A&P 106: Chapter 7 - Axial Skeleton

What important function is associated with the ribs?

Breathing The ribs are quite mobile, due to their complex musculature, dual articulations at the vertebrae, and flexible connections to the sternum. The ribs curve downward and away from the vertebral column. Because of the curvature, they change the position of the sternum during breathing and change the dimensions of the thoracic cavity. As we will see in the respiratory system discussion, this causes inspiration and expiration during breathing.

The area of the greatest degree of flexibility along the vertebral column is found from __________.

C3 to C7 The area of the greatest degree of flexibility along the vertebral column is found from C3 to C7. This area of the cervical spine needs to have the greatest mobility because it supports the head and neck, and thus it needs to accommodate rotation, flexion, and extension of the head and neck. In contrast to the more stabilizing lumbar vertebrae, the cervical vertebrae are much lighter and have more extensive processes, which act as attachments for muscles in the back and neck.

Which of the ribs are referred to as vertebral ribs?

Rib pairs 11 and 12 The ribs are named for their articulations. However, rib pairs 11 and 12 connect to the vertebral column posteriorly but they do not connect to any bones anteriorly. Thus they are called vertebral ribs.

Which ribs are named false ribs?

Rib pairs 8-12 Rib pairs 8-12 are called false ribs, because they do not attach directly to the sternum. Pairs 8-10 have to be included in this group. Instead they connect to cartilage anteriorly that connects to the cartilage of rib pair 7. But those are not the only false ribs. Pairs 11 and 12, (the floating ribs) do not connect to the sternum and are also called false ribs. They are floating ribs and have no anterior connection to the sternum.

Which of the following consists of five fused vertebrae and articulates with the pelvic girdle?

Sacrum The sacrum consists of five fused vertebrae and articulates with the pelvic girdle. These five bones do not completely fuse until around the age of 25. The sacrum is bordered by the lumbar vertebrae along its superior ridge and by the coccyx on its inferior aspect. Although the spinal cord ends in the area of L1, the sacrum contains a canal for nerves and membranes that continue to extend from this area. The coccyx does not articulate with the pelvic girdle. The manubrium is at the top of the sternum and does not articulate with the pelvis. The sternum does not articulate with the pelvis.

Which of the following is NOT a cranial bone? a. maxilla b. temporal bone c. occipital bone d. frontal bone

The maxilla is a facial bone. Facial bones do not form the enclosure of the cranial cavity. The maxilla forms the upper jaw, which closes on the mandible during the act of mastication. Both the maxilla and the mandible contain specialized joints known as gomphoses, which stabilize the position of the teeth in these bones.

Which bone forms the lateral wall and rim of the eye orbit?

Zygomatic The zygomatic bone forms the lateral rim and the lateral wall of the eye orbit. The frontal bone articulates with the zygomatic but forms the roof of the orbit. The maxilla also articulates with the zygomatic, but forms most of the orbital floor. The sphenoid also articulates with the zygomatic but forms the back wall of the orbit.

Which fontanelle might indicate dehydration in an infant?

Anterior fontanelle The anterior fontanelle might indicate dehydration in an infant. This is primarily because of the size and area that this fontanelle covers; this area becomes depressed and indented when blood volume decreases.

Why can the skull be distorted without damage during birth?

Fibrous connective tissue connects the cranial bones Fibrous connective tissue connects the cranial bones, which enables the skull to be distorted without damage during birth. The flexibility of these areas lets the skull bones move independently and gives pliability to the skull, which is not present in an adult. These areas of fibrous connective tissue are known as fontanelles and form sutures by the age of 2.

Which are the largest and most massive of the vertebrae?

Lumbar vertebrae Lumbar vertebrae are the largest and most massive of the vertebral bones. These vertebrae have the largest vertebral bodies since these bones support the biggest load of all the vertebral column. The combined mass of the head, the shoulders, the upper limbs, and the torso is supported by the lumbar region. These bones need to have the largest bodies in order to be able to support this large amount of mass. Cervical vertebrae are among the smallest vertebrae. Thoracic vertebrae are not the most massive vertebrae. Sacral vertebrae are not the most massive vertebrae.

What type of vertebrae are characterized by short, stumpy spinous processes and large bodies?

Lumbar vertebrae The lumbar vertebrae are characterized by short, stumpy spinous processes and large bodies. They are the most massive of the vertebral bones and have the largest bodies. These large bodies are needed to support the mass of the torso, head, and upper limbs. Cervical vertebrae are characterized by their small bodies. Thoracic vertebrae are characterized by their larger vertebral foramina. Sacral vertebrae have smaller bodies.

