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• The brachial plexus is a network of nerves supplying the entire upper limb.
• It can be divided into formation, components & course, 2 parts, branches, and applied anatomy.
• The brachial plexus is formed by the ventral rami of C5-T1 spinal nerves.

Components

• Roots
• Trunks
• Divisions
• Cords
• Branches (Nerves)

Roots

• Ventral rami of C5-T1 spinal nerves.

Trunks

• Superior/upper trunk is formed by the union of C5, and C6 roots.
• Middle trunk is a simple continuation of the C7 root.
• Lower/inferior trunk is formed by the union of C8 and T1 roots.

Divisions

• Anterior (ventral) and posterior (dorsal) divisions.

Cords

• Medial cord is a simple continuation of the anterior division of the lower trunk.
• Lateral cord is formed by the union of the anterior divisions of the upper and middle trunks.
• Posterior cord is formed by posterior divisions of all three trunks.

Important note

• Divisions do not give rise to any branches directly.

Parts

• Supraclavicular (roots, trunks) is present in the posterior triangle of the neck.
• Infraclavicular (cords & branches) is present in the axillary part.

Branches from roots

• Dorsal scapular nerve (C5) supplies the levator scapulae, rhomboid major, and rhomboid minor muscles.
• Long thoracic nerve (C5, C6, C7) supplies the serratus anterior muscle.

Branches from the upper trunk

• Suprascapular nerve (C5, C6) supplies the supraspinatus and infraspinatus muscles.
• Nerve to subclavius (C5, C6) supplies the subclavius muscle.

Branches from the cords

• Lateral pectoral nerve (C5, C6, C7)
• Musculocutaneous nerve (C5, C6, C7)
• Lateral root of the median nerve
• Medial pectoral nerve (C8, T1)
• Medial cutaneous nerve of arm
• Medial cutaneous nerve of forearm
• Medial root of median nerve (C8, T1)
• Ulnar nerve (C7, C8, T1)
• Radial nerve (C5, C6, C7, C8, T1)
• Upper subscapular nerve (C5, C6)
• Lower subscapular nerve
• Thoracodorsal nerve (C6, C7, C8)
• Axillary nerve (C5, C6)

Largest branch of the brachial plexus

• Radial nerve (C5-T1) is the largest branch

Median nerve is formed by

• Medial root from medial cord (C8, T1)
• Lateral root from lateral cord (C5, C6, C7)
• The contributions to median nerve originate from C5, C6, C7, C8, and T1

Related nerves and their spinal segments

• Ulnar nerve: C7, C8, T1
• Axillary nerve: C5, C6
• Musculocutaneous nerve: C5, C6, C7
• Long thoracic nerve

Applied anatomy

• Erb's palsy is usually due to birth injury, which results in paralysis.
• The meeting point of 6 nerves at the upper trunk of the brachial plexus is known as Erb's point.
• Injury to Erb's point leads to Erb's palsy.
• In Erb's palsy, the upper limb is adducted and medially rotated.
• In Erb's palsy, the forearm is extended and pronated.
• In Erb's palsy, the hand is flexed, resulting in "policeman's tip deformity".

Klumpke's palsy

• Klumpke's palsy is due to injury to the lower trunk of the brachial plexus
• Nerve roots involved in Klumpke's palsy are C8 and T1
• Complete claw hand deformity is seen in Klumpke's palsy.
• Klumpke's palsy is due to paralysis of intrinsic muscles of the hand, mainly lumbricals.
• Clinical features include extension of metacarpophalangeal joints and flexion of interphalangeal joints.
• Horner's syndrome is associated with Klumpke's palsy.
• Erb’s palsy involves C5, C6 nerve roots, while Klumpke’s palsy involves C8, T1 nerve roots.
• The deformity in Erb’s palsy is “policeman’s tip deformity”, while The deformity in Klumpke’s palsy, the deformity is claw hand deformity.
• In Klumpke’s palsy, all intrinsic muscles of the hand are paralyzed.

Pectoral Region

• It is located anteriorly in the thoracic wall.
• Consists of 3 anterior thoracic muscles
• Pectoralis major
• Pectoralis minor
• Subclavius

Pectoralis Major

• Larges muscle of the Pectoral region
• Crosses the shoulder joint anteriorly
• The Pectoralis major has two heads: sternocostal and clavicular.
• Sternocostal head originates from anterior surface of sternum, and upper 6 coastal cartilage.
• Clavicular head originates from medial half of clavicle.
• Inserts into the lateral lip of the intertubercular sulcus of the humerus
• Pectoral nerves medially and laterally innervate the Pectoralis major
• Actions include flexion/forward movement of the shoulder joint, adduction, and medial rotation.

