chapter number ten. Muscular system .pptx

muscular system

1. MUSCULAR SYSTEM 7/24/2024 1

2. At the end of this lecture student will be able to Define fascia, epimysium, perimysium, endomysium, tendons and aponeurosis Describe the major muscles of the Neck Face Back Arms Legs 7/24/2024 2 Objectives

3. Muscular System of the body 7/24/2024 3

4. A whole skeletal muscle is considered an organ of the muscular system. Muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue. Skeletal muscles vary considerably in size, shape, and arrangement of fibers. STRUCTURE OF MUSCLE TISSUE 7/24/2024 4

5. They differ in size from massive masses like the muscles of the leg to incredibly little strands like the stapedium muscle of the middle ear. Skeletal muscles vary in form from broad to narrow. The fibers run parallel to the long axis of some muscles while being oblique in others. 7/24/2024 5 SIZE AND SHAPE OF MUSCLES

6. Each skeletal muscle fiber is a single cylindrical muscle cell. An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering. MUSCLE FIBER 7/24/2024 6

7. Blood vessels and nerves are abundant in skeletal muscles. Each neuron that enters a skeletal muscle is often accompanied by an artery and one or two veins. Muscular tissue contains a large number of capillaries, which are tiny blood vessels. One or more capillaries are in close proximity to every muscle fibre . The blood capillaries transport heat, waste from muscle metabolism, and nutrients and oxygen into the body. An enormous amount of ATP is produced and used by a muscle fibre , especially during contraction (adenosine triphosphate). These reactions call for molecules that are transported to the muscle fibre in the blood, such as oxygen, glucose, fatty acids, and others. Blood Supply 7/24/2024 7

8. The neurons that stimulate skeletal muscle to contract are somatic motor neurons. Each somatic motor neuron has a threadlike axon that extends from the brain or spinal cord to a group of skeletal muscle fibers. The axon of a somatic motor neuron typically branches many times, each branch extending to a different skeletal muscle fiber. Nerve Innervation 7/24/2024 8

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11. COMPONENTS OF MUSCLE TISSUE 7/24/2024 11

12. Fascia Fascia is a dense sheet or broad band of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body. Fascia allows free movement of muscles; carries nerves, blood vessels, and lymphatic vessels; and fills spaces between muscles Fascia is consequently flexible and able to resist great tension forces . 7/24/2024 12

13. Fasciae are similar to ligaments and tendons as they have collagen as their major component. They differ in their location and function: ligaments join one bone to another bone, tendons join muscle to bone, and fasciae surround muscles and other structures 7/24/2024 13

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15. Epimysium is the outer layer, encircling the entire muscle. It consists of dense irregular connective tissue. Perimysium is also a layer of dense irregular connective tissue, but it surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles Endomysium penetrates the interior of each fascicle and separates individual muscle fibers from one another. The endomysium is mostly reticular fibers . The epimysium, perimysium and endomysium all are continuous with the connective tissue that attaches skeletal muscle to other structures, such as bone or another muscle. 7/24/2024 15

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17. A tendon is a rope-like thread of robust, elastic tissue. Muscles and bones are joined by tendon tissue. Tendons provide limb movement. By absorbing some of the impact muscles experience when someone runs, jumps, or perform other activities, they also assist in preventing muscle injury. There are thousands of tendons in the human body. From the head to the toes, there are tendon present. The largest tendon in the human body is the Achilles tendon which joins calf muscle to your heel bone . Tendon 7/24/2024 17

18. Tendons are not elastic yet have a high tear resistance. This indicates that they are susceptible to injury when stressed (extended to the point of partial rope fibre rupture), and their recovery period may be prolonged. There are tendons present in whole body, .Depending on which muscles they are connected to, tendon length and sizes vary. Muscles that produce a lot of force typically have tendons that are wider and shorter. Muscles that carry out more delicate actions typically have tendons that are longer and thinner . 7/24/2024 18

