Chapter 40: The human Chapter 40: The human musculoskeletal systemmusculoskeletal system

Leaving Certificate BiologyLeaving Certificate Biology

Higher LevelHigher Level

Function of the SkeletonFunction of the Skeleton• Functions:

1.Shape and support

2.Protection: of internal organs

3.Movement: muscles use skeleton as levers

4.Production of red and white blood cells

5.Hearing: ossicles vibrate and amplify vibrations

6.Ingestion and digestion: physical digestion in the mouth

7.Storage: of minerals (calcium and phosphorus) that can be taken by the body when needed

CRANIUM

MANDIBLE

RIBS

RADIUS

ULNA

FEMUR

TIBIAFIBULA

PATELLA

PELVIS

VERTEBRAE

HUMERUSSCAPULA CLAVICLE

Structure Structure of the of the

Human Human SkeletonSkeleton

Appendicular Appendicular SkeletonSkeleton

• 126 bones:– Pectoral girdle– Pelvic girdle– Limbs

Axial SkeletonAxial Skeleton• 80 bones:

– Skull– Ossicles– Spine– Ribs– Sternum

Axial skeleton (blue)

Appendicular skeleton (pink)

Axial SkeletonAxial Skeleton

• 80 bones: skull, ossicles, vertebrae, ribs, sternum

• Skull: cranium (8 fused bones) and facial bones

• Vertebral column: 33 small bones - appears as only 26 due to fusion of the vertebrae of the sacrum (5 fused vertebrae) and coccyx (4 fused vertebrae)

Axial Skeleton - continuedAxial Skeleton - continued

• Ossicles: hammer (malleus); anvil (incus); stirrup (stapes)

• Ribs: 12 pairs originate from the vertebral column; 7 pairs are “true ribs” (attached directly to sternum); 3 pairs are “false ribs” (attached indirectly to the sternum by only cartilage); and 2 pairs are “floating ribs” (attached to spine only)

Ossicles: Hammer, Anvil, StirrupOssicles: Hammer, Anvil, Stirrup

Rib CageRib Cage

• 7 pairs of true ribs

• 3 pairs of false ribs

• 2 pairs of floating ribs

C1 - 7

T1 - 12

L1 - 5

S1 - 5

Co1 - 4

Vertebral Vertebral ColumnColumn

Vertebrae and Vertebral DiscsVertebrae and Vertebral Discs

• Vertebrae: protect spine and give support to thoracic cavity and abdomen

• Invertebral discs:– Located between each vertebra – held in place

by ligaments– Elastic and compressible– Provide flexibility and act as shock absorbers– Can “slip” – where soft centre of disc bulges out.

It is called prolapsed invertebral disc. Can push against nerve often causing severe pain.

Structure of VertebraeStructure of Vertebrae

Appendicular SkeletonAppendicular Skeleton

• 126 bones involving:– Pelvic girdle (hips)– Pectoral girdle (shoulders):

• Scapula• Clavicle (collar bone)

– Limbs:• Arms: humerus, radius, ulna, carpals, metacarpals,

and phalanges• Legs: femur, tibia, fibula, tarsals, metatarsals, and

phalanges

Anatomy of Anatomy of the Human the Human HandHand

I-V. Metacarpal bones1 and 4. Distal phalanx2. Middle phalanx3,5. Proximal phalanx6. Sesamoid bones7. Distal interphalangeal joint8. Proximal interphalangeal joint9. Metacarpophalangeal joint10. Carpometacarpal joints11. Trapezium12. Trapezoid13. Capitate14. Hamate15. Scaphoid16. Lunate17. Triquetrum18. Pisiform19. Radius20. Ulna

A-E: Toes  1-5. (A:Great toe)I-V. Metatarsals1,3: Distal phalax4: Middle phalax2,5: Proximal phalax6. Interphalangeal joints7. Metatarsophalangeal joints8. Sesamoids9. Head of metatarsal10. Shaft (body) of metatarsal11. Base of metatarsal12. Cuneiforms (medial; intermediate;

and lateral)13. Navicular14. Cuboid15. Talus16. Calcaneus17. Tibia18. Fibula19. Tarsometatarsal joints20. Transverse midtarsal joint

Macroscopic Anatomy of a Macroscopic Anatomy of a Long BoneLong Bone

• Bone is mixture of organic (35%) and inorganic (65%) material

PeriosteumPeriosteum

• Thin layer of connective tissue that covers the outer surface of bone in all places except at joints (which are protected by articular cartilage)

