Bones and joints

1. Bones and joints HBS 3B

2. Label the diagrams

3. A – dendrite B – nucleus C – myelin sheath D – axon E – Schwann cell F – side or colateral branch of axon G – node of Ranvier H - motor end plate/axon terminal I - neurilemma Label the diagrams A – motor neuron B – connector neuron C – sensory neuron 1 – cell body of the sensory neuron 2 – synapse 3 – cell body of connector neuron 4 – synapse 5 – axon of motor neuron 6 dendrite of motor neuron 7 – muscle fibre 8 – motor end plate 9 – dendrite of sensory neuron 10 – receptor cell

4. The human skeleton

5. Functions of the skeleton The skeleton has a number of functions: • support • movement • protection • storage • blood cell manufacture

6. EXTERNAL STRUCTURE OF A LONG BONE PROXIMAL EPIPHYSIS DIAPHYSIS (SHAFT) DISTAL EPIPHYSIS CONDOYLE

7. Internal structure of a bone 1 = articular cartilage 2 = spongy or cancellous bone 3 = compact bone 4 = periosteum 5 = nutrient artery 6 = diaphysis or shaft 7 = Haversian system

8. Functions of bone structures 1. allows smooth movement at the joint 2. filled with red marrow. Red marrow is important for manufacture of red cells, and storage of minerals 3. strength and support 4. is responsible for laying down bone on its inner surface (the outer surface of the shaft), to allow bone growth and repair, as well as providing a surface for the attachment of tendons Endosteum is responsible for laying down bone on its outer surface (the inner surface of the shaft), to allow bone growth and repair 5. provide nutrients and oxygen for the bone. Yellow marrow (fat) fills the cavity of the shaft

9. This is the type of tissue that makes up articular cartilage.Cartilage has relatively few cells and lots of matrix to make it strong and slightly elastic

10. This is compact bone seen from aboveYou can see several haversian systems side by sideCompact bone has quite a few cells but also lots of rocky matrix to make it strong

11. Spongy Bone Reddish colour, • Softer than compact bone because there are more spaces in spongy bone • This is where the red marrow is • Blood cells are made in the red marrow of bones • Provides support for the skeleton without the heavy weight of compact bone

12. Articular cartilage shiny, bluish colour hard but still slightly elastic Is for protection of end of bone Is for shock absorption Loss of articular cartilage is called osteoarthritis. has a poor blood supply Compact bone white coloured tissue hard, bony/rocky Is for support is made of columnar shaped structures called haversian systems has a good blood supply

13. Microscopic structure of bone Describe the main features and roles of the following in bone: • Matrix – non-cellular material, secreted by osteocytes – consists of protein with large amounts of inorganic salts (eg calcium and phosphotes) • Haversian system – or osteons – are units of organisation found in compact bone. These run parallel to the length of the bone and provide strength. • Osteocytes – bone cells – these make the matrix and are found within the lacunae – small spaces in the matrix • Lamellae – concentric layers of matrix • Canaliculae – tiny canals running between lacunae, containing projections from osteocytes • Trabeculae – irregular arrangements of bony plates found in spongy bones. Osteocytes are found within the spaces of these plates

14. Microscopic structure of cartilage Describe the main features and roles of the following in cartilage: • Chondrin – protein-carbohydrate matrix • Fibres – protein called collagen that are embedded in the chondrin • Chondroblasts – cells that secrete matrix • Chondrocytes – mature chondroblasts, fully surrounded by matrix • Lacunae – small spaces containg the chondroblasts/chondrocytes • Perichondrium – fibrous layer covering cartilage. This contains blood vessels which supply the cartilage with nutrients

15. Types of cartilage Describe the main characteristics of • Hyaline cartilage – many tightly packed very fine collagenous fibres. This gives great strength and flexibility. Examples include articular cartilage and the rings of bronchi and trachea • Elastic cartilage – contains elastic fibres as well as collagen fibres, which are not so tightly packed. An example is the outer ear • Fibro-cartilage – has parallel bundles of thick collagenous fibres which are less compacted than hyaline cartilage and so can be compressed slightly. Examples include intervertebral discs, articular cartilage of the knee and tissue joining the 2 sides of the pelvis

16. Joints • A joint is a point of the skeleton at which two or more bones meet. • A joint allows the skeleton to move (or articulate) at that point. • Joints are points where the bones grow • There are three kinds of joints in the human skeleton 1. Fixed or fibrous joints 2. Slightly movable (Cartilaginous) joints 3. Freely movable (Synovial) joints

17. Fixed (Fibrous) joints allow no movement.They do allow the bone to flex or give under pressure.They are found between the bones of the skullWhen the baby is born some of these joints are open…the fontanelle

18. Slightly movable or Cartilaginous joints allow a little movement.Examples of cartilaginous joints include the pubis symphysisand intervertebral discs

