7  Skeletal System, the Axial Skeleton

Figure 7.1 Human Skeleton.

7.1 Objectives

This lab will introduce you to the axial skeleton. You will review anatomy and physiology.

7.2 Your objectives for this lab are:

• Identify the major divisions of the skeleton, axial vs appendicular, and which bones belong to each group.
• Provide examples of each type of bone classification by shape
• Identify disarticulated bones as left or right. Be able to describe how you made this determination.
• Identify the axial bones and the specific bone markings required for each bone.

7.3 Cranial and Facial Bones of the Skull

• Frontal bone
• Parietal bones
• Occipital bone
  • Foramen magnum
  • Occipital condyles.
• Temporal bone
  • Mastoid process
  • Styloid process
  • External auditory canal (external acoustic meatus)
• Ethmoid bone
  • Perpendicular plate
  • Nasal conchae
  • Cribriform plate
  • olfactory foramina
• Sphenoid bone
  • Sella turcica
• Nasal bones
• Maxilla(e)
• Lacrimal bones
• Zygomatic bones
• Palatine bones
• Mandible
  • Mental foramen
  • Mandibular condyles

7.4 Sutures (these are joints between bones, but not bones themselves)

• Coronal suture (frontal suture)
• Squamous suture
• Sagittal suture
• Lambdoidal suture

7.5 Vertebral column

1. Identify vertebrae by name and number if articulated
2. Identify vertebra from different regions by their characteristic features if articulated or disarticulated

• Body/centrum
• Vertebral arch
  • Pedicles
  • Lamina
  • spinous process
• Transverse processes
• Transverse foramen (what structures pass through here?)
• Vertebral foramen (what structure passes through here?)
• Cervical vertebrae (C1-C7), you should also be able to identify C1 and C2 as disarticulated bones.
  • Atlas (C1)
  • Axis (C2)
    • Dens/Odontoid process
• Thoracic vertebrae (T1-T12)
  • Articulating facets (for ribs)
• Lumbar vertebrae (L1-L5)
• Sacrum
• Coccyx
• Intervertebral discs (an important structural component of the spine, but not a bone)

7.5.1 The Thorax

• Sternum,
  • Manubrium,
  • Body,
  • Xyphoid process
• Ribs
• Costal cartilages (an important structural component of the thorax, but not a bone)
• Identify ribs as True, False, and/or Floating ribs.

7.6 Prelab Activities

7.7 Prelab Activity 7.1

7.8 Definitions

Define the following key terms: axial skeleton.

• Axial skeleton ________________________________________________
• Cranial bones _________________________________________________
• Facial bones __________________________________________________
• Suture _______________________________________________________
• Hyoid bone ___________________________________________________
• Vertebrae _____________________________________________________
  • Cervical _________________________________________________
  • Thoracic ________________________________________________
  • Lumbar _________________________________________________
  • Sacrum _________________________________________________
  • Coccyx _________________________________________________

7.9 Prelab Activity 7.2:

7.10 Labeling

7.11 Label the following diagrams:

On the image below circle and label the axial and appendicular portions of the skeleton.

Figure 7.2 Anterior Aspect of a Human Skeleton.

Identify and label the following bones in the axial skeleton.

• Skull
  • Frontal bone
  • Nasal bones
  • Mandible
  • Maxilla(e)
• Thorax
  • Ribs
  • Costal cartilages
  • Sternum
• Vertebral column
  • Cervical vertebrae
  • Thoracic vertebrae
  • Lumbar vertebrae
  • Coccyx

Figure 7.3 Unlabeled Axial Skeleton.

Label the bones, sutures, and the features of the diagrams 7.4 and 7.5.

Figure 7.4 Adult Skulls (Frontal and Lateral Views).

Figure 7.5 Superior View of the Cranium

7.12 Lab Activities

7.13 Lab Activity 7.1

Bone Features: Review the information in table 7.1 before moving on to the next activity.