Why does the adult vertebral column have fewer vertebrae than that of a newborn?

Some vertebrae fuse together after birth. During development, the sacrum originates as a group of five vertebrae and the coccyx begins as three to five very small vertebrae. The vertebrae of the sacrum are completely fused into one bone by age 25-30. The distal coccygeal vertebrae fuse together after puberty. This fusion reduces the total number of vertebrae in the adult.

The mucous membrane of the paranasal sinuses responds to environmental stress by __________.

accelerating the production of mucous The mucous membrane of the paranasal sinuses responds to environmental stress by accelerating the production of mucus. This is a protective feature that can help flush the epithelial surface of irritating substances. This can also help flush the surface of pathogens and prevent them from advancing further and deeper into the respiratory tract. Creating swirls and eddies in the sinuses is a result of inhalation and is not a response to environmental stress. Breaking up air flow in the nasal cavity is a result of inhalation and is not a response to environmental stress.

The foramen that allows the medulla of the brainstem to connect with the spinal cord is the __________.

foramen magnum The occipital bone forms much of the posterior and inferior surfaces of the cranium. Located on the inferior surface of the occipital bone is the foramen magnum. It connects the cranial cavity with the spinal canal, which is enclosed by the vertebral column. This foramen provides the passageway for the connection between the brain and the spinal cord.

The associated bones of the skull include the __________.

hyoid and auditory ossicles The associated bones of the skull include the hyoid and auditory ossicles. These bones do not form parts of the cranial cavity or the facial structures. The hyoid bone does not form a joint with other bones like that seen in other parts of the body, but it does form a major attachment site for muscles and structures in the area. The auditory ossicles are suspended inside the temporal bone and transduce sound. The nasal and lacrimal bones form parts of the face and skull. The mandible and maxillary bones form parts of the facial structure. The vomer and palatine bones form parts of the facial bones.

Which part of the sphenoid bone houses the pituitary gland?

sella turcica The sella turcica is the part of the sphenoid bone that houses the pituitary gland. The name sella turcica means "Turkish saddle" and describes the form of this portion of the sphenoid bone. This saddle-like structure supports the pituitary gland from below, allowing this endocrine gland to sit on top. The styloid process is on the temporal bone. The crista galli is in the ethmoid bone. The frontal squama are in the frontal bone.

The first seven ribs are called __________, and they connect to the sternum by individual costal cartilages.

true ribs The first seven ribs are called true ribs, and they connect to the sternum by individual costal cartilages. These long, curved bones are also known as vertebrosternal ribs and form a superior part of the thoracic cage, which protects the lungs and heart. In the anterior aspect of the thoracic cage, these ribs connect to the sternum by way of individual hyaline cartilages. In the posterior aspect, the ribs connect directly to articular surfaces of the vertebral column.

The structure that encloses and protects the spinal cord is the __________.

vertebral canal Posterior to the body of the vertebrae is the vertebral arch. It is formed by two walls, called pedicles, and a roof formed by the laminae. This arch creates a foramen called the vertebral foramen. Together the vertebral foramina of successive vertebrae form the vertebral canal, which encloses and protects the spinal cord.

Ribs pairs 8, 9, and 10 are called __________.

vertebrochondral ribs The costal cartilages of ribs 8-10, the vertebrochondral ribs, fuse together and merge with the cartilages of rib pair 7 before they reach the sternum. Because they do not make a joint directly with the sternum but rather with cartilage that joins to the sternum, they are called vertebrochondral ribs. Remember that chondros is a Greek word meaning cartilage.

Why does the most significant growth in the skull occur before 5 years of age?

The brain stops growing, and cranial sutures develop. The most significant growth in the skull occurs before 5 years of age because the brain stops growing, and cranial sutures develop. These two structures need to be coordinated in their growth since any lack of expansion of the skull during brain growth can be potentially damaging. The head of an infant is much larger relative to the rest of the body, so after the age of 5, the rest of the body grows to catch up in proportion to the head. Brain development is complete before maturity. The cranium of a child is not larger than that of an adult. The ossification and articulation processes are not complete before the age of 5.

What bones connect the axial skeleton and the lower appendicular skeleton?

The sacrum and the pelvic girdle The sacrum consists of the fused components of five sacral vertebrae. Through paired articulations on each side of the sacrum, it attaches the axial skeleton to the paired hipbones, or pelvic girdle, of the appendicular skeleton. This joint is called the sacroiliac joint and involves the sacrum and the two iliac bones of the pelvic girdle.

