The Skeletal System

1. The Skeletal System Stefanie Moreira Ms. Tahseen Ashley Acosta Period 4 Frances Lindo 11.18.13

2. Overview • The skeletal system is made up of all the bones in the body, along with the tendons, ligaments, and joints that connect them. • The main functions of the skeleton are support, protection of the internal organs, and movement. • Bones store minerals such as calcium. • Produce red blood cells. • At birth, we start with over 300 bones! But as we grow, bones fuse together and and become one, totaling 206 bones.

3. What are bones made of? • A bone is enclosed in a tough, fibrous tissue called the periosteum. It contains blood vessels. • Beneath the periosteum is an outer layer of compact bone,which is dense, smooth and sturdy. • Inside of it is a layer of cancellous bone, which is spongy and more flexible. • In the middle of bones is bone marrow, which produces red blood cells.

4. Classification • Bones are classified according to their shape. • There are 5 types: • Long bone (femur) • Short bone (wrist, ankle) • Flat bone (scapula) • Irregular bone (vertebrae) • Round bone

5. Anatomy of a Long Bone • A long bone has a main shaft, called the diaphysis, made of compact bone. It’s covered with a sheet of living cells, called the periosteum. Inside it is the medullary cavity (lined with a thin, fibrous membrane called endosteum), which consists of bone marrow. The bone marrow holds fat and produces blood cells. • At the ends of the diaphysis are epiphyses, made of spongy bone. Beyond that is the articular cartilage (named because it occurs where the joints articulate, or join).

8. Bone Growth and Repair • Bones have living tissues. It’s shown in their ability to grow and be repaired. • The formation of bone, or ossification, begins during embryonic development. • Many different types of cells involved in bone growth and repair: • Osteoprogenitor Cells: found in inner and outer surfaces of the bone • Osteoblasts: bone forming cells, derived from osteoprogenitor cells. • Osteocytes: mature cells derived from osteoblasts that maintain bone tissue. • Osteoclasts: perform bone resorption, meaning they break down bones and assist in depositing calcium and phosphate in the blood.

10. Bone Growth and Repair Cont. • When a bone fractures, it undergoes a series of 4 steps: • Hematoma (blood escapes from ruptured blood vessels and clots) • Fibrocartilaginous Callus (tissue repair starts, fibrocartilage fills space b/w broken bones) • Bony Callus (osteoblasts, bone forming cells, turn the fibro.cart. into bony callus and joins the broken bones together) • Remodeling

11. Table 6.1 p100

12. Axial Skeleton • Skeleton is divided into the axial and appendicular skeleton. • The axial skeleton (80 bones) lies in the middle of the body and contains the skull, hyoid, vertebral column, and the thoracic cage. • Skull: Formed by the cranium & facial bones. • -“These bones contain sinuses, air spaces lined by mucous membranes, that reduce the weight of the skull and give the voice a resonant sound.” (pg. 100) • Sinusitis: inflammation of the paranasal sinuses • Mastoiditis: inflammation of the mastoid sinuses

13. Cranial Bones • Sutures: immovable joints that separate the cranial bones. • Frontal bone: forehead • 2 Parietal bones: posterior to frontal • Occipital bone : back of the skull • 2 Temporal bones: inferior to parietal bones on the sides of the cranium. • Sphenoid bone: helps form the sides and floor of the cranium. • Ethmoid bone: anterior to sphenoid bone and helps form the floor of the cranium.

15. Bones of the Face • Maxillae: the 2 maxillae form the upper jaw. • Zygomatic bones: form sides of the orbits and contribute to cheek bones. • Lacrimal bones: located on the medial walls of the orbits. • Nasal bones: form bridge of the nose. • Vomer bone: forms the nasal septum. • Inferior Nasal Conchae: form part of the inferior lateral wall of the nasal cavity. • Mandible: the lower jaw, only movable part of the skull.

19. Hyoid: superior to the larynx; only bone in the body that does not articulate to another. • Vertebral column: Series of separate bones; extends from the skull to the pelvis. • Vertebrae are named according to location • Has 4 normal curvatures – cervical & lumbar (convex, or curved outward, anteriorly) – thoracic & sacral (concave anteriorly) • Curvatures are subject to abnormalities. • An exaggerated lumbar curvature is called lordosis, or swayback. • Increased roundness of thoracic curvature is called kyphosis, or hunchback. • Abnormal lateral (side-to-side) curvature is called scoliosis.

22. Atlas and Axis • Atlas: supports and balances the head; allows movement. • Axis: has an odontoid process, or dens, that projects into the ring of the atlas. When the head moves from side to side, the axis turns around the odontoid process.

23. Sacrum and Coccyx • The sacrum articulates with the pelvic girdle and forms the posterior wall of the pelvic cavity. • The coccyx, or tailbone, is the last part of the vertebral column.

