Lecture note for 200 level students Skeletal system.pptx

lecture note

1. SKELETAL SYSTEM BY SADIQ RABIU UMAR B.Sc. (YUMSUK), M.Sc. (BUK In view), MASSON AMINU DABO COLLEGE OF HEALTH SCIENCES AND TECHNOLOGY KANO STATE NIGERIA. GENERAL STUDIES UNIT 2022/2023 session   1/30/2023 1

2. Contents Introduction Division of skeletal system Axial skeleton Appendicular skeleton Clinical Anatomy 1/30/2023 2

3. Introduction Skeleton: is a bony frame work which gives support to the body structures. The s keletal system ( osteology ) consists of bones, joints and cartilages, it provides shape, support, protection and locomotion to the body. Bone: is a highly specialized, hard form of connective tissue that makes up most of the skeleton. Its major constituent (65%) is a mixture of calcium salt, mainly calcium phosphate. Cartilage: is a resilient, semi-rigid form of connective tissue that forms parts of the skeleton. Ligament: are bands of tough, elastic connective tissue that surround a joint to give support and limits the joint’s movement 1/30/2023 3

4. Con.t’ The periosteum and perichondrium are fibrous connective tissue that cover bone and cartilage respectively and nourish the external aspects of the skeletal tissue . BONE DEVELOPMENT All bones derive from mesenchyme (embryonic connective tissue) by two different processes Intramembranous ossification (directly from mesenchyme) and Endochondral ossification (from cartilage derived) from mesenchyme. The histology of a bone is the same by either process . Type of Bones Cancellous  (spongy bone or trabecular bone ) Compact bone  (dense bone or cortical bone) 1/30/2023 4

5. Cont.’ There are three types of bone cell Osteoblasts, bone-building cells are are responsible for the deposition of both inorganic salts and osteoid in bone tissue. Osteocytes, mature bone cells these are mature bone cells that monitor and maintain bone tissue , and are nourished by tissue fluid in the canaliculi that radiate from the central canals. Osteoclasts, bone-reabsorbing cells t hese cells breakdown bone, releasing calcium and phosphate. They are very large cells with up to 50 nuclei, which have formed from the fusion of many monocytes. Note: A good balance of osteoblast and osteoclast activity, maintains normal bone structure and functions. 1/30/2023 5

6. Functions of Skeletal S ystem Besides contributing to body shape and form our body bones, perform several important body functions. It provides support to the body (forms the internal framework that supports the body and houses its soft organs) Forming the boundaries of the cranium, thorax and pelvis and protecting the organs they contains Haemopoiesis, the production of blood cells in red bone marrow Minerals storage, especially calcium-phosphate Allowing movement of the body as a whole and parts of the body, by forming joints that are moved by muscles. Provides place for attachment to muscles and tendons. 1/30/2023 6

7. Hormonal Regulation of Bone Growth There are some hormones that play a role in regulating the growth, size and shape of bones and these includes: Growth hormone and thyroid hormones (thyroxine and tri- iodothyronine ); its important especially during infancy and childhood. Deficiency or excess secretions of these hormones result in abnormal development of the skeleton. Testosterone and oestrogen hormones : these hormones control the physical changes that occur at puberty and help to maintain bone structure throughout life. Calcitonin and parathyroid hormones: these control blood levels of calcium by regulating its uptake into and release from bone. 1/30/2023 7

8. Cont.’ Calcitonin increases calcium uptake into bone (reducing blood calcium), and parathyroid hormone decreases it (increasing blood calcium) Exercise and bone: weight-bearing exercise stimulates thickening of bone, strengthening it and making it less liable to fracture. Lack of exercise reverses these changes, leading to lighter and weaker bones. Diet and bone: healthy bone tissue requires adequate dietary calcium and vitamins A, C and D . And smaller amount of other minerals such as iron and manganese are essential for adequate mineralization of bone. 1/30/2023 8

