Introduction
Due to varying concerns and interests, it has become necessary for medical professionals to study how human movement is initiated, performed, maintained, and controlled. By studying and analyzing the musculoskeletal bases of movement, it is feasible to have an anatomical framework on which the dynamics of human movement can be referenced and illustrated in an unequivocal manner (Trew & Everett, 2001). Seminal investigations have demonstrated that the human body has an estimated 640 skeletal muscles, varying in size and purpose from minute vestigial muscles to large muscles such as the gluteus maximus (Jones & Barker, 2002). According to the authors, over one-third of the human body’s overall mass is made up of skeletal muscles. It is the purpose of this paper to offer a descriptive analysis of the bones and soft tissue structures that make up the arches of the foot.
The arches of the foot are of particular importance by virtue of being tasked with the responsibility of allowing the foot to support the total weight of the body in an upright position with the least weight (Myers, 1997). Studies on this area are of concern to many professionals, including medical doctors, sports trainers, sportsmen, massage therapists, physiotherapists, and, to a large extent, ordinary people seeking to have knowledge on how they are able to coordinate movement and maintain stability in an erect posture.
Brief Description of Human Movement
The importance of skeletal muscles cannot be underestimated because without them, the body would be incapable of attaining its characteristic upright posture as may be witnessed by the devastating effects of Paraplegia. Movement becomes difficult when the body is unable to assume its normal upright position. According to Jones & Barker (2002) the “…muscles, exited by the nervous system, act on the skeletal structure of the body to promote movement and to provide stability to the skeleton” (p. 50). The muscles produce forces that put pressure on the joints of the body to either provide movement or offer skeletal stability. In normal circumstances, the amount of force applied by a muscle to cause mobility or stability is dependent on the muscle volume, biomechanical attributes and the constitution and position of the joint (Jones & Barker, 2002). Consequently, a wholly functioning musculoskeletal system is fundamental for proper movement to take place.
The Arches of the Foot
The human foot is exceedingly intricate in its structures and function. The structure itself is comprised of 26 bones, soft tissue structures, muscles, joints and tendons (Myers, 1997). Holistically, the foot is tasked with the twin functions of weight absorption and propulsion, and therefore requires a high level of flexibility and stability to successfully perform these functions. In essence, the foot acts as a very energetic base, requiring invariable adaptation to changing weight patterns from above. It becomes difficult, if not impossible, to support weight or achieve balance if the foot is not well-founded on the most basic structural level (Banks et al, 2001).
One important facet of the foot that helps it to support any weight and absorb pressure from activities such as jumping or running is the arches, which are formed through a complex interplay between the multiple bones found in the foot, tendons, and soft tissue structures. A normal healthy foot has three arches, namely the lateral longitudinal arch, the medial longitudinal arch, and the transverse arch (see figure 1). It is imperative to note that “…the bones of the foot do not lie flat on the substrate but are maintained as arches with only the ends of the arch in contact with the ground” (Sellers, n.d., p. 9).
Anatomically, the medial longitudinal arch is the most prominent of the three arches, and runs from the front through to the rear along the inside continuum of the foot (Myers, 1997). It is located on the medial part of the foot between the top of the first metatarsal bone and the calcaneal tuberosity. Studies also demonstrate that it is the highest arch of the three, measuring about 1cm. According to Buchanan & Berlet (2009) “…the medial arch is composed of the calcaneus, talus, cuneiforms, and the first through third metatarsals” (para. 18). Other bones that make up the medial arch include the navicular and sesamoid. The talus, supporting the weight of the body from above, is joined into the navicular from its rounded forward end. The navicular in turn offers support to the three cuneiform bones and their corresponding metatarsals (Myers, 1997). This explains why the first three toes of the foot are associated with the medial longitudinal arc. The interlocking capability of these bones coupled with the orientation of the joints and input from several tendons forces the bones into an arch (Sellers, n.d).
The second arch, known as the longitudinal arch, runs parallel to the medial arch but along the periphery of the foot. The arch, according to Myers (1997) is made up “…of the calcaneus, the cuboid, and the fourth and fifth metatarsal” (para. 34). Anatomically, the cuboid bone resembles a trapezium, with the wider aspect facing the top. This arrangement allows for the firm joining of the calcaneus on one side, and the forth and fifth metatarsals on the other, making the cuboid bone to be lifted off the ground. The lateral arch is known to be very stable (Myers, 1997).
