![]() ![]() A fracture is a broken bone, often with nearby soft tissue, blood vessel and nerve damage, and is most commonly caused by injury to the bone. Both sprains and strains cause pain and swelling, but strains may cause muscle spasm as well. A strain is an injury to a muscle and/or a tendon, resulting from excessive physical effort. A ligament may be stretched or torn and local bleeding and bruising present with restricted movement. Despite the rigidity of the skeleton, humans are capable of moving and bending in almost any direction and this flexibility is largely due to the skeleton’s many movable joints (Figure 36.2).Ī sprain is an injury to a ligament, caused when a joint is forced beyond its normal ROM. oestrogen affects bone formation) and physical factors. Normal bone growth depends on a healthy diet, as well as other hormonal factors (e.g. Bone remodelling (the creation and destruction of bone) is a lifelong process and performed by bone-forming cells called osteoblasts, and bone-absorbing cells called osteoclasts. Bone begins as cartilage that eventually hardens to form bone. Long bones in the arm and leg differ from short bones in the wrist and ankle, and flat bones that form the shoulder blade are different again from irregular shaped bones such as the jaw and vertebrae. Axial skeleton bones form the head and trunk, all others belong to the appendicular skeleton, or bones of the extremities.įigure 36.1 The skeleton, anterior viewThe axial skeleton appears a darker grey than the appendicular skeletonīone is composed of different tissue and classified by location and shape, such as long, short, flat, irregular or sesamoid, such as the patella, or kneecap. The human skeleton is separated into the axial and appendicular skeleton. Normally there are over 200 separate bones and supportive ligaments, as well as fibrous bands of tissue called tendons, which connect muscle to bone. ![]() The skeleton (Figure 36.1) gives the body shape, protection, stores minerals, forms blood cells (haematopoiesis) and allows movement. However, when you frown, the forehead muscle furrows the brow, eye-socket muscles narrow the eyes, while the lower lip muscle (depressor labii inferioris) pulls the lower lip down and you appear angry or upset. For instance when you smile your upper lip muscle (levator labii superioris) lifts your top lip, at the same time your cheek and jaw muscles pull the mouth up and out so that you look happy. However, unlike other muscles, they are actually attached to the skin, so that people can change expression with a slight muscle movement. The erect position of the trunk is maintained as a result of coordination of groups of muscles.Ī good example of muscle coordination is our facial expressions, which come about as a result of many tiny complex facial muscles working together to allow an incredible range of expressions. Extension of the arm is made possible by the relaxation of the biceps, as the triceps contracts and pulls on the arm. For example, during elbow flexion, the triceps muscle relaxes to allow the forearm to be pulled up when the biceps muscle contracts. Most skeletal muscles work in pairs or groups, with one pair or group antagonising the action of another pair or group to achieve controlled movement. The muscular system plays a vital role in maintaining correct body posture by means of good muscle tone and coordinated activity. CLINICAL INTEREST BOX 36.1 Muscle coordination and facial expressions
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