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Overview of PNS Spinal Nerves Guo Ling, MD, PhD Department of Anatomy.

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Presentation on theme: "Overview of PNS Spinal Nerves Guo Ling, MD, PhD Department of Anatomy."— Presentation transcript:

1 Overview of PNS Spinal Nerves Guo Ling, MD, PhD Department of Anatomy

2 Peripheral Nervous System(PNS) spinal cord brain cranial nerves spinal nerves visceral nerves CNS PNS NS Overview of Nervous System Central nervous System(CNS) Spinal nerves

3 Nerve : It is a long & solid macrostructure into which numerous nerve fibers only in PNS are bundled. Nerve fibers:They are long microstructures formed by neuronal processes which are enveloped by both thick/ thin myelin sheath and neurilemma; or are only covered by neurilemma. The fibers distribute in CNS or PNS.

4 Classification of PNS 1. Based on distributions of component: somatic nerve & viseral nerve 2.Based on functions of component: afferent(sensory) & efferent (motor) nerves 3. Based on combination of the above two items: (1) somatic nerve : sensory and motor nerves (2) viseral nerve: 1) sensory nerve 2) motor nerve (vegetative nerve / autonomic nerve) a. sympathetic nerve b. parasympathetic nerve 4. Based on relay stops of nervous informatiom (1) cranial ganglia as well as spinal ganlia (g) (2) sensary ganglia(8):spinal g, genulate g of CN7, cochlear g & vestibular g of CN8,super g & infer g of CN9, super g & infer g of CN10) (3) ganglia of vegetative nerve:1)ganglia of sympathetic nerve: paravetebral g (19~24) & prevertebral g (4):celiac g,aorticorenal g, super mesenteric g & infer mesenteric g) 2)ganglia of parasympathetic nerve:a.paraorganic ganglia in head (4): ciliary g of CN3, otic g of CN9, pterygopalatine g & submandibular g of CN7 b.paraorganic ganglia in body except those in head & intraorganic ganglia in body including those in head

5 Spinal Nerve (SN) Focus on the following items: 1.Buildup o f Spinal Nerve 2. Functional Features of Each Primary branch of SN 3.Composition and Position of Each Plexus of SN 4.Typical Nerves in Each Plexus (1)Innervation of skin areas (2)Innervation of muscular groups (3)Vulnerable places of nerve injury (4)Subsequent symptoms resulting from the Injury

6 Spinal Nerves 1.Formation: Each nerve consists of the ant.root and pos.root,which are conjoined together at an intervertebral foramen. 2.Division: 31 pairs in total,8C(C 1- 8),12T(T1-12), 5L( L1-5), 5S( S1-5) & Co1. 61 separate nerves.

7 3. Branches of Each Spinal Nerves : 4 pairs (1) meningeal branches (containiung sensory &sympathetic fibers-mixed nerves) (2) communicating branches(white & gray )→ sympathetic trunks (containing visceral motor fibers) (3)dorsal branches (mixed nerves) (4) anterior branches(mixed nerves,C,L,S&Co first form plexes,and then send concrete nerves;while only T immediatedly gives off its own nerves.)

8 Focusing on the following items of anterior branch forming plexuses: 1.Compsition of each plexus 2.Position of each plexus 3.Representive nerves of each plexus (1) Invervation of specific skin areas (2) Invervation of concrete skeletal muscles (3) Places vulnerable to injury (4) Relative symptoms & signs

9 (1) Formation It is made up of the anterior branches from C1-4. (2) Location It lies in the upper part of the neck. 4.Cervical Plexus

10 (3) Main Branches 1) Superficial branches(sensory) a. Greater auricular N b. Lesser occipital N c. Transverse N of neck d. Supraclavicular N The four are all sensory Ns and emerge from the middle point of the post border of the sternocleidomastoid,which is a fixed mark for anaesthenia pucture. 2) Deep branches(mixed N) e. phrenic nerve

11 Phrenic nerve

12 1) Greater auricular N 2) Lesser occipital N 3) Transverse N of neck 4) Supraclavicular N → 5) Phrenic nerve → (4) Distributions of Cervical Spinal Nerves The skin of neck The skin of sup. part of thoracic wall Diaphragm Diaphragmatic and mediastinal pleurae Pericardium,liver, gallbladder, biliary system

13 5.Brachial Plexus (1) Formation: the ant. branches of C 5 ~ 8 and most part of the ant. branch of T 1 (2)Branch Transition: ant branches→sup,mid,inf trnuks →3 cords Lateral cord : a.musculocutaneous N →lat Antebrachial cutaneous N b.median N lat root Medial cord : c. median N. med.root d.ulnar N. Posterior cord : e.radial nerve f.axillary N. g.long thoracic N.→serratus ant. h.thoracodorsal N.→latissimus dorsi

14 long thoracic N. thoracodorsal N. (3). Location: lying in scalene fissure , supraclavicular fossa & axillary fossa

15 Axillary N innervates deltoid& the skin of shoulder

16 Lateral antebrachial cutaneous N Skin of lat.side of forearm

17 Radial N→ Triceps brachil Brachioradialis Extensor of the forearm,the skin on radial side of dorsum of the hand,proximal digits of the lateral two & half fingers Radial N & its distribution

