The supraspinatus is most frequently involved in shoulder pathology. However, the musculotendinous architecture of the supraspinatus has not been well documented. Therefore, the purpose of this study is to investigate the detailed three-dimensional architecture of the supraspinatus throughout its volume. Ten male formalin embalmed cadaveric specimens (mean age 61.9 +/- 16 years) without any evidence of rotator cuff pathology were used. Three-dimensional coordinates (x, y, and z) of the tendon and muscle fiber bundles were collected in situ, using serial dissection and digitization. The data was reconstructed into a three-dimensional model using Maya. Fiber bundle lengths, pennation angles (PA), muscle volumes, and tendon dimensions for each architecturally distinct area were computed and then analyzed using paired t-tests and ANOVA (P < 0.05). The supraspinatus was found to consist of anterior and posterior regions, which were each further subdivided into superficial, middle, and deep parts. Mean PA were found to be significantly different between the distinct parts of the anterior region of the muscle. Medial PA was also found be significantly different between the superficial and middle, and superficial and deep parts of the posterior region. These results provide insight into the normal function of the muscle and its possible contribution to the initiation and progression of supraspinatus tendon tears.

A thorough understanding of the normal structural anatomy of the pectoralis major (PM) is of paramount importance in the planning of PM tendon transfers or repairs following traumatic PM tears. However, there is little consensus regarding the complex musculotendinous architecture of the PM in the anatomic or surgical literature. The purpose of this study is to model and quantify the three-dimensional architecture of the pectoralis muscle and tendon. Eleven formalin embalmed cadaveric specimens were examined: five (2M/3F) were serially dissected, digitized, and modeled in 3D using Autodesk Maya; six (4M/2F) were dissected and photographed. The PM tendon consisted of longer anterior and shorter posterior layers that were continuous inferiorly. The muscle belly consisted of an architecturally uniform clavicular head (CH) and a segmented sternal head (SH) with 6-7 segments. The most inferior SH segment in all specimens was found to fold anteriorly forming a trough that cradled the inferior aspect of the adjacent superior segment. No twisting of either the PM muscle or tendon was noted. Within the CH, the fiber bundle lengths (FBL) were found to increase from superior to inferior, whereas the mean FBLs of SH were greatest in segments 3-5 found centrally. The mean lateral pennation angle was greater in the CH (29.4 +/- 6.9 degrees ) than in the SH (20.6 +/- 2.7 degrees ). The application of these findings could form the basis of future studies to optimize surgical planning and functional recovery of repair/reconstruction procedures.

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Lumbar multifidus (LMT) is a key muscle, which provides stability to the lumbar spine, and has been shown to have altered neuromuscular recruitment following acute episodes of low back pain. Architectural parameters are important determinants of function, but have not been well documented for LMT. Therefore, the purpose of this study is to model and quantify the architecture of LMT throughout its volume. Nine male and one female formalin-embalmed cadaveric specimens (average age 80 +/- 11 years) without any evidence of spinal deformity/pathology were used. The musculotendinous components of LMT were serially dissected and digitized. Next, the data were imported into MAYA to create a three-dimensional model of each segment of LMT from which architectural parameters including fiber bundle length (FBL), fiber bundle angle (FBA), and tendon length were quantified. Water displacement was used to determine volume. The data were analyzed using paired t-tests and ANOVA followed by Tukey's post-hoc test (P

To date, the architecture of supraspinatus (SP) and its relation to joint position has not been investigated. The purpose of this study was to quantify the dynamic architecture of the distinct regions of SP using ultrasound (US). Seventeen subjects (8 M/9 F), mean age 36.4 +/- 12.7 years, without tendon pathology were recruited. The SP was scanned in relaxed and contracted states. For the contracted state, SP was scanned with the shoulder actively abducted to 60 degrees and the glenohumeral joint in neutral rotation; 80 degrees external rotation; 80 degrees internal rotation. Fiber bundle length (FBL) and pennation angle (PA) of distinct regions, and muscle thickness were computed. Measurements of the posterior region were limited because of acromion shadowing. Parameters between regions and changes between relaxed and contracted states were analyzed using paired t-tests and repeated measures ANOVA (P < 0.05). On contraction in the anterior region, mean percentage of FBL shortening ranged between 9% and 21%. However, in the posterior region, shortening of approximately 2% only occurred in two of the three positions; lengthening of approximately 2.5% occurred in internal rotation. For the anterior region, the mean PA increased the least in the externally rotated position, and the mean PA of the middle part was smaller than the deep part for all states. Findings suggest changes in the architecture are not uniform throughout the muscle and joint position may play an important role in force production. The US protocol may serve as an outcome measure of adaptive changes of muscle function following surgery, training, and rehabilitation.