Table 7.1 General Types Bone Features

Marking	Description	Example
Head	Prominent rounded surface	Head of femur
Facet	Flat surface	Articular facets of vertebrae
Condyle	Rounded surface	Occipital condyle
Process	Projection from the bone	Spinous process of vertebrae
Spine	Short, sharp projection	Transverse process of vertebrae
Tubercle	Small, rounded process	Ischial spine
Tuberosity	Large, rough surface of a bone	Tubercle of humerus
Line	Smaller elevated ridge of bone	Temporal lines of parietal bone
Crest	Larger elevated ridge of bone	Iliac crest
Fossa	Larger pit in a bone	Mandibular fossa
Fovea	Smaller pit in a bone	Fovea capitis of femur
Sulcus	Groove	Sigmoid sulcus of temporal bone
Canal	Small passage in bone	Auditory canal
Fissure	Slit through bone	Inferior orbital fissure
Foramen	Hole through bone	Foramen magnum
Meatus	Opening into a canal	External auditory meatus
Sinus	Open space in bone	Nasal sinus

7.14 Lab Activity 7.1 continued.

7.15 Classifications of Bones

• Review the material in your text on the classification of bones based on shape and structure, section 6-2, p143 and 144.
• Obtain an articulated skeleton and a box of bones from the classroom lab supplies.
• Use the information from the previous lab (i.e., Lab 6), your text, Figure 7.6 below, and your skeleton to fill in the table below.

Note if you are part of an online course and are completing this lab remotely, you can use a diagram as a substitute. (e.g.,: https://commons.wikimedia.org/wiki/File:701\_Axial\_Skeleton-

01.jpg#/media/File:701\_Axial\_Skeleton-01.jpg)

Table 7.2 Review of the Appendicular and Axial Bones

Bone Name	Bone Shape Classification	Is this an axial or appendicular bone?
Facial bone, e.g., maxilla
Thoracic vertebra
Scapula (“shoulder” bone)
Radius (lateral forearm bone)
Tarsal bones (7 bones of the ankle)
Phalanges (“finger and toe” bones)
Ribs
Patella (“knee” bone)

7.16 Organization of the Skeletal System

7.17 Overview of the Whole Skeletal System

The skeletal system can be divided into two divisions, the axial and the appendicular divisions. The axial skeleton forms the main axis of the body. It includes the skull, the vertebral column, and the rib cage (see Figure 7.6). The appendicular skeleton consists of all of the bones of the limbs , including the girdles.

Figure 7.6 Organization of the Skeleton.

7.18 Axial Skeleton

Figure 7.7 Labeled Diagram of the Axial Skeleton.

7.19 The Skull

Activity: In this exercise the objective is to do the following:

• List and identify the cranial and facial bones.
• Locate the major suture lines of the skull and name the bones associated with each.
• Define the paranasal sinuses and identify the location of each.
• Name the bones that make up the walls of the orbit and identify the openings associated with the orbit.
• Identify the bones and structures that form the nasal septum and nasal conchae and locate the hyoid bone.
• Identify the bony openings and markings of the skull.

Figure 7.8 Cranial Bones and Suture (Lateral View).

7.19.1 Skull

7.20 Cranial Bones of the Skull

• Frontal bone
• Parietal bones 2
• Temporal bones 2
• Occipital bone

7.21 Major Skull Sutures

• Coronal suture
• Sagittal suture

7.21.1 Other Skull Features

• Temporal bones:
  • Mastoid process
  • Styloid process
  • External auditory meatus
  • Mandibular fossa
• Sphenoid bone:
  • Sella turcica
  • Optic canal
• Hard palate
• Zygomatic arch

7.22 Facial Bones of the Skull

• Maxillae (maxillary bones) 2
• Zygomatic bones 2
• Lacrimal bones 2
• Nasal bones 2

7.23 Hyoid bone (not attached to the skull)

7.23.1 Activity

During this period, you need to identify the bones on the articulated skeleton, disarticulated bones as well as on a picture or diagram. Pair up into working groups. Use the information and figures that follow to identify the bones and required bone markings for the axial skeleton and label them for later review. These are listed in the objectives above and at the beginning of this lab. Use labelling tape to identify the bones and markings. Have another group come to your demonstration table to review your identifications. Once finished ask your lab instructor to review your identifications.