19. Tendons are mostly collagen, one of the most abundant proteins in your body. Tendons also contain blood vessels and nerves. Collagen fibers are flexible, strong and resistant to damage. A tendon’s structure is similar to a fiberoptic cable or a rope, with small collagen fibers arranged in bundles. This bundling reinforces the tendon and makes it strong, Anatomy of a Tendon 7/24/2024 19

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21. Aponeurosis An aponeurosis is a type of connective tissue found throughout the body. Aponeuroses provide an attachment point for muscles to connect to bone, and can also envelope muscles and organs, bind muscles together, and bind muscles to other tissues. They are important for muscle movement and posture. urosis looks quite different than a tendon. An aponeurosis is made of layers of delicate, thin sheaths. Tendons, in contrast, are tough and rope-like. An aponeurosis is made primarily of bundles of collagen fibers distributed in regular parallel patterns, which makes an aponeurosis resilient. 7/24/2024 21

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23. Occipitofrontalis (unpaired). This consists of a posterior muscular part over the occipital bone , an anterior part over the frontal bone and an extensive flat tendon or aponeurosis that stretches over the dome of the skull and joins the two muscular parts. It raises the eyebrows. MAJOR MUSCLES OF THE FACE 7/24/2024 23

24. Temporalis A thick-fan shaped muscle that closes the mouth and assists the jaw to move side-to-side to grind up food. 7/24/2024 24

25. Buccinator muscle Sometimes known as the ‘trumpeter muscle’, the Buccinator’s role is to puff out the cheeks and prevent food from passing to the outer surface of the teeth during chewing. 7/24/2024 25

26. Masseter Muscle This runs from the cheekbone to the lower jaw and brings the teeth back together to grind up food. The Masseter is the strongest muscle in the human body. 7/24/2024 26

27. Mentalis Sometimes called the ‘pouting muscle’, contraction of the Mentalis raises and thrusts out the lower lip to mak E uspout . 7/24/2024 27

28. Depressor Labii Inferioris This muscle pulls down the bottom lip allowing us to sulk. 7/24/2024 28

29. Orbicularis Oris The circular muscle around our mouth is Orbicularis Oris and this muscle brings our lips together so we can pucker up for a kiss! 7/24/2024 29

30. Orbicularis oculi. This muscle surrounds the eye, eyelid and orbital cavity. It closes the eye and when strongly contracted 'screws up' the eyes . 7/24/2024 30

31. Pterygoid. This muscle extends from the sphenoid bone to the mandible. It closes the mouth and pulls the lower jaw forward. 7/24/2024 31

32. Levator palpebrae superioris. This muscle extends from the posterior part of the orbital cavity to the upper eyelid. It raises the eyelid. 7/24/2024 32

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35. Muscles of the neck There are many muscles situated in the neck but only the two largest are considered here. Sternocleidomastoid. This muscle arises from the manubrium of the sternum and the clavicle. It assists in turning the head from side to side. When the muscle on one side contracts it draws the head towards the shoulder . Trapezius . This muscle covers the shoulder and the back of the neck. It pulls the head backwards, squares the shoulders and controls the movements of the scapula when the shoulder joint is in use. 7/24/2024 35

36. MUSCLES OF THE BACK There are six pairs of large muscles in the back in addition to those that form the posterior abdominal wall. The arrangement of these muscles is the same on each side of the vertebral column. trapezius teres major psoas latissimus dorsi quadratus lumborum sacrospinalis. 7/24/2024 36

37. Quadratus lumborum. This muscle originates from the iliac crest then it passes upwards, parallel and close to the vertebral column. Together the two muscles fix the lower rib during respiration and cause extension of the vertebral column. If one muscle contracts it causes lateral flexion of the lumbar region of the vertebral column. Sacrospinalis (erector spinae). This is a group of muscles lying between the processes of the vertebrae. They originate from the sacrum and are finally inserted into the occipital bone.Their contraction causes extension of the vertebral column. 7/24/2024 37

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41. Latissimus dorsi. This arises from the posterior part of the iliac crest and the spinous processes of the lumbar and lower thoracic vertebrae. It adducts, medially rotates and extends the arm. Teres major. This originates from the inferior angle of the scapula and is inserted into the humerus just below the shoulder joint. It extends, adducts and medially rotates the arm. 7/24/2024 41

