[ANATOMY #12] April 28, 2013

Sympathetic chain :

 Sympathetic chain is each of the pair of ganglionated longitudinal cords of the sympathetic nervous system; extend from level of atlas (base of skull) till .  It is paravertebral (next to the vertebral column ) in location.  Situated on either side of the vertebral column or in front of the of the ribs.( Between the neck of the rib and lateral side of the vertebra).  The sympathetic chain is divided into the following parts, depending on the region of the body where the chain is present: 1) Cervical part ( in the neck region) : Three ganglia (3) : superior / middle / inferior . 2) Thoracic part ( in the chest) : 12 ganglia . 3) Abdominal part : 4-5 sympathetic ganglia. 4) Sacral region: 4-5 sympathetic ganglia. 5) Coccyx: 1 sympathetic ganglion ( it is called “ganglion impar” ).

 The summation: 26 sympathetic ganglia.  The origin of sympathetic : thoracolumber origin. ( thoraco : all the thoracic vertebrae / lumber : L1 & L2 ).  The origin of parasympathetic nerves: craniosacral. ( cranio : through cranial nerves “brain stem” / sacral : S2,S3,S4 ). preganglionic fibers :

 Originated from sympathetic nucleus present in the lateral horn of gray matter of spinal cord. (Note ) -gray matter : H- shaped area of the spinal cord where many types of neurons synapse. - composed of 3 horns : anterior horn/posterior horn/lateral horn.  They leave the spinal cord to go through the ventral roots >> spinal >> sympathetic ganglion. . white ramus : contains a preganglionic fibers through the spinal nerve. (The afferent fibers to the ganglia). . How many spinal nerves that contain white rami ? ( 14 on each side ) . Why 14 ?? ( because the nuclei in the lateral horns are 14 in number. And each nucleus gives a preganglionic fiber (white ramus) . . From wiki : “Each of the thoracic, and the first and second lumbar nerves contribute a white ramus [ANATOMY #12] April 28, 2013

communicans to the adjoining sympathetic ganglion.” . 12 thoracic nerves + L1+L2=14 . These preganglionic fibers may: 1- Synapse in the Corresponding ganglion. 2- Ascend upward to synapse in higher ganglion. 3- Descend downward to synapse in lower ganglion. 4- Not synapse in the sympathetic chain.

*Note the ascending preganglionic fiber in this picture.

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. These preganglionic fibers that don’t synapse in the sympathetic chain go to prevertebral ganglia to synapse there. - These are called ( ) - They synapse in the prevertebral ganglia : 1- Celiac ganglion. 2- Superior mesenteric ganglion. [ANATOMY #12] April 28, 2013

3- Inferior mesenteric ganglion.

Postganglionic fibers :

 They arise from the sympathetic ganglia and go backwards through the spinal nerve to the spinal cord.  Gray ramus : contains postganglionic fibers through the spinal nerve. ( the efferent fibers of the sympathetic ganglia). . How many gray rami ? 31 . Why 31? ( because each spinal nerve contains postganglionic sympathetic fiber). Gray rami are present in all segments.

Note : sympathetic fibers go to :

1- Bllod vessels . ( mainly )

2- Smooth muscles.

3- erector spinae muscles in the skin.

Nervs which leave the sympathetic chain :

1) Gray rami ( 31 post ganglionic fibers join spinal nerves )

**Note : the cervical part of sympathetic chain possesses 3 ganglia : superior/middle/ inferior.

1) From Superior cervical ganglion : Gray rami communicans are given to lower 4 cranial nerves and anterior rami of upper four cervical spinal nerves ( C1,C2,C3,C4) 2)From : Gray rami communicans are given to the anterior rami of 5th and 6th cervical spinal nerves ( C5,C6). 3)From Inferior cervical ganglion: Gray rami communicans: These are given to the anterior rami of seventh and eighth cervical spinal nerves ( C7,C8).

