Nerves I PDF

Spinal nerves. Cervical plexus and brachial plexus – formation, topography, branches, supplying regions. 11th practical class Normunds Bauers Spinal nerves  Nn. spinales Are 31 symmetric and metameric paired nerves. Each spinal nerve is formed by radix anterior and radix...

Spinal nerves. Cervical plexus and brachial plexus – formation, topography, branches, supplying regions. 11th practical class Normunds Bauers Spinal nerves  Nn. spinales Are 31 symmetric and metameric paired nerves. Each spinal nerve is formed by radix anterior and radix posterior and contains both – a erent and e erent bres. ff ff fi  Afferent (sensory) fibres Convey impulses to the central nervous system – they are peripheral processes of pseudounipolar neurons of the spinal ganglions. There are somatic and visceral a erent bres. ff fi Somatic afferent fibres Somatic a erent bres start from exteroreceptors and proprioreceptors. ff fi Visceral afferent fibres Visceral a erent bres also are peripheral processes of pseudounipolar neurons of the spinal ganglions, but they reach the spinal nerve through rr. communicantes albi from interoreceptors of the organs. ff fi Efferent fibres Convey impulses from the central nervous system to periphery and are of two groups.  Efferent fibres Somatic e erent bres (motor bres) are axons of nuclei motorii (the anterior column of the grey matter), which run to supply the skeletal muscles. fi ff fi  Visceral efferent fibres (vegetative fibres) From nucleus intermediolateralis start sympathetic (preganglionic) bres; they run in content of the all thoracic and upper two lumbar spinal nerves and then via rr. communicantes albi join ganglions of the sympathetic trunk, fi Visceral efferent fibres (vegetative fibres) From nucleus parasympathicus sacralis start parasympathetic (preganglionic) bres; they run in content of the 2nd, 3rd and 4th sacral spinal nerves, then through the ventral branches of the corresponding sacral nerves to the pelvic parasympathetic ganglions. fi Spinal nerve branches Ramus meningeus Ramus communicans albus Ramus posterior Ramus anterior Ramus meningeus Contains sensory bres, returns into the vertebral canal to supply the meninges fi Ramus communicans albus Communicates the spinal nerve with the sympathetic trunk Ramus posterior (dorsalis) Usually is smaller than the ventral branch; dorsal branches supply skin and muscles of the back and posterior region of the neck. Ramus posterior of C1 N. suboccipitalis – it leaves the vertebral canal between the occipital bone and the atlas; usually it has no sensory bres and supplies deep muscles of the back in the neck region – mm. suboccipitales (m. rectus capitis posterior major et minor, mm. ogliquus capitis superior et inferior) fi Ramus posterior of C2 N. occipitalis major – it leaves the vertebral canal between the 1st and 2nd cervical vertebra, supplies skin of the occipital region and deep muscles of the back in the neck region (m. semispinalis capitis, m splenius capitis, m. longissimus capitis) Rami posteriores of L1 L2 L3 Branches of these nerves form nn. clunium superiores to supply skin of regio glutea upper part Rami posteriores of the sacral spinal nerves These branches form nn. clunium medii to supply skin of regio glutea middle part Ramus anterior (ventralis) Supplies skin and muscles of the lateral and anterior parts of the trunk and the limbs. Metamerity is still present only concerning the thoracic spinal nerves (nn. intercostales). Other plexuses Plexus cervicalis is formed by the anterior branches of four upper cervical spinal nerves Plexus brachialis is formed by the anterior branches of four lower cervical spinal nerves and partly by the 4th cervical and 1st thoracic spinal nerves Other plexuses Plexus lumbalis is formed by the anterior branches of three upper lumbar spinal nerves Plexus sacralis is formed by the anterior branches of the 4th and 5th lumbar, all sacral and coccygeal spinal nerves. Plexus cervicalis Plexus cervicalis Plexus cervicalis is formed by rami anteriores of the upper four cervical spinal nerves. It lies on the deep muscles of the neck (in trigonum colli laterale). It is covered by m.sternocleidomastoideus. There are three groups of branches arising from the plexus: motor, sensory and mixed. Motor branches Rr. musculares Supply muscles of the lateral, deep and craniothoracal groups of the neck Ansa cervicalis It is formed by two roots – radix superior et inferior. Radix superior origins from rami anteriores of the 1st and 2nd cervical spinal nerves, passes with n. hypoglossus, then leaves it and joins with radix inferior. Radix inferior arises from rami anteriores of the 2nd and 3rd cervical spinal nerves. Ansa cervicalis lies on the bundle of nerves and blood vessels; it supplies straight muscles of the neck (except m. geniohyoideus). Sensory branches N. occipitalis minor It appears at the middle part of m. sternocleidomastoideus, ascends along its