The Skeleton For descriptive purposes, the skeleton is divided into: Axial Skeleton Appendicular Skeleton For descriptive purposes, the skeleton is divided into: Axial Skeleton Appendicular Skeleton For descriptive purposes, the skeleton is divided into: Axial Skeleton Appendicular Skeleton

Structured from eighty bones segregated into three regions: The Axial Skeleton Structured from eighty bones segregated into three regions: Skull Vertebral column Bony thorax

Axial Skeleton Supports the: Protects the: Head Neck Trunk Brain spinal cord Organs in the thorax

Bones of the Axial Skeleton Figure 7.1

Most complex bony structure Formed by two groups of 22 bones : The Skull Most complex bony structure Formed by two groups of 22 bones : The cranial bones or cranium Facial bones

Encloses and protects the brain Furnish attachment sites for: The Cranium Made of 8 bones Encloses and protects the brain Furnish attachment sites for: Head muscles Neck muscles

Anatomy of the Cranium Eight cranial bones (Thin and remarkably strong for their weight): Paired: Two parietal Two temporal Unpaired: Frontal Occipital Sphenoid Ethmoid

Frontal Bone Figure 7.2a

Forms anterior portion of the cranium Frontal Bone Forms anterior portion of the cranium Articulates posteriorly with the parietal bones via: The coronal suture (joint) Major markings: The supraorbital margins The supraorbital foramen The anterior cranial fossa The frontal sinuses

Frontal Bone Figure 7.2a

Frontal Sinuses: Figure 7.11

Two large, curved, & rectangular bones Form most of : Parietal Bones Two large, curved, & rectangular bones Form most of : The superior aspect of the skull, and The lateral aspects of the skull Articulate with: other cranial bones through: Four large sutures (joints)

Parietal Bones & Major Associated Sutures The four sutures marking the articulations of the parietal bones include: Coronal suture: between parietal and frontal bones, anteriorly Sagittal suture: between right and left parietal bones, superiorly Lambdoid suture: between parietal and occipital bone, posteriorly Squamous suture: where parietal and temporal bones meet

Parietal Bones and Major Associated Sutures Form most of the superior and lateral aspects of the skull Figure 7.3a

Occipital Bone and Its Major Markings Forms most of skull’s posterior wall and base Major markings: The posterior cranial fossa Foramen magnum Occipital condyles External occipital protuberance Figure 7.2b

Temporal Bones Form: Divided into four major regions: Major markings: The inferolateral aspects of the skull Parts of the cranial floor Divided into four major regions: Squamous (bordering the parietals) Tympanic (surrounds ext. ear opening) Mastoid (posterior to ear) Petrous (lateral portion of skull base) Major markings: Zygomatic, styloid, and mastoid processes Mandibular fossa and external acoustic meatus

Temporal Bones Figure 7.5

Sphenoid Bone Butterfly-shaped bone Spans the width of the middle cranial fossa Central wedge that articulates with all other cranial bones Consists of central body & three paired processes: Central body: contains paired sinuses Greater wings: forms part of middle cranial fossa, dorsal walls of orbit, and skull wall Lesser wings: forms part of anterior cranial fossa and medial walls of orbit Pterygoid processes: projects ineriorly and forms attachment site for pterygoid muscles (chewing)

Sphenoid Bone Major markings: Major openings: Sella turcica (pituitary gland location) Major openings: Optic canals Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum

Break Biol2401.5039Oct 3rd

Sphenoid Bone Figure 7.6a

Sphenoid Bone Figure 7.6b

Lies between the sphenoid and nasal bones Forms: Ethmoid Bone Lies between the sphenoid and nasal bones Forms: most of the bony area between the nasal cavity and the orbits Major markings: Perpendicular plate Lateral masses (riddled with ethmoid sinuses) Nasal conchae (superior & middle)

Ethmoid Bone Figure 7.7

Sutural (Wormian) Bones Tiny irregularly shaped bones Appear within sutures Unknown functiom

