Chapter 7 Notes Skeletal System

Transcription

1 Chapter 7 Notes Skeletal System An individual bone is composed of a variety of tissues, including bone tissues, cartilage, epithelial tissues, fibrous connective tissue, blood, and nervous tissue. A bone contains very active, living tissue. Bone Structure Although the various bones of the skeletal system differ greatly in size and shape, they are similar in their structure, development, and tissues. Parts of the Lone Bone: Epiphysis at each end of the bone where there is an expanded portion which forms a joint with another bone. Articular Cartilage on the outer surface of the epiphysis, made of hyaline cartilage. Spongy Bone irregular connected spaces occur between plates and help reduce the weight of the bone. Typically a layer of compact bone is found on top. Diaphysis the shaft of the bone; located between the epiphysis. Compact Bone the wall of the diaphysis has this tightly packed tissue. Mainly for solid, strong, and resistance to bending. Periosteum the tough, vascular covering of fibrous tissue, not on the ends where the articular cartilage is. **Each bone has a shape closely related to its functions.** Medullary Cavity tube with a hollow chamber. Marrow fills the medullary cavity; specialized type of soft connective tissue. - The shape of bone cells are circular. - The shape of compact bone is due to the osteocyte cells forming around a canal of blood vessels and nerves. - Spongy bone is still made of osteocyte cells but arranged differently. BONE DEVELOPMENT AND GROWTH 2 Major Types of Bones: 1. Some appear between sheet-like layers of connective tissues and are called intramembranous bones. Examples: broad, flat bones of the skull

2 2. Others begin as masses of cartilage, which later are replaced by bone tissue. These are called Endochondral Bones. - Most bones of the skeleton are endochondral bones. - These bones grow very fast for a while and then begin to undergo changes. Development of an Endochondral Bone: 1. Bone starts from a mass of hyaline cartilage with a shape similar to the bone it will become. 2. First change occurs in the center of the diaphysis where the cartilage breaks down and disappears. 3. Periosteum starts to form. 4. Blood vessels start to form where the cartilage is disappearing. 5. Spongy bone fills in around the blood vessels. This area is called the Primary Ossification Center. 6. Secondary Ossification Center appears in the epiphysis to form spongy bone. 7. An Epiphyseal Disk forms between the two ossification centers. The area of this disk is where the new cells are begin made to make the bone longer. Extra Things To Know!! If an Epiphyseal Disk is damages before it becomes ossified, growth of the long bone may cease prematurely, or if growth continues, it may be uneven. For this reason, injuries to the Epiphyses of young person s bones are of special concern. On the other hand, an epiphysis is sometimes altered surgically in order to equalize the growth of bones that are developing at very different rates. READ PAGE 132!! Repair of a Bone Fracture Organization of the Skeleton Axial Skeleton: 1. skull cranium and facial bones 2. hyoid 3. vertebral column vertebrae, sacrum, coccyx 4. thoracic cage ribs, sternum Appendicular Skeleton: 1. pectoral girdle scapula, clavicle 2. upper limbs humerus, radius, ulna, carpals, metacarpals, phalanges 3. pelvic girdle coxal bones 4. lower limbs femur, tibia, fibula, patella, tarsals, metatarsals, phalanges Skull 22 bones 8 cranial bones 13 facial bones 1 mandible Cranial Skeleton: 1. Frontal bones (Only 1) forehead 2. Parietal Bone (2) top of head

3 3. Occipital Bone (1) back of skull 4. Temporal Bone (2) side of head - External Auditory Meatus opening in temporal bone for ears - Mastoid Process projection under ear (attachment for muscles for neck) - Styloid Process projection under ear (attachment for muscles for tongue and pharynx) 5. Sphenoid Bone (1) wind-like structure which extends laterally toward each side of the skull. 6. Ethmoid Bone (1) in front of sphenoid bone; 2 masses on each side of the nasal cavity Facial Skeleton: 1. Maxillae (2) upper jaw, contains sockets of upper teeth 2. Palatine Bone (2) behind maxillae 3. Zygomatic Bone (2)- cheek bones 4. Lacrimal Bone (2) thin, scale-like structure located in the medial wall of each eye. 5. Nasal Bone (2) bridge of nose 6. Vomer 91) midline of nasal cavity 7. Inferior Nasal Conchae (2) scroll-shaped bones attached to the sides of the nasal cavity Mandible: - jaw; moveable portion - Mandibular Condyle top of mandible that fits into joint Vertebral Column Vertebral Column skull to pelvis and composed of vertebrae Intervertebral Disks fibrocartilage that separates the vertebrae; cushions and softens movements. Vertebral Column supports head and trunk and protects spinal cord through the vertebral canal. Cervical Vertebrae (7) -transverse processes of vertebrae are distinctive because of the transverse foramina passage way for arteries Atlas 1 st vertebrae; supports and balances head Axis 2 nd vertebrae; allows head to turn side to side Thoracic Vertebrae (12) - starts with vertebrae # 8 - increases in size as move down - adapted for stress from body weight - ends with vertebrae #20 Lumbar Vertebrae (5) - small of back - adapted for more support of weight Sacrum - triangular structure

