Section 4

Question 1

What does the appendicular system consist of?

Answer 1

The upper and lower limbs

Question 2

What does the pectoral girdle do?

Answer 2

Connects the upper limb to the axial skeleton.

Question 3

Describe the parts of the pectoral girdle.

Answer 3

1. Clavicle
   - An S-shaped bone
   - joins with the manubrium of the sternum medially (proximally) and the scapula laterally (distally)
2. Scapula
   - triangular in shape
   seen on the anterior surface:
   - the coracoid process is seen here. kind of pops out and helps to stabilize the shoulder joint along with the acromion.
   seen on the posterior surface:
   - acromion and the spine
   seen on the lateral surface:
   - the glenoid fossa, which articulates with the head of the humerus (arm bone) to contribute to the shoulder joint

Question 4

Describe the distal aspect of the humerus

Answer 4

Anterior:
Two depressions and two bumps

On the lateral side we have a round shaped structure called the capitulum, which articulates radially with the radius of the forearm.

On the medial side there is a spool-shaped structure called the trochlea. This articulates with the ulna of the forearm.

The epicondyles (epi = upon). On the lateral side we have the lateral epicondyle which is upon our capitulum. On the medial side, the medial epicondyle is upon our trochlea.

Posterior:
There is one single depression or fossa called the olecranon fossa which articulates with the olecranon process of the ulna.

Question 5

How do you know if the humerus is left or right bone

Answer 5

The head always faces medially. On the anterior side we find two depressions and two bumps, whereas posteriorly there is only one single fossa.

If the two depressions and two bumps are in the front (anterior) it would be a left humerus.

Question 6

What is the difference between the anatomical neck and surgical neck of the humerus?

Answer 6

The anatomical neck is what connects the head to the rest of the bone.

The surgical neck is immediately below the tubercles. Its called this because its a common site for humeral fractures that require surgery.

Question 7

Where are the lesser and the greater tubercles on the humerus?

Answer 7

Opposite to the head:
- head is medial
- the tubercles are lateral

Question 8

What is the humerus and what does it connect?

Answer 8

The humerus the single main bone found in the arm.

The head of the humerus faces medially. This part articulates proximally with the glenoid fossa of the scapula to form the shoulder joint

Also distally with the radius and ulna to form the elbow joint.

Question 9

What are the two bones in the forearm?

Answer 9

Radius and ulna

Question 10

Describe the radius bone of the forearm.

Answer 10

The radius is laterally placed (thumb side) with reference to the forearm.

It has:
- Head (proximal end): round disc-shaped head with articulates with the capitulum (distal end) of the humerus. it also articulates with the ulna
- Shaft
- Neck
- Distal end: wide and flat, articulates with the carpal (wrist) bones to form the wrist joint. styloid process is there.

Question 11

Describe the ulna bone of the forearm.

Answer 11

The ulna is medially placed (pinky finger side) with reference to the forearm. It looks like a pipe wrench.

It has:
- Proximal end: articulates with the distal end of the humerus. The olecranon fits into the olecranon fossa of the humerus. The trochlear notch is a c-shaped depression which interlocks with the trochlea of the humerus
- Shaft
- Neck
- Head (distal end): has styloid process

Question 12

Name the kinds of bones found in the wrist and hand.

Answer 12

They are composed of many smaller bones:

Wrist:
- 8 carpal bones (short bones)

Palm/hand:
- 5 metacarpal bones (long bones)

Digits/fingers:
- 14 phalanges (long bones)

Question 13

How many bones are in the lower limb?

Answer 13

30, or 31 including the innominate bone.

Question 14

What does the lower limb consist of?

Answer 14

1. Pelvic Girdle
2. Thigh (femur)
3. Leg (tibia and fibula)
4. Ankle and foot

Question 15

What does the pelvic girdle do?

Answer 15

• Attaches the lower limb to the axial skeleton
• Is formed by the hip (innominate) bones

Question 16

What does the hip bone consist of?

Answer 16

The ilium, ischium and pubis.

Question 17

Describe the location and structure of the ilium

Answer 17

• It is the largest bone of the pelvic girdle
• It makes up the superior portion of the pelvic girdle

Consists of:
- Posterior superior iliac spine (PSIS)
- Posterior inferior iliac spine (PIIS)
- Iliac crest
- Anterior superior iliac spine (ASIS)
- Anterior inferior iliac spine (AIIS)

Question 18

The pubis fuses with both the ilium and ischium. It also unites with the other pubic bone at the pubic symphysis.