2) visceral nerves: 1) Internal and external carotid nerves: from superior cervical sympathetic ganglia to corresponding arteries ( external and internal arteries which supply the parotid/submandibular glands. 2) pharyngeal branch : from superior cervical sympathetic ganglia to pharyngeal plexus. 3) pulmonary nerves : from 2nd , 3rd& 4th 4) cardiac nerves : from 2nd , 3rd& 4th thoracic ganglia + 3 . 5) splanchnic nerves : greater, lesser and lowest splanchnic nerves

[ANATOMY #12] April 28, 2013

3) Splanchnic nerves :

1) Greater splanchnic nerve. - From T5-T9 and maybe T10 thoracic ganglia. - Pierces the cruss of the diaphragm to synapse in the celiac ganglia. - Carries sympathetic fibers. - The postganglionic fibers accompany the branches of the celiac artery and follow them to their distribution. - There are 2 celiac ganglia surrounds the celiac trunk making the celiac plexus. - The parasympathetic fibers from the vagus nerve also accompany the branches of the celiac artery. 2) Lesser splanchnic nerve : - From T9,T10 thoracic ganglia. - Pierces the cruss of the diaphragm . - Synapse in the superior mesenteric ganglia. - Distributed with branches of superior mesenteric artery. - Postganglionic fibers supply the smooth muscles, glands of small intestine, ascending and transverse parts of colon. - Carries sympathetic fibers to the midgut. - The parasympathetic fibers from the vagus nerve. 3) The lowest splanchnic nerve : - From T12 or from both T11 and T12. - Pierces the diaphragm to end in the renal plexus. - poseganglionic fibers to the suprarenal glands. - It may not present - The parasympayhetic fibers from the vagus nerve. 4) Lumber splanchnic nerve : - Arise from L1& L2 ganglia. - Ends in inferior mesenteric ganglia. - Postgangilionic fibers go to sigmoid and pelvic colon. - Distributed through the branches of inferior mesenteric artery as a plexus ( hypogastric plexus) - Other postgangilionic fibers arise from the hypogastric plexus to supply bladder, rectum and genetalia. -The hypogastric plexus has both sympathetic and parasympathetic fibers. The parasympathetic fibers arise from S2,S3,S4.

[ANATOMY #12] April 28, 2013

5) sacral branch :

 Arises from the sacral part of sympathetic chain .  Goes to pelvic viscera mainly.  Distributed through the hypogastric plexus of nerves.

The abdominal part of the sympathetic chain :

- It possesses 4-5 ganglia. - It descends downward along the medial border of the psoas major muscle. - Enters the behind the medial arcuate ligament of the diaphragm. [ANATOMY #12] April 28, 2013

- It continues as the pelvic part in the behind common iliac vessels. - The right sympathetic part : lies behind the right border of inferior vena cava ( can't be seen). - The left sympathetic part: lies close to the left border of the aorta ( can be seen).

Nerves in the posterior abdominal wall :

1) Subcostal nerve : ( lacated below the last rib) 2) Ilioinguinal nerve + iliohypogastric nerve ( originated from L1 ) These three nerves (mentioned above) are located posterior to the kidneys. 3) Genitofemoral nerve ( from L1,L2 )  Genital branch : goes through the inguinal canal to supply the cremasteric muscle.  femoral branch : supplies the skin over the upper medal side of the thigh.

Cremasteric reflex :

This reflex is elicited by scratching the upper medial side of the thigh → sensory fibers of the femoral branch are stimulated and carry impulses to L1,L2 →activation of the motor fibers of genital branch → contraction of the cremasteric muscle → cremasteric muscle pulls the testis upwards.

4) Lateral cautaneous nerve of the thigh : (from L2,L3)  To anterior suoerior iliac spine → goes below the inguinal ligament → then to the lateral side of the thigh.

5) Femoral nerve :

 From the posterior division of anterior rami of L2,L3 amd L4.  Supplies the anterior compartment of the thigh.  It has both sensory and motor fibers.

6) obturator nerve :

 from the anterior division of the anterior rami of L2,L3 and L4.  supplies the medial compartment of the thigh.  it has both sensory and motor fibers. 6) lumbosacral trunk ( L4,L5 and S1 )

[ANATOMY #12] April 28, 2013

 the nerves in the posterior abdominal wall are related to the psoas major muscle :

1) On the medial side : obturator nerve / lumbosacral trunk. 2) Anterior : genitofemoral nerve ( it goes throgh the fibers of psoas majo muscle ). 3) On the lateral side : femoral nerve/ iliohypogastric nerve/ ilioinguinal nerve.

Note : ** the innervation of psoas major muscle : from the anterior rami of L1,L2,L3 and L4. ** the innervation of the quadratous lumborum : from the ventral rami of T12,L1,L2 and L3.

The second part of lecture is about embryology. It will be included within the next sheet (#13) by our  اسراء أبو هنية colleague

I’m sorry for being late to write this sheet :/

Sorry for any mistake