Download MBBS Anatomy PPT 85 Brachial Plexus Notes

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Learning objectives


? Formation of brachial plexus
? Components ? roots, trunks, divisions &

branches

? Relations ? cervical & axillary part
? Main nerves of arm, forearm & hand
? Nerve course, injuries & applied aspects









Wasted Thenar Muscles


Winging of scapula


Winging of

scapula



Wrist drop


Week 7

Week 5

RULE -
Limbs are outgrowths of ventral
body wall that undergo distal

growth and dif erentiation...5th
Week

and rotation...7th week

Upper Limb

Anterior

Muscle

Compartments

Humerus

Arm

Posterior

Anterior

Forearm

Radius

Ulnar

Posterior

Anterior

Hand

5th metacarpal


Anterior

Humerus

Arm

Posterior

Few muscles of posterior
compartment are present in
anterolateral aspect of

Anterior

forearm (*brachioradialis,
supinator)

Forearm

*

Radius

Ulnar

Posterior

Anterior

Hand

No posterior compartment in the hand

5th metacarpal

Anterior

Musculocutaneous n.

Motor innervation

Muscle Compartments

Humerus

Radial n.

Posterior

Anterior

Median n. & Ulnar n.

Radius

Ulna

Radial n.

Posterior

Ulnar n. & Median n.

Anterior

5th metacarpal

Posterior


Muscles of Arm: Cross elbow Move forearm

? Two compartments ? Anterior & posterior
? 1. Anterior: Flexors of forearm
? 2. Posterior: Extensors of forearm
Anterior Compartment ? MCN + Axillary A & Brachial A

? Biceps brachii = Musculocutaneous nerve

? Brachialis = Musculocutaneous nerve

? Coracobrachialis = Musculocutaneous nerve

? Brachioradialis = Radial nerve

Posterior Compartment ? RN + Profunda Brachii Artery

? Triceps brachii = Radial nerve

? Anconeus = Radial nerve

RULE : Ventral vs. dorsal limb mm.

Developmentally-dorsal muscles:

? Lie posterior to the long bones in anatomical position
(* exceptions)

Developmentally-ventral muscles:

? Lie anterior to the long bones in anatomical position

*


Brachial plexus

? Supraclavicular part ? neck ? posterior

triangle b/w sclaneus anterior & sclaneus
medius ? roots & trunks

? Infraclavicular part ? axilla ? divisions /cords

& branches

? Cords ? named as per relation to second part

of axillary artery ? deep to pectoral minor

? Lateral cord ? lateral , posterior cord ?

posterior & medial cord ?medial to 2nd part
of axillary artery



Brachial Plexus
(right side; simplified)

"Roots of BP"

(=ventral rami)

C5

C6

Trunks

C7

U

Divisions

C8

M

Cord

Terminal

Lat

L

T1

Branches

Post

Med

Anterior (ventral) division

Posterior (dorsal) division


Brachial Plexus
(right side; simplified)

"Roots of BP"

(=ventral rami)

C5

C6

Trunks

C7

U

Divisions

C8

M

Cord

Terminal

Lat

L

T1

Branches

Post

Musculocutaneous n.

Med

Median n.

Radial n.

Anterior (ventral) division

Ulnar n.

Posterior (dorsal) division

Brachial plexus - cords



Lateral cord ? LML ? Lateral Pectoral n, Musculocutaneous

n, lateral root of Median n



Medial cord ? MMMMU ? Medial pectoral n, Medial

cutaneous n of forearm, Medial cutaneous n of arm , Ulnar
n & Medial root of median n.



Posterior cord ? LUNAR ? Lower subscapular n, Upper

subscapular n , Nerve to latissimus dorsi, Axillary n & Radial
n.

31
Brachial plexus - cords



1. Lateral cord ? LML ? Lateral Pectoral n,

Musculocutaneous n, lateral root of Median n


2. Medial cord ? MMMMU ? Medial pectoral n,

Medial cutaneous n of forearm, Medial

cutaneous n of arm , Ulnar n & Medial root of

median n.


3. Posterior cord ? LUNAR ? Lower subscapular n,

Upper subscapular n , Nerve to latissimus dorsi,

Axillary n & Radial n.

