Peripheral Nervous System Anatomy Flashcards
What nerves form the Cervical plexus
Ventral rami of C1-C4
Describe the supply of the cervical plexus
C1 - geniohyoid and thyrohyoid
Ansa cervicalis (C1-3) - all strap muscles: sternothyroid, sternohyoid, & superior/inferior bellies of omohyoid
Great Auricular (C2&3) - most of the ear skin
Lesser occipital (C2) - skin over back of head to vertex
Transverse cervical (C2 &3) - supplies skin over anterior cervical triangle
Supraclavicular (C3&4) - supply skin over clavicle
Most branches lie in anterior triangle
What nerves form the brachial plexus
C5-T1
What structures does the roots of the brachial plexus pass through
sclenius anterior and medius muscles in the neck
Describe the structure of the brachial plexus (rugby team drinks cold beer)
Roots: C5-T1
Trunks: Upper C5 & C6, Middle C7, Lower C8 & T1
Divisions: Anterior/Posterior Located behind clavicle
Cords: around axillary artery, Posterior - from ALL posterior divisions (C5-T1), Lateral - anterior division s of upper and middle trunk (C5,6,7), Medial - lower trunk of anterior division
Branches
Describe the radial nerve and its supply
Radial (C5-T1): All the muscles of the posterior compartment of the arm and forearm BEAST - Brachioradialis, all Extensors of the wrist, Abductors of the thumb and Supinator muscles, Triceps and anconeus
Describe the median nerve and it’s supply
Median (C5-T1): supplies all muscles of forearm (except flexor crapi ulnaris and and the ulnar half of FDP) plus LOAF muscles of the thumb (Lumbricals 1&2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis)
The anterior interosseous branch supplies the flexor pollicis breves, pronator quadratus, and radial half of FDP
Describe the musculotcutaneous nerve and its supply
C5, 6, 7: (BBC) Biceps, Brachialis, and Coracobrachialis and skin of the lateral forearm
Describe the axillary nerve and its supply
C5&6: passes through the quadrangular space and supplies the deltoid and teres minor plus skin over the insertion of the deltoid muscle
Describe the branches from roots of the brachial plexus
Dorsal Scapular (C5) - Supplies the levator scapulae, rhomboid major & minor
Long thoracic (C5,6,7) - supplies serratus anterior (damage causes winged scapula)
Describe the branches form the trunks of the brachial plexus
Suprscapular (C5&6) - supplies supraspinatus and infraspinatus
Nerve to subclavius (C5-6) supplies subclavius
Name the branches from the cords
Posterior cord:
upper and lower subscapular C5&C6 - subscapularis
lower subscapular also supplies the teres minor
Thoracodorsal (C6-8) - subclavius
Medial cord:
Medial pectoral (C8&T1) - pec major and minor
Medial brachial cutaneous - medial arm
medial antebrachial cutaneous - medial forearm
Lateral cord: Lateral pectoral (C5,6,7) - Pec major
What is erb-duchenne palsy
Damage to C5 and C6 - elbow extended, forearm pronated, and fingers flexed
Describe Klumpke’s palsy
damage to C8 and T1 resulting in a claw hand
What cord levels make up the lumbar plexus
Ventral rami of L1-L4 formed within the psoas major
All of the lumbar plexus nerves leave the lateral aspect of the psoas major EXCEPT
genitofemoral - exits anterioly
obturator - exits medially
Branches and their innervations of the lumbar plexus
iliohypogastric L1 - lower abdomen above inguinal region
ilioinguinal L1 - supplies inguinal region
genitofemoral L1,2 - medial upper thigh, anterior scrotum and cremasteric muscle
lateral femoral L2,3 - supplies the anterolateral aspect of the thigh
femoral L2,3,4 posterior divisions - supplies the extensor thigh compartment
obterator L2,3,4 anterior divisions - supplies the adductor thigh compartment
contributaries - to the formation of the lumbosacral trunk L4,5
What nerve levels form the lumbosacral plexus
L4,5, S1-4
Sacral nerves exit the anterior sacral foramina and unite in front of the piriformis muscle where they are joined by the lumbosacral trunk
Describe the branches of the lumbosacral trunk and their innervations
Superior gluteal (L4, 5, S1) - gluteus medius, minimus and tensor fascia lata and passes through the greater sciatic foramen
inferior gluteal (L5 S1,2) through greater sciatic, supplies gluteus maximus only
pudendal (S2,3,4) - supplies external anal sphincter, deep and superficial perineal, penis (clitoris) and posterior scrotum (labia)
Sciatic,
Describe the Sciatic nerve
L4, 5, S1, 2, 3
Largest, passes beneath piriformis through greater sciatic notch
Supplies the muscles of the posterior thigh and all the muscles below the knee
Supplies skin below the knee EXCEPT for a thin strip along the medial aspect of the leg and foot (saphenous branch of the femoral nerve)
Describe the tibial portion of the sciatic nerve
Tibial (L4,5,S1,2,3) :
all muscles in posterior compartment of leg
all muscles in the plantar aspect of the foot
Divides into medial and lateral plantar branches after passing behind the medial malleolus
supplies skin over posterior aspect of leg and the planta aspect of foot
Medial plantar - corresponds with median n. in hand, supplies FDB, flexor hallucis brevis, abductor hallicus, and first lumbrical of the foot
Lateral plantar - corresponds with ulnar n. and supplies rest of the muscles in the sole of the foot
Describe the common peroneal part of the sciatic nerve
Common peroneal (L4,5 S1,2): anterior and lateral compartment of the leg
Winds around neck of the fibula and then divides into superficial and deep branches
Superficial:
lies in lateral compartment
peroneous longus and brevis
skin of most of the dorsum of the foot EXCEPT the web space between first and second toes
Deep:
passes through peroneus longus (does not supply) enters anterior compartment of leg
tibialis anterior
extensor hallicus longus and brevis
peroneus tertius
skin in web space between first and second toes
What structures pass through the greater sciatic foramen
superior gluteal VAN above the piriformis, pudendal n, inferior gluteal VAN, nerve to obterator internus and sciatic nerve below the piriformis
What structures pass through the lesser sciatic foramen
Pudendal nerve, internal pudendal artery and vein, nerve to obterator internus, tendon of obterator internus
