Adapted from Martini Human Anatomy 7th ed. Chapter 6 The Skeletal System: Axial Division Introduction The axial skeleton: Composed of bones along the central axis of the body Divided into three regions: Skull Vertebral column Thoracic cage Introduction Functional anatomy of the axial skeleton: Framework that supports and protects organs in the dorsal and ventral body cavities Protects special sense organs for taste, smell, hearing, balance, and vision Attachment sites for muscles that: Adjust the posture of the head, neck, and trunk Move the thoracic cage for respiration Stabilize the appendicular skeleton Cranial and Facial Subdivisions of the Skull The skull consists of Face Cranium Associated bones The face: 14 individual bones The cranium: 8 individual bones The associated bones: 7 individual bones Posterior view of the occipital bone Lambdoid suture Suture between the occipital bone and the two parietal bones (superior skull) Sagittal suture Suture between the two parietal bones External occipital protuberance Bulge about midway of the occipital bone Superior view of the skull Parietal bones Left and right parietal bones Sagittal suture Page 1 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Between the two parietal bones Coronal suture Between the frontal bone and the two parietal bones Lateral view of the skull Temporal bone Mastoid process External acoustic meatus Zygomatic arch Styloid process Greater wing of the sphenoid bone Squamous suture Select features of the anterior skull Frontal bone Supra-orbital foramen Zygomatic bone Zygomaticofacial foramen Maxilla Infra-orbital foramen Anterior view of the skull (continued) Mandible Mental protuberance Mental foramen Nasal bones Frontonasal suture Anterior view of the nasal cavity Superior nasal concha (not visible in this view) Middle nasal concha Inferior nasal concha Nasal septum Vomer Inferior view of the skull Occipital bone Foramen magnum Occipital condyles Basioccipital Between the foramen magnum and the vomer Condyloid fossa Condyloid foramen (within the condyloid fossa) Page 2 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Inferior view of the roof of the mouth Palatine process of the maxilla (anterior palatine) Incisive fossa Incisive foramen (within the incisive fossa) Palatine bone (posterior palatine) Greater palatine foramen Lesser palatine foramen Inferior view of the skull (continued) Internal nares Vomer Inferior view of the skull (continued) Temporal bone Foramen lacerum Carotid canal Foramen ovale Foramen spinosum Jugular foramen Stylomastoid foramen Internal view of the skull Frontal bone Ethmoid bone Crista galli Cribriform plate Cribriform plate foramina (olfactory foramina) Sphenoid bone Internal view of the skull (continued) Sphenoid bone Sella turcica Dorsum sellae Hypophyseal fossa Tuberculum sellae Internal view of the skull (continued) Sphenoid bone Optic canals Page 3 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Foramen rotundum Foramen lacerum Foramen ovale Foramen spinosum Internal view of the skull (continued) Temporal bone Carotid canal Internal acoustic meatus Petrous portion of the temporal bone (organs for balance and hearing are embedded in this structure) Internal view of the skull (continued) Occipital bone Clivus (slant between the foramen magnum and the dorsum sellae) Foramen magnum Hypoglossal canal Sagittal view of the skull Ethmoid bone Crista galli (anterior brain attachment) Sphenoid bone Hypophyseal fossa (pituitary gland sits in this fossa for protection) Sagittal view of the skull (continued) Occipital bone Foramen magnum area Clivus (slant from the dorsum sella to the foramen magnum) Nasal cavity Vomer Sagittal view of the skull (continued) Sinuses Frontal sinus Sphenoidal sinus The Occipital Bone Foramen magnum Page 4 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Opening for the spinal cord Occipital condyles Articulate with the first cervical vertebra Hypoglossal canals Opening for the hypoglossal nerve that innervates the tongue Condyloid foramen The Temporal Bone Squamous part of the temporal bone Relatively flat bone of the skull Mastoid process Consists of the mastoid sinuses Mandibular fossa of the temporal bone Styloid process Neck muscle attachment External acoustic meatus Entrance into the ear canal The Sphenoid Bone Sella turcica Dorsum sellae Hypophyseal fossa (fossa for the pituitary gland) Tuberculum sellae Anterior clinoid processes Posterior clinoid processes Optic canals Openings for the optic nerves The Ethmoid Bone Superior portion of the nasal septum Crista galli Superior portion of the perpendicular plate of the ethmoid Cribriform plate Borders the crista galli Cribriform plate foramina (olfactory foramina) Openings for the olfactory nerves The Cranial Fossa Anterior cranial fossa Consists of the frontal and ethmoid bones Middle cranial fossa Extends from the internal nares to the petrous portion of the temporal bone Consists of the sphenoid, temporal, and parietal bones Page 5 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Posterior cranial fossa Extends from the petrous portion of the temporal bone to the posterior skull Consists mainly of the occipital bone The Maxillae Make up the upper jaw Consists of a left and right maxilla Maxillary sinuses Infra-orbital foramen Openings for the maxillary nerve passing through the foramen rotundum The Maxillae (continued) Make up the upper jaw Anterior nasal spine Palatine process Anterior palatine bone (roof of the mouth) Incisive foramen Opening for nerve and small arteries that innervate the palatal surface The Mandible Makes up the lower jaw Head (mandibular condyle) Articulates with the mandibular fossa of the temporal bone Mandibular notch Coronoid process The Mandible (continued) Ramus Angle Body Mental foramina (openings for the passage of nerves) Mental protuberance (bony ridge on the anterior edge) The Orbital Complex Made of 7 bony structures Frontal (roof of the orbit) Zygomatic (lateral edge of the orbit) Maxilla (floor of the orbit) Palatine bone (part of the floor of the orbit) Lacrimal bone (medial edge of the orbit) Ethmoid bone (medial edge of the orbit) Sphenoid bone (posterior edge of the orbit) Page 6 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
