ANTHROPOMETRIC AND SONOGRAPHIC STUDIES OF THE HUSOLEUS MUSCLE ARCHITECTURE
The human soleus muscle plays a major role in posture and locomotion, providing a significant proportion of the tension in the tendo calcaneus during quiet standing and of the propulsive force in locomotion (Alexander & Vernon, 1975).
It has become clear that varying the length of the soleus muscle by flexion and extension of the ankle joint affects many aspects of its behaviour: the shape of electrically-evoked EMG (electromyography) responses (Gerilvsky, Gydkov &Radicheva, 1977): the threshold and amplitude of reflex responses (Davies & Lader, 1983; Weiss, Kearney & Hunter, 1986); the torque generated about the ankle (Sale et al., 1982).
Predicting the behaviour of each of these length-dependent properties in soleus depends, therefore, on an accurate knowledge of its length or, more specifically, the relationship between length and ankle joint angle.
General characteristics of length-dependence, applicable to other muscles may be inferred if soleus length is expressed in terms of its resting length, lr.
This is the length of the muscle found when the ankle angle is zero, the foot being at right angles to the leg and it is the base unit of functional muscle length.
Its use allows comparison of length, length change and rate of change between muscles of widely differing form and function (Prochazka, Stephens & Wand, 1979).
Once this information is available, fractional changes in lr may be calculated from simple trigonometric functions such as the ‘cosine rule’ (Greer & Hancox, 1978) or that stipulated by Hufschmidt & Schwaller (1987).
Evidently, the reliability of such calculations depends critically on the anthropometric data used to evaluate them, but obtaining such data in intact subjects requires surface measurements to be made of structures whose topographical relationship to the skin surface does not remain constant.
The purpose of this study was to provide data from which empirical relationships might be derived to predict soleus lr in intact subjects.
The results show that some of the values previously assumed for soleus (e.g. by Hufschmidt & Schwaller,1987) are not justified empirically.
Ultrasonography has been used in medical practice since early 1950s, when Wild and colleagues discovered the ability of high-frequency ultrasound wavesto visualize living tissues (Wild&Neal, 1951).
Since then, the technique of ultrasound has rapidly evolved, leading to its widespread use in almost all fields of medicine because of its non-invasive nature and real-time display. In 1980, it was first discovered that diseased muscle showed a different ultrasound appearance compared to healthy muscles (Heckmatt et al., 1980)
Neuromuscular disorders, malignancies, infections and hematomas and ruptures of the musculoskeletal system can also be detected with ultrasound (Campell et al., 2005; Fornage, 2002; Hashimoto, 1999; Peetrons 2002).
The sonographic appearance of muscle is fairly distinct and can easily be discriminated from surrounding structures such as subcutaneous fat, bone, nerves, and blood vessels (Peetrons, 2002). Normal muscle is relatively black, i.e has low echo intensity (Sigrid, 2010).
Ultrasonography is a quick, relatively less expensive, safe (no radiation danger), non-invasive and widely accessible imaging technique for muscle assessment (Grassi et al., 2000; O’connr et al., 2004). The knowledge of normal muscle thickness is important so as to know when there is abnormality in muscle thickness.
Ultrasonography is the use of ultrasound to produce image of structures in the human body. Using ultrasonography to access the thickness of soleus muscle, also identify different variations in the thickness and size of the soleus muscle.
This study will therefore be conducted to investigate the thickness of calf muscle among young healthy adults using ultrasound. The thickness of these muscle will possibly be a pointer to the functional status of the muscle; its use among adults; its possible relationship with the Achillles tendon thickness and its role in force generation during human propulsion.
The anthropometric and sonographic studies of the soleus muscle architecture will determine the following;
(1) The normal length of a relaxed soleus muscle in a population of young male adults in Nigeria.
(2) To determine the angle of pennation, the fibre bundle length, and muscle thickness.
(3) To determine if there exists dimorphism in the parameters of study among the given population.
The anthropometric and sonographic studies of the human soleus muscle determines the dimensions of the human soleus muscle.
In this study, the resting length of the soleus muscle which is the length of the muscle found when the ankle angle is zero, with the foot at right angles to the leg will be determined. The resting length of the soleus muscle is determined using the anthropometric studies.
The sonographic studies determine the muscle architecture in relaxed human soleus muscle of normal live subjects. The study gave information on the fiber bundle length, muscle thickness, and angles of pennation in different sites of the muscle.