What feature of the skeleton eventually allow a child to maintain balance while walking and running?

The secondary curves of the vertebral column The secondary curves of the vertebral column develop after birth. They are the cervical curve and the lumbar curve. The cervical curve develops as the infant learns to balance the weight of the head on the vertebrae of the neck. The lumbar curve balances the weight of the trunk over the lower limbs. It develops with the ability to stand. The curves allow the infant to be erect and move about without toppling over. Obviously this is not perfect at first, so there are still some crashes.

Humans are distinguished from many animals by having an upright body position. What parts of the skeleton help us to maintain that upright body position?

The vertebral column (SPINE) The vertebral column consists of the vertebrae, the sacrum, and the coccyx. The vertebrae provide a column of support, bearing the weight of the head, neck, and trunk and ultimately transferring that weight to the lower appendages. The vertebrae also protect the spinal cord and help maintain an upright body position as we sit or stand.

Which region of the vertebral column articulates with the ribs?

Thoracic Each thoracic vertebra articulates with the ribs along the dorsal surfaces of the body of the vertebra. The costal facets on the vertebral bodies articulate with the heads of the ribs. The transverse processes contain transverse costal facets for rib articulation.

What is the function of the intervertebral foramina?

To connect spinal nerves to the spinal cord. The vertebral arch has walls called pedicles and a roof formed by flat layers of bone called laminae. Intervertebral discs separate adjacent vertebral bodies and gaps separate the pedicles of successive vertebrae. These gaps, called intervertebral foramina, permit the passage of nerves to and from the enclosed spinal cord.

What is the term for the opening in the vertebrae that encloses the spinal cord?

Vertebral foramen The vertebral foramen is the term for the opening in the vertebrae that encloses the spinal cord. This foramen changes diameter as we proceed from the inferior part of the vertebral column up to the superior portion. As we move toward the foramen magnum at the base of the occipital bone, the vertebral foramen enlarges.

What is the difference between vertebrosternal ribs and vertebrochondral ribs?

Vertebrosternal ribs connect directly to the sternum, whereas vertebrochondral ribs do not. Vertebrosternal ribs, or true ribs, attach directly to the sternum by separate costal cartilages. Vertebrochondral ribs have costal cartilages that merge with the cartilages of rib pair 7 before they reach the sternum. They do not directly connect to the sternum.

Which of the following is NOT likely to cause kyphosis? a. Abdominal obesity causing an exaggeration of the lumbar curvature b. Abnormal vertebral growth c. Chronic contraction of muscles that insert on the vertebrae d. Osteoporosis with compression fractures affecting the anterior portions of the vertebral bodies

a. Abdominal obesity causing an exaggeration of the lumbar curvature Abdominal obesity causing an exaggeration of the lumbar curvature would be an unlikely cause of kyphosis since the exaggeration of the lumbar curve would not affect the thoracic curve. It is the thoracic curvature that is abnormal in kyphosis. Some of the causes include collapse of the cervical vertebrae due to osteoporotic deterioration, abnormal bone growth, and muscle spasms in the cervical region.

Which of the following is the largest fontanelle and is commonly called the "soft spot" in newborn babies? a. Anterior fontanelle b. Mastoid fontanelle c. Sphenoidal fontanelle d. Occipital fontanelle

a. Anterior fontanelle The anterior fontanelle is the largest fontanelle and is commonly called the "soft spot" in newborn babies. This area of fibrous connective tissue is at the top of the skull at a major intersection of multiple skull bones. Much of this tissue is just posterior to the frontal bones and includes the areas of the frontal and sagittal sutures.

Which of the following clinical problems is associated with the sternum? a. Breaking of the ribs or sternum can occur during CPR b. Respiratory problems c. Separation of the ribs from the sternum during physical exercise d. Compression of the trachea during CPR

a. Breaking of the ribs or sternum can occur during CPR During cardiopulmonary resuscitations (CPR), there is considerable pressure applied to the sternum. This pressure is transferred to the heart to compress it and artificially squeeze the heart to circulate the blood. It is critical during CPR to have proper hand positioning to reduce the chances of breaking ribs or the xiphoid process and injuring the heart or lungs in the thoracic cavity, or the liver in the abdominal cavity.