As you prepare for the upcoming lab practical you should take pictures of the skeleton and disarticulated bones. Later you should identify and label the bones and their features. Include these identifications in your study guide.

• Maxillae (maxillary bones)
• Sphenoid bone
• Ethmoid bone
• Squamous sutures
• Lambdoid suture
• Occipital bone:
  • Occipital condyles
  • Foramen magnum
• Ethmoid bone:
  • Cribriform plate
  • Crista galli
  • Perpendicular plate
• Mandible:
  • Coronoid process
  • Mandibular condyle
• Palatine bones 2
• Vomer
• Mandible

Figure 7.9 Anterior View of the Skull.

Figure 7.10 Lateral View of the Skull.

Figure 7.11 Illustration of the Temporal Bone.

Figure 7.12 Posterior View of the Skull.

Figure 7.13 Superior and Inferior Views of the Skull.

7.23.2 The Sphenoid Bone

Figure 7.14 Illustration of the Sphenoid Bone.

Figure 7.15 Sagittal Section of the Skull: Cranial and Facial Bones

7.24 Skull: Facial Bones

Figure 7.16 Facial Bones.

7.25 Medial Views of the Nasal Cavity

Figure 7.17 Nasal Cavity.

Figure 7.18 Nasal Cavity Bones.

7.26 Maxilla

Figure 7.19 The Maxilla.

7.27 Mandible

Figure 7.20 Mandible

7.28 Orbital Socket

Figure 7.21 Bones Forming the Orbit.

7.29 Hyoid Bone

Figure 7.22 Hyoid Bone.

7.30 Lab Activities

During this period, you need to identify the bones on the articulated skeleton, disarticulated bones as well as on a picture or diagram. Pair up into working groups. Use the information and figures that follow to identify the bones and required bone markings for the axial skeleton. These are listed in the objectives below and at the beginning of this lab. Use labelling tape to identify the bones and markings. Have another group come to your demonstration table to review your identifications. Once finished ask your lab instructor to review your identifications.

As you prepare for the upcoming lab practical you should take pictures of the skeleton and disarticulated bones. Later you should identify and label the bones and their features. Include these identifications in your study guide.

7.31 Vertebral Column and Bony Thorax

Transverse foramina

7.31.1 General Vertebral Features

Body Vertebral canal Transverse processes Spinous process Intervertebral discs

7.32 Specific Vertebrae

Cervical vertebrae Atlas (C1) Axis (C2) Odontoid process Thoracic vertebrae Lumbar vertebrae Sacrum Coccyx

7.32.0.1 Ribs Sternum

True ribs False ribs Floating ribs Costal cartilages Manubrium Body Xiphoid process

7.33 Vertebral Column

Figure 7.23 Vertebral Column with Labelled Curves.

7.34 Vertebrae

Figure 7.24 Types of Vertebrae.

7.35 General Markings and Projections

Figure 7.25 Vertebral Markings and Projections.

7.36 Cervical Vertebrae

Figure 7.26 Cervical Vertebrae.

7.37 Thoracic Vertebrae

Figure 7.27 Thoracic Vertebrae.

7.37.1 Lumbar Vertebrae

Figure 7.28 Lumbar Vertebrae.

7.38 Sacrum and Coccyx

Figure 7.29 Sacrum and Coccyx.

7.39 Rib Cage

Figure 7.30 Ribs and Sternum.

