Brachial Plexus Anatomy PDF

www.egasmoniz.com/pt Brachial Plexus - Animal Body Function IX Master Degree in Veterinary Medicine www.egasmoniz.com/pt INTEGRATED MASTER IN VETERINARY MEDICINE...

www.egasmoniz.com/pt Brachial Plexus - Animal Body Function IX Master Degree in Veterinary Medicine www.egasmoniz.com/pt INTEGRATED MASTER IN VETERINARY MEDICINE David Vicente  Cervical nerves www.egasmoniz.com/pt 8 pairs of cervical nerves Cervical nerves leave the vertebral canal via intervertebral foramina cranial to the vertebra - of the same number with the exception of the first and last Master Degree in Veterinary Medicine pairs of cervical nerves Cervical plexus - Many ventral branches of cervical nerves communicate with one another and run variable distances in common before joining still other branches.  Cervical nerves www.egasmoniz.com/pt Dorsal and the ventral branches communicate with each other to form the dorsal and ventral cervical plexus - Master Degree in Veterinary Medicine  1st Cervical nerve: www.egasmoniz.com/pt Located just caudal to the foramen magnum, and is surrounded by the cranial portion of the atlas Dorsal branch (suboccipital nerve) – No cutaneous branches; Innervates muscles of the cranial portion of the neck. Ventral branch joins the hypoglossal nerve in the cervical loop (ansa cervicalis) - Innervation of sternohyoid, sternothyroid and omohyoid muscles - Master Degree in Veterinary Medicine  2nd Cervical nerve: www.egasmoniz.com/pt Dorsal and ventral roots fuse peripheral to the 2nd intervertebral foramen and the spinal ganglion lies completely outside of the vertebral canal Dorsal branch of the 2nd cervical nerve or the greater occipital nerve: Supply sensation to the skin of the - occipital and nuchal regions. Master Degree in Veterinary Medicine Ventral branch of the 2nd cervical nerve: Transverse cervical nerve: Provides sensory innervation to the skin of the neck and shoulder region Great auricular nerve: runs along the ventral border of the ear and provides sensation to the skin of the ear flap and the surrounding area. The nerve is also responsible for controlling some of the muscles that move the ear  Dorsal Branches of Cervical Nerves (III-VII) www.egasmoniz.com/pt Each of these branches sends a small branch medially into the m. multifidus cervicis Peripheral portions divide into medial (cutaneous) and lateral (muscular) branches. - Gradually decrease in size caudally. C7 nerve's dorsal branch mainly innervates Master Degree in Veterinary Medicine deep muscle fibers. C8 nerve's dorsal branch may be absent. Middle cervical nerves' dorsal branches perforate the m. multifidus cervicis, running dorsally with a slight caudal inclination and bifurcate into medial and lateral branches.  Medial Branches of Cervical Nerves (III-VII) www.egasmoniz.com/pt Perforate the m. intertransversarius, run almost directly dorsal. Lie between multifidus cervicis and - spinalis cervicis muscles medially, and complexus and biventer muscles Master Degree in Veterinary Medicine laterally. Cutaneous areas are segmentally aligned along the cervical region dorsum.  Ventral Branches of Cervical Nerves (II-V) www.egasmoniz.com/pt Pass between muscle bundles of the intertransversarius cervicis to reach the omotransversarius. Intermingle with the accessory nerve, - especially between cervical nerves II, Master Degree in Veterinary Medicine III, and IV. Supply the skin of the ventrolateral neck and various muscles including the longus capitis and longus colli. Cutaneous branches cover large areas, extending to the brachium and overlapping with other nerve areas.  Specific Cervical Nerve Branch Functions www.egasmoniz.com/pt Lateral branch of the C3 supplies the middle portion of the complexus muscle. - Lateral branches of C4 and C5 Master Degree in Veterinary Medicine innervate the middle portion of the biventer muscle. Splenius muscle innervated by branches from C3 and C4  Cervical nerves www.egasmoniz.com/pt 4th (cat) and 5th (dog) to 7th Cervical nerve: Ventral roots form the phrenic nerve, which runs caudally within the mediastinum to innervate the diaphragm. - Supraclavicular branches: Master Degree in Veterinary Medicine Arise from ventral branches and innervate the skin over the shoulder joint.  