Ch.8 - The Skeletal System: The Appendicular Skeleton (upper limb)

Question 1

Upper Limb (Extremity)

Answer 1

Each upper limb consists of 30 bones including the humerus, ulna, radius, carpals, metacarpals, and phalanges.

Question 2

Humerus

Answer 2

1. The LONGEST and LARGEST bone of the upper limb

2. It articulates proximally with the scapula and distally with the radius and the ulna

Question 3

Ulna and Radius

Answer 3

1. Ulna - located on the MEDIAL aspect of the forearm
2. Radius - located on the LATERAL aspect of the forearm
3. Both the radius and the ulna articulate with the humerus at the elbow joint, with each other, and with three carpal bones.

Question 4

Carpals, Metacarpals, Phalanges

Answer 4

1. 8 carpal bones
2. 5 metacarpal bones are in the palm of each hand
3. 14 phalanges in each hand; each finger, EXCEPT thumb and 1st digit) is composed of 3 phalanges (proximal, middle, distal)

Joints include: carpometacarpal, metacarpophalangeal, interphalangeal

Question 5

Lower Limb (Extremity)

Answer 5

1. Each lower limb is composed of 30 bone; consists of femur, tibia, fibula, tarsals, metatarsals, and phalanges.

Question 6

The Femur (Thighbone)

Answer 6

1. The LARGEST, HEAVIEST, and STRONGEST bone of the body

2. Articulates with the hip bone and the tibia but NOT the fibula

Question 7

The Patella (Kneecap)

Answer 7

1. A sesamoid bone located anterior to the knee joint.
2. Forms the patellofemoral joint where it functions to: INCREASE the leverage of a tendon of the quadriceps femurs muscle, to MAINTAIN position of the tendon when the knee is bent, and to PROTECT the knee joint.

Clinical Connection ; Patellofemoral stress syndrome is a common knee problem in runners.

Question 8

Tibia (Shinbone) and Fibula

Answer 8

1. The tibia is the larger, medial, weight-bearing bone of the leg
2. The fibula is parallel and lateral to the tibia and does NOT bear weight.

Clinical Connection: Because the fibula is not a weight bearing bone, it is a good source for bone grafting.

Question 9

Tarsals, Metatarsals, and Phalanges

Answer 9

1. Seven tarsal bones constitute the ankle and share weight associated with walking
2. Five metatarsal bones are contained in the foot (sole)
3. The arrangement of phalanges in the toes are arranged the same as described for the fingers and the thumbs.

Clinical Connection: Bone Grafting
Clinical Connection: Metatarsals are frequently broken.

Question 10

Arches in the Foot

Answer 10

The bones of the foot are arranged in two nonrigid arches that enable the foot to support the weight of the body; provide an ideal distribution of body weight over the hard and soft tissues , and provide leverage while walking.

Clinical Connection: Flatfoot and clawfoot are caused by decline, elevation, or rotation of medial longitudinal arches.

Question 11

Development of the Skeletal System

Answer 11

1. Most skeletal tissue arises from the middle primary germ layer in the embryos known as the mesoderm.
2. Most of the skull arises from the outer layer called the ectoderm.

Question 12

Skull bones develop in 2 ways (neurocranium)

Answer 12

The neurocranium forms the bones of the skull itself, it is divided into:

a. Cartilaginous neurocranium (hyaline cartilage that undergoes endochondral ossification)
b. Membranous neurocranium that undergoes intramembranous ossification

Question 13

Skull develops in 2 ways (viscerocranium)

Answer 13

The viscerocranium forms the facial bones.

a. Cartilaginous viscerocranium - comes from the cartilage of the pharyngeal arches. This forms the ear bone bones and hyoid bone.
b. Membranous viscerocranium - comes from mesenchyme of the first pharyngeal arch, undergoes intramembranous ossification and forms the facial bones.