MMT Nerve Innervation and Muscle Function 1 — Questions and Answers
Question 1: Which nerve innervates the deltoid muscle, making it the primary nerve tested during shoulder abduction MMT?
- Musculocutaneous nerve
- Axillary nerve (Correct answer)
- Radial nerve
- Suprascapular nerve
Correct answer: Axillary nerve
The axillary nerve (C5-C6) innervates the deltoid muscle, which is the primary mover tested during shoulder abduction in MMT.
Question 2: The biceps brachii, tested during elbow flexion MMT, is primarily innervated by which nerve?
- Radial nerve
- Median nerve
- Musculocutaneous nerve (Correct answer)
- Ulnar nerve
Correct answer: Musculocutaneous nerve
The musculocutaneous nerve (C5-C6) innervates the biceps brachii, which performs elbow flexion and forearm supination.
Question 3: In MMT, weakness of the wrist extensors most directly implicates which peripheral nerve?
- Median nerve
- Ulnar nerve
- Radial nerve (Correct answer)
- Axillary nerve
Correct answer: Radial nerve
The radial nerve (C6-C8) innervates the wrist extensors; complete radial nerve injury produces wrist drop.
Question 4: Which nerve innervates the gluteus medius, the primary muscle tested during hip abduction MMT?
- Inferior gluteal nerve
- Superior gluteal nerve (Correct answer)
- Sciatic nerve
- Obturator nerve
Correct answer: Superior gluteal nerve
The superior gluteal nerve (L4-S1) innervates the gluteus medius and minimus, which are the primary hip abductors tested in MMT.
Question 5: Ankle plantarflexion weakness during MMT most directly implicates which nerve root level?
- L4
- L5
- S1 (Correct answer)
- S3
Correct answer: S1
Ankle plantarflexion (gastrocnemius/soleus) is primarily innervated at S1-S2, making S1 the key root level implicated by plantarflexion weakness.
Question 6: The intrinsic hand muscles including all interossei are primarily innervated by which nerve, tested in fine hand function MMT?
- Median nerve
- Radial nerve
- Ulnar nerve (Correct answer)
- Musculocutaneous nerve
Correct answer: Ulnar nerve
The ulnar nerve (C8-T1) innervates most intrinsic hand muscles including all interossei and hypothenar muscles.
Question 7: Which spinal nerve root level is the primary target when MMT assesses knee extension strength?
- L2
- L3
- L4 (Correct answer)
- L5
Correct answer: L4
Knee extension via the quadriceps is innervated by the femoral nerve with L4 as the dominant root level clinically tested in MMT.
MMT Nerve Innervation and Muscle Function 1
Which nerve innervates the deltoid muscle, making it the primary nerve tested during shoulder abduction MMT?