Human Skeletal system

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The skeletal system includes all of the bones and joints in the body. Each bone is a complex living organ that is made up of many cells, protein fibers, and minerals. The skeleton acts as a scaffold by providing support and protection for the soft tissues that make up the rest of the body. The skeletal system also provides attachment points for muscles to allow movements at the joints. New blood cells are produced by the red bone marrow inside of our bones.
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  • 1. SKELETAL SYSTEM Prof. Amol B Deore MVP’s Institute of Pharmaceutical Sciences, Nashik (India)
  • 2. • The framework of joined bones and cartilage that protect internal organs and allow movements is called as the skeleton. • The skeletal system consists of bones and other structures that make up the joints of the skeleton. Bone is a strong and durable type of connective tissue. • It consists of mineral salts like calcium carbonate and calcium phosphate embedded in the matrix of the bone tissue. Almost 300 bones are to be present in human at birth but they become 206 in adults. Osteology is the study of bone structure and treatment of bone disorders.
  • 3. FUNCTIONS OF THE SKELETAL SYSTEM 1.Support: Skeletal system provides a boney framework for the body by supporting soft tissue and providing point of attachment for many skeletal muscles. 2.Protection: It protects vital and delicate internal organs of the body from injury. For example cranial bones protect the brain; thoracic cage protects the heart and lungs. 3.Assists in movement: Skeletal muscles attached to the bones. When muscle contact, they pull on bones and together they produce movement.
  • 4. 4. Blood cell production: bones consist of specialized cells called as red bone marrow, which produce RBCs, WBCs and platelets. This process is called as hematopoiesis. 5. Mineral reservoir: It acts as temporary reservoir for minerals, especially phosphorous and calcium, and fats which are important in muscle contraction and other functions.
  • 5. 6. Storage of energy: Fats and lipids stored in yellow bone marrow cells which act as chemical energy reserve. 7. Criminology: Skeletal system helps in Criminology for sex determination of victim based on shape of pelvic girdle; it also helps to examine the cause of death if by blunt force, stubbing, hit by objects or weapons, or by hammering on skull.
  • 6. BONE TISSUE • Bone cells are called osteocytes, and the matrix of bone is made of calcium salts and collagen. The calcium salts are calcium carbonate and calcium phosphate, which give bone the strength required to perform its supportive and protective functions.
  • 7. DIVISIONS OF THE SKELETON • The axial skeleton part consists of the bones which lie around the axis; skull (including the cranial and facial, the hyoid bone), the vertebrae, the ribs, and the sternum. • The appendicular skeleton part consists of the bones of the upper extremities or arms (including bones of the shoulder girdle) and the bones of the lower extremities or legs (including the bones of the pelvic girdle).
  • 8. AXIAL SKELETON SKULL The skull is rest on the upper end of the vertebral column. The skull consists of two sets of bones: cranial bones and facial bones. The cranium is formed by number of flat and irregular shaped bones that provide a bony protection to the brain and special sense organs like the brain, eyes and ears. Muscles for chewing and muscles for head movement attach to certain cranial bones. The bones of cranium are • 1 Frontal bone • 2 Parietal bone • 2 Temporal bone • 1 Occipital bone • 1 Sphenoid bone • 1 Ethmoid bone
  • 9. • Frontal bone is the bone of forehead. It forms part of orbital cavities (eye sockets) and prominent ridges above the eyes. • Two Parietal bone these bones form the sides and roof of the skull. They joined to each other at the sagittal suture. • The two temporal bones help form the lower sides and base of the cranium. Each temporal bone encloses an ear and consists of a fossa for articulation with the lower jaw or mandible. The temporal bones are irregular in shape. Projecting from its lower part is the zygomatic process that forms the lateral part of the cheek bone.
  • 10. • The occipital bone is a single bone that forms the back and base of the cranium. The inferior portion of this bone consists of a large opening called the foramen magnum through which the spinal cord connects with the brain. On each lower side of the occipital bone is a process called the occipital condyle. This occipital condyle articulates with the first cervical vertebra (atlas), thus allowing the head to connect with and rest onthe vertebrae. • The single sphenoid bone forms the anterior portion of the base of the cranium. It acts as an anchor binding all of the cranial bones together. • The single ethmoid bone is the principle supporting structure of the nasal cavities and helps form part of the orbits.
