median nerve also supplies

periosteum, elbow, radiocarpal and midcarpal joints, usually communicates with ulnar nerve at wrist

clinical considerations of median nerve

hand of oath/benediction, carpal tunnel syndrome, unable to pronate

hand of oath/benediction

flexion of 4th/5th digits while hyperextended at metacarpophalangeal joints, similar to claw hand but median nerve affected

carpal tunnel syndrome

nerve often compromised in multiple places, adds up to paresthesia/numbness, tingling in hand

branches off posterior cord of brachial plexus

superior/inferior subscapular nerves, thoracodorsal nerve, axillary nerve, radial nerve

superior subscapular nerve

contains fibers from C5-C6, supplies RCM subscapularis

thoracodorsal nerve

contains fibers from C6-C8, travels along posterior axillary wall to supply the latissimus dorsi, descends on posterior thorax

inferior subscapular nerve

contains fibers from C5-C6, supplies teres major and RCM subscapularis

axillary nerve

contains fibers from C5-C6, travels posteriorly around surgical neck of humerus, suplies deltoid and RCM teres minor, gives off superior lateral cutaneous nerve of the arm at same level of branch to teres minor then travels to deltoid

superior lateral cutaneous nerve of the arm

supplies skin over lateral shoulder and upper arm

radial nerve

largest branch of posterior division, contains fibers from C5-T1, supplies all the muscles in the posterior compartment of the arm and forearm,

course of radial nerve

spirals around to posterior of humerus from medial bicipital sulcus → gives off posterior and inferior lateral cutaneous nerves of arm, muscular branches, and posterior cutaneous nerve of the forearm→ gives off branches at lateral epicondyle supplying brachioradialis and extensor carpi radialis longus → enters forearm anterior to elbow between brachialis and brachioradialis → divides into superficial and deep branches at level of radial head

posterior cutaneous nerve of the arm

branches off radial nerve in upper arm, supplies skin on posterior side of upper arm

inferior lateral cutaneous nerve of the arm

branches off radial nerve in middle of arm

muscular branches given off radial nerve in arm

supply all 3 heads of triceps brachii, anconeus (via branch off the branch to medial head of triceps brachii), small contribution to brachialis (in combo with musculocutaneous nerve)

posterior cutaneous nerve of the forearm

given off radial nerve in upper arm, supplies narrow area of skin on lateral side of posterior forearm

branches of radial nerve given off at level of lateral epicondyle

supplies brachioradialis and extensor carpi radialis longus

superficial branch of radial nerve

sensory supply to radial side of posterior hand, extensor side of thumb, extensor side of proximal phalanges of digits 2 and 3, lateral half of extensor side of ring finger; follows brachioradialis to distal third of forearm → travels between brachioradialis and radius to posterior surface of hand → gives rise to dorsal digital nerves, also gives off communicating branch with ulnar nerve → sends articular branches to shoulder and wrist

deep branch of radial nerve

penetrates supinator muscle → gives off series of branches to supply posterior forearm muscles → terminates as posterior interosseous nerve to supply extensor muscles of hand and supinator and abductor pollicis longus

clinical considerations of radial nerve

wrist drop, triceps and brachioradialis reflexes

wrist drop

patient has no extension of hand/wrist muscles (even against gravity)

muscles that extend finger(s)

extensor digitorum, extensor digiti minimi, extensor pollicis brevis, extensor pollicis longus, extensor indicis

muscles that extend wrist

extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, extensor indicis

Erb-Duchenne/Erb’s Palsy

injured supraclavicular nerve (C5, C6 roots/superior trunk), ‘waiter’s tip’, likely caused from birth trauma, ¾ of rotator cuff muscles affected (supraspinatus, infraspinatus, teres minor), biceps brachii, brachialis, coracobrachialis, deltoid

Klumpke’s Palsy/Dejerine-Klumpke’s

injured infraclavicular nerve (C8, T1 roots/inferior trunk), caused form birth trauma, affects hand muscles, flexor carpi ulnaris, and flexor digitorum profundus, atrophy of hand muscles, can be associated with Hoerner’s syndrome

Hoerners syndrome

T1 injured, ptosis (sagging eyelid), and miosis (lots of blinking)

thoracic spinal nerves

12 roots, each a mixed nerve that divides into anterior and posterior primary rami (except C1), posterior divides further into medial and lateral branches

medial branches of thoracic spinal nerves

have both motor and sensory function, T1-T12, motor- upper 6 supply semispinalis, lower 6 supply longissimus, multifidi, sensory supply to skin paraspinally

lateral branches of thoracic spinal nerves

have both motor and sensory function, increase in size from superior to inferior, motor- longissimus, iliocostalis, levator costarum, sensory- skin near costal angles

anterior primary rami of thoracic nerves

follow the same course as the rib above, T1 contributes to brachial plexus and a small branch forms first intercostal nerve, T2 (and sometimes T1) contribute to intercostobrachial nerve

intercostobrachial nerve

correlates with medial intercostal nerves

intercostal nerves

each gives off a lateral cutaneous branch which then divides into anterior and posterior branches, supplies skin over hips, give off muscular branches along ribs, supply adjacent blood vessels, bones, joints, and ligaments, terminate as anterior cutaneous branches

