L2. Skeleton PDF - Anatomy

Skeleton  By the end of the lecture, the students will be able to: Describe the divisions of skeletal Learning system, types of bones, structure of long bone and periosteum Outcomes  Following an automobile accident, a 22-year-...

Skeleton  By the end of the lecture, the students will be able to: Describe the divisions of skeletal Learning system, types of bones, structure of long bone and periosteum Outcomes  Following an automobile accident, a 22-year- old woman with acute pain and swelling in her left forearm sought the emergency room. Following an X-ray, the left ulna was fractured. What kind of bone is this? Case scenario A. Long B. Short C. Irregular D. Flat  Functions of skeleton Support of the body Give shape of the body Protection of soft organs Movement due to attached skeletal muscles Storage of minerals and fats Blood cell formation Bone: It consists of bone cells, intercellular matrix made of collagen fibers, inorganic salts and minerals  Classification of bones Compact bone: hard ,dense like ivory forming surface of bones Cancellous (spongy) bone: present inside bone & consists of trabeculea with spaces like a sponge. 6  The human adult skeleton consists of 206 named bones Bones of the skeleton are grouped into two Divisions of principal divisions according to bone position: the Skeletal 1. Axial skeleton Consists of the bones that lie around the System longitudinal axis of the human body  2. Appendicular skeleton Divisions of Consists of the bones of the upper and the Skeletal lower limbs (extremities), plus the bones forming the girdles that connect the limbs to System the axial skeleton  The Axial Skeleton Forms the longitudinal part of the body Contains Skull Sternum Ribs Vertebral column Hyoid bone  Vertebral Column (Regions) Cervical Region Cervical vertebrae (C1–C7) Thoracic Region Thoracic vertebrae (T1–T12) Lumbar Region Lumbar vertebrae (L1–L5) Sacrum The sacrum is a triangular bone formed by the union of five sacral vertebrae (S1–S5) Coccyx It is formed by the fusion of four coccygeal vertebrae  The Appendicular Skeleton Shoulder Bones of upper limb girdle Shoulder girdle: scapula& clavicle Arm connect upper limb to trunk at sternoclavicular joint Arm: humerus Forearm: radius &ulna Hand: Forearm Carpal (8) Metacarpals (5) numbered from one to five from lateral to medial Phalanges 3 in each finger except Hand thumb 2  The Appendicular Skeleton Bones of lower limb Pelvic girdle: hip bone connect lower limb to axial skeleton at sacroiliac joint Thigh : femur Leg: tibia & fibula Foot o Tarsal bones(7) o Metatarsals (5) numbered from medial to lateral o Phalanges 3 in each finger except big toe 2  According to bone shape: Divisions of the bone Shape of Bones Bones can be classified into 6 types based on shape: Long Short Flat Irregular Pneumatic Sesamoid Shapes of the bone 1. Long bones: e.g. humerus, femur, metacarpals and phalanges 2. Short bones: e.g. carpal and tarsal bone 3. Flat bones: e.g. vault of the skull, ribs, sternum and scapula 4. Irregular bones: have various shape (e.g. vertebrae, hip bone) 5. Pneumatic bones: these are the bones containing air spaces ( maxilla and frontal bones) 6. Sesamoid bones: are small bones deposited or buried in the tendons of some muscles, as patella Structure of long bone Diaphysis: shaft of bone formed of outer compact bone covered by periostium and has an inner medullary cavity Two epiphysis: at the 2 ends of bone, formed of cancellous bone covered by compact, at the articular surface is covered by hyaline cartilage 21  Two metaphysis: part of diaphysis close to epiphysis Two epiphyseal plates of cartilage: cartilaginous disc between epiphysis & diaphysis for growth of bone in length  Periosteum It is a fibrous connective tissue covering the surrounding bone except at the site of articular cartilage It is very sensitive and has rich nerve supply  Functions: Give attachment to muscles, tendons & ligaments Source of blood supply Growth of bone in width Healing of fractured bones Bone marrow It is the fatty vascular tissue filling the medullary cavity of the long bone and the meshes of all the cancellous bone It concerned with the formation of blood cells The form of the bone marrow vary with the age: 1. At birth :only red bone marrow fills all the marrow cavities of all bone 2. During childhood: yellow bone marrow replaces the red one in the distal long bones 3. In adults :the red bone marrow is only present in the meshes of spongy bones ( in the skull, vertebrae, sternum, ribs, hip, the upper end of the femur and the humerus. The medullary cavity of all the long bones contains only yellow bone marrow  Classification according to ossification Membranous Ossification: bone develop from membrane of connective tissue called mesenchymal ossification ; ✓ skull bones ✓ shaft of clavicle ✓ facial bones 27 Cartilaginous Ossification : Bone develop from cartilage e.g. long bones, vertebral column and thoracic cage Starts in intra uterine life 8th week by appearance of primary center of ossification in middle of shaft the part ossified is called diaphysis After birth secondary center of ossifications appear in ends of long bones this part is called epiphysis leaving a plate of cartilage for elongation of bones called epiphyseal plate Complete fusion occurs at puberty in girls earlier than boys  Case scenario, Clinical Correlate, Practice points 65 years old female came to ER after road traffic accident with severe pain and swelling in her left leg. After X-ray there was fracture in left tibia. What is the type of this bone a) Long b) Short c) Irregular d) Flat Questions Which is the type of bone of the middle phalanx of the little finger: A. Long B. Short C. Irregular D. Flat Questions Which is the type of bone of thoracic vertebrae: A. Long B. Short C. Irregular D. Flat Which of the following is an example of pneumatic bone A. Humerus B. Skull C. Tibia D. Sternum Discussion & Feedback  Gray's Clinically References anatomy for oriented students anatomy