Which of the following collections of bones include bones that are unpaired in the skull? a. Occipital and frontal bones b. Nasal and zygomatic bones c. Parietal and temporal bones d. Lacrimal and maxillary bones

a. Occipital and frontal bones The occipital and frontal bones are unpaired bones in the skull. The occipital bone forms the posterior and inferior aspects of the cranium, which also contains the foramen magnum. This foramen is the largest along the vertebral column and forms the entrance into the cranial cavity. The frontal bones form the anterior and superior aspects of the cranium and form the forehead.

Which of the following bones is NOT part of the orbital complex? a. Temporal bone b. Maxillary bone c. Zygomatic bone d. Frontal bone

a. Temporal bone Temporal bones do NOT form part of the orbital complex. Instead, they form the lateral portion of the skull and also house the auditory ossicles. The external acoustic meatus is the opening in the temporal bones that forms a passageway for the transfer of sound waves from the outside to the auditory ossicles, which transduce vibrations in the air to the fluid of the inner ear.

Which of the following bones does NOT directly articulate with the skull but is an important site for muscle attachment for the larynx, pharynx, and tongue? a. auditory ossicles b. hyoid bone c. vomer d. mandible

b. hyoid bone Hyoid bones do NOT directly articulate with the skull but are an important site for muscle attachment for the larynx, pharynx, and tongue. Hyoid bones do not form joints as seen in other parts of the body, but they do have a connection to the temporal bones. For the most part, the hyoid bones are a scaffolding structure that stabilizes the positions of other structures and muscles in the region. Mandibles directly articulate with the temporal bones. Vomer bones are facial bones, but they are not important attachment sites for muscles. Auditory ossicles are located inside the middle ear.

What is the name of the first cervical vertebra?

atlas (c1) The atlas is the name for the most superior vertebral bone, which is the first cervical vertebra. This first cervical vertebra supports the mass of the skull and gets its name from the Greek Titan that supported the heavens on his shoulders. This bone has a ring-like structure and lacks a body and spinous process. The axis is the second cervical vertebra. The vertebra prominens is the seventh cervical vertebra. The dens is the tooth-like structure of the axis.

Which of the following is NOT part of the axial skeleton? a. skull b. upper limb c. vertebral column d. thoracic cage

b. upper limb Upper limbs are part of the appendicular skeleton, which is composed of the humerus, radius, and ulna. The humerus attaches to the pectoral girdle, which is composed of the scapula and clavicle. These attach to the axial skeleton at the sternum. The skull is part of the axial skeleton. The thoracic cage is part of the axial skeleton. The vertebral column is part of the axial skeleton.

C1 and C2 have specific names, which are the __________.

atlas and the axis C1 and C2 have specific names, which are the atlas and the axis. These two bones have very different structures from those of the rest of the vertebral bones. The atlas has a ring-like structure and lacks spinous processes as well as a vertebral body. The axis has a structure not found on any other vertebral bone, the dens. This tooth-like projection enables the atlas to pivot on the axis. Sacrum and coccyx are inferior regions of the vertebral column. Cervical and costal are not specific bone names. The coccyx is an inferior region of the vertebral column.

The lines, tubercles, crests, ridges, and other processes on bones represent areas that are used primarily for __________.

attachment of muscles to bones The lines, tubercles, crests, ridges, and other processes on bones represent areas that are used primarily for attachment of muscles to bones. These irregularities on the bone surface, which are also called landmarks, serve as anchor sites from which tendons can connect muscle to bone. This attachment would not be possible if the surfaces of bones were perfectly smooth. Attachment of bone to bone is done with ligaments. Joint articulation is not enabled by bone landmarks. Increasing the surface area of bones would not directly help tendons do their work.

Which bones conduct sound vibrations from the tympanic membrane to the inner ear?

auditory ossicles Auditory ossicles conduct sound vibrations from the tympanic membrane to the inner ear. These bones, the smallest bones in the body, are contained within the temporal bones and transduce the vibrations at the tympanic membrane into vibrations in the fluid of the inner ear. The auditory ossicles are suspended in the middle ear and are connected sequentially. Maxillae are facial bones and do not specialize in sound transduction. Lacrimal bones are facial bones and do not specialize in sound transduction. Occipital condyles are features of the occipital bone.

Which bone forms the posterior and inferior portions of the cranium and contains a large opening called the foramen magnum? a. frontal bone b. mandible c. occipital bone d. parietal bone

c. occipital bone The occipital bone forms the posterior and inferior portions of the cranium and contains a large opening called the foramen magnum. This skull bone supports the back of the brain and the cerebellum as well as the medulla oblongata. The portion of the CNS just inferior to the foramen magnum forms the spinal cord. The frontal bone forms the anterior and superior structures of the forehead. The parietal bone forms the lateral and superior portions of the cranium. The mandible forms the lower jaw.