Pectoralis Minor

• The Pectoralis minor does not cross shoulder joint.
• Arises from ribs 3rd, 4th, and 5th.
• Inserts into the coracoid process of the scapula.
• Medial and lateral pectoral nerves innervate the Pectoralis minor

Innervation

• Both pectoral nerves supply both Pectoralis muscles
• Action: protraction/forward movement of the scapula by assisting Serratus Anterior.

Subclavius

• The Nerve to Subclavius, a branch of the brachial plexus, innervates the Subclavius
• Action: stabilizes the clavicle during its movement.

Deltoid

• The deltoid muscle forms the shoulder region.
• Three groups of fibers present:
• Anterior fibers
• Posterior fibers
• Anterior/Middle/Acrominal fibers
• The anterior one-third of the lateral part of the clavicle is the origin of the acrominal fiber of the deltoid muscle.
• From Acromian process the scapula the M fibers originate.
• Posterior fibers originate from the spine of the scapula
• Inserts to deltoid tuberosity of humerus
• Axillary nerve innervates and enables flexion, medial rotation, abduction, and rotation.

Movements

• All movements, excluding adduction are carried out by the deltoid muscle.
• Intramuscular injection is given in the lower part of deltoid to avoid any axillary nerve damage.
• Content of deltopectoral groove is the cephalic vein.
• Nerves in direct contact with Humerus are
• Axillary nerve
• Radial nerve
• Ulnar nerve

Clavipectoral Fascia

• Lies deep to pectoralis major muscle
• Attaches medially to the first rib, laterally to the coracoid process of the scapula, superiorly to the clavicle, and inferiorly continues as suspensory ligament of axilla
• Encloses 2 muscles, the subclavius, and pectoralis minor.
• Structures Piercing Clavipectoral Fascia contains the Cephalic vein and is referred to as CALL.
• VAN Lymph - Cephalic vein. Lateral pectoral Nerve with Acromiothoracic artery/Thoraco acromial artery.
• Lateral pectoral Nerve does not pierce, but is median

Axillary Nerve

• Also called the circumflex nerve as it winds around the surgical neck of the humerus
• Formation: branch of the posterior cord of the brachial plexus
• Root value: C5 and C6
• It enters the quadrangular space, accompanied by posterior circumflex humeral artery
• Axillary nerve divides into anterior and posterior branches
• Function: innervates deltoid and teres minor muscles
• Cutaneous branch: upper lateral cutaneous nerve of arm
• Causes of axillary nerve injury:
• Inappropriate IM injection
• Fracture to surgical neck of humerus
• Inferior dislocation of shoulder joint
• Clinical effects include: paralysis of deltoid and teres minor muscles
• Deltoid palsy: loss of rounded shape of shoulder, loss of abduction (15-90 degrees)

Rotator Cuff Muscles

• Four muscles
• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis
• Supraspinatus, Infraspinatus, and Teres minor inserted in Greater tubercle & Subscapularis on Lesser tubercle
• Intertubercular sulcus / Bicipital groove with 3 parts that Lady b/w 2 majors (Pect. major, Latidorsi, T. major
• Actions, with corocoid process giving gives attachment to 3 muscles
• The muscles anterior of arm is Flexor Compartment
• Biceps Brachi , Brachialis, Coraco brachialis

Supply

• Musculo cutanery Nerve that contains long head where M is used
• Radial, ulnar, and median nerves are all involved in different actions
• Flexion of Elbow is caused by Biceps Brachi, Braccialis, and Brachio radialis.

Musculocutaneous Nerve (C5,C6, C7)

• Formed as a branch of the lateral cord of the brachial plexus.
• Course: pierces corocobrachialis muscle and passes between biceps and brachialis muscles.
• Termination: continues as the lateral cutaneous nerve of the forearm.
• Content and nerve branches of MC, Median of Mammary and Gland

Mammary Gland

• Anterior muscles with Blood

• Location : Superficial fascia of Pect region, located vertically 2nd rib to 6th rib in Mid, horizontally Lat border of sternum to Mid

• Extent/Deep

• Skin structure: The glandular part contains lobes(15-20) divided into Nebules.

