Skip to main content

Brachial Plexus|Upper Limbs|Anatomy

BRACHIAL PLEXUS



FORMATION :

 It is formed by ventral primary rami of C5, C6, C7, C8 and T1.

COMPONENTS :

The brachial plexus consists of four components:
• Roots
• Trunks
• Divisions
• Cords

LOCATION :

• Roots and trunks lie in the root of neck.
• Divisions lie behind the clavicle.
• Cords lie in the axilla.




BRANCHES :

From Roots
• Dorsal scapular nerve (C5) for rhomboids.
• Nerve to serratus anterior (C5, C6 and C7) for serratus anterior as the name implies.
From Trunk (Only Upper Trunk Gives Branches)
• Suprascapular nerve (C5 and C6) for supraspinatus and infraspinatus muscles.
• Nerve to subclavius.

From Cords
• Lateral cord
Lateral pectoral nerve (C5-C7)
Lateral root of median nerve (C5-C7)
Musculocutaneous nerve (C5-C7)
Mnemonic: Laila Loved Majnu.

• Medial cord
Medial pectoral nerve for pectoralis major and pectoralis minor
Medial cutaneous nerve of arm
Medial cutaneous nerve of forearm
Medial root of median nerve
Ulnar nerve
Mnemonic: M4U

• Posterior cord
Upper subscapular nerve for subscapularis muscle
Lower subscapular nerve for subscapularis and teres major muscles
Nerve to latissimus dorsi (thoracodorsal nerve)
Axillary nerve for deltoid and teres minor muscles
Radial nerve
Mnemonic: ULNAR

APPLIED :

• Erb paralysis. It occurs due to injury of the upper trunk of brachial plexus at the Erb's point.

• Klumpke paralysis: It occurs due to injury of the lower trunk of brachial plexus.

• Horner syndrome: It occurs due to involvement of the sympathetic fibres (T1) • Winging of scapula: It occurs due to injury of the nerve to serratus anterior.

Erb Paralysis 
Site of injury :
Erb's point (the region of upper trunk where six nerves meet, i.e. ventral rami of C5 and C6, anterior and posterior divisions of the upper trunk, and suprascapular nerve and nerve to subclavius)

Cause :
 Undue (i.e. too much) separation of head from shoulder, e.g. (a) pulling of fetal head by forceps during delivery (birth injury) and (b) fall on shoulder.





Clinical features :
Arm hangs by the side. It is adducted and medially rotated, i.e. person is unable to abduct and laterally rotate the arm.

Forearm is extended and pronated, i.e. person is unable to flex and supinate the forearm.

Loss of sensations over a small area on the lower part of the deltoid.



Labels:

Comments

Post a Comment

Popular posts from this blog

Shoulder Joint|Upper Limbs|Anatomy

  SHOULDER JOINT CLASSIFICATION Synovial joint of ball and socket type. ARTICULAR SURFACES They are formed by the large hemispherical head of humerus and shallow glenoid cavity of scapula. The glenoid articular surface is deepened by the glenoid labrum . Glenoid labrum • It is a rim of fibrocartilage attached to the peripheral margin of the glenoid cavity. • It is triangular in cross-section and deepens the shallow glenoid cavity. LIGAMENTS Capsular Ligament • Attachments  Medially - To peripheral margin of glenoid cavity outside the glenoid labrum. The supraglenoid tubercle is intracapsular. Laterally - To anatomical neck of humerus except on medial side where it descends about 2-3 cm on the shaft, up to the surgical neck of humerus . • Muscles strengthening the capsule  In general, the capsule is loose and lax, but it is strengthened by the musculotendinous (rotator) cuff formed by the following muscles   Supraspinatus- above  Subscapularis- in front Infraspi...
Post a Comment
Read more

Radial Nerve|Upper Limbs|Anatomy

  RADIAL NERVE The radial nerve is the thickest and largest nerve of the upper limb. ROOT VALUE Ventral rami of C5, C6, C7, C8 and T1 ORIGIN COURSE & RELATIONS The course and branches of the radial nerve, which passes through three regions of the arm: axilla, radial groove on the back of the arm, and front of the forearm. Axilla: In axilla the radial nerve lies against the muscles forming the posterior wall of the axilla, and it gives two muscular branches to supply the long and medial heads of triceps and one cutaneous branch. Radial Groove :  In the radial groove it gives three muscular branches to supply the long and medial heads of triceps and anconeus and two cutaneous branches. Arm:  On the front of the arm, the radial nerve lies between brachialis on the medial side and brachioradialis and extensor carpi radialis longus on the lateral side. Forearm:  In the forearm, the radial nerve divides into two terminal branches: the deep terminal branch (posteri...
Post a Comment
Read more