  • 11. SUTURES • Suture is an immovable (fixed) joint that found only between skull bones. • Coronal suture: The coronal suture is found where the frontal bone joins the two parietal bones. • Sagittal suture: The two parietal bones form the upper sides and roof of the cranium. They are joined at the sagittal suture in the midline. • Lambdoid suture: The occipital bone is a single bone that forms the back and base of the cranium and joins the parietal bones superiorly at the lambdoid suture. • Frontal suture: The frontal suture is a fibrous joint that divides the two halves of the frontal bone of the skull in infants and children. •
  • 12. FACIAL BONES • Like the bones of the cranium, the facial bones are also united by immovable sutures, with one exception: the lower jaw bone (or mandible). • This bone is capable of movement in a number of directions. It can be elevated and depressed as in talking and it can protract and retract and move from side to side as in chewing.
  • 13. • The two nasal bones are thin and delicate bones that join in a suture to form the bridge of the nose. • The two maxillary bones make up the upper jaw.The maxillary bones stand the teeth of the upper jaw. • The single mandible bone develops in two parts. It is the strongest and longest bone of the face. It consists of a U-shaped body to bear the teeth of the lower jaw. It allows the wide range of movement of the lower jaw bone. • The two lacrimal bones make up part of the orbit at the inner angle of the eye. These very small and thin bones lie directly behind the frontal process of the maxilla. Their lateral surface has a lacrimal sac or tear sac. • The two nasal bones are very thin and fragile. They help form a series of shelves in the nasal cavity where air is moistened, warmed, and filtered. • The single vomer bone is a flat bone that makes up the lower posterior portion of the nasal septum. • The hyoid bone is like a horseshoe shaped acts as a support for the tongue and its associated muscles. It also helps elevate the larynx during swallowing and speech.
  • 14. TRUNK • The sternum, ribs, and vertebral column make up the trunk (or backbone) of the axial skeleton. The vertebral column is composed of a series of bones called vertebrae. Its length is about 71 cm in adult male and 61 cm in adult female. • The vertebrae are rigid and provide support for the body but the intervertebral discs between the vertebrae allow for a high degree of flexibility. The discs and vertebrae protect the delicate spinal cord. The vertebral column is formed from a series of 33 vertebrae, separated and cushioned by the intervertebral discs.
  • 15. Typical Vertebra • Body is the thick, disc shape anterior portion which is the weight bearing part of a vertebra. Superior and inferior surfaces are rough for the attachment of intervertebral discs. • Vertebral foramen is the space between vertebral arch and body. The spinal cord passes through the vertebral foramen. The vertebral foramina of all vertebrae together form the vertebral canal. • Spinous process (spine) projects posteriorly and inferiorly from the laminae. • Two transverse processes extend laterally on each side. • Two superior articular processes articulate with vertebra superior to them. • Facets are the articulating surfaces of the articular processes.
  • 16. Types of vertebrae Types of Vertebrae a) Cervical vertebrae (7) neck b) Thoracic vertebrae (12) upper back c) Lumbar vertebrae (5) middle back Total 33 vertebrae d) Sacral vertebrae (5) lower back e) Coccyx vertebrae (4) tail bone
  • 17. • Cervical vertebrae (C1-C7) • The cervical vertebrae are the smallest vertebrae. The first two have been given special names. • Atlas (C1): The first is called the atlas; it supports the head by articulation with the condyles of the occipital bone. • Axis (C2): The second vertebra is the axis; it acts as the pivot on which the atlas and head rotate. • Thoracic vertebrae (T1-T12) • The thoracic vertebrae have two distinguishing characteristics: the long spinous process pointing downward and six facets, three on each side forarticulation with a rib. • Lumbar vertebrae (L1-L5) • The lumbar vertebrae are the largest and the strongest. They are modified for theattachment of the powerful back muscles.
  • 18. • Sacrum (S1-S5) • It consists of five vertebras fused to form a triangular and slightly curved bone. The vertebral foramina are present for the passage of spinal nerves. • Coccyx (Co1-Co4, tail bone) • The curving coccyx can move slightly to increase the size of the birth canal during delivery in the female.
  • 19. Functions of vertebral column 1)The vertebral column is a strong, flexible rod that bends anteriorly, posteriorly, laterally and rotates. 2)It forms the axis of the trunk, giving attachments to the ribs, shoulder girdle, upper limbs, pelvic girdle and lower limbs. 3)The vertebral foramina of vertebral column provide bony protection for the spinal cord and support the body. 4)It supports the skull. 5)Transverse foramina on both sides of vertebras provide opening for spinal nerves and blood vessels. 6)The intervertebral discs act as cushion and shock absorber. Thus protecting the brain. 7)It permits number of body movements.
