The Skeletal System: The Axial Skeleton

Question 1

How does the axial skeleton contribute to homeostasis?

Answer 1

By protecting the body’s organs (brain, spinal cord, heart, lungs), support, and releases and stores calcium

Question 2

What makes up the musculoskeletal system?

Answer 2

Bones, muscles and joints

Question 3

Orthopedics

Answer 3

Branch of medical science concerned with prevention or correction of disorders of musculoskeletal system

Question 4

How many bones does an adult, children, and infants have?

Answer 4

Adults have 206 bones, children and infants have more and some of their bones fuse later in life.

Question 5

What bones and how many are in the axial skeleton?

Answer 5

The Axial skeleton has 80 bones including the cranial cavity and facial bones of the skull, auditory ossicles, hyoid bone, ribs and sternum of the thorax, and vertebral column. There are 8 cranial cavity bones and 14 facial bones that make up the skull, 6 auditory ossicles, 1 hyoid bone, 1 sternum and 24 ribs of the thorax, and 26 bones of the vertebral column.

Question 6

What are the 5 types of bone based on shape?

Answer 6

Long, short, flat, irregular, and sesamoid

Question 7

What are long bones? What characteristics do they have? Which bones are considered long bones?

Answer 7

Long bones are greater in length than width. They consist mostly of compact bone tissue in a diaphysis, spongy bone tissue in various number of epiphyses, and are slightly curved. Long bones include the femur, tibia, fibula, humerus, ulna, radius, and phalanges.

Question 8

What is the significance of long bones being curved?

Answer 8

Curved bones provides strength and resistance to fractures by absorbing strain at several different points and allows the body’s weight to be evenly distributed.

Question 9

What are short bones? What do they consist of? Which bones are short bones?

Answer 9

Short bones are slightly cube-shaped and almost equal in width and length. They consist of spongy bone tissue and a thin layer of compact bone tissue at the surface. Most carpal and tarsal bones are short bones.

Question 10

What are flat bones. What are their characteristics and function. Which bones are flat bones?

Answer 10

Flat bones are generally thin. They consist of 2 nearly parallel plates of compact bone tissue around a layer of spongy bone tissue and provide protection and a lot of areas for muscle attachment. Cranial cavity bones, the sternum and ribs are flat bones.

Question 11

What are the characteristics of irregular bones and which bones are irregular?

Answer 11

Irregular bones have complex shapes and can’t be grouped into any category. They vary in amount of spongy and compact bone. Vertebrae, hip bones, certain facial bones, and the calcaneus are irregular bones.

Question 12

Where do sesamoid bones develop and what are their functions? Which bones are sesamoid bones?

Answer 12

Sesamoid bones meaning shaped like a sesame seed develop in certain tendons where there’s a lot of tension, friction, and physical strain. They’re typically only a few mm in diameter and protect tendons from wear and tear and improve mechanical advantage at a joint by changing direction of pull of a tendon. These bones vary in number from person to person with the exception of the 2 patellae present in everyone.

Question 13

What bone is classified by location? Where are these bones found?

Answer 13

Sutural bones are small flat bones located in sutures (joints) between certain cranial cavity bones and number of bones vary by person.

Question 14

What are surface markings? What are the 2 types and how do they develop?

Answer 14

Surface marking are structural features adopted for specific functions. Most aren’t present at birth but develop from certain forces and are mainly present in adult skeleton.
1. Processes: Raised areas or projections/outgrowths on bone that form joints or serve as attachment points for ligaments and tendons. They result to bone being deposited in response to tension on bone surface from tendons, ligaments, aponeuroses, and fasciae. 2. Depressions and openings: sites that allow passage of blood vessels, nerves, ligaments, and tendons or form joints. They result from compression on a bone surface.

Question 15

What are the 5 types of depression and openings?

Answer 15

Fissure, foramen, fossa, sulcus, meatus

Question 16

Fissure

Answer 16

A narrow slit between bones for passage of blood vessels and nerves.

Question 17

Foramen (pl. foramina)

Answer 17

Opening for passage of blood vessels, nerves or ligaments

Question 18

Fossa (pl. fossae)

Answer 18

Shallow depression

Question 19

Sulcus (pl. sulci)

Answer 19

Groove along bone surface for blood vessel, nerve or tendon

Question 20

Meatus (pl. meati)

Answer 20

Tubelike opening

Question 21

What are the 3 processes that form joints?

Answer 21

Condyle, facet, head

Question 22

Condyle (pl. condylus)

Answer 22

Large, rounded projection with smooth articular surface at end of bone

Question 23

Facet

Answer 23

Smooth, flat, slightly concave or convex articular surface

Question 24

Head

Answer 24

Usually rounded articular projection supported on neck (constricted portion) of bone

Question 25

What are the 7 processes that form attachment points for connective tissue?

