Brachial Plexus Anatomy Lecture PDF

BRACHIAL PLEXUS Slide Title  INTRODUCTION  ARRANGEMENTS/FORMATION OF THE PLEXUS  BRANCHES OF THE PLEXUS  VARIATIONS IN THE FORMATION OF THE PLEXUS  RELATIONSHIPS OF SOME BRACHIAL NERVES TO BONES  APPLIED ANATOMY OF THE PLEXUS Slide Title Make Effective Presentations Using Awes...

BRACHIAL PLEXUS Slide Title  INTRODUCTION  ARRANGEMENTS/FORMATION OF THE PLEXUS  BRANCHES OF THE PLEXUS  VARIATIONS IN THE FORMATION OF THE PLEXUS  RELATIONSHIPS OF SOME BRACHIAL NERVES TO BONES  APPLIED ANATOMY OF THE PLEXUS Slide Title Make Effective Presentations Using Awesome Backgrounds Engage your Audience Capture Audience Attention  INTRODUCTION;  The brachial plexus is a network of nerve that is responsible for the cutaneous and muscular innervations of the entire upper limb with two exceptions;  The trapezius muscle which is innervated by the SPINAL ACCESSORY NERVE and  An area close to the axilla which is innervated by the INTERCOASTOBRACHIALIS NERVE. 02/13/2025 4  The brachial plexus begins in the neck extending through the axillary inlet into the axilla where almost all the branches of the plexus arises after it has crossed the first rib. 02/13/2025 5 02/13/2025 6 ARRANGEMENT/FORMATION OF THE PLEXUS The brachial plexus is formed by the union of the ventral rami of the lower four cervical nerves (C5-C8) and the greater part of the ventral ramus of the first thoracic nerve (T1) forming the roots of the plexus. 02/13/2025 7  These roots passes through the gap between the anterior and middle scalene muscles with the subclavian artery. The roots unite to form the 3 trunks at the inferior border of the neck viz; 02/13/2025 8  Superior trunk- formed by the union of C5 & C6 at the lateral border of the scalenus medius muscle. Middle trunk- formed as a continuation of C7 Inferior trunk- formed from the union of C8 & T1 posterior to the scalenius anterior muscle. the three trunks incline laterally, and either just behind or above the clavicle each divides into an anterior and a posterior division. 02/13/2025 9  The anterior division will supply the anterior compartments of the upper limb while the posterior division supplies the extensor (posterior) compartment of the upper limb. The six (6) divisions of the brachial plexus unite to form the three cords; 02/13/2025 10  The lateral cord; formed by the union of the anterior divisions of the superior and middle trunk. Medial cord; formed as a continuation of the anterior division of the inferior trunk. Posterior cord; formed by the union of 02/13/2025 the posterior divisions of the three trunks. 11  The cords of the plexus bear the relationship to the second part of the axillary artery that is indicated by their names; The lateral cord is lateral to the axillary artery, the medial cord is medial to it while the posterior is posterior to it. 02/13/2025 12  Branches of the plexus Branches are described as supraclavicular and infraclavicular. The supraclavicular branches arises from the roots and trunks and are approachable through the neck. 02/13/2025 13  Supraclavicular branches; 1. Dorsal Scapular nerve (C5)- pierces the middle scalene muscle and runs deep to supply the levator scapulae, enters the deep surface of the Rhomboids muscle supplying it. 02/13/2025 14 2. Suprascapular Nerve (C5-6)- passes laterally through the posterior triangle of the neck and through the suprascapular foramen to enter the posterior scapular region; supplies the supraspinatus, infraspinatus muscles and glenohumeral joint. 3. Nerve to Subclavius (C5-6)- originates from the superior trunk of the brachial plexus; Innervates the subclavius muscle. 02/13/2025 15 4. Long Thoracic Nerve (C5-C7)- passes through the cervicoaxillary canal and posterior to other BP components to supply the serratus anterior muscle. 02/13/2025 16  Infraclavicular branches of the plexus Lateral cord 5. Lateral Pectoral Nerve (C5- 7)- is the most proximal of the branches from the lateral cord. It innervates the pectorialis major muscle. 02/13/2025 17 6. Musculocutaneous Nerve (C5-7)- is a large terminal branch of the lateral cord, it penetrates the coracobrachialis muscle and pass between the biceps brachii and brachialis muscles in the arm, and innervates all three flexor muscles in the anterior compartment of the arm. innervates the Biceps brachii, Brachialis and Coracobrachialis muscles.  It therefore supplies the anterior compartment muscles of the arm and continues as the lateral cutaneous nerve of the forearm. 02/13/2025 18 02/13/2025 19 7. Lateral Root of Median nerve (C5-7)- is the largest terminal branch of the lateral cord and passes medially to join a similar branch from the medial cord to form the median nerve. Medial cord 8. Medial Root of Median Nerve (C8-T1)- it joins the lateral roots from the lateral cord to form the median nerve (C5-T1). The median nerve is formed anterior to the third part of the axillary artery by the union of lateral and medial roots originating from the lateral and medial cords of the brachial plexus. 02/13/2025 20  It passes into the arm anterior to the brachial artery, through the arm into the forearm where branches innervate most of the muscles in the anterior compartment of the forearm (except for the flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle, which are innervated by the ulnar nerve). 02/13/2025 21  The median nerve continues into the hand to innervate: the three thenar muscles associated with the thumb; the two lateral lumbrical muscles associated with movement of the index and middle fingers; the skin over the palmar surface of the lateral three and one-half digits and over the lateral side of the palm and middle of the wrist. 