The third foot arch, called the transverse arch, transverses the mid-foot from the exterior to the interior of the foot. This particular arch is formed by the proximal components of the five metatarsal bones, the cuboid, and the three cuneiform bones (Myers, 1997). Here, it is important to note that the three cuneiform bones resemble a wedge pointed downwards. Their structure makes the bones to form a natural arch while leaning on the end of the cuboid. A closer look at the ends of the five metatarsals reveals some rounded bones which hardly come into contact with each other. According to Myers, “…this part of the transverse arch is certainly not held in place by the shapes of the bones, and depends on the integrity of the muscles, particularly the adductor hallucis, to maintain it” (para. 32).
All the three arches are enhanced and sustained by the soft tissues that go through the plantar surface of the foot. The soft tissues of the foot include muscles, fasciae, and tendons. Chief among the soft tissues is the plantar fascia, which spans from the heel bone located behind the foot to each of the five metatarsal bones (Myers, 1997). The planter fascia functions like a ‘bowstring’ to the allay of bones, providing a tensional spring to the heel bone and the metatarsal bones whenever the ankle is pressed down by weight from above. The arches would most probably collapse in the absence of the planter fascia. Another soft tissue – the calcaneo-navicular – offers some kind of trampoline for the talus bone each time weight is exerted on it from above (Myers, 1997).
The basic support for the medial arch is derived from the tibialis anterior, “…which arises from the anterior compartment just lateral to the tibia, and passes just in front of the ankle joint to attach into the joint between the first cuneiform and the first metatarsal bones” (Myers, 1997, para. 43). Due to some weak links in the medial arch, the resilient pull provided by the tibialis anterior functions as a muscular support to the health and wellbeing of the medial arch.
The peroneus longus, on its part, originates from the fibular head and travels down just behind the lateral malleolus. At this juncture, it dips more deeply, passing under the cuboid, and ultimately attaching purposively “…on the lateral side of the first cuneiform-first metatarsal joint” (Myers, 1997, para. 44). This muscle is known to assist in the formation and strengthening of the arches of the foot. In particular, peroneus longus support and sustains the lateral and transverse arches by elevating up against the cuboid or by compressing the cuneiform bones and the cuboids together (Banks et al, 2001).
The tibialis posterior, which originates from the deepest sections of the calf, go down just behind the medial malleolus to attach into other muscles found beneath the foot. In this way, the tissue supports the formation of the medial arch (Myers, 1997). Another soft tissue worth mentioning is the peroneus brevis, which originates from the lower section of the fibula to attach at the bottom of the fifth metatarsal bone. Its major function is to pull the fifth metatarsal bone decisively into the cuboid, thereby assisting to support the lateral arch.
The main functions of the arches of the foot include weight bearing, pressure absorption and propulsion. For instance, lateral arches are known to absorb much of the shock of impact experienced while walking, sprinting, or jumping (Banks et al, 2001). The arches convert the foot from an inflexible lever to a spring-like mechanism, profoundly increasing jumping or running efficiency and performance. More importantly, the arches, especially the transverse arch, provide the foot with stability and flexibility while going about our daily activities (Banks et al, 2001).
Conclusion
This discussion has demonstrated adequate evidence about the bones and soft tissues that make up the arches of the foot, and their importance in necessitating our own movement and stability. The intricate circumstances surrounding human movement has been discussed in detail, with particular emphasis being directed at describing the multiple bones and tissues that come into play to form the arches. One of the critical points that have reverberated all along is that the three arches work in complimentary roles to mop up pressure or bear weight that is coming from above. Also, it has been revealed that the bones must interlock in a certain manner, aided by the muscles and tendons, to form the arches. Clearly, the arches of the foot serve critical roles in the process of enhancing our own movement.
Reference List
Banks, A.S., Downey, M.S., Martin, D., & Miller, S.J. (2001). McGlamry’s comprehensive textbook of foot and ankle surgery, Volume 1-2. Philadelphia, PA: Lippincott Williams & Wilkins.
Jones, K., & Barker, K. (2002). Human movement explained. Edinburgh: Butterworth-Heinemann.
Myers, T. (1997). Body 3 Cubed: The foot: Understanding the arches. Massage Magazine, Issue 69. Web.
Sellers, B. (n.d.). Functional anatomy of the lower limb. Web.
Trew, M., & Everett, T. (2001). Human movement: an introductory text. London: Harcourt Publishers Ltd.