The Orbital Complex (continued) Superior orbital fissure (opening for the following nerves) Oculomotor Trochlear Ophthalmic branch of the trigeminal nerve The Orbital Complex (continued) Inferior orbital fissure (opening for the following nerve) Maxillary branch of the trigeminal nerve Optic canal (opening for the following nerve) Optic nerve The Nasal Complex Nasal septum Vomer Ethmoid bone Crista galli Superior and middle nasal conchae Maxillary bone Inferior nasal conchae The Nasal Complex (continued) Ethmoid bone Notice how the perpendicular plate of the ethmoid protrudes into the cranial cavity forming the crista galli Protrudes through an area called the notch for the ethmoid Superior and middle nasal conchae The Hyoid Bone Does not articulate with any other bone The inferior portion is connected to the thyrohyoid ligament The superior portion is suspended from the mandible via muscles Stylohyoid muscle Digastric muscle Page 7 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
The Hyoid Bone (continued) Bony projections of the hyoid bone Greater horn Lesser horn Body Review of the Skull There are 22 bones of the skull Facial bones Maxillae 2 Palatine bones 2 Nasal bones 2 Inferior nasal conchae 2 Zygomatic bones 2 Lacrimal bones 2 Vomer 1 Mandible 1 Review of the Skull (continued) There are 22 bones of the skull Cranial bones Occipital bone 1 Parietal bones 2 Frontal bone 1 Temporal bones 2 Sphenoid bone 1 Ethmoid bone 1 Review of the Skull (continued) There are 7 associated bones of the skull Associated bones Auditory ossicles 6 Hyoid bone 1 The Skull of Infants Major features of the infant skull 4 major fontanel areas Membranous areas where sutures will eventually form Anterior fontanel (baby s soft spot ) Posterior fontanel Sphenoidal fontanels Mastoid fontanels Page 8 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
The Skull of an Infant Functional anatomy of the fontanels Allow flexibility of the skull bones during the birthing process These membranous areas are actually the dura mater of the brain, which is a thick membranous material that helps to protect the brain. You can feel the infant s pulse in the area of the anterior fontanel. Blood vessels lie deep to the fontanel. The adult vertebral column is made up of 26 bones: 24 vertebrae 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 1 sacrum (5 fused vertebrae) 1 coccyx (3 to 5 fused vertebrae) Functional anatomy of the vertebral column Encloses and protects the spinal cord Supports the skull Supports the weight of the head, neck, and trunk Transfers weight to the lower limbs Helps maintain the upright position of the body There are 4 major curves of the vertebral column Cervical curve Thoracic curve Lumbar curve Sacral curve These curves, along with muscle attachment to the various vertebral processes, help to maintain balance The developing infant lacks balance They lack the proper curvature They lack muscle coordination Special features of the vertebrae Cervical number 1 is the atlas The atlas articulates with the occipital condyles of the skull Cervical number 2 is the axis The axis allows rotation of the head The ribs articulate with the 12 thoracic vertebrae The lumbar vertebrae support the weight of the torso Page 9 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Abnormal curvatures of the vertebral column Scoliosis Abnormal lateral curvature Kyphosis Exaggerated posterior curvature of the thoracic region Lordosis Exaggerated anterior curvature of the lumbar region Vertebral Processes (Cervical Vertebrae) Vertebral body Vertebral foramen Spinous process Transverse process Transverse foramen Lamina Pedicle Vertebral Processes (Thoracic Vertebrae) Vertebral body Vertebral foramen Spinous process Transverse process Lamina Pedicle Vertebral Processes (Lumbar Vertebrae) Vertebral body Vertebral foramen Spinous process Transverse process Lamina Pedicle Special features of the atlas and axis In addition to the structures other cervical vertebrae have, the axis also has a structure called the dens The atlas pivots on the dens of the axis Sacrum and Coccyx Sacral foramina Median sacral crest Lateral sacral crest Sacral cornu Page 10 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1
Sacral hiatus Ala Coccygeal cornu The thoracic cage has two functions: It protects the heart, lungs, thymus, and other structures within the cavity It serves as the attachment site for muscles involved in: Respiration Positioning the vertebral column Movements of the pectoral girdle and upper limb Sternum Manubrium Body Xiphoid Jugular notch Ribs (one type of classification) True ribs: 1 7 False ribs: 8 12 Ribs (another type of classification) Vertebrosternal ribs: 1 7 Vertebrochondral ribs: 8 10 Vertebral ribs (floating ribs): 11 12 (no anterior cartilage) Rib Articulation Head Neck Tubercle of rib Angle Body Page 11 of 11 BIOL 218 F 2011 Lecture Outline Ch 6 110815.1