7.39.1 Axial Skeleton Videos

• Watch these videos to learn about bones and markings of the axial skeleton:
  • https://youtu.be/kJNilqGxW3g
  • https://youtu.be/LiLrDTcIbkQ
  • Watch this video (http://openstax.org/l/skull1) to view a rotating and exploded skull, with color-coded bones. Which bone (yellow) is centrally located and joins with most of the other bones of the skull?
• Use this tool (http://openstax.org/l/vertcolumn) to identify the bones, intervertebral discs, and ligaments of the vertebral column. The thickest portions of the anterior longitudinal ligament and the supraspinous ligament are found in which regions of the vertebral column?
• More Practice identifying bones and markings with these websites:
  • https://webanatomy.umn.edu/various-bones
  • https://webanatomy.umn.edu/skulls-skeletons
  • http://academic.pgcc.edu/~aimholtz/AandP/Practicals.html
  • https://pierceanatomy.weebly.com/
  • https://www.getbodysmart.com/skeletal-system
• Watch this video to learn about the bones and markings of the vertebrae: https://www.youtube.com/watch?v=V4qkP8nFMys

7.40 Other related videos:

• Visit this website (http://openstax.org/l/fracturequiz) to review different types of fractures and then take a short self-assessment quiz.
• View this animation (http://openstax.org/l/headblow) to see how a blow to the head may produce a contrecoup (counterblow) fracture of the basilar portion of the occipital bone on the base of the skull. Why may a basilar fracture be life threatening?
• Osteoporosis is a common age-related bone disease in which bone density and strength is decreased. Watch this video (http://openstax.org/l/osteoporosis) to get a better understanding of how thoracic vertebrae may become weakened and may fracture due to this disease. How may vertebral osteoporosis contribute to kyphosis?
• Watch this video (http://openstax.org/l/herndisc1) to learn about a herniated disc. Watch this second video.
• (http://openstax.org/l/herndisc2) to see one possible treatment for a herniated disc, removing the damaged portion of the disc. How could lifting a heavy object produce pain in the lower limb?
• Sternal video: https://en.wikipedia.org/wiki/File:Sternum\_Anatomy\_by\_Jason\_Christian.web m

7.41 Post Lab Activities: Check Your Understanding

7.42 Post Lab Activity 7.1 Matching

Table 7.3 Match the Term with the Best Definition.

Letter	Definition	Term
1.	The cribriform plate is a surface filled with small foramina on the bone	a. turbulence
2.	The nasal conchae create, which increases the ability of the nose to trap dust.	b. zygomatic
3.	The of the mandible articulate with the temporal bone.	c. nasal
4.	Blood vessels and nerves reach the chin and lower lip through the of the mandible	d. mandibular condyles
5.	The bones are found deep to the upper lip; they form part of the ‘cheekbone’ and the lateral aspects of the bridge of the nose.	e. mental foramina
6.	The bone, together with the temporal bone and maxilla, forms the bony part of each cheek.	f. ethmoid
7.	The mirror-image bones that form the anterior aspect of the bridge of the nose are the bones.	g. maxilla

Table 7.4 Match the Term with the Best Definition.

Letter	Definition	Term
1.	Main weight bearing portion of the vertebrae	a. axis
2.	Two parts of the vertebral arch that protect the spinal cord	b. Thoracic vertebra
3.	Contains the spinal cord	c. lumbar vertebrae
4.	Type of vertebra(e) containing foramina in the transverse processes.	d. Articular process
5.	Tailbone comprised of 5 fused vertebrae	e. atlas
6.	Massive weight bearing vertebrae	f. Intervertebral
7.	Seven unfused vertebrae	g. Cervical vertebra
8.	Twelve unfused vertebrae	h. Sacrum
9.	Supports the head articulates with the occipital condyles	i. Body
10.	the odontoid provides a pivot for the rotation of the first cervical vertebra	j. Coccyx

7.43 Post Lab Activity 7.2

7.44 Identifications

Figure 7.31 Human Skull Illustration (Anterior View).

Table 7.5 Identify the following bones

Identification number	Bones
1
2
3
4
5
6
7
8
9
10

Figure 7.32 Human Skull Illustration (Lateral View).

Table 7.6 Identify the Following Bones

Identification number	Bones
1
2
3
4
5
6
7
8
9
10
11

Figure 7.33 Inferior aspect of the Skull: Identify the Following Bones and Features.

