Which of the following muscles extends the forearm at the elbow joint? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Brachioradialis m. b Triceps brachiim. c Biceps brachii m. d Brachialis m. Which of the following muscles flexes the thigh at the hip? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a lliopsoas m. b Biceps femoris m. c Vastus intermedius m. d Gluteus medius m. Select all that apply. Which of the following muscles flex the forearm at the elbow joint? (1) Multiple answers: Multiple answers are accepted for this question Select one or more answers and submit. For keyboard navigation… SHOW MORE ? a Flexor digitorum superficialis m. b Triceps brachii m. c Brachioradialis m. d Brachialis m. e Flexor hallucis longus m. f Biceps brachii m.
The correct answer and explanation is:
Correct Answers:
- Which muscle extends the forearm at the elbow joint?
b. Triceps brachii m. - Which muscle flexes the thigh at the hip?
a. Iliopsoas m. - Which muscles flex the forearm at the elbow joint? (Select all that apply)
c. Brachioradialis m.
d. Brachialis m.
f. Biceps brachii m.
Explanation:
- Triceps Brachii and Forearm Extension:
The triceps brachii is the primary muscle responsible for forearm extension at the elbow joint. It has three heads—long, lateral, and medial—that originate from the scapula and humerus and insert onto the olecranon process of the ulna. The triceps brachii is innervated by the radial nerve (C6–C8) and functions mainly to straighten the elbow, counteracting flexor muscles like the biceps brachii and brachialis. - Iliopsoas and Hip Flexion:
The iliopsoas muscle is a deep hip flexor composed of two muscles: the psoas major and iliacus. It originates from the lumbar vertebrae and iliac fossa and inserts on the lesser trochanter of the femur. The iliopsoas is innervated by the femoral nerve (L2–L4) and is crucial for flexing the thigh at the hip joint. It is essential for movements like walking, running, and maintaining posture. - Forearm Flexors:
- Biceps brachii: A two-headed muscle on the anterior arm that flexes the elbow and supinates the forearm. It is innervated by the musculocutaneous nerve (C5–C6).
- Brachialis: Located underneath the biceps, it is the primary elbow flexor, exerting the most force in elbow flexion. It is also innervated by the musculocutaneous nerve (C5–C6).
- Brachioradialis: Although part of the forearm, this muscle assists in elbow flexion, especially in a neutral grip position (thumbs-up). It is innervated by the radial nerve (C5–C7).