Cervical nerves www.egasmoniz.com/pt 2 types of plexuses exist: Somatic plexus: Plexuses supplying the body wall and the appendages No cell bodies of neurons; thus no synapses are found in them. - Two major somatic plexuses: Master Degree in Veterinary Medicine Consist of intermingling axons coming from ventral branches of spinal nerves - Brachial plexus - Lumbosacral plexus Visceral plexus: Plexuses found around arteries supplying the viscera, and in the walls of visceral organs. May have associated ganglia with cell bodies of autonomic sympathetic neurons in them and thus have synapses occurring within them  Brachial plexus www.egasmoniz.com/pt (plexus brachialis) Ventral branches of the 6th - 8th cervical and 1st and 2nd thoracic spinal nerves Innervate: - Muscles and skin of the thoracic limb Master Degree in Veterinary Medicine Parts of the shoulder girdle musculature Lateral wall of the thorax and abdomen Exceptions: brachiocephalic, the omotransverse, the rhomboid, and the trapezius muscles and the skin over the upper shoulder region. Innervated by dorsal and ventral branches of the cervical and thoracic spinal nerves.  Brachial plexus www.egasmoniz.com/pt Location: cranial to the 1st rib between the long muscle of the neck and the scaleni muscles The roots of the plexus reach the medial aspect of the shoulder by - passing between the middle and Master Degree in Veterinary Medicine ventral portions of the scalenus. In carnivores the roots pass ventral to the middle scalene muscle. Branches usually mixed (include autonomous fibres from the stellate ganglion). www.egasmoniz.com/pt Brachial plexus Several branches of the plexus have very restricted local distributions on the wall of the thorax and are of no clinical importance. - Master Degree in Veterinary Medicine www.egasmoniz.com/pt Long thoracic nerve Arises from the ventral branch of the 7th cervical nerve It passes caudally on the lateral surface of the - thoracic part of the ventral serrate muscle, which it innervates. The cervical portion of this muscle is Master Degree in Veterinary Medicine supplied by cervical spinal nerves. It has no cutaneous branches.  Thoracodorsal nerve www.egasmoniz.com/pt It arises from the last (8th) cervical spinal nerve It is the motor nerve to the latissimus dorsi muscle. - Master Degree in Veterinary Medicine  Lateral thoracic nerve www.egasmoniz.com/pt It arises from caudal parts of the plexus (C8 and Th1) and passes along the latissimus dorsi to innervate the abdominal part of the cutaneous muscle. - Some branches conjoin the intercostal nerves to form the intercostobrachial Master Degree in Veterinary Medicine nerve Innervates the skin caudal to the triceps and over the ventral thorax and abdomen  Cranial pectoral nerve www.egasmoniz.com/pt Irregular in number and origin but usually arise as two branches from the 6-8th cervical nerves Innervate the superficial pectoral muscle and in ungulates the subclavian muscle. They do not give off any cutaneous branches - Master Degree in Veterinary Medicine  Caudal pectoral nerve www.egasmoniz.com/pt Origin: C8-T2 Represented by 3-4 branches that innervate the deep pectoral muscle. It has no cutaneous branches - Master Degree in Veterinary Medicine www.egasmoniz.com/pt Subscapular nerve It arise either as individual nerves or as a plexus from the cranial part of - the brachial plexus (6th-7th cervical nerves) Master Degree in Veterinary Medicine www.egasmoniz.com/pt Subscapular nerve On the medial surface of subscapular muscle, which allows extensive sliding movement of the scapula on the - thorax during locomotion Master Degree in Veterinary Medicine without nerve injury. No cutaneous branches www.egasmoniz.com/pt Composition of the most important nerves of the brachial plexus - Master Degree in Veterinary Medicine Master Degree in Veterinary Medicine - www.egasmoniz.com/pt www.egasmoniz.com/pt Suprascapular nerve Origin: C6-7 Runs between the subscapular and the suprascapular muscles to reach the cranial margin of the neck of the - scapula, around which it winds to the lateral aspect of the bone, Master Degree in Veterinary Medicine Innervates the supraspinatus and infraspinatus muscles. Paralysis of the suprascapular nerve usually results in atrophy of the muscles it innervates No cutaneous branches  Musculocutaneous nerve www.egasmoniz.com/pt Arises caudal to the suprascapular nerve from the brachial plexus. It runs parallel to the median nerve, with which it joins in ungulates to form a loop around the axillary artery (ansa axillaris). - Gives muscular branches to the Master Degree in Veterinary Medicine coracobrachialis, biceps brachii, and brachialis Lesion paralyse the main flexors of the elbow and loss of sensation of the skin on the medial aspect of the antebrachium. The paralysis can be compensated by the radial nerve, which also contributes to the innervation of the brachial muscle.  