posterior margin and supplies skin of the occipital region and skin of the posterior part of auricula N. auricularis magnus It ascends along the surface of m. sternocleidomastoideus and supplies skin at the region of angulus mandibulae and auricula N. transversus colli Passes horizontally, crosses m. sternocleidomastoideus and supplies skin in trigonum colli mediale Nn. supraclaviculares Supply skin of trigonum colli laterale and the shoulder girdle to the level of the 2nd rib. Mixed branch N. phrenicus Descends along m. scalenus anterior, passes between a. et v. subclavia and through superior thoracic aperture enters the thoracic cavity. It lies in mediastinum superius and in mediastinum medium; then it descends between pleura mediastinalis and pericardium and runs in front of radix pulmonis. N. phrenicus The nerve reaches the diaphragm; the sensory bres supply pericardium, pars mediastinalis et diaphragmatica pleurae parietalis, peritoneum parietale in region around pancreas and liver, and thymus, while the motor bres supply the diaphragm. fi fi Plexus brachialis Plexus brachialis It is formed by rami anteriores of the lower four cervical spinal nerves and by some bres of the 4th cervical and 1st thoracic spinal nerves. It lies in space between m. scalenus anterior and m. scalenus medius with a. subclavia, crosses trigonum colli laterale, then enters the axillary fossa. fi Divisions of plexus brachialis The plexus is divided by the clavicle into two parts Pars supraclavicularis Pars infraclavicularis Pars supraclavicularis  Pars supraclavicularis It gives o : N. subclavius (supplies m. subclavius) Nn. pectorales (medialis et lateralis) (supply m. pectoralis major et minor) N.thoracicus longus descends over the super cial surface of m. serratus anterior and supplies it N. subscapularis (supplies m. subscapularis, m. teres major and art. humeri) fi ff Pars supraclavicularis It gives o : N. suprascapularis passes posteriorly below m. trapezius to reach fossa supraspinata (through incisura scapulae below ligamentum superius scapulae) and supplies m. supraspinatus et m. infraspinatus N. thoracodorsalis runs downward over the posterior wall of the axilla to reach m. latissimus dorsi and supplies it N. dorsalis scapulae pierces m. scalenus medius, runs posteriorly and supplies m. levator scapulae, mm. rhomboidei. ff Pars infraclavicularis Pars infraclavicularis It lies in fossa axillaris and supplies muscles and skin of the upper limb. It surrounds a. axillaris and can be divided into three cords: Fasciculus medialis Fasciculus lateralis Fasciculus posterior Fasciculus medialis Fasciculus medialis It consists of 4 nerves: N. cutaneus brachii medialis N. cutaneus antebrachii medialis N. ulnaris Radix medialis n. mediani N. cutaneus brachii medialis Runs along sulcus bicipitalis medialis and supplies skin at the anterior and medial region of the brachium. N. cutaneus antebrachii medialis Descends along sulcus bicipitalis medialis, continues to the antebrachium and supplies skin at the anterior and medial parts of it. N.ulnaris It passes along sulcus bicipitalis medialis together with N. medianus N. cutaneus brachii medialis N. cutaneus antebrachii medialis N. brachialis Vv. brachiales V. basilica N.ulnaris In the cubital region it is covered only by fascia and skin; it lies in sulcus n. ulnaris on epicondylus medialis humeri. Then the nerve pierces m. exor carpi ulnaris, runs between m. exor carpi ulnaris and m. exor digitorum super cialis, goes through canalis ulnaris to the palm and divides into two branches. fi fl fl fl Branches of n.ulnaris Ramus super cialis divides into the 3 nn. digitales palmares proprii, which supply skin over the hypothenar eminence, the ulnar side of the ring nger and the little nger fi fi fi Branches of n.ulnaris Ramus profundus supplies muscles of the little nger, mm. interossei palmares et dorsales, the 3rd and 4th mm. lumbricales, m. adductor pollicis, m. exor pollicis brevis (caput profundus). fi fl Side branche of n.ulnaris Rr. articulares supply art. cubiti Rr. musculares supply m. exor carpi ulnaris and the ulnar side of m. exor digitorum profundus fl fl Side branches of n.ulnaris R. dorsalis curves around the ulnar side of the hand to the dorsal surface, supplies skin of this region and divides into 5 nn. digitales dorsales to supply skin on the dorsal surface over the little nger, the ulnar side of the ring nger, the radial side of the proximal phalanx of the ring ger, the ulnar side of the proximal phalanx of the middle nger. fi fi fi fi Radix medialis n.mediani Joins with radix lateralis n. mediani from fasciculus lateralis to form n. medianus. Fasciculus lateralis Fasciculus lateralis It consists of two nerves: Radix lateralis n. mediani N. musculocutaneus Radix lateralis n. mediani Joins with radix medialis n. mediani from fasciculus medialis to form n. medianus. N. medianus It is formed in front of a. axillaris by junction of two roots