AP1 M 4.1 Anatomy of the skeleton

Question 1

skeleton

Answer 1

The skeleton, comprised of a network of bones held together at joints, has many functions. The skeleton protects vital internal organs. For example, the skull forms a protective encasement for the brain. The rib cage provides protection for the heart and lungs. Flat bones, such as those of the skull, ribs, and breastbone, produce blood cells.

The five basic bone shapes: Long, flat, short, irregular, and sesamoid

Figure 4.1

Question 2

bones

Answer 2

All bones are storage areas for inorganic calcium and phosphorus salts. Bones also provide sites for attachment of muscle, tendons, and ligaments. The long bones, particularly those of the legs and the arms, permit flexible body movement. The large, heavy bones of the legs support the body against the pull of gravity

Question 3

five types of bones

Answer 3

• Long bones are long and thin, designed to support body weight and enable movement. Examples of long bones include the humerus, ulna, radius, tibia, fibula, metacarpals, and metatarsals.
• **Flat **bones (such as in the cranium) form the roof of the skull to protect the brain.
• **Short **bones are small and cube-shaped. The carpals in the hand and tarsals in the foot are short bones.
• ** Irregular **bones are varied in structure with ridges or irregular surfaces. The vertebrae are irregular bones designed to protect the spinal cord as well as enable spinal movements. The pelvic bones (ilium, ischium, and pubis) are also irregular bones.
• **Sesamoid **bones are small and round, reinforcing tendons. The patella is an example of a sesamoid bone.

Question 4

bone landmarks

Answer 4

Each bone has distinct markings, ridges, grooves, or holes called bone landmarks. Bone landmarks serve several functions. Some bone landmarks allow for tendons to attach. Other markings indicate where nerves and blood vessels run alongside the bone or penetrate the bone to provide blood and nervous supply.

Question 5

Foramen, canal, fissure

bone landmarks

Answer 5

Foramen, canal, fissure - openings in bone to allow for nerves, blood supply, or a passageway

Question 6

Sinus

bone landmarks

Answer 6

Sinus - hollow chamber in bone, usually filled with air

Question 7

Process, ramus

bone landmarks

Answer 7

Process, ramus - elevations in bone

Question 8

Trochanter, tuberosity, tubercle, crest, line, spine

bone landmarks

Answer 8

Trochanter, tuberosity, tubercle, crest, line, spine - processes or projections for tendon or ligament attachment

Question 9

Head, neck, condyle, trochlea, facet -

bone landmarks

Answer 9

Head, neck, condyle, trochlea, facet - processes designed for articulation with adjacent bones

Question 10

Fossa, sulcus

bone landmarks

Answer 10

Fossa, sulcus - depressions in bone

Question 11

human skeleton

Answer 11

The human skeleton has two main divisions: the axial skeleton and appendicular skeleton.

Figure 4.2 The axial skeleton (blue) includes the skull, vertebral colum

Figure 4.3 Lateral view of the axial skeleton, appendicular skeleton removed

Question 12

axial skeleton

Answer 12

The axial skeleton lies on the midline of the body and consists of the skull, vertebral column, sternum, laryngeal skeleton, and thoracic (rib) cage

Question 13

skull

Answer 13

The skull is formed by 22 bones: the cranium (8 bones) and facial bones (14 bones).

Figure 4.4 Fontanelles are present in newborns until around two years of

Question 14

cranium

Answer 14

The cranium protects the brains and is composed of eight bones fitted tightly together in adults. In newborns, certain bones are not completely formed and instead are joined by membranous regions called fontanelles (see Figure 4.4), commonly called “soft spots.” Fontanelles allow the bones of the skull to compress during childbirth and expand to accommodate a rapidly growing infant brain. These regions begin to close around two months but may last up to two years.

Figure 4.5 and 4.6 Lateral view of the cranial bones.

Question 15

large bones of the cranium

Answer 15

The large bones of the cranium have the same names as the lobes of the brain: frontal, parietal, temporal, and occipital.

Figure 4.5 and 4.6 Lateral view of the cranial bones.

Question 16

frontal bone

large bones of the cranium

Answer 16

On the top of the cranium, the frontal bone forms the forehead

Figure 4.5 and 4.6 Lateral view of the cranial bones.

