Ross Wilson Anatomy

Communication Right common carotid Left common carotid artery Left subclavian artery Coeliac artery ~"' ---++-----Left common iliac artery '~~-+-----'c-----left internal iliac artery external iliac artery Figure 5.29 The aorta and its main branches. embedded in fascia, called the carotid sheath. At the level of the upper border of the thyroid cartilage they divide into: • external carotid artery. • internal carotid artery. The carotid sinuses are slight dilatations at the point of division (bifurcation) of the common carotid arteries into their internal and external branches. The walls of the sinuses are thin and contain numerous nerve endings of the glossopharyngeal nerves. These nerve endings, or baroreceptors, are stimulated by changes in blood pressure in the carotid sinuses. The resultant nerve impulses initiate reflex adjustments of blood pressure through the vasomotor centre in the medulla oblongata (p. 92). The carotid bodies are two small groups of specialised cells, called chemoreceptors, one lying in close association with each common carotid artery at its bifurcation. They are supplied by the glossopharyngeal nerves and their cells are stimulated by changes in the carbon dioxide and oxygen content of blood. The resultant nerve impulses initiate reflex adjustments of respiration through the res- piratory centre in the medulla oblongata. External carotid artery (Fig. 5.31). This artery sup- plies the superficial tissues of the head and neck, via a number of branches. and runs upwards, backwards and to the left in front of the trachea. It then passes downwards to the left of the trachea and is continuous with the descending aorta. Three branches are given off from (Fig. 5.30): its upper aspect • • • brachiocephalic artery or trunk left common carotid artery left subclavian artery. The brachiocephalic artery is about 4 to 5 cm long and and to the right. At passes obliquely upwards, backwards the level of the sternoclavicular joint it divides into the right common carotid artery and the right subclavian artery. Circulation of blood to the head and neck Arterial supply The paired arteries supplying the head and neck are the common carotid arteries and the vertebral arteries (Fig. 5.31). Carotid arteries. The right common carotid artery is a branch of the brachiocephalic artery. The left common carotid artery arises directly from the arch of the aorta. They pass upwards on either side of the neck and have the same distribution on each side. The common carotid arteries are

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Transcript of Ross Wilson Anatomy

Communication

Right common carotid Left common carotid artery

Left subclavian artery

Coeliac artery

~"' ---++-----Left common iliac artery

'~~-+-----'c-----left internal iliac artery

external iliac artery

Figure 5.29 The aorta and its main branches.

embedded in fascia, called the carotid sheath. At the level ofthe upper border of the thyroid cartilage they divide into:

• external carotid artery.• internal carotid artery.

The carotid sinuses are slight dilatations at the point ofdivision (bifurcation) of the common carotid arteries into their internal and external branches. The walls of the sinuses are thin and contain numerous nerve endings ofthe glossopharyngeal nerves. These nerve endings, or

baroreceptors, are stimulated by changes in blood pressure in the carotid sinuses. The resultant nerve impulses initiate reflex adjustments of blood pressure through the vasomotor centre in the medulla oblongata (p. 92).

The carotid bodies are two small groups of specialisedcells, called chemoreceptors, one lying in close associationwith each common carotid artery at its bifurcation. Theyare supplied by the glossopharyngeal nerves and theircells are stimulated by changes in the carbon dioxide andoxygen content of blood. The resultant nerve impulsesinitiate reflex adjustments of respiration through the res-piratory centre in the medulla oblongata.

External carotid artery (Fig. 5.31). This artery sup-plies the superficial tissues of the head and neck, via anumber of branches.

and runs upwards, backwards and to the left in front ofthe trachea. It then passes downwards to the left of thetrachea and is continuous with the descending aorta.

Three branches are given off from(Fig. 5.30):

its upper aspect

•••

brachiocephalic artery or trunkleft common carotid arteryleft subclavian artery.

The brachiocephalic artery is about 4 to 5 cm long andand to the right. Atpasses obliquely upwards, backwards

the level of the sternoclavicular joint it divides into theright common carotid artery and the right subclavian artery.

Circulation of blood to the head and neck

Arterial supplyThe paired arteries supplying the head and neck are thecommon carotid arteries and the vertebral arteries (Fig. 5.31).

Carotid arteries. The right common carotid artery is abranch of the brachiocephalic artery. The left commoncarotid artery arises directly from the arch of the aorta. Theypass upwards on either side of the neck and have the samedistribution on each side. The common carotid arteries are