Problem 21 - Anatomy and Physiology of Animals

Question

Which of the following statements is true? a. The left and right common carotid arteries both branch off of the brachiocephalic trunk. b. The brachial artery is the distal branch of the axillary artery. c. The radial and ulnar arteries join to form the palmar arch. d. All of the above are true.

Step-by-Step Solution

Answer

b and c are true; a is false.

Step 1: Evaluate Option a

The left common carotid artery branches directly from the aortic arch, while the right common carotid artery branches from the brachiocephalic trunk. Thus, this statement is false.

Step 2: Evaluate Option b

The brachial artery is indeed the distal continuation of the axillary artery after it passes the lower margin of the teres major muscle. So, this statement is true.

Step 3: Evaluate Option c

The radial and ulnar arteries do indeed join to form the superficial and deep palmar arches in the hand. Thus, this statement is true.

Step 4: Determine Correct Answer

Since option a is false but options b and c are true, only option "c. The radial and ulnar arteries join to form the palmar arch" is entirely accurate.

Key Concepts

Common Carotid Artery

The common carotid artery is a major blood vessel responsible for supplying oxygen-rich blood to the head and neck. There are two common carotid arteries, left and right.

- **Left Common Carotid**: This artery arises directly from the aortic arch, which is a large curved blood vessel coming out of the heart. - **Right Common Carotid**: In contrast, the right common carotid artery branches from the brachiocephalic trunk. This trunk is a major artery that splits off from the aortic arch and also gives rise to the right subclavian artery. Understanding these pathways is crucial for medical professionals dealing with cardiovascular and cranial procedures. They are often reference points during surgeries related to neck and head trauma or disease.

It is essential to note that these arteries eventually bifurcate into the internal and external carotid arteries, which further supply various head and facial structures.

Brachial Artery

The brachial artery is a key vessel in the upper arm. It serves as the main supplier of blood to the arm and hand. Starting as a continuation of the axillary artery, it begins at the lower border of the teres major muscle.

- **Positioning**: It runs down the arm and is typically located near the medial side of the biceps muscle. - **Branches**: The brachial artery gives rise to several important branches, including:

• The deep brachial artery, which supplies muscles in the arm.
• Radial and ulnar arteries at the elbow, essential for forearm and hand blood supply.

The brachial artery’s location makes it an ideal site for measuring blood pressure using a sphygmomanometer. This artery is important not just for delivering blood, but also in medical diagnostics and treatments, such as the administration of injections or arterial blood samples.

Radial and Ulnar Arteries

The radial and ulnar arteries are significant for blood circulation in the forearm and hand. They begin where the brachial artery splits, which typically occurs around the elbow.

- **Radial Artery**: This artery travels down the lateral side of the forearm and is best known for its role in clinical settings where the radial pulse is checked at the wrist. - **Ulnar Artery**: Running along the medial side of the forearm, the ulnar artery primarily supplies blood to the medial aspect of the forearm and hand. Together, these arteries form an important circulatory structure known as the palmar arches:

• **Superficial Palmar Arch**: Primarily fed by the ulnar artery, supplies most of the hand.
• **Deep Palmar Arch**: Dominated by the radial artery, serves the fingers.

Understanding these arterial structures is crucial for medical and fitness professionals as it affects everything from physical performance to recovery from hand injuries.