Table 7.7 Identify the bones in figure 7.34

Identification number	Bones or features
1
2
3
4
5
6
7
8
9
10
11
12
13

Figure 7.34 Superior aspect of the Skull: Identify the Following Bones and Features.

Table 7.8 Identify the bones in figure 7.35

Identification number	Bones or features
1	ID the bone
2	ID the bone
3	ID the bone
4	ID the feature
5	ID the feature
6	ID the feature
7	ID the feature
8	ID the feature
9	ID the feature
10	ID the bone
11	ID the bone
12	ID the bone

Figure 7.35. Human Skeleton (Anterior View) LadyofHats, derivative work. Identify and label all of the bones and features of the axial skeleton area.

7.45 Post Lab Activity 7.3

Complete the following crossword puzzle.

Figure 7.36 Bone Anatomy.

7.45.1 Across

• 5 The largest opening in the occipital bone (7,6)
• 8 A cavity inside a bone (5)
• 10 The lambdoid suture is formed by articulation of <which bones>? (9,0,8)
• 11 The _____ bones are found deep to the upper lip; they form part of the ‘cheekbone’ and the lateral aspects of the bridge of the nose. (7)
• 12 The coronal suture is formed by articulation of the ___ and ___ bones (8,7)

7.45.2 Down

• 1 The cribriform plate is a surface filled with small foramina on the _____ bone (7)
• 2 The external acoustic meatus is located in the _____ bone. (5,7)
• 3 A fossa is a _____. (10)
• 4 The _____ suture is formed by articulation of the occipital and parietal bones. (8)
• 6 The mirror-image bones that form the anterior aspect of the bridge of the nose are the _____ bones. (5)
• 7 Blood vessels and nerves reach the chin and lower lip through the _____ of the mandible (6,8)
• 9 A foramen (pl. foramina) is a _____ through a bone (7)

Complete the following identifications.

7.46 Post Lab Activity 7.4

Name the bones.

	Vertebra	Name
1.	Figure 7.37	a. Cervical
2.	Figure 7.38	b. Thoracic
3.	Figure 7.39	c. lumbar
4.	Figure 7.40	d. atlas
5.	Figure 7.41	e. axis
6.	Figure 7.42

7.47 Answers to the questions

7.47.0.1 Crossword

7.47.1 Axial Skeleton – Skull

Across	Down
5 foramen magnum	1 ethmoid
8 sinus	2 Sella turcica
10 occipital parietal	3 depression
11 maxilla	4 lambdoid
12 parietal frontal	6 nasal
	7 mental foramina
	9 passage