32

Brachial plexus - cords



1. Lateral cord ? LML ? Lateral Pectoral n,

Musculocutaneous n, lateral root of Median n



2. Medial cord ? MMMMU ? Medial pectoral n, Medial

cutaneous n of forearm, Medial cutaneous n of arm ,
Ulnar n & Medial root of median n.



3. Posterior cord ? LUNAR ? Lower subscapular n, Upper

subscapular n , Nerve to latissimus dorsi, Axillary n &
Radial n.

33
Brachial plexus ? supraclavicular
branches - roots & trunks

? Branch to Phrenic nerve ?C5 ?anterior to sclaneus

anterior

? Dorsal scapular n ? C5 ? pierces sclaneus medius,

supplies rhomboids & levator scapulae

? Long thoracic n ? C5C6C7 ? (C7 ? may be absent) upper

two roots C5C6 pierce sclaneus medius , runs b/w
sclaneus ant & medius ? Supply - serratus anterior.

? TRUNKS ? Upper
? Nerve to subclavius ? Erb's Point - C5 C6 ?subclavius (

gives - accessory phrenic nerve ?C5)

? Suprascapular n- C5C6 ? supra & infraspinatus , articular

? shoulder, acromioclavicular,

34

Brachial plexus-

? Lateral pectoral n- C5C6C7 ? LC -larger, pierces

clavipectoral fascia ,ant to axillary art- pectoralis major
& minor.

? Medial pectoral n- C8T1-MC- , pierces pectoralis minor

& supplies both pectoralis major & minor.

? Upper sub scapular n- smaller ? frequently double.
? Lower sub scapular n- subscapularis & teres major.
? Axillary n- ant branch ?deltoid & post branch- has

pseudoganglion supplies teres minor ,cutaneous ? as-
upper lateral cutaneous nerve of arm .






Brachial Plexus

C5

(branches)

C6

supraspinatus

suprascapular n.

C7

& infraspinatus

*

mm.

C8

T1

**

upper subscapular n.

subscapularis m.

axillary n. thoracodorsal n.

latissimus dorsi

lower subscapular n.

m.

deltoid & teres minor mm.

Brachial Plexus
(branches)

rhomboid mm.

dorsal
scapular n.

C5

C6

suprascapular n.

C7

*

C8

pectoralis mm. lateral pectoral n.

serratus

T1 anterior m.

musculoskeletal
n.

long

thoracic n.

medial n.

medial pectoral n.

pectoralis

**

mm.

upper subscapular n.
thoracodorsal n.

axillary n.

lower subscapular n.

ulnar n.

radial n.


Brachial Plexus
(all branches)

Dorsal
scapular n.

C5

C6

Suprascapular n.

C7

*

C8

Lateral pectoral n.

T1

Musculoskeletal n.

Long

thoracic n.

Medial n.

Medial pectoral n.

**

Upper & lower subscapular nn.
Thoracodorsal n.

Axillary n.

Ulnar n.

* Nerve to subclavius

Radial n.

** Medial brachial & antebrachial cutaneous nn.

Brachial plexus - cords



Lateral cord ? LML ? Lateral Pectoral n, Musculocutaneous

n, lateral root of Median n



Medial cord ? MMMMU ? Medial pectoral n, Medial

cutaneous n of forearm, Medial cutaneous n of arm , Ulnar
n & Medial root of median n.



Posterior cord ? LUNAR ? Lower subscapular n, Upper

subscapular n , Nerve to latissimus dorsi, Axillary n & Radial
n.

39
Brachial plexus - cords



? Lateral cord ? LML ? Lateral Pectoral n,

Musculocutaneous n, lateral root of Median n



? Medial cord ? MMMMU ? Medial pectoral n, Medial

cutaneous n of forearm, Medial cutaneous n of arm ,
Ulnar n & Medial root of median n.



? Posterior cord ? LUNAR ? Lower subscapular n, Upper

subscapular n , Nerve to latissimus dorsi, Axillary n &
Radial n.