Compact boneCompact bone

• Dense and forms the surface of bones (80% of the weight of human skeleton)

• Hard with very few gaps

• Function: support and protection

Medullary cavityMedullary cavity

• Central cavity of the bone shaft where yellow marrow (adipose tissue) is stored

• Located in the main shaft of the bone (diaphysis)

• In children this area is also involved in the formation of red blood cells, so red marrow is present

• Function: storage of fat and formation of RBCs in children

Spongy boneSpongy bone

• Found at the expanded heads of long bones• Low density and low strength but very high surface

area• Fills the inner cavity of long bones• In some bones the spaces are filled with red bone

marrow where the production of blood cells occurs• Contains most of the arteries and veins• Functions: production of RBCs and delivery of

oxygen and nutrients

CartilageCartilage• Type of dense connective tissue• Composed of collagenous fibers and/or elastic

fibers which are embedded in a firm gel-like ground substance called the matrix

• Cartilage is avascular (contains no blood vessels) and nutrients can only diffuse through the matrix

• Cartilage is found in many places in the body including the joints, the rib cage, the ear, the nose, the bronchial tubes and between intervertebral discs

• Functions: provides framework upon which bone deposition can begin and supplies smooth surfaces for the movement of articulating bones

Compact bone

JointsJoints

• Immovable – fused joints of the skull

• Slightly movable – vertebral joints

• Free-moving/Synovial:– ball-and-socket joints of the shoulder and hip– hinge joints such as the elbow and knee

Ligaments and TendonsLigaments and Tendons

• Ligaments are strong, slightly elastic bands of fibrous tissue (collagen) – they control the range of movement of a joint

• Tendons are extremely strong, inelastic bands/cords of collagen – they attach muscles to bone

Skeletal MuscleSkeletal Muscle

• Contractile tissue – has ability to shorten and generate a pulling force

• Voluntary muscles – we can consciously control contractions of skeletal muscle

• Function: movement and temperature regulation in the body as they generate a lot of heat during movement

Antagonistic Muscle PairsAntagonistic Muscle Pairs

• Antagonistic muscle are pairs of muscles where the action of each pulls the attached bone in the opposite direction to the other

• Most of the body’s 700 muscles operate as part of antagonistic muscle pairs– e.g. biceps and triceps of the upper arm– e.g. hamstrings and quadriceps of the upper

leg

Musculoskeletal DisorderMusculoskeletal Disorder

• Brittle-bone disease - bones are porous/less dense• Often results in compression fractures in the vertebrae and in

the neck of the femur (broken hip)• Possible cause: - Bone replacement has slowed down

- Menopause in women• Prevention: - Physical exercise during puberty reduces

- risk of developing the disease in old age- Calcium-rich diet and drinking

fluoridated - water maintains bone density• Treatment: - Females use HRT (but bone material

- already lost is not replaced!- Physical exercise, dietary calcium, and - vitamin D are recommended

Osteoporosis

Musculoskeletal DisorderMusculoskeletal Disorder

• Joint (fingers, wrists, ankle most common) become stiff and sore (inflammation occurs)

• Articular cartilage has been destroyed and bones fuse

• Possible cause: - Immune reaction against the body’s own - cartilage

• Prevention: - No known preventative measure - yet

• Treatment: - Pain-killers and anti-inflammatory drugs - are administered

- Badly affected areas, such as hip or knee - can be replaced with artificial joints

Rheumatoid Arthritis

Growth and Development in BonesGrowth and Development in Bones

• Skeleton of early embryo is mostly cartilage

• Bone formation begins just before week 8

• Specialised cells called osteoblasts secrete a thick layer of bone around the cartilage of the diaphysis – a tube of bone now encircles the diaphysis

• Cartilage continues to grow at ends – epiphyses – bone elongates

• After birth the epiphyses start to calcify

Growth and Development in BonesGrowth and Development in Bones

• Cartilage remains at the junctions between the diaphyses and epiphyses – this area is called the growth plate

• The growth plates enable the bones to elongate during childhood and puberty and eventually calcify and are replaced by bone at the end of puberty when fully grown – 18 in females and 21 in males

Growth and Development in BonesGrowth and Development in Bones

Bone RenewalBone Renewal• Bone is a living organ and is capable of self-

renewal• Bone is constantly broken down and replaced

(parathormone involved)• Skeleton is completely replaced every 7 years

and complete replacement slows down with age• Osteoclasts remove calcium and osteoblasts

lay calcium down• Renewal of bones is affected by the hormone

parathormone but also by exercise levels and dietary calcium