  • 20. THORAX The term thorax refers to the entire chest. The skeletal portion of the thorax is a bony cage formed by the sternum, costal cartilage, ribs and the bodies of thoracic vertebrae. Functions of the Thorax • This bony cage encloses and protects the heart and lungs. • It also supports the bones of the shoulder girdle and the bones of the upper extremities. • It produces blood cells. This process is called hematopoiesis and occurs chiefly in red bone marrow.
  • 21. Sternum The sternum is a flat bone just under the skin in the middle front of chest. Sternum consists of red bone marrow which is the most common site for withdrawal of sample in bone marrow biopsy. It develops in three parts: the manubrium, the gladiolus, and the xiphoid process. No ribs are attached to the xiphoid but it provides attachment for some abdominal muscles. The manubrium and gladiolus have notches on each side for attachment of the first seven costal cartilages. The manubrium articulates with the clavicle to form sternoclavicular joint.
  • 22. THORACIC RIBS (12 PAIRS OF RIBS) Twelve pairs of ribs make up the sides of the thoracic cavity. Each rib articulates anteriorly with sternum and posteriorly with its corresponding thoracic vertebra. • True ribs (1st to 7th) • The upper seven pairs articulate directly with the sternum by costal fibrocartilage, they are called true ribs. • False ribs (8, 9,10th) • The lower three pairs are called false ribs. The costal cartilages of the eighth, ninth, and tenth rib pairs are attached to the cartilage of the seventh rib so they join the sternum only indirectly. • Floating Ribs (11 and12th) • Because the 11th and 12th pairs of ribs have no cartilage and do not attach at all anteriorly to sternum. Hence these “false” ribs have another name, floating ribs. Of course, all ribs attach posteriorly to the thoracic vertebrae.
  • 23. APPENDICULAR SKELETON BONES OF UPPER EXTREMITIES (UPPER LIMB) The bones of the upper extremities include the bones of the shoulder girdle (pectoral girdle), the arm, the forearm, the wrist, the hand, and the fingers. The bones of the pectoral girdle (shoulder girdle) are the scapula and the clavicle.
  • 24. SCAPULA The scapula or shoulder blade is a large, flat, triangular shaped bone located on the dorsal portion of the thorax, covering the area from the second to the seventh ribs. Acromion process of the scapula articulates with clavicle. Two other prominent bony projections on the scapula are the coracoids process, which functions as an attachment for muscles that move the arm, and the glenoid cavity which receives the head of the humerus and helps form the shoulder joint.
  • 25. Clavicle The clavicle or collarbone is a long slim bone located at the root of the neck just below the skin and anterior to the first rib. Clavicle is long ‘S’ shaped bone with double curves, one convex and one concave. The medial end of the clavicle is rounded and articulates with sternum to form sternoclavicular joint. The lateral end articulates with acromion cavity of scapula called as acromioclavicular joint.
  • 26. Humerus The humerus (arm bone) is the largest and longest bone of the upper arm. The rounded head of the humerus articulates with the glenoid cavity of the scapula to form shoulder joint (type of ball and socket joint). The head also consists of two projections of bone, greater and lesser tubercles for attachment of skeletal muscles. The distal end of humerus consists of capitulum cavity which articulates with the head of the radius. The trochlea is located medial to the capitulum which is a pulley like surface that articulates with the ulna. The coronoid fossa is anterior depression that receives part if ulna when the forearm is flexed. Olecranon fossa is a posterior depression that receives the olecranon of the ulna when the forearm is extended.
  • 27. ULNA The ulna is the longer, medial bone (little finger side) of the forearm and is longer than the radius. Its shaft is triangular and the distal or lower end is called the head. At its proximal end of the ulna is the olecranon process (or elbow). The coronoid process is an anterior projection that together with the olecranon receives the trochlea of the radius. A styloid process is on the posterior side of the distal end. Radius and ulna articulate with humerus at elbow joint.
  • 28. RADIUS The radius is the shorter, lateral bone (thumb side) of the forearm. The proximal end of the radius has a head that articulates with the capitulum of the humerus and radial notch of ulna. The styloid process of the radius articulates with some of the bones of the wrist. Radius and ulna articulate with carpals at wrist joint.
  • 29. Carpals They are also known as wrist Bones. The carpals consist of eight small bones joined to one another by ligaments. They are arranged in two rows, with four bones in each row. In the proximal row from medial to lateral they are the pisiform, triquetral, scaphoid, hamate, capitates, lunate, trapezoid, and the trapezium.