anterior cutaneous branches

terminal branches of intercostal nerves, supply skin close to midline of body

muscles intercostal nerves supply

all- external/internal/innermost intercostals, serratus posterior, transversus thoracis; only nerve 7-11- transverse abdominal, internal/external abdominal obliques, rectus abdominis

subcostal nerve (T12)

largest thoracic nerve, follows course similar to intercostal nerves, contributes to lumbar plexus, supplies skin over lumbar spine as far inferior as superior buttocks through cluneal nerves

thoracic nerve communications

each nerve communicates with sympathetic trunk by way of both white and gray rami communicans, white rami carry preganglionic sympathetic fibers, gray rami carry receive postganglionic sympathetic fibers from sympathetic trunk

lumbar spinal nerves

5 pairs named for vertebrae above nerve, each nerve root divides into an anterior and posterior primary ramus

posterior primary rami of lumbar spinal nerves

purely motor, travel posteriorly and divide into medial and lateral branches, medial supply multifidus, lateral supply erector spinae group

anterior primary rami of lumbar spinal nerves

contribute to lumbar (L1-L4) and sacral (L4,L5) plexuses

lumbar nerve communications

nerves communicate with sympathetic trunk, usually 4 lumbar sympathetic ganglia, white rami communicans associated with L1, L2 and sometimes L3, gray rami communicans associated with every nerve

lumbar plexus

formed by anterior primary rami of L1-L3, part of L4, and T12 by a communication with L1; contains- muscular branches, iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, lateral cutaneous nerve of the thigh, femoral nerve, obturator nerve, L4 and L5 contribute to lumbosacral trunk

muscular branches of lumbar plexus

L1- quadratus lumborum and psoas minor, L2- quadratus lumborum and both psoas major/minor, L3 and L4- supply quadratus lumborum and psoas major

iliohypogastric nerve

contains fibers from T12 and L1, supplies 2 muscles- internal abdominal muscle and transverse abdominal; travels anterior and inferior between quadratus lumborum and kidney → travels through transverse abdominal muscle → travels between TA and internal abdominal oblique → gives off lateral cutaneous branch → continues anterior cutaneous branch

lateral cutaneous branch

given off iliohypogastric nerve after it travels between transverse abdominal muscle and internal oblique, supplies posterolateral gluteal region

anterior cutaneous branch

what iliohypogastric nerve continues as after giving off lateral cutaneous branch, supplies skin of pubic region

ilioinguinal nerve

contains fibers from T12 and L1, sensory info to skin of upper medial thigh, base of penis and scrotum in men vs mons pubis and labium majora in females; innervates 2 muscles- internal abdominal oblique, transverse abdominal; follows path similar to iliohypogastric nerve, enters and is transmitted through inguinal canal → leaves inguinal canal through superficial inguinal ring → travels with spermatic cord/round ligament

genitofemoral nerve

contains fibers from L1 and L2, passes anteriorly through psoas major and divides into genital and femoral branches

genital branch of genitofemoral nerve

motor to cremaster muscle, sensory to skin of superior anterior scrotum in males, skin of mons pubis and labium majorum in females; cremasteric reflex

cremasteric reflex

when pressure is put on medial aspect of thigh the testis on that side should lift

femoral branch of genitofemoral nerve

passes into thigh posterior/under the inguinal ligament, supplies skin of upper anterior thigh

lateral cutaneous nerve of the thigh

contains fibers from L2 and L3, sensory only- supplies skin of lateral thigh superior to knee; leaves abdominal cavity by passing under inguinal ligament → travels anterior to sartorius and through fascia lata to reach skin

meralgia paresthetica

tingling, numbness, and burning of lateral aspect of thigh, occurs from tight pants or belts compressing lateral cutaneous nerve of the thigh

femoral nerve

largest branch of lumbar plexus, contains fibers from L2-L4, only gives off branches in abdomen and femoral triangle, in abdomen- muscular branches to iliacus and pectineus, sends fibers to femoral artery; in femoral triangle- divides into anterior and posterior divisions

course of femoral nerve

forms posterior to psoas major → emerges lateral to psoas major and anterior to iliacus → passes posterior to inguinal ligament and enters femoral triangle just lateral to femoral artery → runs inferior and medially through adductor canal into leg and knee

anterior division of femoral nerve

gives rise to 3 nerves, 2 sensory- intermediate and medial cutaneous nerves of the thigh, 1 motor- nerve to sartorius

intermediate cutaneous nerve of the thigh

branch off anterior division of femoral nerve, divides into 2 branches and supplies skin on anterior thigh down to knee, lateral branch communicates with femoral branch of genitofemoral nerve

medial cutaneous nerve of the thigh

branch off anterior division of femoral nerve, crosses anterior to femoral artery → sends branches to supply skin of medial thigh and knee across to lateral side of patella; some branches supply skin of medial leg through communications with saphenous nerve

posterior division of femoral nerve

gives rise to muscular branches- supply quadriceps muscles, vascular branches- supply femoral artery and its branches, and articular branches to knee joint; continues into leg as saphenous nerve

saphenous nerve

transmitted through adductor canal → crosses femoral artery so it is medial to it emerging from adductor canal → supplies skin medial and anterior to patella → travels with great saphenous vein and supplies skin of medial leg and foot