The pubic symphysis is made of which type of cartilage?

Answer 18

Fibrocartilage

Question 19

The bones of the pelvic girdle fuse to form two structures. Describe the parts of these structures.

Answer 19

The greater sciatic notch: located between the PIIS and the ischial spine. It allows the passage of major nerves and vessels from the pelvic cavity into the posterior region of the lower limb.
The lesser sciatic notch: located between the ischial spine and the ischial tuberosity. It permits the passage of structures from the pelvic cavity to the genital region.

Acetabulum: Deep curved depression for articulation with the head of the femur.
Obturator foramen: Large opening on the anterior and inferior aspect of each pelvic girdle for the passage of nerves and blood vessels.

Question 20

Which bones contribute to the obturator foramen?

Answer 20

The ischium and pubis

Question 21

Which bones contribute to the acetabulum?

Answer 21

The ilium, ischium and pubis

Question 22

Compare and contrast the structure and bony features of the pelvic girdle (lower limb) and the pectoral girdle (upper limb) by listing similarities and differences. Explain why you think the differences exist.

Answer 22

Both the pelvic girdle and pectoral girdle function to connect the appendicular skeleton to the axial skeleton. Additionally, the glenoid fossa (pectoral girdle) and acetabulum (pelvic girdle) are both structures that articulate with the rounded head of long bones, the humerus and femur respectively.

There is a difference in the number and size of the bones between the girdles. Since the lower limb plays a critical role in bearing weight and locomotion, the pelvic girdle is larger and has more bones as compared to the pectoral girdle.

Question 23

What is the bone of the thigh?

Answer 23

The femur

Question 24

Describe the proximal end of the femur

Answer 24

The head of the femur faces medially and articulates with the acetabulum of the pelvic girdle, forming the hip joint.

In addition to the head and neck, the proximal end of the femur has other bumps/projections and ridges that serve as surfaces for muscle attachment. (won’t be talked about in the course)

Question 25

Describe the distal end of the femur

Answer 25

It articulates with the tibia and patella (knee cap)

• has the medial (longer and points lower than lateral) and lateral condyles, these are the parts of the knee that form the knee joint with the tibia)
• has the patellar (knee cap) surface which is the articular surface on the anterior aspect of the femur and forms a groove for the patella

The condyles are separated on the posterior distal aspect by a notch called the intercondylar fossa/notch

Question 26

How to tell if the femur is the left or right femur

Answer 26

the head is located medially
the smooth articular patellar surface is located on the anterior side, whereas the posterior side is notched

Question 27

Compare and contrast the structure of the femur and humerus. Explain why differences exist.

Answer 27

Both the humerus and femur are similar in structure. Both bones have heads, necks, and medial and lateral condyles.

However, since the femur plays a critical role in supporting the body’s weight, it is larger in size than the humerus. It has a wider shaft, a larger and more circular head, and larger condyles

Question 28

What two bones is the leg composed of, and where are they placed?

Answer 28

Tibia and fibula

Tibia is placed medially and the fibule is placed laterally in the leg

Question 29

Describe the structure of the tibia

Answer 29

The tibia is the only weight-bearing bone of the leg.

Proximal end:
- medial and lateral condyles: articulate with the medial and lateral condyles of the femur
- tibial tuberosity
Shaft
Distal end:
- medial malleolus

Question 30

Describe the structure of the fibula.

Answer 30

The fibula does not bear or transfer any weight, however the lateral malleolus (distal tip of the fibula), provides lateral stability to the ankle joint.

Proximal end:
- medial head which articulates with the tibia
Neck
Shaft
Distal end:
- lateral malleolus

Question 31

Compare and contrast the structure of the leg (lower limb) and forearm (upper limb). Explain why differences exist.

Answer 31

There are two bones in the leg (fibula and tibia) and forearm (radius and ulna). However, there is a size difference. The bones in the forearm, the radius and ulna, are similar in size to one another. On the other hand, since the tibia is the weight-bearing bone in the lower leg, it is much wider than the fibular.

Question 32

Describe the bones of the ankle and foot.

Answer 32

Made up of many small bones. The tarsals are short, irregular bones, while the metatarsals and phalanges, although small, are classified as long bones.

Ankle:
- 7 tarsal bones (short bones)

Foot:
- 5 metatarsal bones (long bones)

Digits/toes:
- 14 phalanges (long bones)