Skeletal System Part B Skeletal System Part B VERTEBRAL COLUMN VERTEBRAL COLUMN Extends from the skull to the pelvis and protects the spinal cord. It is composed of a vertebrae separated by intervertebral disk. An infant has 33 vertebral bones and an adult has 26 The vertebral bones have 4 curvatures- Cervical, thoracic, lumbar, and pelvic. VERTEBRAL COLUMN Vertebra A Typical Vertebra All vertebrae have a common structural pattern. Each vertebra consists of a body, vertebral arch, vertebral foramen and vertebral canal. Vertebra Cervical Vertebrae (7) C1 and C2 are the smallest and are unusual. Often called the atlas and the axis They have no intervertebral disc between them and are highly modified. The dens of the axis (2nd vertebra) provides a pivot for the atlas when the head is turned from side to side. C1 has no spinous process nor body. Vertebra Cervical Vertebrae (7) The remaining cervical vertebra help to make up the neck. Vertebra Thoracic Vertebrae (12) Larger than the cervical Slope downward and faces the sides of bodies articulate with the ribs Vertebra Lumbar Vertebrae (5) Large and strong Vertebra Sacrum Starts as 5 bones but fuses together between 18-30 Triangular structure that bears rows of dorsal sacral foramina United with coxal bones at the sacroiliac joints. Provides a guide for determining the size of the pelvis. Sacrum Vertebra Coccyx Composed of 4 bones that fuse together by age 25 Forms the lowest part of the vertebral column Acts a shock absorber when a person sits. THORACIC CAGE Includes the ribs, thoracic vertebrae, sternum, and costal cartilages It supports the shoulder girdle and upper limbs, protects viscera, and functions in breathing. THORACIC CAGE RIBS 12 pairs of ribs are attached to the 12 thoracic vertebrae First 7 rib pairs are called true ribs, join the sternum directly by their costal cartilages. Remain 5 pairs called false ribs, their cartilages do NOT reach the sternum directly. THORACIC CAGE RIBS In fact the first 3 of the false ribs join the cartilage of the 7th true rib. The remain two ribs are called floating ribs, because they have no attachment to any cartilage. Typical rib has a shaft, head, and tubercle that articulate with the vertebrae. THORACIC CAGE Sternum is a flat elongated bone that develops in three parts- an upper Manubrium, a middle body, and a lower xiphoid process. Articulates with costal cartilages and clavicles. PECTORAL GIRDLE Composed of 2 clavicles (collar bone) and 2 scapulae (shoulder blades) It forms an incomplete ring that supports the upper limbs and provides attachments for muscles that move the upper limbs PECTORAL GIRDLE CLAVICLE Rodlike bones that run horizontally between the sternum and shoulders. Hold shoulders in place and provide attachments for muscles. Has a medial (sternal) end and a lateral (acromial ends) PECTORAL GIRDLE PECTORAL GIRDLE SCAPULA Broad, triangular bones Articulate with the humerus of each limb and provides attachment for muscles of the upper limbs and chest. Has a Acromion process that forms the tip of the shoulder A Coracoid process that curves anteriorly and inferiorly to the clavicle. Has a Glenoid cavity, it articulates with the head of the arm bone (humerus). UPPER LIMBS Providethe frameworks and attachments of muscles, and function in levers that move the limb and its parts. UPPER LIMBS Humerus-extends from scapula to elbow. Radius-Located on thumb side of the forearm between elbow and wrist Ulna-Longer than radius and overlaps the humerus posteriorly. Hand- Has a wrist, palm, and 5 fingers 8 carpals that form a carpus, 5 metacarpals, and 14 phalanges. HUMERUS Its upper end has a smooth round head that fits into the glenoid cavity. Below the head are two processes a greater tubercle on the lateral side and a lesser tubercle on the anterior side. Near the middle of the bony shaft on the lateral side is a rough V-shaped area called the deltoid tuberosity. On the bottom section of the humerous are Epicondyles which provide attachments for muscles and ligaments of the elbow. (medial and lateral) HUMERUS HUMERUS Radius Radius-Located on thumb side of the forearm between elbow and wrist. Shorter than the ulna A thick-disklike head at the upper end On the radial shaft just below the head is a process called the radial tuberosity. An attachment for muscles. At the distal end of the radius, a lateral styloid process provides attachments for ligaments of the wrist. Ulna Longer than radius and overlaps the humerus posteriorly. A Medial Styloid process at the distal end of the ulna proves attachemnts for ligaments of the wrist. The Ulna also has a head…on the opposite side as the radius Styloid Process Remember….when thinking of medial/lateral processes…you must put your arms in the correct anatomical position! Radius and Ulna Wrist and Hand The wrist joint is at the junction of the forearm and the hand. The skeleton of the wrist consists of 8 small carpal bones that are firmly bound in two rows of four bones each. The resulting compact mass is called a carpus. Wrist and Hand • Hand- Has a palm, and 5 fingers. • Five metacarpals bones, one in line with each finger, form the framework of the palm. These bones are cylindrical, with rounded distal