Short note on right coronary artery

Short note on right coronary artery 

Aortic sinus : It arises from anterior aortic sinus of ascending aorta

Size : Smaller than the left coronary artery

Course

1.       It passes forwards and to right between the pulmonary trunk and right auricle

2.       Then it passes along the anterior right part of atrioventricular groove

3.       Then it crosses the inferior border

4.       Then it passes downwards and to the left along the posterior part of atrioventricular groove

5.       Then it reaches crux of the heart

6.       Then it descend through the posterior interventricular groove

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Branches:

1. Right conus artery: it is the first branch of right coronary artery. It supplies anterior surface of the pulmonary conus (infundibulum of right ventricle)  
2. Arterial branches : they supply the atria . one of the atrial branch – the artery of sinuatrial node also known as sinuatrial nodal artery supply the SA node in 60% cases.In 40% of individuals it arises from the left coronary artery
3. Right marginal artery : or The right marginal branch of right coronary artery is a large marginal branch which follows the acute margin(inferior border )  of the heart and supplies blood to both surfaces of the right ventricle.
4. Anterior ventricular branches:they are two or three in number and supply the anterior surface of the right ventricle  
5. Posterior ventricular branches or  Posterior interventricular artery: it runs in the posterior interventricular groove upto the apex . it supply the posterior 1/3 of interventricular septum , AV node in 60% of the cases , parts of right and left ventricle

Distribution

It supplies

1.       whole of right atrium

2.       most of the right ventricle except a strip along the anterior interventricular septum

3.       posterior inferior one third of ventricular septum

4.       S.A. node  and A.V. node in the majority (60%) of subjects

Coronary dominance

90% individuals are right coronary dominance. it means ventricular septum is supply by both right and left coronary artery.

posterior inferior part of 1/3 of ventricular septum is  supply by posterior interventricular branch of right coronary artery

anterior superior part of 2/3 of ventricular septum is supply by anterior interventricular branch of left coronary artery 

Venous drainage of thoracic wall / azygos system of veins

Venous drainage of thoracic wall / azygos system of veins

Azygos vein of posterior thoracic wall

Location

It is present only on the right side in the upper abdominal wall

Tributaries

·         Right ascending lumbar vein

·         Right subcostal vein

·         Right superior intercostals vein (created by 2-4^th right posterior intercostals veins

·         Hemiazygos vein

·         Accessory hemiazygos vein

·         Right brochial veins

·         Esophageal veins

·         Mediastinal veins

·         Pericardial veins 

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Formation

Its formation is variable:

1.    It is formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebra, 

2.    Arises from the posterior aspect of the inferior vena cava near the renal veins

3.    As a continuation of right subcostal vein

4.    Occationally it may arise from the right renal or right first lumbar vein

Course

 It enters the thorax via the aortic hiatus in the diaphragm and ascends posteriorly alongside the vertebral bodies, arching over the right main bronchus at T5-T6 and enters the superior vena cava (SVC) at T4 

Variant anatomy

The azygos vein may rarely drain into the right brachiocephalic vein, right subclavian vein, intrapericardial SVC or directly into the right atrium

Drainage area

Thoracic wall and upper lumbar region 

Hemiazygos vein of posterior thoracic wall 

Location

It is also known as inferior hemiazygos vein . it lies on the left side only and corresconds to the lower part of the azygos vein

Tributaries

1.    Lower 3 (9-11^th ) left posterior intercostals veins

2.    Left subcostal vein

3.    Left ascending lumbar vein

4.    Small esophageal and mediastinal veins

Formation

It is formed on the left side similar to the azygos vein by the union of left ascending lumbar vein and left subcostal vein

It may arise from the posterior surface of the left renal vein

Course

The hemiazygos vein enters the thorax either through the aortic hiatus or directly through the diaphragmatic crura. It then courses superiorly to the left of the midline in the posterior mediastinum, adjacent to the thoracic vertebrae until the level of T8 or T9 vertebral bodies, where it crosses the midline anteriorly to the vertebral column to drain into the azygos vein. 

