The Skeleton: Lower Limb

Question 1

What does the lower limb consist of?

Answer 1

Thigh, leg and foot

Question 2

Name the bones of the lower limbs and the joints they articulate

Answer 2

• Thigh: femur, *hip joint *
• Leg: tibia, patella, fibula
  tibia and patella articulate with femur at knee joint

Question 3

What are the bones of the foot called

Answer 3

• Tarsals (articulate with tibia/fibula at ankle joint)
• Metatarsals
• Phalanges

Question 4

Label the lower limb

Answer 4

Question 5

What is the pelvic girdle and how is it joined to axial skeleton?

Answer 5

Formed by 2 hip bones
Bound to the axial skeleton at the immobile sacro-iliac joints

Question 6

How is the hip bone formed by 3 elements?

Answer 6

• Ilium
• Pubis
• Ischium

Question 7

Where does the hip bone articulate with the sacrum?

Answer 7

Sacroiliac joint

Question 8

Where is the ilium, pubis or ischium?

Answer 8

• Ilium forms the large curved plate of bone, reaching above the iliac crest
• The pubis forms the anterior part of the bone, articulating in the midline at the pubic symphysis (second cartiliganous joint)
• Ischum lies inferior to publus and ilium.
  When sitting, ischial tuberosities support the body weight

Question 9

Whats the acetabulum?

Answer 9

• Where the ilium, ischium and pubis meet
• Lateral deep socket which articulates with head of femus at the ball and socket synovial joint

Question 10

What parts does the femus compose of?

Answer 10

Long bone comprising:
* Head
* Neck
* Lesser and greater trochanters
* Shaft
* Medial and lateral femoral condyles
* Articular surfaces

Question 11

Label knee joint

Answer 11

Question 12

Whats the difference between the tibia and the fibula?

Answer 12

• Tibia is the larger weight bearing bone
• Thinner lateral fibula associated with muscle attachment

Question 13

Whats at the distal end of the tibia and fibula?

Answer 13

• Tibia: medial malleolus
• Fibula: lateral malleolus

Question 14

How are the tibia and fibula joined together? Do they pronate/supinate?

Answer 14

• Joined at the superior and inferior tibio-fibular joints (fibrous joint - syndesmosis)
• No pronation or supination

Question 15

Whats the strong connective tissue membrane which binds the tibia and fibula?

Answer 15

The interosseous membrane (functions as an attachment site for muscles)

Question 16

What bone/part of the body does the tibio-fibular joint articulate with?

Answer 16

The tibio-fibular joint articulates with one of the tarsal bones the talus

• Talus is a synovial hinge joint permitting flexion (plantarflexion) and extension (dorsiflexion) of the foot

Question 17

How many bones are in the foot?

Answer 17

26 total
* 7 tarsal
* 5 metatarsal
* 14 phalanges

Question 18

What is the arrangement of tarsal bones (foot)?

Answer 18

• Proximal row comprising talus and calcaneus (heel bone)
• Single intermediate tarsal
• The Navicular
• Distal row of 4 bones, the cuboid and 3 cuneiforms

Question 19

Label bones of the foot

Answer 19

Question 19

How are the metatarsal bones arranged?

Answer 19

• Numbered 1-5 medial to lateral
• Opposite way to the hand because the big toe is medial in anatomical position whereas thumb is lateral

Foot

Question 20

How are the metatarsals composed/articulated?

Answer 20

• Head at distal end articulating with phalanges
• Shaft and a base articulating with the tarsal bones and eachother

Question 21

Whats connective tissue formed from?

Answer 21

• Cells
• Fibres (collagen, elastin)
• Ground substance (extracellular matrix)

Question 22

How are the functions of connective tissue differentiated?

Answer 22

By differences in the cell population and constituuents in the ECM

Question 23

Where are cells of connective tissue derived from? What are the types of cells of connective tissue?

Answer 23

Cells of connective tissue dervied from mesenchymal cells from the mesoderm layer

• Fibroblasts are most common cell type. Produce most of the ECM fibres and ground substance. Abundant cytoplasm & proliferate readily
• Fibrocytes: scanty cytoplasm, less active.

Both are spindle-shaped with oval/thin nuclei

Question 24

Whats the function of collagen and how many types are there?

Answer 24

* Provides strength and rigidity * 27 different types, type 1 being most common

Question 25

What are reticular fibres?

Answer 25

* Formed from collagen type 3 forming a mesh-structure * Use in supporting parenchyman tissue of organs e.g. liver, spleen, bone marrow

Question 26

Whats the main constituent of ground substance?

Answer 26

* Glycosaminoglycan (GAG) e.g. hyaluronic acid

Question 27

What are the 2 major types of connective tissue?

Answer 27

* Connective tissue proper: further classified as loose or dense. Dense further into regular or irregular * Special connective tissues: includes cartilage, bone, adipose and blood

Question 28

What are characteristics of: * Loose connective tissue * Dense connective tissue

Answer 28

* Loose: more cells than fibres. Found throughout the body, surrounding blood vessels and organs * Dense: more fibres than cells. Found in areas where non-rigid strength required. * Dense regular: fibres aligned and more strength (e.g. ligaments or tendons) * Dense irregular: not aligned, random, density confers strength

Question 29

What cells form cartilage?

Answer 29

* ECM produced by chondroblasts * Chondrocytes are present = mature cells * Highly resilient tissue, smooth, shock absorbing, low friction articular surface for joints and permits bone growth

Question 30

Is cartilage vascular? What does this mean?

Answer 30

* Cartilage is avascular * Has a low metabolic rate and limited capacity for regeneration following trauma

Question 31

What are the 3 types of cartilage?

Answer 31

* Hyaline: most common, lines articular surfaces of synovial joints * Elastic: highly flexible, found in epiglottis, auditory tube and pinna of ear * Fibrocartilage: found in secondary cartilaginous joints, including intervertebral discs and pubic smphysis

Question 32

What are the 2 forms of bone tissue?

Answer 32

* Compact bone: outer shell of shafts of long bones and surface of irregular shaped bones, offer great resistance * Cancellous bone: lighter and highly porous. More irregular, arrays of struts called trabeculae

Question 34

What cells are in adipose tissue? What are the 2 types of

Answer 34

* Adipocytes **Uniocular (white fat)**: * pale yellow, makes up 25% of total normal body weight and 20% men * Storage provides protection (e.g. shock absorb for kidneys) * Adipocytes large & rounded **Multilocular (brown fat)** * Darker brown due to vascularity and mitochondria * Main function is thermoregulation

Question 35

Whats the composition of blood?

Answer 35

* Plasma 55% * Cells 45% *Blood cells derived from HSC in bone marrow. Multi-potental meaning divide and mature to become any blood cells*