The only vertebrae that have transverse foramina in the transverse processes are __________.

cervical In the transverse processes of the cervical vertebrae are the transverse foramina. These passageways protect the vertebral arteries and veins. These important blood vessels supply blood to the brain.

The axial skeleton creates a framework that supports and protects organ systems in the __________.

cranial and thoracic cavities The axial skeleton creates a framework that supports and protects organ systems in the cranial and thoracic cavities. The cranial cavity protects and supports the brain and parts of the CNS just superior to the spinal cord. The thoracic cavity protects and supports the lungs, the heart, and portions of the kidneys. The thoracic cage, formed by the ribs and sternum, also protects associated structures such as the esophagus and trachea. The pleural cavity is part of the thoracic cavity. The abdominal cavity is inferior to the thoracic cavity. The pericardial cavity is part of the thoracic cavity.

The nasal complex consists of __________. a. the frontal, sphenoid, and ethmoid bones b. the inferior conchae c. the maxilla, lacrimal bones, and ethmoidal conchae d. all of the listed bones and structures are correct

d. all of the listed bones and structures are correct The nasal complex consists of all of the listed bones and structures. The bones together with the conchae form the complex, which has multiple functions. The conchae themselves help promote air turbulence, which delays transit time through this region. This delay enables the mucous membranes that line this region to warm and humidify the air. The turbulence itself also helps scents in the air reach the olfactory sensory receptors.

Which of the following forms the lower jaw? a. lacrimal bone b. zygomatic bone c. maxilla d. mandible

d. mandible The mandible forms the lower jaw bone. This, together with the maxilla, function in mastication to grind and tear food, mechanically increasing its surface area before swallowing. The mandible, like the maxilla, contains special joints known as gomphoses, which stabilize the teeth in place. The maxilla forms the upper jaw. The zygomatic bone forms the cheek. The lacrimal bone forms part of the orbit.

Which bones make up the nasal septum?

ethmoid and vomer The ethmoid forms the anteromedial floor of the cranium and the roof of nasal cavity. In the middle of this bone is the perpendicular plate of bone. This plate forms the superior portion of the nasal septum. The vomer forms the inferior portion of the nasal septum. This septum divides the nasal cavity into two passageways.

Because of its position in the skull, there is one bone that forms part of the floor of the cranium, the roof of the nasal cavity, a wall of the eye orbit, and divides the nasal cavity into two parts. Which bone does all this?

ethmoid bone The ethmoid bone, although relatively small compared to other bones of the cranium, fills all of the mentioned roles. It forms the anteromedial floor of the cranium, the roof of the nasal cavity, part of the nasal septum (along with the vomer), and the medial wall of the eye orbit.

The superior and middle nasal conchae are part of which bone?

ethmoid bone The superior and middle nasal conchae are part of the ethmoid bone. These structures help create turbulence in the air that is inhaled. This results in a mixing of the air in the nasal cavity, which helps humidify and warm the air. This also helps filter inhaled air as well as present scent to the olfactory epithelium.

The bones that make up the eye socket, or orbit, include the __________.

lacrimal, ethmoid, and sphenoid The bones that make up the eye socket, or orbit, include the lacrimal, ethmoid, and sphenoid bones. In total, seven bones make up this structure that supports the eyes. In addition to the bones just mentioned, this complex also includes the frontal, maxillary, palatine, and zygomatic bones.

The sutures that articulate the bones of the skull are the __________ sutures.

lambdoidal, sagittal, coronal, and squamous The sutures that articulate the bones of the skull are the lambdoidal, sagittal, coronal, and squamous sutures. These sutures are originally composed of fibrous connective tissue in the newborn, which gives a pliability to the skull for travel through the birth canal. As time goes on, these areas of fibrous connective tissue gradually calcify until the skull bones are bound together at these now immovable joints, which give the cranial cavity structural integrity.

The three components of the adult sternum are the __________.

manubrium, body, and xiphoid process The three components of the adult sternum are the manubrium, body, and xiphoid process. The sternum is a flat bone that covers the central anterior portion of the thoracic cage. The manubrium is the superior aspect of the sternum, and this region also articulates with the clavicles. This body of the sternum is directly anterior to the location of the heart. The xiphoid process is the most inferior aspect of the sternum.

Which bones form the medial wall of the eye orbit?

maxilla, lacrimal, and ethmoid The lateral mass of the ethmoid articulates with the lacrimal bone, which articulates with the maxilla. These three bones make up the medial wall of the eye orbit.

