The pre-axial vein cephalic vein of superior extremity

Cephalic vein

It begins as the continuation of lateral end of the dorsal venous arch

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Course:

·         It crosses the roof of anatomical snuff box

·         Then it ascends on the radial border of the forearm , continues upwards in front of the elbow along the lateral border of the biceps

·         It pierces the deep fascia at the lower border of the pectoralis major , the deltopectoral groove up to the infraclavicular fossa

·         In the infraclavicular fossa , it pierces the clavipectoral fascia and drains into the axillary vein (deep vein of upper limb)

Clinical anatomy

·         It is routinely used for giving intravenous injections and for withdrawing blood from donors

·         The cephalic vein is preferred for hemodialysis in patients with chronic renal failure to remove waste products from blood

•          The cut down of cephalic vein in the deltopectoral groove is preferred when superior vena caval infusion is necessary 

·         Cephalic vein is not preferred for cardiac catheterization due to the following reasons

1.    Its diameter does not increase as it ascends

2.    It joins the axillary vein at a right angle hence it is difficult ot maneuver the catheter around sharp cephaloaxillary angle

3.    In deltopectoral groove it frequently divides into small branches

4.    One of the branches ascends over the clavicle and joins the external jugular vein

Dorsal venous arch of hand : superficial vein of upper limb 

The dorsal venous network of the hand is a network of veins in the superficial fascia on the dorsum of hand formed by the dorsal metacarpal veins. 

It is included in the superficial venous system.

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 It is an irregular arrangement of veins with transverse element which lies 2-3 cm proximal to the heads of metatarsal bones

Tributaries : three dorsal metatarsal veins

1.    A dorsal digital vein from the medial side of little finger

2.    A dorsal digital vein from the lateral side of index  finger

3.    Two dorsal digital veins of the thumb

4.    Veins draining palm of hand

a) veins that pass around the margins of the hand and

b) perforating veins which pass dorsally through the interosseous spaces

Function

1.    Its main function is the venous drainage of the hand.

2.    It not only receives blood from the palm around the borders of the hand, but also from veins that go through the interosseous spaces.

3.    In practical terms, this means that even when there is pressure on the palm from a gripping action, venous return does not slow.

4.    In addition, the cephalic and basilic veins come up from the dorsal venous arch. These are responsible for joining the deep veins and the lymphatics.

Drainage:

It drains into cephalic and basilica veins – the efferent vessels of dorsal venous arch  but most of the blood from the entire hand drains into the arch of the hand.

Ilioinguinal nerve

The ilioinguinal nerve is a branch of lumbar plexus

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Root value: L1

Relations :  It separates from the first lumbar nerve along with the larger iliohypogastric nerve.

Course :

It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, and passes obliquely across the quadratus lumborum and iliacus.

The ilioinguinal nerve then perforates the transversus abdominis near the anterior part of the iliac crest, and communicates with the iliohypogastric nerve between the transversus and the internal oblique muscle.

It then pierces the internal oblique muscle, distributing filaments to it, and then accompanies the spermatic cord (in males) or the round ligament of uterus (in females) through the superficial inguinal ring.

Sometimes the ilioinguinal nerve passes deep to the inguinal ligament .  

Distribution :

Its fibres are then distributed to the skin of the upper and medial part of the thigh, and to the following locations in the male and female:

·         In the male ("anterior scrotal nerve"): to the skin over the root of the penis and upper part of the scrotum.

·         In the female ("anterior labial nerve"): to the skin covering the mons pubis and labia majora.

The ilioinguinal nerve does not pass through the deep inguinal ring, and thus only travels through part of the inguinal canal. It mediates the cremasteric reflex.

Short note on left coronary artery

Short note on left coronary artery 

Aortic sinus :It arises from left posterior  aortic sinus of ascending aorta

Size: Bigger than the right coronary artery

Course

1.       It runs forwards and to the left between the pulmonary trunk and left auricle

2.       Then it  divides into anterior interventricular branch and circumflex branch

3.       The anterior inter-ventricular branches of left coronary artery descend downward along the anterior inter-ventricular groove and anastomosis with posterior inter-ventricular branch of left coronary artery

4.       The circumflex branch cross the left border of heart

5.       It then passes along the left posterior part of atrioventricular groove

6.       Then it anastomosis with branch of right coronary artery just left of the crux of heart
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Branches

1.       Anterior interventricular artery: it supplies anterior part of interventricular septum , greater part of the left ventricle and part of right ventricle and a part of left bundle branch of His  

2.       Circumflex artery : it gives a left marginal artery that supplies the left margin of the left ventricle up to the apex of the heart

3.       Diagonal artery: it may arise directly from the trunk of the left coronary artery  

4.       Conus artery : it supplies the pulmonary conus

5.       Atrial branches: they supply the left atrium

Distribution

It supplies :

1.       Most of the left atrium

2.       Most of the left ventricle except a strip along the posterior and inferior surfaces of the heart posterior and inferior surfaces of the heart

3.       Anterior superior 2/3 of the ventricular septum

Coronary dominance

10% individuals are left coronary dominance. It means ventricular septum is supply only by left coronary artery.

posterior inferior part of 1/3 of ventricular septum is  supply by circumflex branch of  branch of left coronary artery

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

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.