Variant anatomy

·         hemiazygos continuation of the IVC: often occurs with duplicated IVCs

·         interazygos vein: occurs when forming a common trunk with the accessory hemiazygos vein anterior to the aorta

Drainage area

It drains the left inferior hemithorax

Accessory hemiazygos vein

Location

It is also known as superior hemiazygos vein . it lies on the left side only and corresponds to the upper part of azygos vein

Tributaries

·         5^th to 8^th left posterior intercostals vein

·         Left bronchial veins (occationally )

Formation

The accessory hemiazygos vein is formed by the confluence of the middle left posterior intercostal veins. 

Course

It descends to the left of midline, adjacent to the thoracic vertebrae and crosses posteriorly to the aorta at the level of T7-8 to drain into the azygos vein. It normally anastomoses with the left superior intercostal vein.

Variant anatomy

·         drains via a common trunk with the hemiazygos vein into the azygos vein

·         forms a common trunk with the hemiazygos vein that passes anterior to the aorta called the interazygos vein 

·         drains directly into the left brachiocephalic vein (rare) 

Drainage area

It drains the left superior hemithorax.

Accessory hemiazygos vein of posterior thoracic wall

Location

It is also known as superior hemiazygos vein . it lies on the left side only and corresponds to the upper part of azygos vein

Tributaries

·         5^th to 8^th left posterior intercostals vein

·         Left bronchial veins (occationally )

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Formation

The accessory hemiazygos vein is formed by the confluence of the middle left posterior intercostal veins. 

Course

It descends to the left of midline, adjacent to the thoracic vertebrae and crosses posteriorly to the aorta at the level of T7-8 to drain into the azygos vein. It normally anastomoses with the left superior intercostal vein.

Variant anatomy

·         drains via a common trunk with the hemiazygos vein into the azygos vein

·         forms a common trunk with the hemiazygos vein that passes anterior to the aorta called the interazygos vein 

·         drains directly into the left brachiocephalic vein (rare) 

Drainage area

It drains the left superior hemithorax.

Hemiazygos vein of posterior thoracic wall

Hemiazygos vein of posterior thoracic wall 

Location

It is also known as inferior hemiazygos vein . it lies on the left side only and corresconds to the lower part of the azygos vein

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Tributaries

1.    Lower 3 (9-11^th ) left posterior intercostals veins

2.    Left subcostal vein

3.    Left ascending lumbar vein

4.    Small esophageal and mediastinal veins

Formation

It is formed on the left side similar to the azygos vein by the union of left ascending lumbar vein and left subcostal vein

It may arise from the posterior surface of the left renal vein

Course

The hemiazygos vein enters the thorax either through the aortic hiatus or directly through the diaphragmatic crura. It then courses superiorly to the left of the midline in the posterior mediastinum, adjacent to the thoracic vertebrae until the level of T8 or T9 vertebral bodies, where it crosses the midline anteriorly to the vertebral column to drain into the azygos vein. 

Variant anatomy

·         hemiazygos continuation of the IVC: often occurs with duplicated IVCs

·         interazygos vein: occurs when forming a common trunk with the accessory hemiazygos vein anterior to the aorta

Drainage area

It drains the left inferior hemithorax

Azygos vein of posterior thoracic wall

Azygos vein of posterior thoracic wall

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Location

It is present only on the right side in the upper abdominal wall

Tributaries

·         Right ascending lumbar vein

·         Right subcostal vein

·         Right superior intercostals vein (created by 2-4^th right posterior intercostals veins

·         Hemiazygos vein

·         Accessory hemiazygos vein

·         Right brochial veins

·         Esophageal veins

·         Mediastinal veins

·         Pericardial veins 

Formation

Its formation is variable:

1.    It is formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebra, 

2.    Arises from the posterior aspect of the inferior vena cava near the renal veins

3.    As a continuation of right subcostal vein

4.    Occationally it may arise from the right renal or right first lumbar vein

Course

 It enters the thorax via the aortic hiatus in the diaphragm and ascends posteriorly alongside the vertebral bodies, arching over the right main bronchus at T5-T6 and enters the superior vena cava (SVC) at T4 

Variant anatomy

The azygos vein may rarely drain into the right brachiocephalic vein, right subclavian vein, intrapericardial SVC or directly into the right atrium

Drainage area

Thoracic wall and upper lumbar region 

Genitofemoral nerve : lecture note including clinical significance

Genitofemoral nerve

1.    Plexus

2.    Root value & type

3.    Relation

4.    Branches

5.    Distribution

6.    Function

7.    Nerve block

8.    Clinical importance

1.    Plexus :  It is arises from lumbar plexus

2.    Root value : ventral divisions fo L1 and 2

3.    Type : mixed nerve ( both motor and sensory )

4.    Branches :  The nerve divides into two branches, the genital branch and the lumboinguinal nerve also known as the femoral branch,

5.    Relation : It passes downwards, pierces the psoas major and emerges from its anterior surface. Genital and femoral branch of genitofemoral nerve then continue downwards and medially to the inguinal and femoral canal respectively.