24. Thoracic (rib) cage: • Protects heart and lungs • 12 pairs • All connect to vertebral column blue-axial orange-appendicular

25. Appendicular System • Contains the bones of the pectoral girdle, upper limbs, pelvic girdle and lower limbs. • Pectoral Girdle: Consists of 4 bones : 2 clavicles and 2 scapulae. Supports the arms and serves as a place of attachment for the arm muscles. Is held in place by ligaments and muscles. It is possible to dislocate the shoulder. • Clavicle: (Collar bones) slender and S shaped, medial to the manubrium of the sternum. Only place that is attached to the axial skeleton. It is structurally weak and will fracture under pressure.

26. Scapulae: (sing. scapula) a.k.a shoulder blades, they resemble triangles. The scapulae are not joined together and each one has a spine. • Acromion process: articulates with a clavicle, attach arm and chest muscles. • Coracoid process: attachment for arm and chest muscles. • Gleniad cavity: articulates with the head of the arm bone (humerus).

27. Upper Limbs • Bones of the arm (humerus), forearm (radius and ulna), and hand (carpals, metacarpals and phalanges.) • Humerus: Bone of the arm, long bone. • Radius and Ulna: Bones of the forearm. Radius is on the lateral side- thumb side. Ulna is the longer bone of the forearm. • Hand: Wrist, palm and five fingers. • Wrist – carpals, “wrist watch", or distal forearm. • Fingers- metacarpal bones; contain phalanges.

28. Upper limbs: Humerus, Radius and Ulna

29. Pelvic Girdle • Two coxal bones (hipbones), as well as the sacrum and coccyx. • Coxal bones have 3 parts : • Ilium-largest part flares outward, hands rest on iliac crest. Ischium: inferior (most) ischialtuberosity allows a person to sit. • Pubis: anterior part of the coxal, two bones joined at the pubic symphasis, posterior to that is the obturator foramen. • All 3 points meet at the acetabulum- connects the femur. • False pelvis – bound to the trunk. True pelvis – upper and lower inlet and outlet – in females moves apart to let the baby be born.

31. Gender Differences • Female – iliac crest more flared • Broader hips • Wider between ischial spines and ischialtuberosities • Inlet and outlet are wider • Pelvic cavity more shallow • Lighter and thinner bones • Pubic arch U shaped • Male – pelvic cavity funnel shaped • Pubic arch V shaped

32. Lower Limb • Bones of the thigh (femur), kneecap (patella), leg (tibia and fibula) and foot (tarsals, metatarsals and phalanges). • Femur: a.k.a thighbone, longest and strongest bone in the body. • Tibia: a.k.a shinbone, medial to the fibula. Thicker than the fibula and bears weight from the femur. • Fibula: lateral to the tibia, more slender. Lateral malleolus articulate talus forms over ankle. • Foot: Consists of the ankle, instep and 5 toes. • Ankle 7 bones talus move freely. Largest ankle bone is the calcaneus or heel bone. • Metatarsal bone - instep, ball of the foot. • Toes – phalanges, the big toe only has two phalanges, while the other toes have three.

34. Lower limbs: Femur, Tibia and Fibula

35. Articulation • Two systems for classifying joints: (1) according to the amount of movement they allow, (2) according to their structure • [1] Synarthorosis - an immovable joint • [2] Amphiarthorosis – allows slight movement • [3] Diarthorosis – freely movable • Fibrous joints: occur where fibrous connective tissue joins bone to bone typically immovable though there are exceptions. (for all three types) [1] • Cartilaginous joints: occur where fibrocartilage or hyaline cartilage joins bones. [2] • Synovial joints: are formed where bone ends do not contact each other, but are enclosed in a capsule. [3]

36. Fibrous joints: adult cranium, coronal suture between the parietal bones and the frontal bone, lambodial suture between the parietal and occipital bone, squamosal suture between each parietal bone and each temporal bone, and the sagittal suture between the parietal bones. The joints formed by each tooth in its tooth jacket are also fibrous joints. • Cartilaginous joints: The ribs are joined to the sternum by costal cartilages, which are hyaline cartilage. The bodies of adjacent vertebrae are separated by fibrocartilage invertebral disks, which increase vertebrae flexibility. • The pubic symphysis, the joint between the 2 pubic bones, consists largely of fibrocartilage. Due to hormonal changes this joint becomes more flexible during late pregnancy, allowing the pelvis to expand during child birth.

37. Synovial joints: The two bones are separated by a joint cavity. The joint cavity is lined by synovial membrane, which produces synovial fluid a lubricant for the joint. • Absence of tissue between the articulating joints enables movement but it also means that the joint must be stabilized in some way. • The joint is stabilized by the joint capsule, a sleeve-like extension of the periosteum of each articulating bone. Ligaments bind the bones (two) to one another and add even more stability. Tendons also help stabilize the synovial joint. • The surface of the articulating joint are protected in several ways: • Bones are covered by an additional layer of hyaline cartilage. • The joint contains menisci (sing. meniscus) crescent shaped pieces of cartilage. • Fluid filled sacs calledbursae, which ease friction between all parts of the joint. The inflammation of the bursae is called bursitis, tennis elbow is a form of bursitis.

