Chapter 7: Axial Skeleton

Question 1

Number and location

Answer 1

Skull, trunk, and spine 80 bones

Question 2

describe how the skeleton is organized into axial and appendicular divisions.

Answer 2

The axial skeleton consists of bones arranged along the longitudinal axis. The parts of the axial skeleton are the skull, auditory ossicles (ear bones), hyoid bone, vertebral column, sternum, andribs.

The appendicular skeleton consists of the bones of the girdles and the upper and lower limbs (extremities). The parts of the appendicular skeleton are the pectoral (shoulder) girdles, bones of the upper limbs, pelvic (hip) girdles, and bones of the lower limbs

Question 3

classify bones based on their shape or location.

Answer 3

1) Long Bones
Shape – Greater length than width, shaft and variable number of extremities of epiphyses, curved to absorb body weight
Location – Thigh, Leg bones, Arm and Forearm bones and finger and toe bones

2) Short Bones
Shape – Nearly equal in length and width, mostly spongy tissue except at the surface where there is a layer of compact bone
Location – Wrist and most ankle bones

3) Flat Bones Shape - Generally two thin parallel plates of compact bone tissue enclosing a layer of spongy bone tissue, considerable protection and muscle attachment
Location – Cranial Bones, Sternum, Ribs, Scapulae

4) Irregular Bones Shape – Complex cannot be grouped into any other category and vary in amount of spongy and compact tissue

Location – Vertebrae, Hip bones, Certain Facial Bones and calcaneus

5) Sesamoid Bones Shape – Sesame Seed shaped, not always ossified, only a few mm in diameter
Location – Develop in areas where there is lots of friction, tension and physical stress (palms and soles), Vary in number from person to person, two kneecaps, protect tendons from excessive wear

6) Sutural Bones

Shape – Small bones located in sutures (joints), classified by location rather than shape Location – Between certain cranial bones

Question 4

describe the principal surface markings on bones and the functions of each.

Answer 4

Surface markings are structural features visible on the surfaces of bones

 Each marking—whether a depression, an opening, or a process—is structured for a specific function, such as joint formation, muscle attachment, or passage of nerves and blood vessels

Question 5

name the cranial and facial bones and indicate whether they are paired or single.

Answer 5

The 22 bones of the skull include cranial bones and facial bones

The eight cranial bones are the frontal, parietal (2), temporal (2), occipital, sphenoid, and ethmoid.

The 14 facial bones are the nasal (2), maxillae (2), zygomatic (2), lacrimal (2), palatine (2), inferior nasal conchae (2), vomer, and mandible

Question 6

describe the following cranial bones and their main features: frontal, parietal, temporal, occipital, sphenoid, and ethmoid.

Question 7

identify the location and surface features of the following bones: nasal, lacrimal, palatine, inferior nasal conchae, vomer, maxillae, zygomatic, and mandible.

Question 8

describe the following special features of the skull: sutures, paranasal sinuses, and fontanels.

Answer 8

Principal Sutures Coronal, Sagittal, Lambdoid, Squamous

Sinuses Paranasal Sinuses, Frontal, Sphenoid, Ethmoid and Maxillae

Fontanels Mesenchyme filled spaces between the cranial bones of fetuses and infants Anterior, Posterior, Anterolateral and Posterolateral After birth fill in and become sutures

Question 9

describe the relationship of the hyoid bone to the skull.

Answer 9

U shaped, Does not articulate with any other bone, supports tongue, provides attachment for some muscles of tongue, neck and pharynx

Question 10

identify the regions and normal curves of the vertebral column, describing its structural and functional features.

Answer 10

The adult vertebral column contains four normal curves (cervical, thoracic, lumbar, and sacral)that provide strength, support, and balance

Question 11

identify the locations and surface features of the cervical, thoracic, lumbar, sacral, and coccygeal vertebrae.

Answer 11

The vertebral column, sternum, and ribs constitute the skeleton of the body’s trunkThe 26 bones of the adult vertebral column are the cervical vertebrae (7), the thoracic vertebrae (12), the lumbar vertebrae (5), the sacrum (5 fused vertebrae), and the coccyx (usually 4 fused vertebrae)

Question 12

identify the bones of the thorax, including sternum and ribs, and their functions.

Answer 12

Thorax - Sternum (manubrium (top) Body (Middle) Xyphoid Process (bottom)), Ribs, Costal Cartilage, Thoracic Vertebrae