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6.    Distribution :

Distribution of Genital branch of genitofemoral nerve:

The genital branch passes through the deep inguinal ring and enters the inguinal canal.

In male, the genital branch supplies the cremaster and scrotal skin.

In female , the genital branch accompanies the round ligament of uterus, terminating in and innervating the skin of the mons pubis and labia majora

Distribution of femoral branch of genitofemoral nerve :

The femoral branch passes underneath the inguinal ligament, travelling through the lateral muscular compartment of the femoral canal where it innervates skin of the upper leg. Passing through the cribriform fascia of the saphenous opening of the fascia lata of the thigh, it then supplies the skin of the upper, anterior and medial side of thigh

7.    Variation : In this study of 200 bodies (400 nerves), 80.2% presented as a single trunk and 19.75% as two rami: genital and femoral. The trunk or rami were usually formed by nerve fibers from L1, L2 from the lumbar plexus. The level of emergence of the nerve or nerves from the psoas major muscle and the level of division into terminal branches were individually highly variable. These characteristics were unrelated to each other, sex, age, height or weight or side of the body. The genitofemoral nerve was present in all cases. Two types were recognized. In type I, the trunk of the nerve divided into two main rami: genital and femoral. In type II, the rami arose separately from the lumbar plexus. Type I was present bilaterally in 70.5%, and type II in 10% of cases.

Spinal nerve L1, was present in nearly all cases, and L2 in all cases sent fibers to the genitofemoral nerve. Fibers from L3 were present in only 0.75% of cases.

8.    Function : femoral branch give sensory supply at the anteromedial aspect of thigh over the femoral triangle

9.    Genital branches gibe sensory supply tunica vaginalis, spermatic fasciae, small area of anterior scrotal skin and in female round ligament of uterus , skin of mons pubis and labium majus

10. Nerve block :  genitofemoral nerve lies immediately lateral to the spermatic cord as it emerges from the superficial Inguinal ring . The spermatic cord Is identified immediately lateral to the pubic tubercle.

 The area for injection, including the scrotum, Is sterilised.

 The spermatic cord is then stabilised and medlallsed using the nondominant hand, and 5ml of 1% lldocaine Is injected subdermally, Immediately lateral to the cord, superficial to the bone.

 Negative aspiration prior to injection ensures non-penetrance of the peritoneum or femoral vessels.

Clinical Significance

The genitofemoral nerve can be injured during surgery in several ways:

• It can be lacerated during injury to the groin. This can occur with penetrating trauma, a knife wound or surgical exploration of the groin. In some cases, during surgery on the saphenous vein for varicose vein ligation, retractors can cause abrasive injury.
• The genitofemoral nerve can also be injured in the inguinal canal, usually during inguinal hernia repair. In most cases, the injury is unnoticed during surgery and diagnosed in the post operative period when the patient complains of pain.
• Lifting heavy objects can also cause injury to the genitofemoral nerve.
• When there is spinal stenosis of the L1 or L2 segments, compression fracture or metastatic lesions to the lumbar spine the nerve roots which give rise to the genitofemoral nerve can be injured.
• Psoas abscess which may occur after an open pelvic fracture or a retroperitoneal hematoma is also known to cause irritation of the genitofemoral nerve.
• Genitofemoral neuralgia is a relatively common pain syndrome observed in both males and females. The patient typically presents with unilateral pain in the lower abdomen. Rarely the pain may be bilateral. The pain is sometimes referred to the groin area (because of the path of the genital nerve) and the upper medial thigh (because of the femoral branch). The pain varies in intensity from moderate to severe and is worsened by movements that cause extension of the lower back. In most patients, palpation of the lower abdomen in the inguinal region can reproduce the pain. In most cases, the cause is compression of the nerve in the inguinal canal, usually after open hernia surgery. The diagnosis is often difficult in patients who have not had surgery.