  • 30. METACARPALS (5) & PHALANGES (14) • The palm of the hand is made up of the five metacarpal bones. Each metacarpal bone consists of proximal base, intermediate shaft and distal end. The bases articulate with distal row of the carpal bones. The head articulates with the proximal phalanges of each finger. Each finger, except the thumb, has three phalanges but the thumb has only two phalanges.
  • 31. BONES OF LOWER EXTREMITIES (LOWER LIMB) The bones of the lower extremities include the pelvic girdle, which supports the trunk and provides attachment for the legs. It consists of the paired hip bones, the lower extremity include the thigh bone (femur), the kneecap, the tibia, the fibula, the ankle bones, the foot, and the toes.
  • 32. PELVIC GIRDLE
  • 33. • The pelvic girdle is actually made up of two hip bones that articulate with one another anteriorly at the pubic symphysis. The pelvic girdle provides a strong and stable support for the lower extremities on which the weight of the body is carried. The hip bones are united to form pubic symphysis. Posteriorly they articulate with the sacrum.
  • 34. Each hip bone consists of three fused bones- ileum, ischium and pubis. • Ilium: The ilium is the uppermost and largest portion of a hipbone. It forms the expanded prominence of the iliac crest. It is wider and broader in females and smaller and narrower in males. The spines act as point of attachment to the skeletal muscles.
  • 35. • Pubis: The pubis is superior and slightly anterior to the ischium. The anterior border of the pubis is called as pubic crest and its lateral end is a projection called as pubic tubercle. Between the pubis and the ischium is the large obturator foramen. • This is the largest foramen in the body and allows for the passage of nerves, blood vessels, and tendons. On the lateral side of the hip just above the obturator foramen is the deep socket called the acetabulum cavity. • All three parts of the pelvic bone meet and unite in this acetabulum cavity socket. It also receives the head of the femur to help form the hip joint. Together with sacrum and coccyx, the two hip bones of the pelvic girdle form the basin like structure called the pelvis.
  • 36. • Ischium: The ischium is the strongest portion of a hipbone and is directed slightly posteriorly. It has the rounded and thick ischial tuberosity, which you sit on, and it bears the weight of the body in the sitting position.
  • 37. Differentiate between male and female pelvic girdle Key Points Pelvic girdle in male Pelvic girdle in female 1. Greater pelvis Deep Shallow 1. Pelvic brim Heart shaped Oval shaped 1. Pubic arch Less than 90° angle Greater than 90° angle 1. Ilium More vertical Less vertical 1. Iliac crest More curved Less curved 1. Acetabulum Large Small 1. Obturator foramen Round Oval
  • 38. FEMUR The femur (or thigh bone), is the largest, longest, strongest and heaviest bone of the body. Its upper end consists of a large head that articulates with the acetabulum cavity of the pelvic bone to form Hip joint. The greater trochanter and lesser trochanter are projections that serve as point of attachment for some of thigh and buttock muscles. Its lower portion is widened into a large lateral condyle and medial condyle. It articulates with the tibia. A depressed area between the condyles on the posterior surface is called as intercondylar fossa. The patella is located between the condyles on the anterior surface.
  • 39. PATELLA The patella is also known as knee cap. It is flat and triangular lying right in front of the knee joint and is enveloped within the tendon of the quadriceps femoris muscle. Its posterior surface contains two articular facets, which articulates with medial condyle and lateral condyle of the femur bone. Patella is a movable bone and it increases the force of the muscles that straighten out the knee.
  • 40. TIBIA Tibia is also known as shin bone. It is larger, medial bone of the leg. It bears the weight of the body. The tibia is the larger of the two bones forming the lower leg. The rounded condyles of the femur articulate with the proximal end of the tibia to form knee joint. The tibial tuberocity on the anterior surface is a point of attachment for patellar ligament. The lower end of tibia forms the Ankle joint with tarsal.
  • 41. FIBULA It is the slim bone of the body. It lies parallel with and on the lateral side of the tibia. It is considerably smaller than tibia. It does not articulate with the femur but attaches to the proximal end of the tibia via its head. The distal end articulates with the talus bone of the ankle.
  • 42. TARSAL BONES (7)
  • 43. • The bones of the ankle are known as the tarsal bones. The seven short tarsal bones similar to the carpal bones of the wrist but are larger. The tarsal bones of the hindfoot are the calcaneum (heel bone/the talus/ankle bone), the navicular and the cuboid, medial, intermediate, and cuneiforms. Talus is the largest and the most superior bone of th
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