Musculocutaneous nerve www.egasmoniz.com/pt Continues in the forearm as the medial cutaneous antebrachial nerve: It runs along the medial aspect of the brachium and antebrachium before terminating in the skin and - subcutaneous tissues of the medial Master Degree in Veterinary Medicine aspect of the carpus Sensory innervation to the skin and subcutaneous tissues of the medial aspect of the forearm  Axillary nerve www.egasmoniz.com/pt Origin: (C6) C7-8; Leaves the axillary space caudodistal to the subscapular muscle and proximal to the teres major muscle Innervates the teres major muscle and - the caudal third of the subscapular muscle. It also innervates the capsular Master Degree in Veterinary Medicine and teres minor muscles. It branches to innervate the deltoid muscle and gives off a branch to the cleidobrachial muscle. Cutaneous branch: ventral border of the deltoid muscle and innervates the skin on the cranial aspect of the arm and antebrachium www.egasmoniz.com/pt Cranial lateral cutaneous brachial nerve Origin: It leaves the axillary nerve just prior to the entry of this nerve into the deltoid - muscle. Master Degree in Veterinary Medicine The cutaneous area of this nerve lies on the lateral surface of the brachium www.egasmoniz.com/pt Cranial lateral cutaneous brachial nerve On entering the forearm, it is named the cranial - cutaneous antebrachial nerve: It terminates in the skin of the Master Degree in Veterinary Medicine proximocraniolateral aspect of the forearm, where overlaps with the cutaneous areas of the radial and musculocutaneous nerves Master Degree in Veterinary Medicine - www.egasmoniz.com/pt www.egasmoniz.com/pt Radial Nerve Largest nerve of the brachial plexus Innervation: All the extensor muscles of the elbow, carpal, - and digital joints and also the supinator, Master Degree in Veterinary Medicine brachioradialis, and abductor pollicis longus muscles Skin on the cranial portion of the antebrachium and the dorsal surface of the paw  Radial Nerve www.egasmoniz.com/pt Origin: C6-T2 nerves Axillary space, it lies lateral to the axillary vein and medial to the axillary artery. Prior to bifurcation on the lateral head of the triceps, it gives off the caudal lateral brachial cutaneous nerve that supplies the skin covering the lateral head of the triceps - muscle Master Degree in Veterinary Medicine Bifurcation: Deep branch: It runs deep to the proximocranial border of the extensor carpi radialis Superficial branch: It runs cranially and becomes superficial between the distocranial border of the lateral head of the triceps and the lateral surface of the deeply lying brachialis muscle. www.egasmoniz.com/pt Radial nerve - Deep branch It supplies all of the extensor muscles of the carpus and the digits: On the lateral aspect of the elbow it passes - deep to the extensor carpi radialis and sends a branch into it and an articular branch to the Master Degree in Veterinary Medicine craniolateral part Injury to the proximal part of the nerve results in the inability to support weight on the thoracic limb.  Radial nerve - Deep branch www.egasmoniz.com/pt Passes deep to the supinator muscle, which it supplies Divides into branches that supply the common and lateral digital extensors, abductor policis longus and extensor digiti I longus et digiti II. - The distal end of the deep branch of the radial Master Degree in Veterinary Medicine nerve supplies the antebrachiocarpal joint.  Radial nerve - Superficial branch www.egasmoniz.com/pt Emerges in the distal border of the lateral head of the triceps muscle, it runs obliquely craniodistal on the brachialis muscle. Divides into a lateral and medial branches; continue to the carpus in relation to the lateral and medial - branches of the cranial superficial Master Degree in Veterinary Medicine antebrachial arteries It provides motor innervation to the extensor muscles of the carpus and digits, as well as sensory innervation to the skin on the dorsolateral aspect of the paw and the dorsal aspect of the carpus.  