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Brachial Plexus and Lumbosacral Plexus

Brachial Plexus and Lumbosacral Plexus

Brachial Plexus and Lumbosacral Plexus

Neuroanatomy block-Anatomy-Lecture 4

Editing file Objectives

At the end of the lecture, students should be able to:

● Describe the formation of (site, roots) ● List the main branches of brachial plexus. ● Describe the formation of lumbosacral plexus (site,roots) ● List the main branches of lumbosacral plexus. ● Describe some important applied Anatomy related to the brachial & lumbosacral plexuses. Color guide

● Only in boys slides in Green ● Only in girls slides in Purple ● important in Red ● Notes in Grey Formation & Divisions of the Brachial Plexus

⤞ It’s formed in the posterior triangle of the . ⤞ Formed by the union of the anterior rami (ventral) of following spinal :

C5 C6 C7 C8 T1

⤞ Then, divisions (stages) begin in the following order: ⤷ Roots (Above the clavicle, in the posterior triangle of the neck) ⤷ Trunks (Above the clavicle, in the posterior triangle of the neck) ⤷ Divisions (Behind the clavicle) ⤷ Cords (Below the clavicle, In the . They’re named in relation to the ) ⤷ Terminal Branches (In the axilla)

⤞ mnemonic is: Rugby Teams Drinks Cold Beer

3 Course of Brachial Plexus

The anterior Each trunk will divisions of the The posterior The anterior Roots of C5 & C6 Roots of C7 Roots of C8 & T1 branch into upper and divisions of division of the unite to form continues as the unite to form anterior and middle trunks three trunks lower trunk Superior trunk Middle trunk Inferior trunk posterior unite to form the continues as the division unite to form the . . .

Branches

from Roots from upper Trunks from Lateral cord (3) from Medial Cord (5) from Posterior Cord (5)

1-Dorsal scapular 1- Suprascapular (2LM) (4MU) (ULTRA) (C5) nerve (C5,C6) 1- 1- 1-. 2- Long thoracic 2- Nerve to subclavius 2- 2- 2- nerve (C5,6,7) muscle (C5,C6) 3- (lateral root) 3-Median nerve (medial root) 3- 4-Medial cutaneous nerve of 4-lower- 5- Medial cutaneous nerve of arm 5-Thoracodorsal

4 Brachial Plexus

5 Important branches and their supply (MSK flashback ) Branched from Branch name Supply

Dorsal scapular nerve (C5) Rhomboideus, levator scapulae muscles Roots (C5, 6, 7) Serratus anterior

Upper trunk (C5, 6) Supraspinatus and infraspinatus muscles

Lateral pectoral nerve (C5, 6, 7) muscle Lateral cord Musculocutaneous nerve (C5, 6, 7) Anterior compartment of arm (Flexors of &

Upper subscapular nerve (C5, 6)

Thoracodorsal nerve (C6, 7, 8)

Posterior cord (C5, 6) Subscapularis and teres major muscles

Axillary nerve (C5, 6) Deltoid and teres minor muscles;

Radial nerve (C5, 6, 7, 8; T1) Posterior compartment of arm & forearm & (Extensors of elbow, & )

Medial pectoral nerve (C8; T1) Pectoralis major & minor Medial cord Ulnar nerve (C8; T1) Anterior compartment of forearm & hand (Flexors of wrist & fingers) Medial & Lateral cord Median nerve (C5, 6, 7, 8; T1)

6 Brachial Plexus

Deformity Damage Result Appearance Nerves related to Erb-Duchenne Adducted arm, and Palsy extended & pronated and it’s or (C5 & C6) forearm fractures Waiter’s tip (Can happen during position baby delivery)

Lower trunk lesion (C8 & T1) Axillary Nerve: Either: it passes around the Complete claw hand. surgical neck which is a Klumpke’s Palsy (median & ulnar ns. affected) dangerous fracture Paralysis of the muscles or Partial claw hand. (Ulnar n. only affected) point, there’s a risk of supplied by the damaged Claw hand it’s . nerve Caused by falling from a height clutching at an object.The first thoracic nerve is usually torn. Radial Nerve: The nerve fibers from this segment run in the It passes through the ulnar and median nerves Partial Complete radial groove, which is also a common fracture Loss of flexion, point risking the nerve injury. Ape’s hand opposition & weak or abduction of the

Median nerve injury Ulnar nerve: Pointing index Loss of flexion of the Can happen in case of a ,paralysis of supracondylar fracture both FDS & FDP of the medial epicondyle where the Paralysis of of extensors nerve passes Radial nerve of wrist & fingers

7

Formation: ⤞ it’s formed by union of the ventral rami of: 01 ⤷ L1, L2, L3 & most of L4 (The rest of L4 will form the )

Site:

⤞ It’s located In the substance of psoas major muscle. (INSIDE it) 02

Branches: ⤞ Iliohypogastric & Ilioinguinal nerves → Supplies the anterior abdominal wall ⤞ Obturator nerve → Supplies the medial 03 compartment of the thigh ⤞ Femoral nerve → Supplies the anterior compartment of the thigh

