Structure of Heart in animals The heart is an involuntary muscular organ which occupies the greater part of the middle mediastinal space. Its shape is an irregular and somewhat flattened cone. It is attached at the base by the great blood vessels but otherwise it is free in the pericardium. Structure of Heart is asymmetrical
Blood Vascular System consists of a series of arteries that carry blood into all parts of the body. They divide into smaller arterioles, which in turn divide on entering the tissues into minute microscopic tubes, the capillaries. The venous capillaries originate from the arterial capillaries and are interposed between the arterial capillaries and the beginning
Angiology is that branch of systematic anatomy, which deals with the organs of circulation. The circulatory apparatus comprises of heart and vessels. The heart is a central hollow muscular organ, which functions as a force and suction pump, situated in the middle mediastinal space of the thorax. It is enclosed in a fibro-serous sac-the pericardium.
The efferent pathways consist of a cranial and a sacral part. The cranial part consists of efferent fibres present in the third, seventh, ninth and tenth cranial nerves. The sacral part consists of efferent fibres present in the third, fourth and fifth sacral spinal nerves. Cranial part The oculomotor parasympathetic fibres arise from the Edinger-Westpal
For purposes of description, the sympathetic system is divided into cephalic, cervical, dorsal, lumbar and sacral parts. Cephalic part The Cephalic part consists of postganglionic distribution from the superior cervical ganglion. The ganglion is situated below the wing of atlas and is an elongated reddish fusiform body. The preganglionic fibres arise from the first four thoracic
Sympathetic system is the larger subdivision of the autonomic system and includes two ganglionated cords with their branches, plexuses and includes two ganglia. It has a much wider distribution as it innervates all the sweat gland of the skin, arrectores pilorum muscles, muscular walls of blood vessels in addition to viscera. The preganglionic fibres of
In Autonomic Nervous System, these headings will be discussed- Sympathetic system Classification of Sympathetic system Parasympathetic system
The lumbosacral plexus supplies the muscles of the hind limb. It is formed by the convergence of the ventral primary branches of the last three lumbar and first two or three sacral spinal nerves. this plexus is in two parts-anterior and posterior parts connected by anastomotic branches. The anterior part is formed by the fourth,
The dorsal branches of Sacral spinal nerves are small, gain exit through the dorsal sacral foramina and supply the muscles and skin of the croup. The ventral branches of the first and second enter into the formation of the lumbo-sacral plexus. The third generally gives off a branch to the plexus and the rest unites
There are six pairs of Lumbar spinal nerves. The dorsal branches are distributed to the muscles, situated above the transverse processes of the lumbar vertebrae and supplies the skin of the loin. The ventral branches slightly differ in their distribution. They pass under the psoas minor and psoas major and emerge at the lateral border
