Autonomic Nervous System(1).ppt

Section 3 The Autonomic Nervous System The autonomic (or visceral or vegetative) nervous system innervates the viscera , cardiovascular system and glands. And contains two groups of fibers: afferent fibers and efferent fibers. The efferent fibers are divided into the sympathetic and parasympathetic divisions.

Parasympathetic division

Sympathetic division

Parasympathetic division

I. The sympathetic division (system) ( or thoracolumbar division) lateral horn of T1 (or C8) -L2 (or L3) segments of the spinal cord(preganglionic neurons) →preganglionic fibers → sympathetic ganglia (postganglionic neurons) →postganglionic fibers → vicera

1. Sympathetic ganglia include the paravertebral ganglia and the prevertebral ganglia. (1) The paravertebral ganglia • cervical ganglia: 3. cervicothoracic (stellate) ganglion • thoracic ganglia: 11-12 • lumbar ganglia: 3-4 • sacral ganglia: 2-3 form the sympathetic trunk, jointed at impar ganglion

Sup. cervical Superior cervicalganglion ganglion

Mid. cervical ganglion

Inf. cervical ganglion

Thoracic ganglion

Lumbar ganglion

Sacral ganglion

Ganglion impar

(2) The prevertebral ganglia • • • •

celiac ganglion aorticorenal ganglion superior mesenteric inferior mesenteric

2. The communicating branches connect the sympathetic ganglion with the corresponding spinal nerve and include the white and grey communicating branches .

3. The general distributions of the sympathetic nerves (1)lateral horn of T1 –T5→preganglionic fibers →the corresponding sympathetic ganglia (C13 and T1-5 paravertebral ganglia) → postganglionic fibers→vicera of the head ,neck and thorax; blood vessels, sweat gland and arrectores pilorum of the upper limb.

T1-T5

L1-L2(or L3)

(2) lateral horn of T5 –T12→ preganglionic fibers →the corresponding sympathetic ganglia (T512 paravertebral ganglia and the celiac, the aorticorenal ganglia ) → postganglionic fibers→vicera of the abdomen and the alimentary tract anterior to the left colic flexure. • Greater splanchnic nerve: from T5-T9 • Lesser splanchnic nerve: from T9-T10

T5-T12

Greater splanchnic n

T5

lesser splanchnic n

T6

T7

Celiac ganglion

(3)lateral horn of L1 –L2(orL3) →preganglionic fibers → the corresponding sympathetic ganglia (L1-L4, S1-S5 paravertebral ganglia and the superior and inferior mesenteric ganglia ) → postganglionic fibers→vicera of the pelvis; blood vessels, sweat gland and arrectores pilorum of the lower limb.

L1-L2(or L3)

II. The parasympethetic division(system) consists of the cranial portion and sacral portion.

1. The cranial portion of the parasympathetic system (l) The parasympathetic preganglionic fibers in the oculomotor nerve : Edinger-Westphal nucleus→ preganglionic fibers(oculomotor N.) →the ciliary ganglion→the postganglionic fibers→ the ciliary muscle and sphincter pupillae. Ciliary ganglion

Oculomotor N.

(2) The parasympathetic preganglionic fibers in the facial nerve ①superior salivatory nucleus→ preganglionic fibers (greater petrosal N.) →pterygopalatine ganglion→the postganglionic fibers→lacrimal gland, mucosa of the nasal cavity and palate ②superior salivatory nucleus→ preganglionic fibers(chorda tympani) → submandibular ganglion →postganglionic fibers→ submandibular and sublingual glands.

(3) The parasympathetic preganglionic fibers in the glossopharyngeal nerve inferior salivatory nucleus→ preganglionic fibers(lesser petrosal nerves) → the otic ganglion→the postganglionic fibers→ the parotid gland.

(4) The parasympathetic preganglionic fibers in the vagus nerve dorsal nucleus of vagus→ preganglionic fibers(vagus) →ganglia which are situated in or near the organs innervated→the postganglionic fibers→ viscera of the neck, thorax and abdomen, the alimentary tract anterior to the left colic flexure.

vagus

2. The sacral portion of the parasympathetic nerve S2-S4 segments of the spinal cord→ preganglionic fibers (pelvic splanchnic nerve) →ganglia which are situated in or near the organs innervated →the postganglionic fibers→ the pelvic organs , the descending and sigmoid colon and rectum

Sacral portion

III. The main differences between the sympathetic and parasympathetic systems 1. The different central center 2. The different locations of the peripheral ganglia 3. The different ratio of the preganglionic fibers to the postganglionic 4. The different distributions 5. The different actions to a visceral organ

IV. The autonomic plexuses the sympathetic nerves, parasympathetic nerves and the afferent fibers of the autonomic system are interweaved into extensive plexuses. Such as : the cardiac plexus, the pulmonary plexus, the celiac plexus, the abdominal aortic plexus, vesical et al.

Abdominal aortic plexus

Inf. mesenteric plexus

Sup. mesenteric plexus

Rectal plexus Vesical plexus

V. The visceral afferent (sensory) nerves 1. Features of the visceral sensation ①insensitive to cutting, crushing or burning ②sensitive to the excessive tension and contraction of smooth muscle ③sensitive to certain pathological conditions ④location of the visceral pain is poorly

VI. The referred pain In pathological condition, visceral pain radiates to cutaneous areas and is therefore assumed by the patient to arise mainly or exclusively in surface areas of the body. The kind of pain is called referred pain.

Skin

T1-T5

T1-T5

Referred pain