chapter 6: bones

In this chapter, we will apply medical terminology to the macro anatomy of the skeleton, which will become helpful when you learn articulations (joints). Each bone name usually derives from a Greek or Latin root word. For example, the occipital bone comes from the Latin word occiput, meaning “back of the head.” Guess where you find the occipital bone? Yep, it’s at the back of the skull.

Divisions of the Skeleton

The human skeleton has two divisions: the axial skeleton and the appendicular skeleton. The axial skeleton includes all bones attached to the axis, or midline, of the human skeleton. The skull bones, vertebrae, and thoracic cage bones comprise the axial skeleton. The appendicular skeleton includes the bones on the periphery of the axial skeleton, such as the upper and lower limbs, and the pectoral and pelvic girdles.

Axial Skeleton

Cranial Bones	Facial Bones	Vertebrae	Thoracic Cage
Frontal Bone	Nasal Bone (two of them)	Cervical Vertebrae (seven of them)	Sternum
Parietal Bone (two of them)	Lacrimal Bone (two of them)	Thoracic Vertebrae (twelve of them)	True Ribs (seven of them)
Temporal Bone (two if them)	Zygomatic Bone (two of them)	Lumbar Vertebrae (five of them)	False Ribs (five of them)
Occipital Bone	Maxilla (two of them)	Sacrum (five fused vertebrae)	Costal Cartilage (Connects the sternum to the first 10 pairs of vertebrae)
Ethmoid Bone	Palatine Bone	Coccyx (four fused vertebrae
Sphenoid Bone	Vomer Bone
	Mandible

 

Surface Markings

Bone act as levers that require muscles to move them. Ligaments are high-tensile strength straps that connect bones at articulations (joints). Tendons connect muscles to bones and comprise of the same tissue as ligaments.

Bones have a myriad of holes, indentions, and raised extensions called surface markings. Surface markings are where tendons and ligaments attach to bone, where bones form articulations and areas where organs, blood vessels, and nerves penetrate, transverse, or parallel bone.

• Sutures
  • Immovable joint; where two bones fuse together and leave a boney scar. 
• Holes and Canals
  • Foramen – A hole in a bone where blood vessels, nerves, or organs (spinal cord) move through
  • Meatus – The opening into a canal
• Articulations
  • Condyle – a rounded knob that forms an articulation with a facet on the opposing bone  
  • Facet – a smooth surface that forms an articulation with condyle from opposing bone (facets can be depressions)
  • Head – a large, rounded expansion of a bone
• Processes – A boney bump
  • Trochanter – Large processes found on the femur
  • Tubercle – Processes found on the humerus
  • Tuberosity – a small, rounded process found on many bones
• Depressions
  • Fossa – A shallow depression in a bone

Surface Markings of the Axial Skeleton

There are myriad surface markings on the bones of the axial and appendicular skeletons; however, you will only need to know a handful of them. The surface markings you will learn are the attachment sites of the muscle you need to know or articulations you will learn about in the next chapter.

Axial Skeleton Surface Markings: The Skull

Sutures	Holes and Canals	Articulations	Processes	Depressions
Coronal suture– A suture in the coronal plane that separates the frontal bone from the parietal bones	Foramen magnum - Largest foramen on the skull, which is located within the inferior portion of the occipital bone; where the spinal cord enters the skull	Mandibular condyles– Rounded knobs on the left and right sides posterior portion of the mandible; forms an articulation with the mandibular fossa of the temporal bone	Mastoid process – A raised portion of the temporal bone that is located posterior to the pinna (external ear)	Mandibular fossa – Depression on the inferior portion of the temporal bones; forms an articulation with the mandibular condyles on the mandible
Sagittal suture – A suture in the sagittal plane that separates the left and right parietal bones	External auditory meatus – Canals on the left and right sides lateral sides of the temporal bone; i.e., the ear canals	Occipital condyles - Two rounded knobs on the left and right sides of the foramen magnum on the occipital bones; forms an articulation with the first cervical vertebra (Atlas)
Lambdoid suture – A suture that looks like the Greek letter lambda; separates the occipital bone from the parietal bones
Squamosal sutures – Two sutures in the transverse plane that separates the temporal bones from the parietal bones