• Each lobe is drained by 1 dactiferous duct

• 4 Quadrents

• Lymphatic drainage/Supply: in the upper headrant of Axillary

• Gland - Lymphatic Drainage Carcinoma: Lymphatic is Superficical and flows with Blood

• Mammary Structures: Pectoral Fascia is Serattus in the Anterior

Axillary Lymph Nodes

• 5 Groups:
• Apical
• Anterior/ Pectoral
• Posterior
• Central
• Apical lateral
• The Subareolar plexus and Lymph Nodes form that
• I: Internal Thoracic nodes and subperotoneal lymphatic plexus

Applied:

• Carcinoma of breast, affecting breast skin.
• “Peau d’ orange” is due to subcuteanous lymphatic blocks.
• Axillary Lymph Nodies

Back of Arm (Extensor Compartment)

• Has Triceps brachii as lateral head of humerus, and from back of humerus, olecranon process, that allows elbow extention.
• Brachio radialis forms outer boundary With a kat. Supra condu ridge that radial and elbow Nerve that causes Flexion. Flexion of Elbow caused by BBB.

Cubital Fossa

• Depression in front of Elbow shaped like a Triangle.
• MBBS contents: Median Nerve, Biceps Brachi tendon-1, and Brachial artery-

Course & Roots

A. Apex : Meeting point Branchioraddils z Pronator Terres

• B. Roof: formed by skin, 1 Superficial fascia & Deep fascic
• Bicipital aponeurosis
• C. Floor A z muscles → Brachialis z volest incisa

Applied

1. Dmedian: Cubital Vein is Elongated from Proximal row
2. B: Brachial: Anitial and Palpated

Cubital Vein

• Superficial vein of the upper portion.
• From the root of Cubital fosse: 2.5 cm belorw elbow.
• MCQ Cephalic continues as Axillary but rains into Arterry

Coronal Carpets

• Proximal/ Distal: S She Looks L looks to Pretty test to catch her: Scaphoid
• Radius is always most

Flexor Retinaculum of WRIST/HAND/UL

• Definition is the thickening of deep fascia at front of the wrist

Structures:

• Distal 2 bones - Scaphoid of Trapezium
• Pisform of hamate
• Flexor pollicis longus
• 3 Superficicial Layers are Radial (Radial / Ulnar)
• 1 Median Nerve
• Flexor tendons, each w/ bursa synovial layer B. Bipinnate

Function Notes

: Maintains tendons position A: Median never B: Transverse carpal tests I: Interosseuous compression

Extensor retinaculum

• Thickening of deep fascia at the back of wrist
• Medially- Attached to Pisiform & triquetral bone
• Laterally- Attached to lower radius
• The wrist has 6 Extensors
• APL/ EPB tendon extensor Brevis
• There is a long digital India

Anatomical snuff box

• Has Radial Arteries
• Extends A and P over the radius
• Contains superficial veins, but no bone
• Has Cephalic Vein

INTRINSIC MUSCLES OF HAND

• Small Muscles that are total, but are 11

• 4 Thenar

• Flexor Pollicis Brevis

• Abductor PB Hypothenar: 5:

• Flexor Digith Minimi 4 lumbricals + 4palmar :

• 4 Dorsal Inteross and

• Abductor DM

• All attach as and attach to the Dorsal Digital

: (Extensor Hood Lumbricals)

• There are radial and nerve positions, as thumb is used with the Median N.

SHOULDER JOINT (Aka Glenohumeral Joint)

Type: Is

• Articular Surface Type
• Ligaments
• Movements and Muscles
• Applied

Surface

1. Glenoid cavity of scapula, shallow depression
2. Head: Rounded
3. Fibrous: Thick, but capsule
4. Coraco

• Muscles: Supraspinat, Teres minor, Subdator for Head of humerus.

1. Fibrous: A. Thickening of fibrous capsule. a. Transverse A. Extends in 2 sides b. Glenoid - up of fibro cartilage. 5: - extends and Acromiun- for Superior position

SHOULDER Anatomy

1. Formed by insertion of head with its socket, and 2 joints
2. Made of the (sits): All rotar (Muscle) Insertion of the Infraspinatus, Teres minor the Lesser/
3. Action. : Subscapularis, P. is in all heads with high tension

Ulnar

1. Ulnar N: Forms and ends with Superficical of Hand with all heads. (2. Palmar) = Palmar, deep branches. 2: The 3 muscles with ADM is the main force.

Radial Nerve

1. Forms and continues with a high loop near elbow joint
2. Branch out as back is with Supinator where it gets pinched.
3. Lateral head has radial, which is spiral.

##Anastomies

1. Radial has Ulnar
2. Around the medial is where structures form by, elbow which gives a full loop.
3. Also helps Elbow has Brachial in hand for blood circulation.

Clinical

During elbow, Brachial is high for flow, but wrist, shoulder, or intermuscular joints can be low for flow.

Axial artery

• Located with the subclavian artery.
• There are many vessel branches as it stretches throughout.

Cephlatic vein

• Blood cell form from radial
• 3 arteries as it passes with many vein branches.
• Can't see in full view, as high density bones are nearby
• Axial is in this direction to flow with pressure.

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