Which bones form part of the bridge of the nose?

nasal bones Nasal bones form part of the bridge of the nose. These bones form the superior part of the bridge and connect with the hyaline cartilage, which forms the more distal part of the nose. These are paired bones that, like many of the bones of the skull and face, connect with other bones via sutures. Vomer bones are deep facial bones. Ethmoid bones are deep cranial bones. Palatine bones form part of the hard palate.

Airflow in the nasal cavity is made turbulent by the ________.

nasal conchae The superior and middle nasal conchae of the ethmoid bone and the inferior nasal conchae project into the nasal cavity, disturbing airflow. These bones and bone processes are lined with nasal mucosa, which secretes a sticky mucus. This forms part of the protection against foreign materials entering the respiratory system.

Foramina located on the bones of the skull serve primarily as passageways for __________.

nerve and blood vessels Foramina located on the bones of the skull serve primarily as passageways for nerves and blood vessels. These openings usually have a circular shape and, since they span these areas, serve as a support for structures in the nervous and circulatory systems. These openings also serve a protective function in addition to this support, which is critical since nerve and blood vessels are relatively delicate structures that may tear under mechanical stress. Sound and light are not passed through foramina. Airways and ducts for secretions are not the functions of foramina. Muscle fibers are not generally served by foramina.

The passageway that allows the optic nerve to reach the eyeball for the sense of vision is the __________.

optic canal The optic canal is the passageway for the optic nerve, which enters the back of the eyeball to innervate the eye for vision. In the orbit, there are passageways for nerves that control the muscles that move the eyeball and innervate the soft tissues of the orbit. These are the superior orbital fissures. There are passageways for the nerves that innervate the lower eyelid and upper jaw area. These are the inferior orbital fissures. The supraorbital foramen allows the passage of a nerve that innervates the upper eyelid and skin of the forehead.

The intervertebral foramina __________.

permit the passage of nerves to and from the spinal cord The intervertebral foramina permit the passage of nerves to and from the spinal cord. These openings are formed from the vertebral arches of adjacent vertebrae. These foramina also form a protective enclosure for the region of the column in which the nerves are located. The intervertebral foramina do not reduce friction by serving as cushioning between the vertebral bodies. The intervertebral foramina do not allow a vertebra to articulate with the vertebrae directly superior and inferior. The intervertebral foramina do not provide a point of attachment for the ligamentum nuchae.

An abnormal lateral curvature of the spine is called __________.

scoliosis An abnormal lateral curvature of the spine is called scoliosis. This lateral displacement of the spine results from chronic muscle spasms in the muscles of the back. When these muscle spasms are unabated, they pull the vertebrae out of alignment, which results in the lateral curvature. Lordosis is an anterior curvature in the lumbar vertebrae. Kyphosis is a posterior curvature of the cervical vertebrae. Amphiarthrosis is a partially movable joint.

Air-filled cavities found in some bones of the skull are called __________.

sinuses Sinuses are air-filled cavities contained in some bones. These structures serve several purposes. In the skull, these bones help lighten the mass of the head. They are also lined by mucous membranes, which help humidify and warm the air as it is inhaled into the lungs. This is important since the alveolar lining is delicate and thin. Sinuses also function in voice production, forming a resonating chamber. Sutures are immovable joints. Septa are separating partitions of tissue. Sulci are grooves in a layer of tissue.

The sinuses, or internal chambers in the skull, are found in the __________.

sphenoid, frontal, ethmoid, and maxillary bones The sinuses, or internal chambers in the skull, are found in the sphenoid, frontal, ethmoid, and maxillary bones. These empty spaces are lined with a mucous membrane and have several functions: They lighten the mass of the skull and help with voice production by creating a resonating chamber. In the nasal cavity, these sinuses help moisten and warm the inhaled air.

Which vertebral process projects posteriorly?

spinous process The spinous process of the vertebrae projects posteriorly. This process is a fin-like structure that is quite prominent in the cervical and thoracic vertebrae. This is also the main aspect of the vertebral column that one can palpate off on the surface of the back. The spinous process is the largest process in the thoracic vertebrae and then becomes smaller as the transition to the lumbar and sacral regions is made. The articular process is a process that projects superiorly or inferiorly. The articular facet is part of the articular process. The transverse process projects laterally.

Except for the mandible, all bones of the skull articulate at joints called __________.

sutures Sutures are immovable, fibrous joints that form to stabilize the bony plates of the skull and are initially made of cartilage early in development. These areas of cartilage are known as fontanelles in the infant, which eventually calcify and close to form the sutures as development moves forward. Synovial joints are freely moving joints. Septa are partitions of tissue. Sulci are grooves of tissue.

