Peripheral Nerve Anatomy Flashcards
peripheral nerves
-continuation from spinal anatomy -spinal nerves split, converge, and branch - form peripheral nerves
Cervical Plexus
Innervates - muscles, joints, and skin in the anterior neck - Ventral Rami C1-C4
Brachial Plexus
Large network of nerves - extend from neck through axilla Innervate the upper extremity Composition -
ventral Rami (Roots) 5 -
Trunks 3 -
Divisions 6 -
Cords 3 -
Branches 4
BP: Roots, Trunks, and Divisions
- Found in posterior triangle of the neck - Supraclavicular
BP: Cords and Branches
-Found in the Axilla - Infraclavicular
BP: Roots
- 5 Rami (Roots) involve C5-T1 - May include C4 and T2
- Pass to lateral border of scalene muscles
- Reorganize to 3 Trunks
BP: Trunks
3 Trunks - Superior C5-C6
-Middle C7
-Inferior C8-T1
Enveloped in fascial sheath
- Interscalene space - between anterior and middle scalene muscle
- Injection into sheath - commonly produces complete block of upper extremity
- May have individual septa - thus we see incomplete blocks
BP: Divisions
Posterior to clavicle divide into:
- 3 ventral (Anterior) divisions-supply flexor portions
- 3 Dorsal (Posterior) Divisions - supply extensor portions
BP: Cords
In axilla:
- 3 Dorsal Divisions combine to form posterior cord
- 3 Ventral divisions combine to form lateral and medial cords
- Now name in position to axillary artery
BP: Branches
- At lateral border of pectoralis minor
- each cord divides into 2 branches
- become peripheral nerves
- Lateral Cord, Medial Cord, Posterior Cord
Lateral Cord
- Musculocutaneous nerve
- Lateral root of median nerve
Medial Cord
- Medial root of medial nerve
- Ulnar Nerve
Posterior Cord
- -Axillary Nerve
- -Radial Nerve
Axillary Nerve
- Formed from C5-C6
- Passes from axilla to shoulder
- Posterior to the neck of humerous
- Innervation - Deltoid and skin covering it
Radial Nerve
Formed from fiber of C5-T1
- Passes from axilla to arm*
- Innervates long head of triceps
- -posterior brachial cutaneous branch
- -innervates skin covering the muscle
Descends along shaft of humerous
- -Inferior lateral cutaneous branch innervates posterior arm
- -Posterior antebrachial cutaneous branch innervates surface of forearm
- Crosses elbow anterior to lateral epicondyle*
- Divides into deep and Superficial branch
- -Superficial continues down to hand innervates dorsum of the hand onto the thumb, index, middle, and ring fingers
- Deep innervates many of the muscles of wrist and hand
Radial Nerve: Response to stimulation
- wrist extension
- metacarpo-phalangeal extension
- thumb abduction
Musculocutaneous Nerve
Formed by fibers from C5-7
- Pierces through coracobrachialis muscle
- -Descends between brachialis muscle and the biceps brachii muscle – innervates all of these muscles
At elbow :
- becomes Lateral antebrachial cutaneous nerve -
- Runs along brachoradialis muscle -
- Innervates skin above muscle
Also innervated elbow and proximal radioulnar joints
Musculocutaneous nerve motor response
Biceps Flexion
Median Nerve
Fibers from C5-T1
- Descends arm with brachial artery
- Crosses cubital fossa medial to the artery
- Passes into forearm through the carpel tunnel
- branches and innervates the skin
Median Nerve Innervation
many of the muscles of forearm, wrist, fingers, and thumb forearm - pronators wrist - flexors fingers - flexors Thumb - abduction and opposition Skin - Thumb, index, middle, lateral half of ring fingers on palmar surface and nail beds
Medial Cutaneous Branches: Branches of Medial Cord (T1)
Medial Brachial cutaneous Branch - Innervates skin covering the medial surface of the arm Medial antebrachial cutaneous branch - crosses the cubital fossa - Innervates skin on the medial aspect of the forearm
Ulnar Nerve
Fibers from C8-T1 - Descends with brachial artery - Crosses the elbow posterior to medial epicondyle - continues down the forearm
Ulnar Nerve innervation
- many muscles in wrist, fingers and thumb Skin - Dorsal and medial surface of the hand - Dorsal surface of the ring and little fingers
motor respone to ulnar nerve stimulation
- ulnar deviation of the wrist - metacarpo-phalangeal flexion - Thumb adduction
Lumbosacral Plexus
- *Formed by Ventral Rami L1-S5**
- May include T12*
-Anterior and Posterior Divisions of some