4 - composed of 5 fused vertebrae Coccyx - lowest part of the vertebral column - composed of 4 fused vertebrae Upper Limb & Hand Notes Upper Limb - functions as levers that move limbs and attachment for muscles - bones in upper limb include: humerus, radius, ulna, carpals, metacarpals, phalanges Humerus - extends from scapula to elbow - head of humerus fits into glenoid cavity - 2 processes: greater tubercle sits up higher (larger) lesser tubercle sits lower - both provide sites for muscle attachment - epicondyles: Lateral Epicondyles provides attachment for muscles; on outside (lateral) of bone Medial Epicondyles provides attachment for muscles; on the inside of bone Radius larger - elbow to wrist and crosses over ulna - head of radius attaches with humerus - radial tuberosity bump of bone on side; bicep muscle attaches here Ulna smaller - head of ulna goes with notch of radius Hand - wrist, palm, fingers - wrist 8 carpals lines up in rows trapezium is bone in wrist associated with thumb - palm 5 metacarpals 1 with each finger cylinder shaped bones with a fat end that forms knuckles thumb begin labeled as #1 Pinky as #5 - fingers 5 phalanges 3 bones in each phalanx (finger) only 2 bones in thumb follows same numbering as palm Proximal Phalanx bone closest to palm of finger

5 Middle Phalanx middle bone of finger Distal Phalanx end of finger Pelvic Girdle & Lower Limb Notes Pelvic Girdle - consists of 2 coxal bones - sacrum, coccyx, and pelvic girdle together for the ring-like pelvis - function is to provide support for the trunk of the body and attachment for the legs and muscles Coxal Bones - develop from 3 parts 1. ilium 2. ischium 3. pubis All 3 fuse in a cup-shaped region called the acetabulum which joins with the femur Ilium - largest & uppermost portion of the coxal bone - flares outward to form the prominence of the hip Ischium - forms the lowest portion of the coxal bone - supports the weight of the body when sitting Pubis - 2 parts to the pubis bone - 2 bones come together to form the symphysis pubis - the angle formed from these 2 bones is called the pubic arch - obturator foramen large opening Difference between females and males: - Pelvic Area female bones are lighter, thinner, and have less obvious muscular attachments obturator foramen and acetabula are smaller and further apart than in a male pelvic cavity if wider, shorter, roomier, and less funnel shaped distance between ischial spins and ischial tuberosity are greater in a male Lower Limb - includes femur, tibia, fibula, metatarsals, phalanges Femur - longest bone in body - goes from hip to knee - head fits into coxal bone - 2 large processes on upper end greater trochanter lesser trochanter

6 both provide attachment for muscles of leg and butt - 2 processes on lower end lateral condyles medial condyles associated with tibia Tibia Fibula Foot - larger of the lower leg bones - medial and lateral condyles attach with femur - medial malleolus serves as the attachment for ligaments - long and slender bone on side of tibia - head is associated with tibia but does not bear much body weight - lateral malleolus associated with ankle and forms the ankle bone on side of leg - ankle, instep, 5 toes Tarsals 7 - one of the 7 is called the talus which moves freely - the rest are fixed Metatarsals 5 - numbered 1 (#1 is the big toe) Phalanges 5-3 phalanges in each toe except big toe - proximal phalanx - middle phalanx big toe does not have - distal phalanx Joints Joints functional joints between bones Immovable Joints occur between bones that come into close contact with one another separate by a thin layer of fibrous connective tissue or cartilage Ex. flat bones of the cranium (in sutures) Slightly Movable Joints - connected by disks of fibrocartilage of by ligaments Ex. vertebral column have limited movement Freely Movable Joints ( also called synovial joints) - covered with hyaline cartilage and held together by a tube-like capsule of dense fibrous tissue

7 - joint capsule- outer layer of ligaments and an inner lining of Synovial membrane which secretes synovial fluid Ex. Knee Joint