Comparison between tract and nerve

-
  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
Post a Comment

Difference between azygos vein and hemiazygos vein

-
Difference between azygos vein and hemiazygos vein
Topics
Azygos vein
Hemiazygos vein
Location
It is present only on the right side in the upper abdominal wall
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.    Right ascending lumbar vein
2.    Right subcostal vein
3.    Right superior intercostals vein (created by 2-4th right posterior intercostals veins
4.    Hemiazygos vein
5.    Accessory hemiazygos vein
6.    Right brochial veins
7.    Esophageal veins
8.    Mediastinal veins
9.    Pericardial veins 
1.    Lower 3 (9-11th ) left posterior intercostals veins
2.    Left subcostal vein
3.    Left ascending lumbar vein
4.    Small esophageal and mediastinal 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
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
 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 
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
The azygos vein may rarely drain into the right brachiocephalic vein, right subclavian vein, intrapericardial SVC or directly into the right atrium
·         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
Thoracic wall and upper lumbar region
·         It drains the left inferior hemithorax

Comments

Post a Comment

Popular posts from this blog

Difference between lumbar and sacral splanchnic nerve

-
Difference between lumbar and sacral splanchnic nerve Name Location of preganglionic neuron Sympathetic ganglion Collateral Ganglion Form Autonomic   Plexus Fibres Functions Lumbar splanchnic nerve Lateral horn of gray matter of Lumbar 1,2 spinal cord segment Lumbar 1,2 Inferior mesenteric ganglion Superior hypogastric plexus Preganglionic Sympathetic Fibres and General visceral afferent fiber Innervate pelvic viscera and vasculature Sacral splanchnic nerve Lateral horn of gray matter of Lumbar 1,2 spinal cord segment Sacral 1-5 Inferior mesenteric ganglion Inferior hypogastric plexus Preganglionic and postganglionic fibres Sympathetic Fibres and General visceral afferent fiber The inferior hypogastric plexus is a plexus of nerves that suppli...
Read more

Difference between greater and lesser splanchnic nerve

-
Difference between greater and lesser splanchnic nerve  Name Location of preganglionic neuron Sympathetic ganglion Collateral Ganglion Form autonomic Plexus Functions Greater splanchnic nerve Lateral horn of gray matter of Thoracic 5-9 spinal cord segment Thoracic 5-9 Synapse with celiac ganglion Celiac plexus   The fibers in this nerve modulate the activity   of the enteric nervous system of the foregut. They also provide the sympathetic innervation to the adrenal medulla, stimulating catecholamine release. Lesser splanchnic nerve Lateral horn of gray matter of Thoracic 10-11 spinal cord segment Thoracic   10-11 Synapse with   aortico-renal ganglion or superior mesenteric ganglion Renal plexus The nerve modulates the activity of the enteric nervous system of the midgut
Read more

Difference between anterior and posterior part of rectus sheath Topics Anterior part of rectus sheath Posterior part of rectus sheath Above costal margin This part of rectus sheath is only formed by single aponeurosis. The aponeurosis of External oblique abdominis No rectus sheath Related with costal cartilage From costal margin to arcuate line This part of rectus sheath is formed by two aponeurosis. The aponeurosis of External oblique abdominis and anterior layer of aponeurosis of internal oblique abdominis This part of rectus sheath is formed by two aponeurosis. The aponeurosis of External oblique abdominis and posterior layer of aponeurosis of internal oblique abdominis Below the arcuate line (this line is situated midway between umbilicus and upper surface of pubis symphysis ) This part of rectus sheath is formed by three aponeurosis. The aponeurosis of External oblique abdominis, internal oblique abdominis and transverses abdominis No rectus sheath Related with fascia transversalis

-
Difference between anterior and posterior part of rectus sheath Topics Anterior part of rectus sheath Posterior part of rectus sheath Above costal margin This part of rectus sheath is only formed by single aponeurosis. The aponeurosis of External oblique abdominis  No rectus sheath Related with costal cartilage From costal margin to arcuate line This part of rectus sheath is  formed  by two  aponeurosis. The aponeurosis of External oblique abdominis  and anterior layer of aponeurosis of internal oblique abdominis This part of rectus sheath is  formed  by two  aponeurosis. The aponeurosis of External oblique abdominis  and posterior layer of aponeurosis of internal oblique abdominis Below the arcuate line (this line is situated midway between umbilicus and upper surface of pubis symphysis )  This part of rectus sheath is formed by th...
Read more