from two cords of plexus brachialis. It descends along sulcus bicipitalis medialis together with: N. ulnaris N. cutaneus brachii medialis N. cutaneus antebrachii medialis A. brachialis Vv. brachiales V. basilica N. medianus Crosses fossa cubitalis, pierces m. pronator teres, runs between m. exor digitorum super cialis et profundus, then through the carpal tunnel and reaches the palm. fi fl  Carpal tunnel In carpal tunnel the nerve lies super cially to the tendons of m. exor digitorum super cialis. In this place pressure or irritation of n. medianus leads to „carpal tunnel syndrome” in which could occur weakness or paralysis of the thenar muscles and sensory changes in the region supplied by the nerve. fi fl fi N. medianus N. medianus on the palm lies below aponeurosis palmaris and rests on the tendons of the muscles. It gives 3 nn. digitales palmares communes which divides into 7 nn. digitales palmares proprii (the 1st n. digitalis communis divides into 3 nerves, the 2nd and the 3rd – into 2 nerves).  Nn. digitales palmares proprii Supply skin over the thumb, index nger, middle nger and the radial side of the ring nger. The terminal branches of these nerves wind to the dorsal side and supply skin over the distal and medial phalanges of the same ngers. fi fi fi fi The 1st n. digitalis palmaris communis Supplies the 1st and the 2nd mm. lumbricales, m. abductor pollicis brevis, m. opponens pollicis, m. exor pollicis brevis (caput super ciale). Nn. digitales palmares communes supply the wrist joint and to the joints of the hand. fi fl  N. medianus side branches Rr. articulares supply art. cubiti, art. radiocarpalis Rr. musculares supply the 1st and 2nd layers of the anterior group of musculi antebrachii except muscles supplied by n. ulnaris (m. pronator teres, m. exor carpi radialis, m. palmaris longus, m. exor digitorum super cialis) fl fi fl  N.medianus side branches N. interosseus antebrachii anterior starts at the upper part of the antebrachium, descends along the ventral surface of membrana interossea antebrachii and supplies the 3rd and 4th layers of the anterior group of musculi antebrachii (m. exor pollicis longus, the radial side of m. exor digitorum profundus, m. pronator quadratus). It also supplies art. radiocarpalis fl fl N.medianus side branches Ramus palmaris arises above canalis carpi; it supplies skin over eminentia thenaris and over the middle part of the palm. N. musculocutaneus Pierces m. coracobrachialis, passes between m. biceps brachii and m. brachialis and supplies the anterior compartment of the arm. Then the nerve lies in sulcus bicipitalis lateralis, a little above the elbow it pierces fascia and continues to the forearm as n. cutaneus antebrachii lateralis to supply skin at the lateral part of the antebrachium. Fasciculus posterior Fasciculus posterior Consists of two nerves: N.radialis N.axillaris N. radialis It lies behind a. axillaris, descends and lies on sulcus n. radialis together with a. profunda brachii, vv. profundae brachii. Then it continues between m. brachioradialis and m. brachialis and in fossa cubitalis divides into two terminal branches. N.radialis terminal branches Ramus super cialis - lies between m. brachioradiallis and m. exor carpi radialis, then under the tendon of m. brachioradialis winds to the dorsal side of the hand to supply skin and divides into 5 nn. digitales dorsales to supply skin of the proximal phalanx of the thumb and the index nger, the radial side of the proximal phalanx of the middle nger. fi fi fl fi N.radialis terminal branches Ramus profundus - pierces m. supinator, curves around collum radii and reaches the dorsal side of the forearm. It descends between the super cial and deep layers of musculi antebrachii to the wrist joint and supplies all muscles of the posterior compartment of the forearm (also the radial part). fi N.radialis terminal branches The terminal part of ramus profundus is n. interosseus antebrachii posterior. It descends along the posterior side of membrana interossea antebrachii and supplies the deep layer of the posterior compartment of musculi antebrachii; with rr. articulares it also supplies the joints of the hand. N.radialis side branches Rr. musculares on the brachium supply the posterior compartment of the arm N. cutaneus brachii posterior supplies skin on the posterior side of the brachium N. cutaneus antebrachii posterior supplies skin on the posterior side of the antebrachium. N. axillaris It passes backward through the posterior wall of the fossa axillaris together with A. circum exa humeri posterior V. circum exa humeri posterior It curves around the posterior side of collum chirurgicum humeri (can be injured if there are dislocations of the shoulder joint or fractures of the surgical neck). fl fl N. axillaris It supplies m. deltoideus, m. teres minor, art. humeri. N. axillaris gives o n. cutaneus brachii lateralis, which supplies skin at the lateral part of the brachium. ff