large abscess in the middle of the right neck

019. A 43 year old woman came with a large abscess in the middle of the right posterior triangle of the neck. The physician incised and drained the abscess. Five days later the patient noticed that she could not extend her right hand above her head to brush her hair. Which of the following are the signs and symptoms of additional harm?

1. Damage to scalenus medius

2. Injury to suprascapular nerve

3. Cut to spinal part of accessory nerve

4. Spread of infection to shoulder joint

Answer

3. Cut to spinal part of accessory nerve

Reference

Gray 38^th Edition Page 1255

Quality

Thinker

Status

Repeat

QTDF

All books

Discussion

The accessory nerve is conventionally described as a single entity though its two components (which join for a relatively short part of its course) are of quite separate origin. The cranial root (the internal ramus), which joins the vagus, has been considered to be a branchial or special visceral efferent nerve, though in animals it contains, in addition, a general visceral efferent component. The spinal root (the external ramus) can be considered as a somatic, special visceral efferent, or mixed nerve, depending on the view taken of the embryological origin of the muscles it supplies, sternocleidomastoid and trapezius.

Explanation

1. Scalenus medius bends the cervical part of the vertebral column to the same side and helps to raise the first rib
2. Suprascapular nerve supplies Supraspinatus and infraspintus and hence the woman will have difficulty in initiation of abduction. Once the arm is abducted for about 15o then deltoid and later trapezius will take over the abduction.
3. Trapezius is needed for hyperabduction (extending the hand above the head to brush hair) and when the spinal part of accessory nerve is cut, the woman will not be able to brush her hair.
4. Spread of infection to shoulder joint limits all movements in general and not hyperabduction in particular

Comments

Ä Abduction is initiated by the supraspinateus 0 to 15 degree and the humerus moves over glenoid (Glenohumeral).

Ä Then from 15 to 90 degree the arm is abducted by deltoid and the humerus moves over glenoid (Scapulothoracic).

Ä Further abduction above 90 degrees (Hyperabduction is done by the trapezius and serratus anterior which rotate the scapula.

Tips

Refer to Question Number 17 (2003 Paper) in the TargetPG Series AIPG Book for a detailed discussion