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The Brachial plexus



The Brachial plexus



The Brachial plexus

1. The brachial plexus is formedby the union of the anterior rami of C5-C8 & T1 (the rootsof the BP).

2. The roots pass laterallybetween the anterior andmiddle scalene muscles withthe subclavian artery.

3. Sympathetic fibers from themiddle and inferior cervical

ganglia join the roots as theypass between the scalenes.

Fig 6.29 p 775



In the supraclavicular area the roots unite to form trunks:1. Superior trunk ± C5& C62. Middle trunk ± C7 continues

3. Inferior trunk ± C8 & T1

Fig 6.28 p 774



As the trunks pass lateral to the 1st rib each trunk splits into anterior and posterior divisions as they pass beneath the clavicle and enter the cervicoaxillary canal: ± Anterior divisions innervate the muscles of the anterior compartment in

the arm and forearm.

± Posterior divisions innervate muscles of the posterior compartment of the arm and forearm

Fig 6.28 p 774



Divisions form cords in the area superior to the pectoral minor: ± Superior & middle anterior divisions unite the from the lateral cord

± Inferior division of the inferior trunk forms the medial cord

± Posterior divisions unite to form the posterior cord.

Fig 2.08 p 21 Grant¶s Dissector 13th Ed., PatrickTank



To simplify understanding and remembering the BP incan be divided into supraclavicular & infraclavicular segments by the clavicle

Fig 6.28 p 774



Supraclavicular branchesThere are four, they arise from roots, a trunk and a division*Root branches Dorasl scapular nerve:pierces middle scalene and passes

inferiorly to the rhomboids Long thoracic nerve: from C5,6,7 roots passes inferiorly on to the

surface of the Serratus anterior

Trunk branch Nerve to subclavius: passes directly to the inferior surface of

clavicle gives branch to sternoclavicular jointDivision branch Suprascapular nerve: runs parallel to the suprascapular artery to

the suprascapular notch (beneath the suprascapular ligament)

supplies the supraspinatus m. around the greater scapular notch tothe infraspinatus m.*Small braches arise from all roots to supply the scalene and longus

coli muscles. C5 gives a root to the Phrenic nerve (C3-5)



Supraclavicular branches

Fig 6.29 p 775



Infraclavicular Branches - -arise from the cords and can be

divided into branches and little branches (very unscientific).

Fig 6.28 p 774



Infraclavicular Branches

Cords BIG branches little

Lateral MusculocutaneousLateral

Lateral pectoral

Posterior Axillary

Radial

Upper Subscapular

Lower Subscapular Thoracodorsal

Medial Ulnar

Medial

Medial pectoral

Medial brachial cutaneous

Medial ante brachial cutaneous

The lateral & medial braches join to form theMedian nerve



Cords Big Branches Little Branches

Lateral Musculocutaneous

Lateral branch

Lateral pectoral

Fig 6.31 p 785



Cords Big Branches Little branchesPosterior Axillary

Radial

Upper subscapular

Lower subscapular

Thoracodorsal

Fig 2.09 p 21, Grant¶s Dissector 13th Ed., Patrick Tank



Cords Big branches Little branches

Medial Ulnar

Medial branch

Medial pectoral

Medial brachial cutaneous

Medial antebrachial cutaneous

Fig. 6.31, p 785



Figure 206.1.² Schematic representation of the brachial plexus nerves and muscles. (PS): paraspinal muscles; (R): rhomboid muscle; DS: dorsoscapular nerve; LT: long thoracic nerve: (SA): serratus anterior muscle; SF:

sympathetic fibers for the eye; (M of M) muscle of Muller: (DP) dilator of the pupil; (SS): supraspinatus muscle; (IS): infraspinatus muscle; SPS:suprascapular nerve; PL: pectoralis lateralis nerves; (P): pectoralis muscle;PM: pectoralis medialis nerve; (TM): teres major muscle; (SBS): subscapularismuscle; SBS: subscapularis nerve; TD: thoracodorsal nerve; (LD): latissimusdorsi muscle; MC: musculocutaneous nerve; (Bi): biceps muscle; (Br):brachialis muscle; M: median nerve; U: ulnar nerve; A: axillary nerve; (TMi):teres minor muscle; (D): deltoid muscle; R: radial nerve.