(one bone)

Question 17

parietal bones

large bones of the cranium

Answer 17

the parietal bones extend to the sides,

Figure 4.5 and 4.6 Lateral view of the cranial bones.

(two, paired bones)

Question 18

occipital bone

large bones of the cranium

Answer 18

the occipital bone curves to form the base of the skull.

Figure 4.5 and 4.6 Lateral view of the cranial bones.

(one bone)

Question 19

temporal bone

Below the much larger bones of the cranium

Answer 19

Below the much larger parietal bones, each temporal bone has an opening that leads to the middle ear.

two, paired bones

Question 20

sphenoid bone

Below the much larger bones of the cranium

Answer 20

The sphenoid bone not only completes the sides of the skull, it also contributes to the floors and walls of the eye sockets.

(one bone)

Question 21

ethmoid bone

Below the much larger bones of the cranium

Answer 21

the ethmoid bone, which lies in front of the sphenoid, is a part of the orbital wall and, in addition, is a component of the nasal septum.

(one bone)

Question 22

foramen magnum

reference to the skull

Answer 22

The occipital bone contains a large opening, the foramen magnum, through which the spinal cord passes to become the brain stem. Note the bone landmarks in Figure 4.7,

Figure 4.7 Posterior view of the occipital bone with major bone landmark

Question 23

sinuses

reference to the skull

Answer 23

The bones of the cranium contain the sinuses, air spaces lined by mucous membrane (see Figure 4.8). Sinuses reduce the weight of the skull and give a resonant sound to the voice. Two sinuses called the mastoid sinuses drain into the middle ear.

Question 24

Mastoiditis

reference to the skull

Answer 24

Mastoiditis, a condition that can lead to deafness, is an inflammation of the mastoid sinuses. A sinus infection (sinusitis) occurs when the soft tissues inside the sinuses become inflamed from a virus, bacteria, or allergy.

Question 25

foramina

reference to the skull. Plural for foramen

Answer 25

The foramina of the skull allow for many functions, such as passage for blood vessels, nerves, and the spinal cord
A foramen (pl. foramina) is an opening that allows the passage of structures from one region to another. In the skull base, there are numerous foramina that transmit cranial nerves, blood vessels and other structures – these are collectively referred to as the cranial foramina.

Question 26

foramen magnum

reference to the skull

Answer 26

The foramen magnum allows for passage of the spinal cord into the skull.

Question 27

carotid canal

reference to the skull…foramina

Answer 27

The carotid canal is an opening of the temporal bone for the internal carotid artery.

Question 28

external acoustic meatus

reference to the skull….foramina

Answer 28

The external acoustic meatus (Figure 4.9, Figure 4.12) is for transmission of sound, also located within the temporal bone.

Question 29

mandible

There are fourteen facial bones

Answer 29

The mandible, lower jaw, is the only movable portion of the skull (Figure 4.10). The mandible and vomer (Figure 4.11, Figure 4.12) are the only non-paired bones of the facial skeleton; all other facial bones are paired.

Question 30

maxillae

There are fourteen facial bones

Answer 30

The maxillae, the upper jaw, forms the anterior portion of the hard palate and contains the infraorbital foramen. Tooth sockets are found in both the mandible and maxillae

Question 31

zygomatic bones

There are fourteen facial bones

Answer 31

The zygomatic bones give us our cheekbone prominences, and the nasal bones form the bridge of the nose

Question 32

palatine bones

There are fourteen facial bones

Answer 32

The palatine bones make up the posterior portion of the hard palate and floor of the nasal cavity

Question 33

lacrimal bone

There are fourteen facial bones

Answer 33

Each thin, scale-like lacrimal bone lies between an ethmoid bone and a maxillary bone

Question 34

vomer

There are fourteen facial bones

Answer 34

Each thin, scale-like lacrimal bone lies between an ethmoid bone and a maxillary bone, and the thin, flat vomer joins with the perpendicular plate of the ethmoid to form the nasal septum

Question 35

inferior nasal conchae

There are fourteen facial bones

Answer 35

The inferior nasal conchae are bones located inferiorly to the middle conchae

Question 36

middle and superior nasal conchae

There are fourteen facial bones

Answer 36

The middle and superior nasal conchae are formed from the grooves of the ethmoid bone. The nasal conchae act to swirl the air as it is breathed in through the nasal passages, helping to warm and humidify the air before it enters the lower respiratory system.