02/13/2025 22 02/13/2025 23 9. Medial Pectoral Nerve (C8-T1)- receives a communicating branch from the lateral pectoral nerve and then passes anteriorly between the axillary artery and axillary vein. innervates the pectorialis minor muscle and part of the pectorialis major muscle too. 10. Medial Cutaneous Nerve of the arm (C8-T1)- supplies the skin of the medial side of the arm and superior part of the forearm and also the floor of the axilla. 11. Medial cutaneous Nerve of the Forearm (C8-T1)- innervates the skin on the medial side of the forearm.  Known as the “fools nerve”. 02/13/2025 24 12. Ulnar Nerve (C8-T1)- is a large terminal branch of the medial cord. Transverse the arm into the forearm without branching.  innervates one and a half muscles in the anterior compartment of the forearm (flexor carpi ulnaris, flexor digitorum profundus).  innervates also all the intrinsic muscles of the hand except (3 thernar muscles and 2 lumbricals).  It innervates skin over the palmar surface of the little finger, medial half of the ring finger, and associated palm and wrist, and the skin over the dorsal surface of the medial part of the hand. 02/13/2025 25 02/13/2025 26  Posterior cord 13. Upper Subscapular (C5-6)- is short, passes into the subscapularis muscle innervating it. 14. Thoracodorsal Nerve (C6-8)- the longest of the 3 side branches of the posterior cord, it passes vertically along the posterior axillary wall and innervates latissimus dorsi. 15. Lower Subscapular Nerve (C5-6)- inervates the teres major muscle as well as the inferior part of the subscapularis muscle. 02/13/2025 27 02/13/2025 28 16. Axillary Nerve (C5-6)- a terminal branch of the posterior cord, exit the axilla through the quadrangular space.  It passes posteriorly around the surgical neck of the humerus.  innervates the teres minor and the deltoid muscle 02/13/2025 29 02/13/2025 30 17. Radial Nerve (C5-8, T1)- is the largest terminal branch of the posterior cord.  The largest branch of the brachial plexus.  It passes out of the axilla and into the posterior compartment of the arm.  Supplies all the extensor muscles of the posterior compartment of the upper limb.  Skin on the posterior aspect of the arm and forearm. 02/13/2025 31 02/13/2025 32  VARIATIONS IN THE FORMATION OF THE BRACHIAL PLEXUS 02/13/2025 33  Variations in the formations of the brachial plexus are common. In addition to the five (5) ventral rami (C5-8) and T1 that form the roots of the brachial plexus, small contributions may be made by the ventral ramus of C4 or T2. 02/13/2025 34  When the contribution from C4 is more than that of T1, the root of the plexus starts from C4 and ends at C8. This type of brachial plexus is termed prefixed. When the contribution from T2 is more and the superior root is C6, it is termed postfixed. 02/13/2025 35  Variation may also occur in the; Formation of trunks, division and cords. Origin and or contribution of branches. Relation to axillary artery and scalene muscle. In some individuals, trunk divisions or cord formations may be absent in one or other parts of the plexus; however the make up of the terminal branches remain unchanged. 02/13/2025 36  RELATIONSHIPS OF SOME BRACHIAL NERVES TO BONES 02/13/2025 37 1. Surgical neck of humerus; The Axillary Nerve, which supplies the teres minor and deltoid muscle, a major abductor of the humerus at the shoulder joint. 2. Radial groove; Radial Nerve, which supplies all the extensor muscles of the upper limb. 3. Medial epicondyle; Ulnar Nerve which supplies medial one and half part of the hand and the anterior compartment of the forearm. 02/13/2025 38  CLINICAL AND APPLIED ANATOMY OF BRACHIAL PLEXUS 02/13/2025 39  The brachial plexus is an extremely complex structure. When damaged, it requires meticulous clinical history taking and examination. Brachial plexus injuries are important because they affect movements and cutaneus sensations in the upper limb. Diseases, stretching and wounds in the posterior triangle of the neck or in the axilla may produce brachial plexus injuries. 02/13/2025 40  Signs and symptoms of the injuries depends on the side of the plexus that is involved. Injuries to superior parts of the brachial plexus (C5 and C6). Usually result from an excessive increase in the angle between the neck and the shoulder. These injuries can occur in a person who is thrown from a motorcycle or a horse and lands on the shoulder in a way that widely separates the neck and shoulder. 02/13/2025 41  Injury to the superior trunk of the plexus is apparent by the characteristic position of the limb ("waiter's tip position"), in which the limb hangs by the side in medial rotation. Upper brachial plexus injuries can also occur in a newborn when excessive stretching of the neck occurs during delivery. Various terms are used to describe superior brachial plexus injuries; Erb palsy (paralysis), Erb- Duchenne palsy (paralysis), Duchenne-Erb palsy (paralysis), and upper radicular syndrome. 02/13/2025 42 02/13/2025 43  The inferior parts of the brachial plexus may also be injured during a breech birth when the infant’s limb are pulled over the head. These events injure the inferior trunk of the brachial plexus (C8-T1) and may pull the dorsal and ventral roots of the spinal nerves from the spinal cord. The short muscles of the hand are affected, and a claw hand results.w 02/13/2025 44 02/13/2025 45 02/13/2025 46  GOODMORNING 02/13/2025 47