42. Psoas muscle. This arises from the transverse processes and bodies of the lumbar vertebrae. It passes across the flat part of the ilium and behind the inguinal ligament to be inserted into the femur. Together with the iliacus it flexes the hip joint Trapezius. This muscle covers the shoulder and the back of the neck. It pulls the head backwards, squares the shoulders and controls the movements of the scapula when the shoulder joint is in use. 7/24/2024 42

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44. Deltoid muscle. These muscle fibers originate from the clavicle, acromion and radiate over the shoulder joint to be inserted into the deltoid tuberosity of the humerus. The anterior fibers cause flexion, the middle or main part, abduction and the posterior fibers extend the shoulder joint. Biceps muscle. This lies on the anterior aspect of the upper arm.It helps to stabilize and flex the shoulder joint and at the elbow joint it assists with flexion and supination. 7/24/2024 44

45. Brachialis muscle. This lies on the anterior aspect of the upper arm deep to the biceps. It is the main flexor of the elbow joint. Triceps muscle. This lies on the posterior aspect of the humerus. It helps to stabilize the shoulder joint, assists in adduction of the arm and extends the elbow joint. Movements Flexion: biceps and brachialis. Extension: triceps. 7/24/2024 45

46. Sartorius a long, narrow muscle running obliquely across the front of each thigh from the hip bone to the inside of the leg below the knee. The sartorius muscle can move the hip joint and the knee joint, but all of its actions are weak, making it a synergist muscle. At the hip, it can flex, weakly abduct, and laterally rotate the femur. 7/24/2024 46 Muscles of the legs

47. The Popliteus is a small, thin, flat, triangular shaped musclotendinous complex of the lower leg with the popliteus muscle and the popliteofibular ligament and constitutes a part of the posterolateral corner of the knee.. It is a deep muscle of the knee joint, forming the floor of the popliteus fossa . Despite its small size, the popliteus is a major stabilizing muscle of the knee. The popliteus is involved in both the closed chain phase and open-chain phase of the gait cycle. During the closed chain phase, which is when the foot is in contact with the ground, the muscle externally rotates the femur on the tibia. 7/24/2024 47 Popliteus

48. At the hip, the long head of the biceps femoris allows for thigh extension and external rotation. Whereas at the knee, the biceps femoris allows for knee flexion and lower leg external rotation. The biceps femoris muscle also stabilizes the pelvis 7/24/2024 48 Biceps femoris

49. Your quad muscles, or quadriceps femoris , are a group of muscles at the front of your thigh. Together, they contain more mass than any other muscle group in your body. You use your quads to perform a variety of movements, including kicking, running, jumping and walking. 7/24/2024 49 quadriceps femoris

50. The gracilis is a long, thin muscle located in the medial compartment of the thigh.   Gracilis acts on the hip and knee joints, resulting in several movements: Strong leg flexion and medial (internal) rotation around the knee joint when the knee is in a semiflexed position. Weak thigh flexion and adduction around the hip joint, simply aiding the other, more powerful thigh adductors. 7/24/2024 50 gracilis

51. The muscles of the  gluteal  region can be broadly divided into two groups: Superficial abductors and extenders – group of large muscles that abduct and extend the femur. Includes the gluteus maximus , gluteus medius , gluteus minimus  and tensor fascia lata . 7/24/2024 51 Abducts femur

52. The pectineus muscle is a flat quadrangular muscle situated in the anterior and medial side of the thigh and belongs to a group of muscles known as the adductor muscles. The pectineus muscle is involved in multiple actions: - adducts the thigh at the hip joint; - flexes the thigh at the hip joint 7/24/2024 52 Pectineus

53. The  adductor magnus muscle is both a dynamic stabilizer of the pelvis and femur and a prime femoral adductor. A portion of the muscle flexes and medially rotates the thigh. Another extends and laterally rotates the thigh. Both segments adduct the thigh. 7/24/2024 53 Adducts femur