Which of the following is a posterior forearm muscle?

• A. Extensor carpi radialis longus
• B. Palmaris longus
• C. Pronator teres
• D. Flexor carpi ulnaris

Answer: (A)

Verified step by step guidance

1. Understand the anatomical location of the forearm muscles. The forearm has two main compartments: anterior (flexor muscles) and posterior (extensor muscles). Posterior muscles are responsible for extension movements.
2. Review the function and location of each muscle listed in the options: Extensor carpi radialis longus, Palmaris longus, Pronator teres, and Flexor carpi ulnaris.
3. Identify that the Extensor carpi radialis longus is located in the posterior compartment of the forearm and is responsible for extending and abducting the wrist.
4. Recognize that Palmaris longus, Pronator teres, and Flexor carpi ulnaris are located in the anterior compartment of the forearm and are involved in flexion and pronation movements.
5. Conclude that the correct answer is Extensor carpi radialis longus, as it is the only muscle listed that belongs to the posterior compartment of the forearm.