18 Ulnar N→ Flexor carpi ulnar Medial half of the flexor digitorum profoundus Ulnar half of the dorsum of the hand Post. Surface of the ulnar one and half fingers The muscles of hypothenar Interosseous muscles 3th, 4 th lumbricales Adductor pollicis

19 Distributions of Median N Pronator Most of the flexor muscles except the brachoradialis the flexor carpi ulnaris Medial half of the flexor digitorum profoundus Thenar muscle except for adductor pollicis 1 st,2 nd lumbricales,the skin of thenar & central part of the palm, the skin of palmar aspect of the thumb, 2 nd,3 rd lateral half of 4 th fingers & the dorsum of the middle & terminal phalanges

20 Humerus Fracture and Relaitve Injuries a. Fracture of surgical neck →axillary N →“winging of the scapula” b.Fracture of middle part of humerus →radial N →“wristdrop” c.Fracture of med epicondyle of humerus→ulnar N →“claw-like hand ” d.Fracture of lower end of humerus→median N →“ape-like hand ”

21 Innervation of Skin of Hand by Median,Ulnar &Radial Ns

22 Flexing elbow joint : biceps brachii brachialis musculocutaneous N. brachioradialis Extending elbow joint : triceps brachii radial N. Innervation of Flexor and Extensor Muscles Acting on the Elbow Joint

23 Nerve Supply of Forearm Muscles a. brachioradialis ----radial N. b. ulnar half of flexor digitorum superficialis, flexor carpi ulnaris ulnar N. c. the remaining muscles of anterior muscular group of forearm----median N. d. all muscles of posterior muscular group of forearm ---radial N.

24 Composition: 12 pairs 11 pairs of intercostal Ns. 1 pair of subcostal N Location:lying along the relative costal groove & going between the int ﹠ ext intercostal Ms Segmental arrangements : T2—-the sternal angle T4----the nipple T6----the xiphoid process T8----the costal arch T10----the umbilicus T12----the ant.superior iliac spine Anterior Branches of Thoracic Nerves (Intercostal Nerves )


26 ② Obturator N ③ iliohypogastric N ④ ilioinguinal N ⑤ Lat. femoral cutaneous N ⑥ Genitofemoral N Lumbar Plexus Composition : ant.branches of L 1 — 3 & parts of the subcostal N and L 4 Location : going within the psoas major Main branches: ① Femoral N → → Saphenous N ① ⑥ ② ③ ④ ⑤

27 Obturator N. Femoral N. Saphenous N.

28 Distributions of the Branches of Lumbar Plexus Femoral N---→muscles of anterior muscular group in the thigh (quadriceps femoris, sartorius, pectineus) Saphenous N →the skin of the medial side of the leg and foot Obturator N→muscles of medial muscular group in the thigh iliohypogastric N →the muscles of the lower part of the abdominal wall, the skin of hypogastric region & inguinal region ilioinguinal N → muscles of lower partof abdominal wall Lat. femoral cutaneous N →skin on ant.& of the thigh Genitofemoral N →cremaster, scrotum(greater lip of pudendum)

29 Composition : the ant. branches of L5~8 , the ant.branches of all the sacral Ns and coccygeal N. Location : in the pelvis , going on ant.surface of the piriformis, looking like a triangle shape. Sacral Plexus

30 1. sup.gluteal N. 2. inf.gluteal N. 3. post.femoral cutaneous N. 4. pudendal N. Main Branches 5. sciatic N.

31 sup.gluteal N. pudendal N. pos.femoral cutaneous N. inf.gluteal N. sciatic N.

32 Pudendal N. →infrapiriformis foramina →the lesser sciatic foramen→the ischiorectal fossa,innervating the muscles and the skin of the perineum

33 Sciatic N Tibial N CommonPeroneal N Medial plantar N lateral plantar N Sural N Superf.peroneal N deep peroneal N

34 Sciatic nerve →muscles of post muscular group & skin in thigh Tibial N →muscles of post muscular group & skin of leg Med.& lat. Plantar N→plantar muscles & skin over the sole of the foot Sup.peroneal N→muscles of lat muscular group & skin of leg Deep peroneal N→muscles of ant muscular group & skin of leg Sup.gluteal N→gluteal medius & minimus,tensor faciae latae Inf.gluteal N→gluteal maxium & lower part of gluteal region Post.femoral cutaneous N→skin of the post part of the thigh Perineal N→the muscles of perineum & the skin of sacrum Distributions of the Branches of Sacral Plexus : Sural N→the skin of post.& lat. surfaces on the leg

35 Innervation of Muscles in Lower Limbs muscles of ant. group in thigh ---femoral N muscles of med. group in thigh ---obturator N muscles of post. group in thigh sciatic N muscles of post. group in leg plantar muscles in foot tibial N muscles of lat. group in leg----- superficial peroneal N muscles of ant. group in leg deep peroneal N

36 Innervation of Muscles Acting on Knee Joint flexing knee joint ( leg ) Extending knee joint ( leg ) muscles nerves gastrocnemius tibial N. Quadriceps femoris femoral N. Ms of post. group in thigh sciatic N. Movements

37 Innervation of Skin of Foot saphenous N. → skin on medial side of foot deep peroneal N. →dorsal skin between 1 st &2 nd toes sup. peroneal N. →most part of dorsum skin of foot tibial N. →sole skin of foot sural N. →dorsal skin on post.& lat.borders of foot

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