19. Freely movable or Synovial joints allow a wide range of movements.An example of a Synovial joint is the hip joint

20. There are six types of Synovial Joints 1. Ball and socket joint…eg hip, shoulder 2. Hinge joint…eg elbow, knee 3. Pivot joint…eg atlas – axis joint 4. Gliding joint…eg between two vertebrae 5. Saddle joint…eg thumb joint 6. Condyloid joint …eg wrist bones – radius & ulna

21. 1. The Ball and Socket joint Consists of a round head at the end of one bone that fits into a cup – shaped depression in the other bone called a socket Can move in three dimensions up and down forward and backwards round and round (circumduction) Examples are hip and shoulder

22. 2. The Hinge joint • Consists one upper bone meeting two lower bones. • Hinge joints can open (extension) and close (flex)

23. Pivot joint Pivot joints come in several different shapes. The easiest to visualise is the Atlas – Axis joint in the spine Pivot joints allow rotational movement only Another example of a pivot joint is the radius – ulna that allows us to rotate our wrist

24. Gliding joint • Examples include the wrist and the vertebral processes • Gliding joints can flex, extend and rotate

25. Saddle joint • The thumb is a saddle joint • Thumbs can move in three directions; flex, extend rotate

26. 6. Condyloid joint • Condyloid joints can flex, extend and manage a little rotation • Examples include the joints between finger bones

27. Structure of a synovial joint

28. Synovial joints Describe the functions of the following structures: • Synovial capsule surrounds the joint and helps stabilise it and hold it all together • Synovial membrane is thin and smooth, to reduce friction, and secretes synovial fluid • Synovial fluid is thick and sticky, and acts as a lubricant for the joint • Articular cartilage provides a smooth surface to reduce friction as the bones move across each other • Articular disc are cartilaginous discs which act as shock absorbers • Bursae are fluid filled sacs which act as shock absorbers • Accessory ligaments join the bones and keep them together Three factors keeping articular surfaces in contact are • The fit of the articulating bones • The strength of the joint ligaments • Tension provided by muscles around the joint

29. The knee joint

30. The knee joint 1 – tendon 2 – patella 3 – bursa 4 – synovial membrane 5 – bursa 6 – menisci (articular discs) 7 – cruciate ligaments 8 – articular cartilage 9 - synovial capsule 10 – fibula 11 – femur 12 – ligament 13 – tibia

31. Movements possible at synovial joints • Flexion is the bending of a joint • Extension is the straightening of a joint • Abduction is movement of a joint away from the body • Adduction is movement of a joint towards the body • Rotation is movement of a bone around its long axis • Circumduction is circular movement • Pronation is rotation of the hand so the palm faces backwards • Supination is rotation of the hand so the palm faces forwards

32. Sample multiple choice Which part of the structure shown above increases the speed of nerve impulse transmission? (a) A (b) B (c) C (d) D Which one of the following statements about the neuron shown above is correct? (a) This neuron does not show evidence of a Schwann cell. (b) Structure B will produce the myelin sheath. (c) Structure D receives impulses from other neurons. (d) Structure A transmits impulses to the cell body.

33. Sample multiple choice Which part of the structure shown above increases the speed of nerve impulse transmission? (a) A (b) B (c) C (d) D Which one of the following statements about the neuron shown above is correct? (a) This neuron does not show evidence of a Schwann cell. (b) Structure B will produce the myelin sheath. (c) Structure D receives impulses from other neurons. (d) Structure A transmits impulses to the cell body.

34. Practice exam question Patients who are admitted to hospital due to damage to their cerebrum experience a loss of function in many parts of their body and yet a number of bodily functions (eg heart beat) continue to work normally. a) Describe the symptoms that you might expect to see in a patient with cerebral damage and relate these to the functions of the cerebrum. b) Give an explanation for how the body is able to still survive in the absence of a fully functioning cerebrum.

35. Practice exam question Patients who are admitted to hospital due to damage to their cerebrum experience a loss of function in many parts of their body and yet a number of bodily functions (eg heart beat) continue to work normally. a) Describe the symptoms that you might expect to see in a patient with cerebral damage and relate these to the functions of the cerebrum. Sensory areas in the cerebral cortex interpret impulses from receptors Motor areas in the cerebral cortex control muscle movements Association areas in the cerebral cortex are concerned with intellectual and emotional processes (eg thinking, memory, etc) Certain areas in the cerebrum are also associated with particular task eg reading, writing, speech, etc Therefore we would expect the symptoms would vary according to the area damaged – but may include impairment of the senses, loss of ability to control movement or difficulty with some tasks eg reading, writing or talking or loss of memory or problem solving abilities b) Give an explanation for how the body is able to still survive in the absence of a fully functioning cerebrum. Lower centres of the brain eg the hypothalamus and medulla are responsible for control of autonomic functions such as breathing, heart rate, blood pressure, secretion of digestive juices, movement of alimentary canal,,body temperature, sympathetic and parasympathetic responses eg diameter of eye, vasodilation and vasoconstriction So long as they are undamaged the body can still survive.