Terms	Definitions
alveolar process of the mandible	upper border of mandibular body that contains the lower teeth
alveolar process of the maxilla	curved, inferior margin of the maxilla that supports and anchors the upper teeth
angle of the mandible	rounded corner located at outside margin of the body and ramus junction
angle of the rib	portion of rib with greatest curvature; together, the rib angles form the most posterior extent of the thoracic cage
anterior (ventral) sacral foramen	one of the series of paired openings located on the anterior (ventral) side of the sacrum
anterior arch	anterior portion of the ring-like C1 (atlas) vertebra
anterior cranial fossa	shallowest and most anterior cranial fossa of the cranial base that extends from the frontal bone to the lesser wing of the sphenoid bone
anterior longitudinal ligament	ligament that runs the length of the vertebral column, uniting the anterior aspects of the vertebral bodies
appendicular skeleton	all bones of the upper and lower limbs, plus the girdle bones that attach each limb to the axial skeleton
articular tubercle	smooth ridge located on the inferior skull, immediately anterior to the mandibular fossa
atlas	first cervical (C1) vertebra
axial skeleton	central, vertical axis of the body, including the skull, vertebral column, and thoracic cage
axis	second cervical (C2) vertebra
body of the rib	shaft portion of a rib
brain case	portion of the skull that contains and protects the brain, consisting of the eight bones that form the cranial base and rounded upper skull
calvaria (also, skullcap)	rounded top of the skull
cervical vertebrae	seven vertebrae numbered as C1–C7 that are located in the neck region of the vertebral column
clavicle	a slender, S-shaped long bone acting as a strut between the sternum (breastbone) and scapula (shoulder blade)
clavicular notch	paired notches located on the superior-lateral sides of the sternal manubrium, for articulation with the clavicle
coccyx	small bone located at inferior end of the adult vertebral column that is formed by the fusion of four coccygeal vertebrae; also referred to as the “tailbone”
condylar process of the mandible	thickened upward projection from posterior margin of mandibular ramus
condyle	oval-shaped process located at the top of the condylar process of the mandible
coronal suture	joint that unites the frontal bone to the right and left parietal bones across the top of the skull
coronoid process of the mandible	flattened upward projection from the anterior margin of the mandibular ramus
costal cartilage	hyaline cartilage structure attached to the anterior end of each rib that provides for either direct or indirect attachment of most ribs to the sternum
costal facet	site on the lateral sides of a thoracic vertebra for articulation with the head of a rib
costal groove	shallow groove along the inferior margin of a rib that provides passage for blood vessels and a nerve
cranial cavity	interior space of the skull that houses the brain
cranium	skull
cribriform plate	small, flattened areas with numerous small openings, located to either side of the midline in the floor of the anterior cranial fossa; formed by the ethmoid bone
crista galli	small upward projection located at the midline in the floor of the anterior cranial fossa; formed by the ethmoid bone
dens (odontoid process)	bony projection (odontoid process) that extends upward from the body of the C2 (axis) vertebra
ear ossicles	three small bones located in the middle ear cavity that serve to transmit sound vibrations to the inner ear
ethmoid air cell	one of several small, air-filled spaces located within the lateral sides of the ethmoid bone, between the orbit and upper nasal cavity
ethmoid bone	unpaired bone that forms the roof and upper, lateral walls of the nasal cavity, portions of the floor of the anterior cranial fossa and medial wall of orbit, and the upper portion of the nasal septum
external acoustic meatus ear	ear canal opening located on the lateral side of the skull
external occipital protuberance	external occipital protuberance small bump located at the midline on the posterior skull
facet	small, flattened area on a bone for an articulation (joint) with another bone, or for muscle attachment
facial bones	fourteen bones that support the facial structures and form the upper and lower jaws and the hard palate
false ribs or vertebrochondral ribs	ribs 8–12 whose costal cartilage either attaches indirectly to the sternum via the costal cartilage of the next higher rib or does not attach to the sternum at all
floating ribs or vertebral ribs	ribs 11–12 that do not attach to the sternum or to the costal cartilage of another rib
fontanelle	expanded area of fibrous connective tissue that separates the brain case bones of the skull prior to birth and during the first year after birth
foremen magnum	a large, oval-shaped opening in the occipital bone of the skull that connects the spinal cord to the brain.
frontal bone	unpaired bone that forms forehead, roof of orbit, and floor of anterior cranial fossa