9. Classification of Bones 1/30/2023 9

10. Cont.’ Long bones: These consist of a shaft and two extremities. As the name suggest, these bones are longer than they are wide. Most long bones are found in the limbs; examples include the femur, tibia and fibula, humerus and ulna etc . Short, Irregular, Flat, and S esamoid bones: These bones have no shafts or extremities and are diverse in shape and size. Short bone e.g.. Carpals and tarsals of the feet, irregular bone e.g.. Vertebral bones and bones of the skull. Flat bones e.g.. Scapula, sternum, ribs and Sesamoid bones e.g.. Patella (knee cap) 1/30/2023 10

11. Blood and nerve supply One or more nutrient arteries supply the bone shaft; the epiphyses have their own blood supply, although in the mature bone the capillary networks arising from the two are heavily interconnected. •Short, irregular, flat and sesamoid bones These have a relatively thin outer layer of compact bone, with spongy bone inside containing red bone marrow. 1/30/2023 11

12. Division of skeletal system The human skeleton is subdivided into two major divisions:- Axial and Appendicular Skeleton . Axial skeleton: forms the vertical, central axis of the body and includes all bones of the skull, sternum or breast bone, ribs, and vertebral column. It serves to protect the brain, spinal cord, heart, and lungs. It also serves as the attachment site for muscles that move the head, neck, and back, and for muscles that act across the shoulder and hip joints to move their corresponding limbs. 1/30/2023 12

13. Division of skeletal system 1/30/2023 13

14. Axial Skeleton SKULL The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones and the cranial vault. In the adult, the skull consists of 22 individual bones, 21 of which are immobile and united into a single unit. The 22 bone is the mandible (only moveable bone of the skull). 1/30/2023 14

15. Cont.’ Sutures of the skull (joint of the skull): there are four (4) in number. Coronal suture Frontal suture Sagittal suture Lamboidal suture Squamous suture Bones of the cranium: 1 frontal bone 2 parietal bone 2 temporal bone 1 occipital bone 1 sphenoid bone 1 ethmoidal bone 1/30/2023 15

16. Con.t’ Vertebral Column It is also known as the spinal column or spine. It consists of a sequence of vertebrae, each of which is separated and united by an intervertebral disc . The vertebral column in an adult typically consists of 33 vertebrae arranged in five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal . Significant motion occurs only between the 25 superior vertebrae. Of the 9 inferior vertebrae, the 5 sacral vertebrae are fused in adults to form the sacrum, and after approximately age 30, the 4 coccygeal vertebrae fuse to form the coccyx. 1/30/2023 16

17. Con.t’ 1/30/2023 17

18. Con.t’ Thoracic Cage The thoracic cage (rib cage) forms the thorax (chest) portion of the body. It consists of the 12 pairs of ribs with their costal cartilages and the sternum . The ribs are anchored posteriorly to the 12 thoracic vertebrae (T1–T12). The thoracic cage protects the heart and lungs. 1/30/2023 18

19. Appendicular Skeleton The appendicular skeleton includes all the bones of shoulder region with upper limbs, and pelvic region with the lower limbs. The Pectoral Girdle The bones that attach each upper limb to the axial skeleton form the pectoral girdle (shoulder girdle). This consists of two bones, the scapula and clavicle. 1/30/2023 19

20. Cont.’ 1/30/2023 20

21. Cont.’ Bones of the Upper L imbs (Arms and Hands) Humerus is the single bone of the upper arm region. The head articulates with the glenoid cavity of the scapula to form the glenohumeral joint . The margin of the smooth area of the head is the anatomical neck of the humerus. The surgical neck is a common site of arm fractures . Ulna and Radius The ulna is located on the medial side of the forearm, and the radius is on the lateral side. These bones are attached to each other by an interosseous membrane. 1/30/2023 21

22. Con.t’ Carpals, Metacarpals and Phalanges 8 carpal bones in 2 rows of 4 bones form wrist. 5 metacarpal bones, numbered 1 to 5 from thumb to little finger, join the wrist bones 14 phalanges (digits), 3 for each phalange except the thumb, which has only 2 (Proximal, middle, & distal ) Thumb has a Sesamoid bone in its flexor tendon and o ther Sesamoid may occur in joints of fingers 1/30/2023 22

23. Con.t’ The Pelvic Girdle and Pelvis The pelvic girdle (hip girdle) is formed by four bones: the right and left hip bones, the sacrum, and the coccyx . It serves as the attachment point for each lower limb . It forms immobile, weight-bearing structure. 1/30/2023 23

