Written by Anjani Mishra
Brachiocephalic trunk
- This vessels originates from the aortic arch at the level of 4th rib and proceeds cranially. It is also termed as anterior aorta. It is about 10-12 cm in length.
- The brachiocephalic trunk leaves the pericardium and passes forward in the cranial mediastinum. It is related dorsally to the trachea and laterally to the vagus and phrenic nerve at the left side and anterior venacava at the right side.
- It detaches the left axillary (subclavian) artery at the level of second intercostal space and the right axillary artery at the level of first rib. After the origin of these two arteries, the brachiocephalic trunk continues forward as bicarotid trunk or common carotid artery. The bicarotid trunk is usually 5cm in length.
- In dogs, the left axillary artery arises directly from the aortic arch.
- About 4cm. close to the thoracic inlet and ventral to the trachea, the bicarotid trunk bifurcates into left and right common carotid arteries.
Axillary artery (subclavian artery)
The axillary artery left and right
arise from brachiocephalic trunk that differ in origin. The right axillary
artery is somewhat shorter than the left axillary artery. They gives off
branches supplying the head, neck, thoracic limb and the cranial portion of the
thoracic cavity.
Both left and right axillary
arteries have intra-thoracic and extra-thoracic part
Left axillary artery (intra-thoracic part)
The branches of intra-thoracic
part of left axillary artery are as follows;
- Costo-cervical artery
- Superficial cervical artery
- Internal thoracic artery
1. 1. Costo-cervical artery
It is further sub-divided into four types;
A.
Dorsal
artery
B.
Intercostal
artery
C.
Deep
cervical artery
D. Vertebral artery
A. Dorsal
artery-
- Sometimes it originates commonly with intercostal artery.
- It ascends under the serratus cervices, towards the anterior angle of scapula and ramify to the upper parts of trapezius and rhomboideus muscles.
B. Intercostal
artery-
- This vessels goes upward and backward and divides into few branches to form second to fourth intercostal arteries. The first intercostal artery also sometimes originates from this vessel.
C. Deep
cervical artery-
- It is variable in its origin. It courses upward and forward at the level of 7th cervical vertebra, reaches the dorsal and lateral aspect of the neck and provides branches to longissimus dorsi, trapezius, rhomboideus, serratus cervicis, splenius.
D. Vertebral
artery-
- As the continuation of the costo-cervical artery, this vessel passes forward and enters the transverse foramen through the foramen transversarium of the 6th cervical vertebra.
- At the level of each intervertebral foramen, it detaches a spinal artery for the spinal cord and meninges. The spinal branches inside the spinal canal divide and join with the adjoining vessels to form dorsal and ventral spinal arteries.
- The vertebral artery reaches the level between second and third cervical vertebrae gives off anastomotic branch to occipital artery and enters the vertebral canal.
- Here it detaches a small branch which joins with condylar artery and the main trunk continues as descending branch.
- On the way it supplies branches to the muscles of head and neck.
2. 2. Superficial cervical artery-
It originates from the axillary artery at the level of 1st rib. It passes downward and forward and divides into a number of branches to supply prescapular and prepectoral lymph glands and brachiocephalicus, omotransversarius and supraspinatus muscles.
3. 3. Internal thoracic artery-
- It arises from the axillary artery at the level of 1st rib, goes downward and backward to the thoracic face of sternum and under the transversus thoracic muscle.
Near
the 8th costal cartilage, it divides into;
A.
Musculophrenic artery
B.
Anterior abdominal (cranial
epigastric) artery
C.
Ventral intercostal artery
A.
Musculophrenic artery
Musculophrenic artery passes backward and upward, detaches
ventral primary branches.
Distribution:- diaphragm and transversus abdominis muscle.
B.
Anterior abdominal (cranial
epigastric) artery
The anterior abdominal artery courses along the floor of the
abdominal cavity by entering in the rectus abdominis muscle. It gives few
branches to the ventral abdominal wall and ultimately its finer branches
anastomoses with the posterior abdominal artery.
Distribution :- rectus and transversus abdominis muscles.
C.
Ventral intercostal artery
These arteries go upward and anastomoses with the respective
dorsal intercostal arteries.
Distribution
:- intercostal muscles and ribs.
Left axillary artery (extra-thoracic part)
It arises at the level of first rib and gives off following branches;
- External thoracic artery
- Suprascapular artery
- Subscapular artery
- Anterior circumflex humeral artery
- Deep brachial artery
- Collateral ulnar artery
- Transverse cubital artery
- Common interosseous artery
- Median artery
- Radial artery
- Ulnar artery
- Dorsal metacarpal
- Volar common digital
1.
External thoracic artery-
It arises from the axillary artery close to the first rib, goes downward and supplies to the pectoral, biceps brachii, and brachiocephalicus muscle.
2.
Suprascapular-
It is a small vessel, goes upward and supplies to the
supraspinatous muscle and to the medial aspect of shoulder joint.
3.
Subscapular artery-
It is a large vessel originates from the dorsal aspect of the main artery at the angular junction between the axillary and brachial part and supplies to the subscapularis muscle.
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