Nerve supply of Scapular Muscles

? Origin on Scapula:

? Latissimus dorsi = Thoracodorsal nerve /N to

latissimus dorsi

? Subscapularis & Teres Major = Subscapular nerves

? Supraspinatus & Infraspinatus = Suprascapular

nerves

? Deltoid & Teres Minor = Axillary nerve

? Insertion on Scapula

? Levator Scapularis & Rhomboids = Dorsal Scapular

nerve

? Pectoralis Minor = lat & medial Pectoral nn.

? Serratus anterior = Long Thoracic n/nerve of bell

? Trapezius = Accessory spinal n.


Branches - Posterior Cord

? Axillary Nerve ( w . Circumflex vs..)

? Supplies:

? Deltoid & Teres minor (motor supply )

? Capsule of shoulder

? skin of lower part covering deltoid (sensory

supply)

? Subscapular Nerves {C5,C6} : Subscapularis &

Teres major

? Thoracodorsal Nerve : Latissimus dorsi

Injury to axillary nerve


Waisting of shoulder

Winging of the Scapula

Combined Axillary and Long Thoracic Nerve

Injuries


Fore arm ?muscles
1. Flexor Compartment : Anterior

(Superficial 5 + Deep 3) - supplied by
Median, Anterior Interosseous Nerve &
Ulnar nerves


2. Extensor Compartment : Posterior

(Superficial + Deep)

Radial & Posterior interosseous nerve.




Radial nerve injury in arm

Wrist drop


Anterior Compartment Forearm = 5 +3

1 Pronator teres

Median n

2 Flexor digitorum superficialis Median n

3 Flexor carpi radialis

Median n

4 Palmaris longus

Median n

5 Flexor carpi ulnaris

Ulnar nerve

1 Pronator quadratus

Anterior interosseous n-Median n

2 Flexor digitorum profundus

Anterior interosseous n-Median n

& Ulnar nerve

3 Flexor pollicis longus

Anterior interosseous n- Median n

Posterior Compartment Forearm ?
superficial - 7

1 Anconeus

Radial n

2 Brachioradialis

Radial n

3 Extensor carpi radialis longus

Radial

4 Extensor carpi radialis brevis

Posterior interosseous? Radial n





5 Extensor digitorum

Posterior interosseous? Radial n


6 Extensor digiti minimi

Posterior interosseous? Radial n

7 Extensor carpi ulnaris

Posterior interosseous? Radial n


Posterior Compartment Forearm ? deep - 5

1 Supinator

Posterior interosseous? Radial n


2 Abductor pollicis longus

Posterior interosseous? Radial n


3 Extensor pollicis brevis

Posterior interosseous? Radial n





4 Extensor pollicis longus

Posterior interosseous? Radial n





5 Extensor indicis

Posterior interosseous? Radial n
Hand ? Median nerve - 5

Flexor pollicis brevis

Median n

Abductor pollicis brevis

Median n

Opponens pollicis

Median n

1st lumbrical

Median n

2nd lumbrical

Median n

Hand ? Ulnar nerve - 15

Flexor digiti minimi

Ulnar n


Abductor digiti minimi

Ulnar n


Opponens digiti minimi

Ulnar n


Interossei ? palmar & dorsal (8) Ulnar n



3rd & 4th lumbricals (2)

Ulnar n

Palmaris brevis

Ulnar n ? superficial branch

Posterior Compartment of Forearm

Muscle

Nerve

? Superficial

? Extensor carpi radialis Longus & Brevis

RN

? Extensor digitorum (communis) RN

? Extensor digiti minimi







RN

? Extensor carpi ulnaris







RN

? Deep (post gp) - PIN

? Supinator









Radial n + PIN

? Abductor pollicis longus







PIN

? Extensor pollicis longus + brevis PIN

? Extensor indicis









PIN


An inability to oppose thumb to little finger

can result from injury to -

a) Axillary n

b) Radial n

c) Ulnar n

d) Median n


Hyperextension of proximal phalanges of

little and ring fingers can happen due to
nerve injury of -

a) Ulnar

b) Axillary

c) Radial

d) Median



Inablity to abduction of arm can happen due

to nerve injury of -

a) Axillary

b) Musculocutaneous

c) Radial

d) Median


Wrist drop can result from damage to -
a) Median n

b) Ulnar n

c) Radial n

d) Anterior interosseous n


This post was last modified on 05 April 2022