38. Types of Synovial Joints • Saddle joint: each bone is saddle shaped and fits into the complementary regions of the other. Ex. Joint between the carpal and metacarpal bones of the thumb. Rotation is possible. • Ball-and-socket joint: the ball-shaped head of one bone fits into the cup-shaped socket of another. Ex. Shoulder and hip joints. • Pivot joint: a small, cylindrical projection of one bone pivots within the ring formed of bone and ligament of another bone. Only rotation is possible. Ex. The joints between the proximal ends of the radius and ulna, and the joint between the atlas and axis.

39. Hinge joint: the convex surface of one bone articulates with the concave surface of another bone. Up and down motion in one plane is possible. Ex. Elbow and knee joints. • Gliding joint: flat or slightly curved surfaces of bones articulate. Sliding or twisting in various planes is possible. Ex. Joints between the bones of the writs and between the bones of the ankle. • Condyloid joint: oval-shaped condyle of one bone fits into the elliptical cavity of another. Rotation is possible. Ex. Joints between the metacarpals and phalanges.

40. Movements permitted by Synovial Joints • Angular movements • Flexion: joint angle, elbow – forearm towards the arm, knee- legs toward the thigh. Dorsiflexionis flexion of the foot upward standing on your heels, and plantar flexion is flexion of the foot downward standing on your toes. • Extension: increases the joint angle. Extension of the flexed elbow straightens the upper limb. Hyperextension occurs when a portion of the body part extended beyond 180˚. It is possible to hyperextend the head and the trunk of the body and also the shoulder/wrist (arm/hand). • Adduction: is the movement a body part toward the midline. Ex. arms to sides. • Abduction: is the movement of a body part laterally away from midline.

41. Circular movements • Circumduction: the movement of a body part in a wide circle, as when a person makes arm circles. • Rotation: the movement of a body part around its own axis. • Supination: the rotation of the forearm so that the palm is upward. • Pronation: opposite move of the forearm so that the palm faces downward. • Special movements • Inversion and eversion: applies only to the feet. Inversion is turning the foot so that the sole faces inward. Eversion is the sole facing outward. • Elevation and depression: refers to the lifting up and down respectively, of a body part, as when you shrug your shoulders or move your jaw.

42. Effects of Aging • Both cartilage and bone deteriorate as a person ages. • Cartilage: • The bluish color typical of young cartilage changes to an opaque, yellowish color. • The chondrocytes die, reabsorption occurs as the cartilage undergoes calcification becoming hard and brittle. • Calcification interferes with the ready diffusion of nutrients and waste products through the matrix. • Osteoarthritis is accompanied by deterioration of the articular cartilage. • Rheumatoid arthritis is the synovial membrane; becomes inflamed and grows thick cartilage. • Autoimmune reaction, the immune system mistakenly attacks the synovial membrane, affects  children and young adults.

43. Gout is caused by an excessive buildup of uric acid  ( metabolic waste) in the blood. Rather than being excreted in the urine, the acid is deposited as crystals in the joints where it causes inflammation and pain. • Osteoporosis - present when weak and thin bone cause aches and pains. Tend to fracture easily.

44. Homeostasis • The bones: • protect the internal organs. • The bones assist all phase of respiration • The bones store and release calcium. • The bone  assist the lymphatic system and immunity.

45. Other Functions • Integumentary: support for skin  helps provide vitamin D for Ca2+ absorption • Muscular: stores Ca2+ for muscle  move joints, muscles, help muscles • Nervous: protects, store Ca2+ for nerve function  sensory input from bones to joints • Endocrine: protects, stores Ca2+ use as second messenger  regulates bone development, parathyroid hormone and calcitonin regulate Ca2+ content

46. Cardiovascular: protects red bone marrow produces blood cell; blood  store Ca2+ for blood clotting  Blood vessels deliver nutrients and O2 to the bones, carry  away wastes. • Lymphatic: Red bone marrow produces white blood cells involved in immunity  pick up excess tissue fluid; protects against infections • Respiratory: protects, assists breathing, bones provide attachment sites for muscles involved in breathing  Picks up excess tissue fluid; protects against infections • Digestive -chew food, hyoid bone assists swallowing  Digestive tract provides Ca2+ and other nutrients  for bone growth and repair • Urinary- support, protection  vitamin D for Ca2+ absorption and help maintain blood level of Ca2+ need for bone growth and repair

47. Video! • http://www.youtube.com/watch?v=8d-RBe8JBVs ~FIN~