Axial Skeleton Surface Markings:: General Surface Markings on the Vertebrae

Holes and Canals	Articulations	Processes	Depressions	Body
Vertebral foramen - A hole found posterior to the body in which the spinal cord travels through		Transverse processes – Two processes attached to the left and right sides of the body; in the transverse plane		Body – Thick anterior potion of the vertebrae that supports the weight of the skull and superior vertebrae
Transverse foramen – Located with the transverse processes of the cervical vertebrae		Spinous process – a single process on the posterior portion of each vertebra; angle and size of process is different for each of the three types of vertebrae

Axial Skeleton Surface Markings: Characteristics of Specific Vertebrae

Cervical Vertebrae	Thoracic Vertebrae	Lumbar Vertebrae	Sacrum	Coccyx
Seven vertebrae that comprise the neck (C1-C7)	Twelve vertebrae that form the thoracic cage (T1-T12)	Five vertebrae that form the lower back (L1-L5)	Five fused vertebrae	Four fused vertebrae
Atlas (C1) – The superior vertebra that forms an articulation with the occipital condyles; named after the Greek Titan who was forced to hold the Earth and Heavens on his shoulders.	Spinous process is thicker than a cervical vertebra's spinous process and is a downward 45 degree angle to the body	Thickest body of the vertebrae	Connects the left and right pectoral girdle bones at the posterior end	Called the caudal vertebrae in animals with a tail
Axis (C2) – Specialized vertebra that allows us to rotate our head	The ribs attach to the end of the transverse processes	Thick, stubby spinous process that is parallel to the body
Spinous process is thin and is parallel to the body	Thicker body than a cervical vertebra's body	Short, Shrek ear-like transverse processes
Contain transverse foramen; however, the vertebral arteries move through the foramen of C1-C6, not C7

Axial Skeleton Surface Markings: The Thoracic Cage

Costal Cartilage	True Ribs	False Ribs	Sternum
Cartilage that connects the true ribs and the first three pairs of false ribs to the sternum	Pairs 1-7; have a direct cartilage pathway to the sternum	Pairs 8-10; share a cartilage pathway to the sternum Pairs 11 and 12; are not connected to the sternum (also known as floating ribs)	Manubrium - Superior portion of the sternum
			Body - Middle portion of the sternum
			Xiphoid process - Inferior portion of the sternum that resembles the tip of a knife

The Appendicular Skeleton

Appendicular Skeleton Surface Markings: The Upper Limb

Humerus	Radius	Ulna	Carpals, Metacarpals, and Phalanges
Greater tubercle (larger and superior to the lesser tubercle)	Radial tuberosity	Olecranon process (forms an articulation with the olecranon fossa on the humerus)	None that you need to learn
Lesser tubercle (smaller an inferior to the greater tubercle)	Head of the radius	Styloid process
Deltoid tuberosity
Olecranon fossa (forms an articulation with the olecranon process on the ulna)
Medial and lateral condyles
Head of the humerus (forms an articulation with the glenoid cavity on the scapula

Appendicular Skeleton Surface Markings: Pectoral Girdle

Scapula	Clavicle
Acromion process (forms and articulation with the lateral end of the clavicle)	None that you have to learn
Coracoid process	Medial end forms an articulation with the manubrium of the sternum
Glenoid cavity (forms an articulation with the head of the humerus)

Appendicular Skeleton Surface Markings: Pelvic Girdle

Ilium	Ischium	Pubis
Iliac crest	Obturator foramen; comprises the ischium and pubic bones	Obturator foramen; comprises the ischium and pubic bones
Acetabulum; comprises all three pelvic bones (forms an articulation with the head of the humerus)	Acetabulum; comprises all three pelvic bones (forms an articulation with the head of the humerus)	Acetabulum; comprises all three pelvic bones (forms an articulation with the head of the humerus)
	Ischial tuberosity

Appendicular Skeleton Surface Markings: The Lower Limb

Femur	Patella	Tibia	Fibula	Tarsals, Metatarsals, and Phalanges
Greater trochanter (superior and larger, and lateral to the lesser trochanter)	None that you need to learn	Medial and lateral tibial plateaus (form an articulation with the medial and lateral condyles on the femur)	Lateral malleolus	None that you need to learn
Lesser trochanter (inferior and smaller, and medial to the greater trochanter)		Medial malleolus
Head of the femur (forms an articulation with the acetabulum on the pelvic girdle)
Medial and lateral condyles (form an articulation with the medial and lateral tibial plateaus)