Which bones of the skull form the lateral walls of the cranium, house the inner ear, articulate with the mandible, and have attachments for muscles that move the jaw and head?

temporal bones The temporal bones form part of both lateral walls of the cranium. The mandibular fossa of the temporal bone articulates with the mandible, forming the temporomandibular joint. The petrous portion of the temporal bones surrounds the sense organs of the inner ear. The temporal bone also has attachments for the muscles that raise the mandible and move the skull.

Which of the following statements about the thoracic cage is FALSE? a. The sternum does not ossify until an individual reaches 30 years of age. b. The false ribs are also known as vertebrochondral ribs. c. Depressing the ribs causes a decrease in the volume of the thoracic cavity. d. The costal cartilages allow increased flexibility in the ribs such that the ribs can bend and move to cushion shocks or absorb some blows.

a. The sternum does not ossify until an individual reaches 30 years of age. The sternum does not ossify until an individual reaches 30 years of age is false because the sternum is ossified quite early in development, unlike some other areas of the skeleton such as the cranial bones. This process of ossification continues throughout life and eventually causes some soft tissues to harden as well. This can be a problem in patients of advanced age. The costal cartilages do allow increased flexibility in the ribs such that the ribs can bend and move to cushion shocks or absorb some blows. Depressing the ribs does cause a decrease in the volume of the thoracic cavity. The false ribs are also known as vertebrochondral ribs.

Of the following, which correctly identifies the sequence of the vertebrae from superior to inferior? a. cervical, thoracic, lumbar, sacrum, coccyx b. cervical, thoracic, sacrum, lumbar, coccyx c. thoracic, cervical, lumbar, coccyx, sacrum d. cervical, lumbar, thoracic, sacrum, coccyx

a. cervical, thoracic, lumbar, sacrum, coccyx The sequence of vertebrae from superior to inferior is cervical, thoracic, lumbar, sacrum, coccyx. As you move down the vertebral column, a few trends can be observed: The vertebral bodies increase in mass as you move toward the lumbar region. At the same time, the vertebral foramina become smaller. The spinous processes also become smaller as you approach the lumbar region.

Which of the following is NOT one of the three parts of the sternum? a. costal groove b. xiphoid process c. body d. manubrium

a. costal groove The costal groove is NOT part of the sternum. The word "costal" refers to a rib structure. The sternum is a flat bone that makes up the anterior aspect of the thoracic cage and is immediately anterior to the heart. The manubrium is the superior aspect of the sternum. The body is the main structure of the sternum. The xiphoid process is the most inferior aspect of the sternum.

In which of the following groups does each bone contain a sinus? a. ethmoid, sphenoid, frontal, and maxillary b. frontal, maxillary, zygomatic, and temporal c. nasal, ethmoid, and sphenoid d. frontal, sphenoid, occipital, and temporal

a. ethmoid, sphenoid, frontal, and maxillary Ethmoid, sphenoid, frontal, and maxillary bones all contain a sinus. These empty spaces in the bone help lessen the mass of the skull, which helps lessen stress on the neck musculature. They also help voice production by forming a resonating chamber. In addition, they are lined with mucous membranes, which help warm and humidify the air.

Which bone is NOT part of the floor of the cranium? a. frontal b. sphenoid c. temporal d. occipital

a. frontal A superior view of a horizontal section through the skull shows the floor of the cranium. In that view, the ethmoid, sphenoid, temporal, and occipital bones are seen. These bones comprise the floor of the cranium and provide the passageways for most nerves and blood vessels to enter or leave the cranial cavity. The frontal bone provides the anterior portion of the cranium.

The mucus secreted by the nasal epithelium does all of the following EXCEPT __________. a. make air flow easier b. moisten the air c. warm the air d. cleanse the air

a. make air flow easier The nasal epithelium secretes moist sticky mucus. This mucus humidifies the air we breathe. It also warms the air and traps foreign particles, such as dust particles and microorganisms. It does NOT improve airflow through the nasal cavity. In fact, when the air hits the mucus membrane-covered nasal conchae, it swirls and slows a little.

