Anatomy question A person with an injury in the axillary ner

Anatomy question:

\"A person with an injury in the axillary nerve has complete loss of arm abduction as the deltoid muscle is not functional.\"

This is a true or false question. I put false for this, but wanted to check it. Why would this be false? We are asked to correct the statement.

Solution

Answer: True

Reason:

Axiallary nerve is mainly innervated to teres minor, triceps brachii, deltoid muscle (promotes abduction), teres major & this nerve originates from the brachial plexus. Therefore, any damage to this nerve is leading to loss of arm abduction as the deltoid muscle is not going to produce motor functions due to lack of neuronal cholinergic activity in the shoulder joint.

Note:

Deltoid: It is the prime mover produces effects such as flexion and extension via medial and lateral rotation along with abduction whereas corachobrachialis is the prime mover of flexion and adduction movement of the shoulder joint.