frontal sinus	air-filled space within the frontal bone; most anterior of the paranasal sinuses
greater wings of sphenoid bone	lateral projections of the sphenoid bone that form the anterior wall of the middle cranial fossa and an area of the lateral skull
hard palate	bony structure that forms the roof of the mouth and floor of the nasal cavity, formed by the palatine process of the maxillary bones and the horizontal plate of the palatine bones
head of the rib	posterior end of a rib that articulates with the bodies of thoracic vertebrae
hyoid bone	small, U-shaped bone located in upper neck that does not contact any other bone
hypoglossal canal	paired openings that pass anteriorly from the anterior-lateral margins of the foramen magnum deep to the occipital condyles
hypophyseal (pituitary) fossa	shallow depression on top of the sella turcica that houses the pituitary (hypophyseal) gland
inferior articular process	bony process that extends downward from the vertebral arch of a vertebra that articulates with the superior articular process of the next lower vertebra
inferior nasal concha	one of the paired bones that project from the lateral walls of the nasal cavity to form the largest and most inferior of the nasal conchae
infraorbital foramen	opening located on anterior skull, below the orbit
internal acoustic meatus	opening into petrous ridge, located on the lateral wall of the posterior cranial fossa
intervertebral disc	structure located between the bodies of adjacent vertebrae that strongly joins the vertebrae; provides padding, weight bearing ability, and enables vertebral column movements
intervertebral foramen	opening located between adjacent vertebrae for exit of a spinal nerve
jugular foramen	irregularly shaped opening located in the lateral floor of the posterior cranial cavity
lacrimal bone	paired bones that contribute to the anterior-medial wall of each orbit
lacrimal fossa	shallow depression in the anteromedial wall of the orbit, formed by the lacrimal bone that gives rise to the nasolacrimal canal
lambdoid suture	inverted V-shaped joint that unites the occipital bone to the right and left parietal bones on the posterior skull
lamina portion of the vertebral arch	vertebral arch on each vertebra that extends between the transverse and spinous process
lesser wings of the sphenoid bone	lateral extensions of the sphenoid bone that form the bony lip separating the anterior and middle cranial fossae
lumbar curve	posteriorly concave curvature of the lumbar vertebral column region; a secondary curve of the vertebral column
lumbar vertebrae	five vertebrae numbered as L1–L5 that are located in lumbar region (lower back) of the vertebral column
mandible	unpaired bone that forms the lower jawbone; the only moveable bone of the skull
mandibular foramen	opening located on the inner (medial) surface of the mandibular ramus
mandibular condyle	the rounded end of the condyloid process of the mandible, which connects the lower jaw to the skull at the temporomandibular joint
mandibular fossa	oval depression located on the inferior surface of the skull
mandibular notch	large U-shaped notch located between the condylar process and coronoid process of the mandible
manubrium	expanded, superior portion of the sternum
mastoid process	large bony prominence on the inferior, lateral skull, just behind the earlobe
maxillary bone (also, maxilla)	paired bones that form the upper jaw and anterior portion of the hard palate
maxillary sinus	air-filled space located with each maxillary bone; largest of the paranasal sinuses
mental foramen	opening located on the anterolateral side of the mandibular body
middle nasal concha	nasal concha formed by the ethmoid bone that is located between the superior and inferior conchae
nasal bone	paired bones that form the base of the nose
nasal cavity	opening through skull for passage of air
nasal conchae	curved bony plates that project from the lateral walls of the nasal cavity; include the superior and middle nasal conchae, which are parts of the ethmoid bone, and the independent inferior nasal conchae bone
nasal septum	flat, midline structure that divides the nasal cavity into halves, formed by the perpendicular plate of the ethmoid bone, vomer bone, and septal cartilage
nasolacrimal canal	passage for drainage of tears that extends downward from the medial-anterior orbit to the nasal cavity, terminating behind the inferior nasal conchae
neck of the rib	narrowed region of a rib, next to the rib head
occipital bone	unpaired bone that forms the posterior portions of the brain case and base of the skull
occipital condyle	paired, oval-shaped bony knobs located on the inferior skull, to either side of the foramen magnum
optic canal	opening spanning between middle cranial fossa and posterior orbit
orbit	bony socket that contains the eyeball and associated muscles
palatine bone	paired bones that form the posterior quarter of the hard palate and a small area in floor of the orbit
palatine process	medial projection from the maxilla bone that forms the anterior three quarters of the hard palate