Answer 25

Crest, epicondyle, line, spinous process, trochanter, tubercle, tuberosity

Question 26

Crest

Answer 26

Prominent ridge or elongated projection

Question 27

Epicondyle

Answer 27

Typically roughened projection above condyle

Question 28

Line (linea)

Answer 28

Long, narrow ridge or border (less prominent than crest)

Question 29

Spinous process

Answer 29

Sharp, slender projection

Question 30

Trochanter

Answer 30

Very large projection

Question 31

Tubercle

Answer 31

Variably sized rounded projection

Question 32

Tuberosity

Answer 32

Variably sized projection that has a rough and bumpy surface

Question 33

What is the skull? What are the 2 groups of bones that make up the skull and it’s components?

Answer 33

The skull is the bony framework of the head and the 22 bones are grouped into the cranial cavity bones and the facial bones. There are 8 bones that form the cranial cavity including the frontal bone, 2 parietal bones, 2 temporal bones, occipital bone, sphenoid bone, and ethmoid bone. The cranial base is the floor of the cranial cavity. There are 14 facial bones that form the anterior part of the skull and consists of bones that surround the mouth, nose, nasal, nasal cavity, and most of the orbits. These bones include 2 nasal bones, 2 maxillae, 2 zygomatic bones, mandible, 2 lacrimal bones, 2 palatine bones, 2 inferior nasal concha bones, and vomer.

Question 34

What are the cavities and sinuses of the skull?

Answer 34

The skull contains the nasal cavity and orbits that open to the exterior and middle ear cavities in the temporal bones that house the auditory ossicles involved in hearing and equilibrium. The paranasal sinuses lined with mucous membranes open into the nasal cavity.

Question 35

Which structures in the skull are movable?

Answer 35

The auditory ossicles and the mandible

Question 36

What are sutures?

Answer 36

Sutures are joints that attach the skull bones together and are noticeable in the outer surface on the skull.

Question 37

What surface markings does the skull have and their functions?

Answer 37

The skull has foramina and fissures that allow blood vessels and nerves to pass

Question 38

What is the function of the cranial cavity and facial bones?

Answer 38

The cranial cavity protects the brain and stabilizes positions of the brain, blood vessels, lymphatic vessels, and nerves by attaching inner surfaces to meninges (membranes). The outer surfaces provide large areas of attachment for muscles that move parts of the head and produce facial expressions. The facial bones form the framework of the face and provide support for entrances to the digestive and respiratory systems. The cranial cavity and facial bones protect and support sense organs for vision, taste, smell, hearing, and equilibrium.

Question 39

Frontal bone

Answer 39

Forms forehead, roofs of orbits and most of anterior part of cranial base.

Question 40

Metopic suture

Answer 40

Joins left and right sides of frontal bone after birth and usually disappears between 6-8 years.

Question 41

Frontal squama

Answer 41

Scalelike plate of bone that forms forehead of skull; slopes inferiorly from coronal suture on top of skull and angles almost vertically above orbits. Frontal sinuses are deep to frontal squama.

Question 42

Supraorbital margin

Answer 42

Thickened frontal bone at superior border of orbits (brow line); frontal bone extends posteriorly from margin to form roof of orbits (part of cranial base).

Question 43

Supraorbital foramen and notch and it’s function

Answer 43

Supraorbital foramen is a hole slightly medial to midpoint within supraorbital margin. Supraorbital notch is an incomplete foramen. The foramen allows passage of the supraorbital nerve and blood vessels.

Question 44

What causes a black eye?

Answer 44

One cause is trauma to the supraorbital margin that fractures the frontal bone and results in blood and other fluids accumulating around the eye and causes swelling and dark discolouration. Surgical procedures can also cause black eyes.

Question 45

Parietal bones

Answer 45

2 bones that form greater portion of sides and roof of cranial cavity. Internal surfaces contain many protrusions and depressions that accommodate blood vessels supplying dura mater (superficial connective tissue) covering brain

Question 46

What is a paired bone?

Answer 46

One member of each bone on right and left sides of body

Question 47

Temporal bones

Answer 47

Paired bones forming inferior lateral aspects of cranial cavity and part of cranial base.

Question 48

Temporal squama

Answer 48

Thin, flat part of temporal bone forming anterior and superior part of temple (region of cranium around ear)

Question 49

Zygomatic process

Answer 49

Projects from inferior portion of temporal squama and articulates with temporal process of zygomatic bone.

Question 50

Zygomatic arch

Answer 50

Formed from zygomatic process of temporal bone and temporal process of zygomatic bone