Question 37

vertebral column

Answer 37

The vertebral column extends from the skull to the pelvis. In a typical spine, the vertebral column has four curvatures that provide more resilience and strength in an upright posture than a straight column could

Question 38

cervical

groups names (anatomical regions)

Answer 38

(neck)

Question 39

thoracic

groups names (anatomical regions)

Answer 39

back, ribs

Question 40

lumbar

groups names (anatomical regions)

Answer 40

lower back

Question 41

sacrum, and coccyx

groups names (anatomical regions)

Answer 41

tail

Question 42

The structure of an individual vertebrae

Answer 42

The structure of an individual vertebrae varies slightly from region to region

Question 43

spinous processes

Answer 43

The spinous processes are located on the dorsal side of the vertebrae and can be **palpated **(examined externally by touch) as bony projections along the midline of the neck and back.

Question 44

palpated

Answer 44

can be **palpated **examined externally by touch

Question 45

vertebral body

structure of an individual vertebrae varies slightly from region to regi

Answer 45

The vertebral body is located on the anterior portion and is the part of the vertebrae with the most surface area.

Question 46

articular facets

structure of an individual vertebrae varies slightly from region to regi

Answer 46

The articular facets allow adjacent vertebrae to articulate with each other. Note how the spinal cord is protected in the center of the vertebrae and the spinal nerves exit between the vertebrae.

Question 47

cervical vertebra

Answer 47

There are seven cervical vertebrae. A typical cervical vertebra has a long spinous process with a bifid tip that splits into two parts posteriorly (except for C1). The cervical vertebral bodies are small, and the vertebral foramen are large.

See Figure 4.15

Question 48

transverse processes

cervical vertebrae

Answer 48

The transverse processes have transverse foramina for the passage of the vertebral arteries and vertebral veins.

See Figure 4.15

Question 49

A typical thoracic vertebra

Answer 49

A typical thoracic vertebra has a long, thin spinous process that does not split (Figure 4.16). The spinous process points inferiorly. The vertebral bodies are medium-sized and contain facets for rib articulations. The transverse processes also have costal facets for rib articulations. There are twelve thoracic vertebrae, all of which contain the facets for rib articulation on the transverse processes except for T11 and T12.

Question 50

A typical lumbar vertebra

Answer 50

A typical lumbar vertebra (Figure 17) has a shorter spinous process that is broader and points posteriorly. The vertebral bodies of the lumbar spine are the largest, enabling it to support the weight of the head, neck, trunk, and upper limbs.

Question 51

transverse processes

lumbar area of spine

Answer 51

The transverse processes are shorter and have no costal facets. The vertebral foramen of the lumbar spine are the smallest and triangular-shaped. Note the other labeled regions in Figure 17 below.

Question 52

sacrum

Answer 52

The sacrum is comprised of five fused bones at the base of the spine (Figure 4.18). The base of the sacrum is the widest portion, which articulates with the L5 vertebra above it.

Question 53

coccyx

Answer 53

The coccyx is comprised of four to five fused vertebrae, which typically begin to fuse by around age 25 (Figure 4.18). The sacrum and coccyx provide attachment sites for many ligaments and tendons. The stability of the sacrum, coccyx, and ligaments anchoring them to the pelvis are key for pelvic stability.

Question 54

Thoracic Cage

Answer 54

All twelve pairs of ribs connect directly to the thoracic vertebrae posteriorly (Figure 4.19). Ribs 1-7 connect directly to the sternum. Ribs 8-10 connect to the sternum indirectly via shafts of cartilage to the sternum.

Question 55

floating ribs

Answer 55

The lower two pairs of ribs (ribs 11 and 12) are called “floating ribs” because they do not attach to the sternum.

Question 56

sternum

Answer 56

The sternum is comprised of three parts: the manubrium, body, and xiphoid process.