Cutaneous areas of the peripheral branches of the superficial branch of the radial nerve www.egasmoniz.com/pt - Master Degree in Veterinary Medicine www.egasmoniz.com/pt Median Nerve Origin: (C7) C8-T1 (T2) After its origin from the brachial plexus, it runs down the medial surface of the antebrachium. It combines with the musculocutaneous nerve to - form a loop around the axillary artery. Master Degree in Veterinary Medicine Does not give off any branches proximal to the elbow joint www.egasmoniz.com/pt Median nerve Dog: It crosses the flexor surface of the elbow joint cranial to the medial epicondyle - Cat: It passes through the Master Degree in Veterinary Medicine supracondylar foramen. Passes deep to the pronator teres and enters the large caudal group of flexor muscles located in the antebrachium It innervates the radial flexor muscle and the deep and superficial digital flexor muscles. Its distribution overlaps with that of the ulnar nerve. In the distal part of the antebrachium it divides into two or more branches, which descend through the carpal canal to innervate most of the structures on the palmar aspect of the distal limb www.egasmoniz.com/pt Ulnar Nerve Origin: (C7) C8-T1 (T2) It arises in close association with the radial and median nerves The median and ulnar nerves descend flanked by - the brachial artery cranially and the brachial vein Master Degree in Veterinary Medicine caudally; Deep to antebrachial fascia. www.egasmoniz.com/pt Ulnar Nerve Does not give off any branches proximal to the elbow joint Cross caudal to the medial epicondyle of - the humerus just proximal to the origin of the humeral head of the superficial digital Master Degree in Veterinary Medicine flexor In the proximal part of the antebrachium, it branches to innervate the ulnar flexor muscle and the deep and superficial digital flexor muscles. It runs deep to the ulnar head of the flexor carpi ulnaris www.egasmoniz.com/pt Ulnar Nerve Dorsal branch arises proximal to the accessory carpal bone and passes dorsally to innervate the skin on the lateral surface of the distal limb. Caudal cutaneous antebrachial branch: - Innervation proximal two thirds of the skin of the caudolateral aspect of the antebrachium Master Degree in Veterinary Medicine The narrow continuation of the ulnar nerve passes through the carpal canal and innervates muscles, skin and deeper structures of the digit. The distribution within the foot is closely related to that of the median nerve Master Degree in Veterinary Medicine - www.egasmoniz.com/pt  Innervation areas of the brachial plexus nerves, supplying the tip of the forelimb. www.egasmoniz.com/pt - Master Degree in Veterinary Medicine  Innervation of the distal limb www.egasmoniz.com/pt Each digit supplied by four nerves: two dorsal and two palmar digital (excluding horse) Radial nerve (superficial branch): Axial and abaxial dorsal digital nerves - Ulnar nerve: dorsal digital nerves of the most Master Degree in Veterinary Medicine lateral digit Palmar digital nerves: Median nerve: 1st to 3rd digits Ulnar nerve: 4th to 5th digits Master Degree in Veterinary Medicine - www.egasmoniz.com/pt  Innervation of the distal limb of the horse www.egasmoniz.com/pt Distal to carpus innervated by the medial and lateral palmar nerves, both of which are branches of the median nerve, and the dorsal and palmar branches of the ulnar - nerve. Master Degree in Veterinary Medicine Median nerve divides into medial and lateral nerves proximal to the carpus. Lateral palmar nerve detaches a deep branch to the suspensory ligament at the level of the carpus.  Innervation of the distal limb of the horse www.egasmoniz.com/pt Palmar branches: Palmar to the metacarpal bone and between the suspensory ligament and the digital flexor tendons. Divides in medial and lateral digital - nerves just proximal to the metacarpophalangeal joint Master Degree in Veterinary Medicine Detach dorsal branches at the level of the proximal and middle phalanges. Variations in their distribution pattern are common.  Ventral branches of the thoracic nerves www.egasmoniz.com/pt 1st two ventral branches of the thoracic spinal nerves contribute to the brachial plexus Generally, the thoracic ventral branches form the intercostal nerves, - which pass ventrally on the caudal aspect of the corresponding rib. The Master Degree in Veterinary Medicine intercostal nerves innervate the intercostal muscles, the transversus thoracis muscle and the rectus thoracis muscle.  Ventral branches of the thoracic nerves www.egasmoniz.com/pt Costoabdominal nerve: ventral branch of the last thoracic nerve. It supplies a band of the abdominal wall that lies adjacent to the caudal border of the last rib - Master Degree in Veterinary Medicine Last 5-10 ventral thoracic branches innervate the abdominal muscles Ventral branches also detach branches to the mammary glands. Questions?