Which of the following is not a function of the axial skeleton? a. providing attachments for muscles that move the legs and feet b. providing attachments for muscles that adjust the position of the head, neck, and trunk c. providing attachments for muscles that carry out respiratory movements d. providing attachments for muscles that stabilize and position parts of the appendicular skeleton

a. providing attachments for muscles that move the legs and feet The axial skeleton is made up of bones of the skull, vertebral column, and the thoracic cage. There are 80 bones in the axial skeleton. Because of this, there is a significant surface area for muscle attachments. These muscles, attached to the bones of the axial skeleton, cause movement of the skull, neck, and trunk, and aid in quiet breathing. They also stabilize and position parts of the appendicular skeleton. However, the axial skeleton does not provide attachments for muscles that move the legs and feet.

Of the following choices, which one includes bones found exclusively in the axial skeleton? a. skull, vertebrae, ribs, sternum, hyoid b. sacrum, ear ossicles, skull, scapula, ilium c. ear ossicles, scapula, clavicle, sternum, hyoid d. vertebrae, ischium, ilium, skull, ribs

a. skull, vertebrae, ribs, sternum, hyoid The skull, vertebrae, ribs, sternum, hyoid are all parts of the axial skeleton. The skull makes up the most superior aspect of the axial skeleton. The vertebral column and thoracic cage comprise the torso. The hyoid bone is located in the laryngeal regions, which act as a point of attachment for muscles and other structures in the area. Vertebrae, ischium, ilium, skull, ribs: The ischium is part of the appendicular skeleton. Ear ossicles, scapula, clavicle, sternum, hyoid: The scapulae and clavicles are part of the appendicular skeleton. Sacrum, ear ossicles, skull, scapula, ilium: The scapulae and ilium are part of the appendicular skeleton.

Which of the following bones contains the auditory ossicles? a. temporal bone b. nasal bone c. maxilla d. occipital bone

a. temporal bone The temporal bones contain the auditory ossicles. They also contain an opening to the outside, known as the external acoustic meatus. The auditory ossicles are the smallest bones of the body and function to transduce sound waves from the outside to the fluid of the inner ear. The occipital bones do not contain auditory ossicles. The maxilla is the upper jaw bone and does not contain auditory ossicles. The nasal bones do not contain auditory ossicles.

The primary spinal curves that appear late in fetal development __________.

accommodate the thoracic and abdominopelvic viscera They are also called accommodation curves, because they accommodate the thoracic and abdominopelvic viscera (internal organs).

Beginning at the superior end of the vertebral canal and proceeding inferiorly, __________.

the diameter of the vertebral foramen decreases, and the size of the vertebral body increases Beginning at the superior end of the vertebral canal and proceeding inferiorly, the diameter of the vertebral foramen decreases, and the size of the vertebral body increases. As we move down the vertebral column, the amount of mass that needs to be supported by the more inferior vertebral bones increases. This amount reaches a maximum in the lumbar region, where the vertebrae need to support the mass of the head, the torso, and the upper limbs. At the same time, the spinal cord ends in this region, so the vertebral foramen reaches a minimum. The statement "The diameter of the vertebral foramen increases, and the size of the vertebral body decreases" is not true since the lumbar vertebrae have the largest bodies. The statement "The diameter of the vertebral foramen decreases, and the size of the vertebral body decreases" is not true since the lumbar vertebrae have the largest bodies. The statement "The diameter of the vertebral foramen increases, and the size of the vertebral body increases" is not true since the vertebral foramen decreases.

The growth of the cranium is usually associated with __________.

the expansion of the brain The growth of the cranium is usually associated with the expansion of the brain. The growth of both the skull and the enclosed brain needs to be coordinated so that they fit together optimally. Any imbalance in the growth of either structure will usually cause damage to the brain. If the skull fails to expand as it should, the smaller space of the cranial cavity will not be able to accommodate the developing brain. Because neural tissue is very sensitive to mechanical stress, this failure to expand could result in brain damage, especially of the underlying structures of the brain stem, which cannot undergo folding to adjust to any changes in volume.

The sagittal suture joins __________.

the parietal bones to each other The sagittal suture joins the parietal bones to each other. The parietal bones form the lateral and superior aspects of the human skull. The sagittal suture is axial and is located in the middle of these two bones. The suture is composed of fibrous connective tissue early in development but gradually calcifies as maturity progresses.

The skeleton of the chest, or thorax, consists of __________.

thoracic vertebrae, ribs, and sternum The skeleton of the chest, or thorax, consists of thoracic vertebrae, ribs, and sternum. This thoracic cage is bordered posteriorly by the thoracic vertebrae and the ribs, which wrap around the lateral aspect and enclose the anterior aspect by connecting with the sternum. These connections are by way of hyaline cartilages that are between the sternum and the ribs.