24. Con.t’ Bones of the Lower Limb Like the upper limb, the lower limb is divided into three regions: thigh, leg and foot regions . The lower limb contains 30 bones are the femur, patella, tibia, fibula, tarsal bones, metatarsal bones, and phalanges. 1/30/2023 24

25. Con.t’ Tibia and Fibula The tibia (shin bone) is the medial bone of the leg and is larger than the fibula, with which it is paired the tibia is the main weight-bearing bone of the lower leg and the second longest bone of the body, after the femur . The fibula is the slender bone located on the lateral side of the leg . The fibula does not bear weight. It serves primarily for muscle attachments and thus is largely surrounded by muscles. 1/30/2023 25

26. Con.t’ Tarsals, Metatarsals and Phalanges The posterior portion of the foot is formed by a group of seven bones, each of which is known as a tarsal bone The mid-foot contains five elongated bones, each of which is a metatarsal bone . The toes contain 14 small bones, each of which is a phalanx bone of the foot. 1/30/2023 26

27. Joints and its classifications 1/30/2023 27 Joint: Is the site at which any two or more bones articulate or come of together (the end or edges of the bones are held together by connective tissues ). It allow flexibility and movement of the skeleton. In some joints the participating bones are fastened together so firmly that no movement between them is possible . Classification of joints Fibrous joints: Synovial joints : Cartilaginous joints :

28. Cont.’ Fibrous joints: The bones forming these joints are linked with tough, fibrous material. Such an arrangement often permits no movement. For example, the joints between the skull bones, the sutures, are completely immovable. This fibrous joint allows a limited amount of movement and stabilizes the alignment of the bones. Synovial joints : Synovial joints are characterized by the presence of a space or capsule between the articulating bones. The ends of the bones are held close together by a sleeve of fibrous tissue, and lubricated with a small amount of fluid. Synovial joints are the most moveable of the body Cartilaginous joints : These joints are formed by a pad of tough fibrocartilage that acts as a shock absorber. The joint may be immovable, as in the cartilaginous epiphyseal plates, which in the growing child links the diaphysis of a long bone to the epiphysis. 1/30/2023 28

29. Types of Synovial Joints Ball and socket joints : The head of one bone is ball-shaped and articulates with a cup-shaped socket of another. Examples include the shoulder and hip. Hinge joints: The articulating ends of the bones fit together like a hinge on a door, and movement is therefore restricted to flexion and extension. Example knee, ankle and the joints between the phalanges of the fingers and toes (interphalangeal joints) and the elbow joint. Gliding joints : The articular surfaces are flat or very slightly curved and glide over one another, but the amount of movement possible is very restricted; this group of joints is the least movable of all the synovial joints. Examples include the joints between the carpal bones in the wrist, the tarsal bones in the foot, and between the processes of the spinal vertebrae. 1/30/2023 29

30. Cont.’ Pivot joints : These joints allow a bone or a limb to rotate. One bone fits into a hoop-shaped ligament that holds it close to another bone and allows it to rotate in the ring thus formed. Example rotation of the head. Condyloid joints: A condyle is a smooth, rounded projection on a bone and in a condyloid joint it sits within a cup-shaped depression on the other bone. Examples include the joint between the condylar process of the mandible and the temporal bone, and the joints between the metacarpal and phalangeal bones of the hand, and between the metatarsal and phalangeal bones of the foot. Saddle joints : The articulating bones fit together like a man sitting on a saddle. The most important saddle joint is at the base of the thumb, between the trapezium of the wrist and the first metacarpal bone. 1/30/2023 30

31. Disorder of B one and J oints Rickets and osteomalacia: In both conditions, bone is inadequately mineralised, usually because of vitamin D deficiency, or sometimes because of defective vitamin D metabolism. Paget’s disease : Paget’s disease is a disorder of bone remodelling, where the normal balance between bone building and bone breakdown becomes disorganised and both osteoblasts and osteoclasts become abnormally active. Other includes: Osteoporosis, Achondroplasia, Rheumatoid arthritis 1/30/2023 31

32. 1/30/2023 32 THANK YOU TEST (10 marks)