Innervates:Lower Abdomen and Lower Extremities
▪Muscles
▪Joints
▪Skin
▪Peritoneal lining
Iliohypogastric Nerve
Formed from T12-L1
Travels in abdominal wall to level of symphysis pubis
Innervates:
- Muscle, skin, and parietal peritoneum
- Skin over inferior abdomen and buttocks
Ilioinguinal Nerve
Formed by T12-L1
- Travels in abdominal wall
- Pierces posterior wall of the inguinal canal
- Passes through superficial inguinal ring
- Terminates on the anterior scrotum or labia majora
Innervates:
- Muscle, skin, parietal peritoneum along course
- Skin
- Superior, medial thigh
- Portions of external genitalia
Genitofemoral Nerve
Formed by L1-L2
- Travels in abdominal wall
- Passes through deep inguinal canal
- Passes through superficial inguinal ring
- Terminates on anterior scrotum or labia majora
Innervates:
- Skin covering femoral hiatus
- Skin on the scrotum or labia majora
Iliohypogastric, Ilioinguinal, Genitofemoral
Pudendal Nerve
Anterior division of S2-S4
- Passes from pelvis through greater sciatic foramen into gluteal region
- Passes posterior to ischial spine and into perineum
Innervates muscle and skin of perineum
Lateral Femoral Cutaneous Nerve
Posterior Division L2-3
- Descends posterior abdominal wall
- Crosses iliac crest into pelvis and down to inguinal ligament and anterior iliac spine
Innervates:
- Skin
- Lateral aspect of thigh to the level of the knee
Posterior Femoral Cutaneous Nerve
Anterior and Posterior Division of S1-S3
- Passes from pelvis into gluteal region
- To posterior thigh
Innervates:
- Skin
- Posterior thigh
- Hip to mid calf
Obturator Nerve
Anterior Division L2-4
- Travels to medial compartment of thigh
Innervates:
- Many muscles of thigh
- Articular branches to hip
- Controls adduction, flexion and extension of hip
- Cutaneous branches to the skin
- Medial thigh
Femoral Nerve
Posterior Division L2-L4
- Through pelvis
- Deep into inguinal ligament
- Enters anterior compartment of thigh
- Divides into multiple branches
- Below inguinal ligament splits to anterior and posterior branches
- Posterior contains saphenous nerve
Position:
- At femoral crease
- Nerve lateral to femoral artery and vein
- From medial – lateral
- VAN
- Venous – Penis
- V for Vagina
- From lateral – medial
- NAVEL
- Nerve, artery, vein, empty space, ligament
Femoral Nerve Innervation
Innervation:
- Muscles
- Rectus femoris
- Vastus lateralis
- Vastus Intermedius
- Vastus medialisSartorious
- Skin
- Anterior thigh
Saphenous Nerve
Posterior Cutaneous Branch from Femoral Nerve
- Follows deep surface of Sartorius muscle to attachment on tibia
- Accompanied by saphenous vein
Passes to skin
-
Innervates
- Medial leg from knee to the arch of the foot
-
Stimulation
- Sartorious muscle contraction (bandlike across thigh)
- Patellar twitch (snap)
Sciatic Nerve
- Formed by junction of
- Tibial Nerve (anterior) L4-S3 (largest)
- Common Peroneal Nerve (posterior) L4-S2
- Distinct nerves from the beginning in the same sheath
- Passes from pelvis through greater sciatic foramen into gluteal region
-
Descends between:
- §gluteus maximus (posteriorly)
- §obturator internus (anteriorly)
- §lateral to ischial tuberosity
- Enters Posterior thigh
- Innervates Muscles there
- Hip Extension
- Flexion of knee
- Descends popliteal fossa where it splits
- Tibial
- Common Peroneal
Tibial Nerve
Anterior division L4-S3
- Exits popliteal fossa and into superficial posterior compartment of leg
- Passes between tibial and fibular heads and enters deep posterior compartment
- Passes posterior to medial malleolus into foot and branches
- Medial plantar nerve
- Lateral plantar nerve
- Two branches innervate plantar surface of foot
Common Peroneal
-
From popliteal fossa
- Follows tendon of biceps femoris to attachment on fibula
- Divides to superficial and deep branches
-
Superficial
- Enters lateral compartment of leg and terminates in lateral and dorsal surface of foot
-
Deep
- Enters anterior compartment
- crosses anterior surface of ankle into foot
- Terminates as cutaneous fibers
- Skin between hallux and second toe
Sural Nerve
Formed from union of branch from tibial and common peroneal
- Travels with the saphenous nerve
- ¡Posterior to the lateral malleolus into foot
Innervates:
- Posterior sole of foot
- Posterior heel
- Achilles tendon above ankle
