Topographic and morphometric anatomy of the proximal part of the dorsal scapular nerve

The dorsal scapular nerve (DSN) entrapment neuropathy has recently been recognized as a common cause of circumscapular pain and cases of winged scapula. Course of the nerve is important because the middle scalene muscle is frequently accessed for surgical treatments. Studies in the literature have not focused on the morphometric relationship of the DSN with the scalene muscles and its relationship with the long thoracic nerve (LTN). The neck regions of 13 adult cadavers were dissected bilaterally. The relationship of DSN with scalene muscles and LTN was evaluated. Cervical spinal nerves involved in the formation of the DSN were identified. Three types of DSN were observed based on the cervical spinal nerves from which it originates, five types of DSN from its relationship with the scalene muscles, and two types of DSN from its relationship with the LTN. The distance from where the nerve pierces the scalene muscle to the mastoid process was found to be greater in DSNs originating from C4 and C5 (93.85 ± 4.11 mm, p = 0.033). In DSNs not connected with LTN, the distance from where the nerve pierces the scalene muscle to the superior trunk/C5 (12.74 ± 7.73 mm, p = 0.008) and the length of the nerve within the scalene muscle (14.94 ± 5.5 mm, p = 0.029) were found to be statistically significantly greater. The topographic and morphometric anatomy of the proximal part of the DSN is important, especially for scalene muscles-focused surgical treatments and interscalene nerve blocks. We believe our results may guide clinical approaches and surgery.

Cleidocervical muscle: a mini literature survey of a human muscle variation

Cleidocervical muscles (CCM) or levator claviculae muscles in humans can be found as supernumerary unilaterally or bilaterally on the neck attached proximally to the clavicle and distally to the transverse process of cervical vertebrae at various levels. Altogether 20 case reports from year 1994 till present including 25 subjects related to CCM were found and analysed where parameters such as cervical insertion level, clavicular insertion at the middle vs. lateral third, unilateral vs. bilateral presence of the muscle, study type, reported gender of the subjects were extracted. Our literature survey shows that the prevalence of CCM in male and female was equally presented in radiological studies whereas almost 3-fold higher prevalence of males was found in cadaver reports. Since body donor system worldwide is male dominant, a 1:1 proportion of male and female in radiological studies could show more reality-based distribution of this muscle. Nevertheless, the presentation of this muscle was found in over 90% of the case reports unilaterally with higher left sided dominance. Even though the attachment points of CCM varied from case to case, the proximal attachment was found slightly more frequent on the middle third of the clavicle whereas the distal insertion was present more often on the superior cervical vertebrae than the lower ones. With prevalence of CCM in the population around 2.0-2.5%, the clinical, radiological and surgical relevance of this variation has to be highlighted to avoid potential misleading diagnostics in the neck.

Diagnosis of closed injury and neoplasm of the brachial plexus by ultrasonography

PURPOSE

To evaluate the feasibility and accuracy of high-frequency sonography (US) in diagnosing traumatic brachial plexus (BP) lesions and neoplasms in the adult.

METHODS

Eleven patients with suspected BP closed trauma, 6 patients with BP neoplasm, and 12 healthy volunteers were scanned. The US findings were compared with surgical findings.

RESULTS

The interscalene space and intervertebral foramina were useful anatomic markers in identifying the BP. In the 24 sites examined in the normal group (12 subjects examined on both sides), the fifth to seventh cervical nerve roots (C5-7, including upper and middle trunk) were seen, whereas the eighth cervical and first thoracic nerve roots (C8, T1, including the lower trunk) were seen in 91.7% (22/24) of the subjects. The BP appeared as three or four discrete rounded hypoechoic nodules between the anterior scalene and middle scalene muscle in transverse views at the C5-7 level, representing the trunks in the sagittal oblique section. In the BP trauma group (n = 11), the normal nerve trunk was interrupted, and lesions were shown as thickening and swelling with indistinct inner structures. In the neoplasm group (n = 6), masses were shown as hypoechoic masses.

CONCLUSIONS

High-frequency US is valuable in diagnosing BP closed injuries and neoplasms.