Brachial Plexus Root Injuries

Upper brachial plexus injury

± Erb-Duchenne Palsy C5&C6 root injury, caused by stretch between the head and

shoulder, shoulder stops head/neck don¶t. The most commonly involved nerves are the suprascapular

nerve, musculocutaneous nerve, and the axillary nerve.

Waiter¶s tip deformity- arm adducted, medially rotated andpronated. Why?

Sensory loss where? Major cause is obstetric injury ($$$$$$$$)



Figure 216.1.² Typical posture of a neonate with Duchenne-Erb palsy [A and B]. The posture consists of arm adduction and internal rotation, extended elbow, forearm pronation, palmar flexion of the wrist, and good finger movements. The presence of wrist flexion indicates minimal or noinvolvement of C7

.



Figure 216.2.² Schematic representation of the brachial plexus and itsnerves and muscles. Site of injury. A: C5 root and C6 spinal nerve; B: upper trunk; (PS): paraspinal muscles; (R): rhomboid muscle; DS: dorsoscapular

nerve; LT: long thoracic nerve; (SA): serratus anterior muscle; (SS):supraspinal muscle; (IS): infraspinal muscle; SPS: suprascapular nerve; PL: pectoral lateralis nerve; (P): pectoralis muscle; PM: pectoralis medialis nerve;SF: sympathetic fibers to the eyes; (M of M): muscle of Müller; (DP): dilator pupillary muscle; (TM): teres major muscle; (SBS): subscapularis muscle;SBS: subscapularis nerves; TD: thoracodorsal nerve; (LD): latissimus dorsi muscle; MC: musculocutaneous nerve; (Bi): biceps muscle; (Br): brachialismuscle; M: median nerve; U: ulnar nerve; A: axillary nerve; (TMi): teres minor

muscle; (D): deltoid muscle; R: radial nerve.



Brachial Plexus Injuries

Lower brachial plexus injury

± Klumpke palsy

C7,C8&T1 injury

Arm abduction injury

Paralysis of the muscles of the distal forearm andhand (all ulnar innervated) plus distal radial &median innervated muscles.

Horner's syndrome (ptosis,meiosis, anhydrosis) if T1 sympathetics involved.



Figure 220.2.² Site of injury in Klumpke palsy. [A] Root of T1 and spinal nerve of C8. [B] Lower trunk. The green lines at T1 represent the most frequent origin of sympathetic fibers for the eyes. (PS): paraspinal muscles; (R): rhomboid muscle; DS: dorsoscapular nerve; LT: long thoracic nerve; (SA): serratus anterior muscle; (SS): supraspinal muscle; (IS): infraspinal muscle; SPS: suprascapular nerve; PL: pectoral lateralis nerve; (P): pectoralis muscle; PM:

pectoralis medialis nerve; SF: sympathetic fibers to the eyes; (M of M): muscle of Müller; (DP):dilator pupillary muscle; (TM): teres major muscle; (SBS): subscapularis muscle; SBS:subscapularis nerves; TD: thoracodorsal nerve; (LD): latissimus dorsi muscle; MC:musculocutaneous nerve; (Bi): biceps muscle; (Br): brachialis muscle; M: median nerve; U:ulnar nerve; A: axillary nerve; (TMi): teres minor muscle; (D): deltoid muscle; R: radial nerve.



Brachial Plexus Injuries

Lower brachial plexus injury

± Klumpke palsy

C7,C8&T1 injury

Arm abduction injury

Paralysis of the muscles of the distal forearm andhand (all ulnar innervated) plus distal radial &median innervated muscles.

Horner's syndrome (ptosis,meiosis, anhydrosis) if T1 sympathetics involved.





Brachial Plexus Variations

Brachial Plexus Variations in Human Fetuses.ANATOMIC REPORTS

Neurosurgery. 53(3):676-684, September 2003.Uysal, Ismihan Ilknur M.D.; Seker, Muzaffer Ph.D.;

Karabulut, Ahmet Kagan M.D., Ph.D.; Buyukmumcu,Mustafa Ph.D.; Ziylan, Taner Ph.D.

This study was performed with 200 BPs fromspontaneously aborted fetuses without detectablemalformations. The BPs were composed mostly of theC5, C6, C7, and C8 nerves and the T1 nerve (71.5%). A

prefixed plexus was observed in 25.5% of cases, and apostfixed plexus was observed in 2.5% of cases.

Another study BPs noted phrenic nerve formation byC5,6&7 in 20% of specimens***



BP Anomalies





Brachial Plexus

Really cool procedure, do the same in lab!



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