paranasal sinuses	cavities within the skull that are connected to the conchae that serve to warm and humidify incoming air, produce mucus, and lighten the weight of the skull; consist of frontal, maxillary, sphenoidal, and ethmoidal sinuses
parietal bone	paired bones that form the upper, lateral sides of the skull
pedicle	portion of the vertebral arch that extends from the vertebral body to the transverse process
perpendicular plate of the ethmoid bone	downward, midline extension of the ethmoid bone that forms the superior portion of the nasal septum
ramus of the mandible	vertical portion of the mandible
ribs	thin, curved bones of the chest wall
sacral canal	bony tunnel that runs through the sacrum
sacral foramina	series of paired openings for nerve exit located on both the anterior (ventral) and posterior (dorsal) aspects of the sacrum
sacral promontory	anterior lip of the base (superior end) of the sacrum
sacrum	single bone located near the inferior end of the adult vertebral column that is formed by the fusion of five sacral vertebrae; forms the posterior portion of the pelvis
sagittal suture	joint that unites the right and left parietal bones at the midline along the top of the skull
sella turcica	elevated area of sphenoid bone located at midline of the middle cranial fossa
skeleton	bones of the body
skull	bony structure that forms the head, face, and jaws, and protects the brain; consists of 22 bones
sphenoid bone	unpaired bone that forms the central base of skull
sphenoid sinus	air-filled space located within the sphenoid bone; most posterior of the paranasal sinuses
spinous process	unpaired bony process that extends posteriorly from the vertebral arch of a vertebra
squamous suture	joint that unites the parietal bone to the squamous portion of the temporal bone on the lateral side of the skull
sternal angle	junction line between manubrium and body of the sternum and the site for attachment of the second rib to the sternum
sternum	flattened bone located at the center of the anterior chest
styloid process	downward projecting, elongated bony process located on the inferior aspect of the skull
superior articular process	bony process that extends upward from the vertebral arch of a vertebra that articulates with the inferior articular process of the next higher vertebra
superior articular process of the sacrum	paired processes that extend upward from the sacrum to articulate (join) with the inferior articular processes from the L5 vertebra
superior nasal concha	smallest and most superiorly located of the nasal conchae; formed by the ethmoid bone
supraorbital foramen	opening located on anterior skull, at the superior margin of the orbit
supraorbital margin	superior margin of the orbit
suture junction	line at which adjacent bones of the skull are united by fibrous connective tissue
temporal bone	paired bones that form the lateral, inferior portions of the skull, with squamous, mastoid, and petrous portions
temporal fossa	shallow space on the lateral side of the skull, above the level of the zygomatic arch
temporal process of the zygomatic bone	short extension from the zygomatic bone that forms the anterior portion of the zygomatic arch
thoracic cage	consists of 12 pairs of ribs and sternum
thoracic curve	anteriorly concave curvature of the thoracic vertebral column region; a primary curve of the vertebral column
thoracic vertebrae	twelve vertebrae numbered as T1–T12 that are located in the thoracic region (upper back) of the vertebral column
transverse foramen	foramen opening found only in the transverse processes of cervical vertebrae
transverse process	paired bony processes that extends laterally from the vertebral arch of a vertebra
true ribs vertebrosternal ribs	ribs 1–7 that attach via their costal cartilage directly to the sternum
tubercle of the rib	small bump on the posterior side of a rib for articulation with the transverse process of a thoracic vertebra
vertebra	individual bone in the neck and back regions of the vertebral column
vertebral (spinal) canal	passageway within the vertebral column for the spinal cord that is formed by the series of individual vertebral foramina
vertebral arch	bony arch formed by the posterior portion of each vertebra that surrounds and protects the spinal cord
vertebral column	entire sequence of bones that extend from the skull to the tailbone
vertebral foramen	opening associated with each vertebra defined by the vertebral arch that provides passage for the spinal cord
vomer bone	unpaired bone that forms the inferior and posterior portions of the nasal septum
xiphoid process	small process that forms the inferior tip of the sternum
zygomatic arch	elongated, free-standing arch on the lateral skull, formed anteriorly by the temporal process of the zygomatic bone and posteriorly by the zygomatic process of the temporal bone
zygomatic bone cheek bone	paired bones that contribute to the lateral orbit and anterior zygomatic arch
zygomatic process of the temporal bone	extension from the temporal bone that forms the posterior portion of the zygomatic arch