CHAPTER 7: THE SKELETON
THE AXIAL SKELETON
SKULL: The skull is the most complex bony structure of the skeleton. It’s composed of 22 bones (not including the
auditory ossicles), and it’s located on the superior end of the vertebral column. The cranial bones of the skull function to
enclose and protect the brain, and the facial bones of the skull function to protect the sense organs in the head and to
provide supportive entrances to the digestive and respiratory tracts. All of the skull bones function as attachment sites for
skeletal muscles that move the head, and the mandible is the only movable bone of the skull.
Cranial bones of skull (cranium): Facial bones of skull:
Frontal bone (1) Mandible (1)
Parietal bone (2) Maxillae (2)
Temporal bone (2) Palatine bone (2)
Occipital bone (1) Zygomatic bone (2)
Sphenoid bone (1) Nasal bone (2)
Ethmoid bone (1) Lacrimal bone (2)
Vomer bone (1)
Inferior nasal conchae (2)
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, CHAPTER 7: THE SKELETON
Unique features of skull:
Sutures: Sutures are immovable joints located between the cranial and facial bones, which function to
hold/join these bones together. EX: coronal suture, sagittal suture, lambdoid suture, squamous suture
Sutural bones: Sutural bones are unique, irregular bones located at sutures. They vary from
person to person, and their significance is unknown.
Paranasal sinuses: Paranasal sinuses are small cavities positioned around the nasal cavity, and they are
located in the frontal, sphenoid, ethmoid, and maxillary bones. These sinuses are lined with mucosae,
and they function to reduce the weight of the skull and to resonate sound as we speak.
Fontanelles: Fontanelles are the “soft spots” on a newborn’s skull. They are areas of unossified fibrous
connective tissue located between cranial bones, and they function to allow baby’s head to be
compressed during childbirth to fit through the vaginal canal and to accommodate brain growth of the
baby.
Page 2
THE AXIAL SKELETON
SKULL: The skull is the most complex bony structure of the skeleton. It’s composed of 22 bones (not including the
auditory ossicles), and it’s located on the superior end of the vertebral column. The cranial bones of the skull function to
enclose and protect the brain, and the facial bones of the skull function to protect the sense organs in the head and to
provide supportive entrances to the digestive and respiratory tracts. All of the skull bones function as attachment sites for
skeletal muscles that move the head, and the mandible is the only movable bone of the skull.
Cranial bones of skull (cranium): Facial bones of skull:
Frontal bone (1) Mandible (1)
Parietal bone (2) Maxillae (2)
Temporal bone (2) Palatine bone (2)
Occipital bone (1) Zygomatic bone (2)
Sphenoid bone (1) Nasal bone (2)
Ethmoid bone (1) Lacrimal bone (2)
Vomer bone (1)
Inferior nasal conchae (2)
Page 1
, CHAPTER 7: THE SKELETON
Unique features of skull:
Sutures: Sutures are immovable joints located between the cranial and facial bones, which function to
hold/join these bones together. EX: coronal suture, sagittal suture, lambdoid suture, squamous suture
Sutural bones: Sutural bones are unique, irregular bones located at sutures. They vary from
person to person, and their significance is unknown.
Paranasal sinuses: Paranasal sinuses are small cavities positioned around the nasal cavity, and they are
located in the frontal, sphenoid, ethmoid, and maxillary bones. These sinuses are lined with mucosae,
and they function to reduce the weight of the skull and to resonate sound as we speak.
Fontanelles: Fontanelles are the “soft spots” on a newborn’s skull. They are areas of unossified fibrous
connective tissue located between cranial bones, and they function to allow baby’s head to be
compressed during childbirth to fit through the vaginal canal and to accommodate brain growth of the
baby.
Page 2