ends that form the knuckles of clench fist. These bones are numbered 1-5 beginning with the metacarpal of the thumb. Wrist and Hand • Hand- Has a palm, and 5 fingers. • Phalanges are the finger bones. There are three in each finger. A proximal, a middle, and a distal phalanx and two in the thumb. Wrist and Hand PELVIC GIRDLE The PG consists of 2 coxal bones (hipbones) that articulate with each other anteriorly and with the sacrum posteriorly. Along with sacrum and coccyx they form the pelvis. Provides support for the weight, and attachments for muscles, and protects visceral organs. PELVIC GIRDLE Each coxae (hipbone) develops from three key parts. An ilium, an ischium, and a pubis. These parts fuse in the region of a cup- shaped cavity called acetabulum. This depression, on the lateral surface of the hipbone receives the rounded head of the femur. PELVIC GIRDLE Illium- largest portion of the coxal bone, flares outward, forming the prominence of the hip. The margin of the prominence is called the Iliac Crest. Joins the sacrum at sacroiliac joint PELVIC GIRDLE Ischium- Lowest portion of the coxa bones. L-shaped. PELVIC GIRDLE Pubis- constitutes the anterior portion of the coxa. The two pubic bones come together at the midline to form a joint called the smyphysis pubis. The angle these bones form below the symphysis is the pubic arch. PELVIC GIRDLE COXA(E) PELVIC GIRDLE Greater and Lesser Pelvis Below the pelvic brim; greater pelvis is above it Lesser pelvis functions as a birth canal; Greater pelvis helps support abdominal organs. PELVIC GIRDLE Difference: Male/Female Female: Tilted forward, adapted for childbearing, cavity of the true pelvis is broad, shallow, and has a greater capacity. Bones are lighter, thinner, and smoother The acetabula are smaller and farther apart The pubic arch is broader and more rounded. The sacrum are wider, shorter, sacral curvature is accentuated. The coccyx more movable and much straighter. PELVIC GIRDLE Difference: Male/Female Male: Tilted less far forward, adapted for support of a male’s heavier build and stonger muscles; cavity of the true pelvis is narrow and deep. Bones are heavier and thicker; and markings are more prominent The acetabula are larger and closer together. The pubic arch is more acute. The sacrum is narrow; longer; The coccyx less movable and curves ventrally. LOWER LIMBS Providethe frameworks of the thigh, leg, and foot. FEMUR FEMUR- Extends from the hip to knee; Longest bone in the body. A large, rounded head at its proximal end which projects medially into the acetabulum of the coxal bone FEMUR Just below the head are a constriction, or neck and two large processes. A greater trochanter and a lesser trochanter. These processes provide attachments for muscles of the lower limbs and buttocks. FEMUR • At the distal end of the femur are two rounded processes, the lateral and medial condyles, articulate with the tibia of the leg. • On the medial surface at its distal end is a prominent medial epicondyle, and on the lateral surface is a lateral epicondyle. These projections provide attachments for muscles and ligaments. FEMUR FEMUR PATELLA Flat seasamoid bone located in a tendon that passes anteriorly over the knee. Controls the angel of this tendon and functions in lever actions associated with lower limbs movement. PATELLA TIBIA AKA- Shin Bone, Larger of the two leg bones. Located on the medial side of the leg TIBIA Its proximal end is expanded into medial and lateral condyles. Below the condyles on the anterior surface is a process called the tibial tuberosity. At its distal end, the tibia expands to form a prominence on the inner ankle called the medial malleolus, which is an attachment for ligaments. (Its lateral cousin is on the fibula). Fibula A long slender bone located on the lateral side of the tibia. Ends are slightly larger, with a proximal head and a distal lateral maleolus. The foot is an amazing and intricate structure. Ankle and Foot The bones in your feet make up about one-fourth of all the bones in your body. Each foot contains 26 bones. It takes 33 joints, 107 ligaments, 19 muscles and numerous tendons to hold the bones in place and to move in a variety of ways. Ankle and Foot In addition, each foot has about 125,000 sweat glands that excrete as much as a half a pint of moisture each day. Ankle and Foot Consists of an tarus, a metatarsus, and five toes. The tarsus is composed of seven tarsal bones. These bones are arranged so that one of them, the talus, can move freely. Ankle and Foot The largest of the tarsals, the calcaneus or heel bone. It helps to support the weight of the body and provides an attachment for muscles that move the foot. Ankle and Foot The metatarsus consists of five elongated metatarsal bones. They are numbered 1-5, beginning on the medial side. Ankle and Foot The phalanges of the toes are shorter, but otherwise similar to those of the fingers, and align, and articulate with the metatarsals. Each toe has three phalanges, a proximal, a middle, and distal phalanx- except the big toe which only has the first two. How well can you do? On a scrape piece of paper take this mini-quiz! How did you do???
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