8 Femoral Nerve

Course Muscular branches Cutaneous branches branch from lumbar plexus In abdomen: To iliacus (flexor of To antero-medial aspects of the L2,3,4 hip joint). thigh. Descends lateral to psoas major In lower limb: To anterior To medial side of knee, leg and muscle & enters the thigh behind compartment of thigh: foot (saphenous nerve) the inguinal ligament. To flexors of hip joint: sartorius It passes lateral to the femoral & pectineus. artery & divides into terminal To extensors of knee joint: branches. quadriceps femoris

Femoral Nerve injury

⤞ Loss of sensation over ⤞ Wasting of quadriceps antero-medial aspect of thigh & Sensory effect femoris medial side of leg & foot (areas ⤞ Loss of knee extension supplied by the femoral nerve, ⤞ Weak flexion of the hip. Injury of the saphenous branch Motor effect (Psoas major is intact, of femoral nerve which supplies because it’s supplied by other the leg & foot) fibers of the lumbar plexus)

9 Sacral Plexus

⤞ Formation: ⤷ it’s formed by the ventral rami of a part of L4 & whole of L5 ()*, S1, S2, S3, and most of S4.

⤞ Site ⤷ Located in front of piriformis muscle.

⤞ Main Branches

1 2 3

Pelvic Splanchnic nerve Pudendal nerve Sciatic nerve ⤞ From the sacral Plexus (S2,3 & 4) ⤞ From the sacral Plexus (S2,3 & 4) ⤞ From the lumbosacral plexus ⤞ Preganglionic parasympathetic ⤞ Supplies the perineum . (L4, L5, S1, S2 & S3) supply to: ⤞ Supplies the lower limb ⤞ Pelvic Vescera ⤞ Hindgut

*The lumbosacral trunk comprises the whole of the anterior division of the fifth and a part of that of the fourth lumbar nerve. 10 Sciatic Nerve To avoid an injury during an IM injection, it should be ⤞ Origin: given in the upper lateral ⤷ From L4, L5, S1, S2 & S3 quadrant of either gluteal ⤷ A terminal branches of the sacral plexus regions.

Course Branches into

Leaves the pelvis through All leg & foot EXCEPT areas supplied by the Cutaneous greater sciatic foramen saphenous n. from femoral n. (below piriformis) To Hamstring (knee flexion & hip extension Passes the gluteal region between ischial tuberosity & Muscular greater trochanter To all muscles of the leg

then to the posterior Common peroneal (Fibular) nerve compartment of the thigh Terminal branches

Motor Injuries: Sensory Injuries:

⤞ Wasting of muscles below knee. (affect the flexion of ⤞ Loss of sensation below the knee EXCEPT the medial knee, extension of hip, all movements of leg & foot) side of leg & foot (supplied by femoral n.) ⤞ Foot assumes “foot drop” position by it’s weight.

11 Tibial & Common Peroneal (Fibular) Nerves Common Fibular nerve Tibial Nerve

Course Course

Leaves the popliteal fossa Descends through the popliteal fossa to the posterior turns around the lateral aspect compartment of the leg of the fibula’s neck (A dangerous position) It’s also accompanied with the posterior tibial vessels

Divides into Passes deep to flexor retinaculum to reach the sole of the foot and divide. Superficial Deep peroneal peroneal Divides into Descends into the Descends into the lateral compartment of anterior compartment Medial planter Lateral planter the leg. of the leg. nerve nerve

Muscles of anterior & lateral compartments of Muscles of posterior compartment of leg & Supplies leg (Dorsiflexors of ankle, Extensors of toes & Supplies intrinsic muscles of sole Plantar Flexors of evertors of foot. ankle, flexors of toes & invertors of foot. 12 Practice Q5: A patient came in with their arm hanging by the side, rotated medially and their Q1: All nerve fibers of the forming plexuses are the union of? forearm is extended and pronated. This lesion is called ___ and due to ___? A. Dorsal Rami A. Erb-Duchanne palsy | Middle trunk lesion B. Anterior Rami B. Klumpke palsy | Lower trunk lesion C. Ganglion C. Waiter’s tip hand | Upper trunk lesion D. Axilla D. Pope’s hand | Upper trunk lesion Q2: Which one of these deformities is the cause of median nerve lesion? Q6: Which of the following movement is affected by a common pernoeal nerve lesion? A. Waiter’s tip position A. Inversion of foot B. Ape hand B. Dorsiflexion of ankle C. Wrist drop C. Extension of knee D. Partial claw hand D. Flexion of toes Q3: Which of the following is a branch from the roots? Q7: The musculocutaneous nerve is a branch of the? A. Lateral pectoral nerve A. Lateral cord B. Nerve to subclavius B. Posterior cord C. Suprascapular nerve C. Medial cord D. Long thoracic nerve D. Upper trunk Q4: A young boy fell from a high place and clutched on something, which Q8 : The superficial peroneal nerve descends into the __ compartment of the leg? nerve is usually torn first? A. Anterior A. First thoracic B. Medial B. Ulnar nerve C. Posterior C. Median nerve D. Lateral

Answers: Q1(B) Q2(B) Q3(D) Q4(A) Q5(C) Q6(B) Q7(A) Q8(D) 13 Members board

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