Facial Bones Made of 14 bones Form the framework of the face Contain cavities for special senses (sight, smell, taste) Provide passageways for air and food Secure teeth Attachment site for facial muscles of expression Made of 14 bones

Facial Bones Unpaired (two): Paired (six): Mandible Vomer Maxillae Zygomatics Nasals Lacrimals Palatines Inferior conchae

Mandible and Its Markings The lower jaw bone largest, strongest bone of the face Its major markings: Coronoid process Mandibular condyle Alveolar margin Mandibular foramen Mental foramina

Mandible and Its Markings Figure 7.8a

Maxillary Bones Medially fused bones Make up: Articulate with: The upper jaw Articulate with: All other facial bones except the mandible Major markings: Palatine, frontal, and zygomatic processes Alveolar margins Inferior orbital fissure (junction with sphenoid greater wing) Maxillary sinuses (largest of paranasal sinuses)

Maxillary Bone Figure 7.8b

Paranasal Sinuses: Maxillary Sinuses Figure 7.11

Zygomatic Bones (cheekbones) Irregularly shaped bones Form: The prominences of the cheeks The inferolateral margins of the orbits Articulate with the zygomatic processes of the: Frontal bone (superiorly) Maxillae (anteriorly) Temporal bones (posteriorly)

Other Facial Bones Nasal bones: Lacrimal bones: Thin medially fused bones Form the bridge of the nose Lacrimal bones: Contribute to the medial walls of the orbit Contain a deep groove – the lacrimal fossa The lacrimal fossa houses the lacrimal sac

Other Facial Bones Palatine bones: Each is an L-shaped bone of two bony plates One is horizontal and the other is perpendicular Form: The posterior portions of the hard palate Part of posterolateral walls of the nasal cavity Small part of the orbits

Inferior nasal conchae: Other Facial Bones Vomer: Plow-shaped bone Forms part of the nasal septum Inferior nasal conchae: Paired, curved bones In the nasal cavity Form part of the lateral walls of the nasal cavity

Orbits Bony cavities where eyes are firmly encased Eyes are cushioned by fatty tissue Formed by parts of seven (3 cranial & 4 facial) bones: Frontal Sphenoid Ethmoid Zygomatic Maxilla Palatine Lacrimal

Orbits Figure 7.9b

Nasal Cavity Constructed of bone and hyaline cartilage Roof formed by: Cribriform plate of the ethmoid Lateral walls formed by: Superior and middle conchae of the ethmoid Perpendicular plate of the palatine Inferior nasal conchae Floor formed by: Palatine process of the maxillae and palatine bone

Nasal Cavity Figure 7.10a

Nasal Cavity Figure 7.10b

Paranasal Sinuses They are mucosa-lined, air-filled sacs Found in five skull bones: Frontal Sphenoid Ethmoid Paired Maxillae Air enters the paranasal sinuses from the nasal cavity Mucus drains into the nasal cavity from the sinuses They: Lighten the skull Enhance the resonance of the voice

Paranasal Sinuses Figure 7.11

Not actually part of the skull Hyoid Bone Not actually part of the skull Lies just inferior to the mandible in the anterior neck Only bone does not articulate directly with another bone Anchors to styloid process of temporal bone by stylo-hyoid ligament Attachment point for neck muscles that raise and lower the larynx during: Swallowing Speech

The Following Slide Are: Only for Reinforcement

Anterior Aspects of the Skull Frontal bone Parietal bone Glabella Frontal squama of frontal bone Frontonasal suture Supraorbital foramen (notch) Nasal bone Supraorbital margin Sphenoid bone (greater wing) Superior orbital fissure Temporal bone Optic canal Ethmoid bone Inferior orbital fissure Lacrimal bone Zygomatic bone Middle nasal concha Perpendicular plate Infraorbital foramen Ethmoid bone Maxilla Inferior nasal concha Vomer bone Mandible Mental foramen (a) Mandibular symphysis Figure 7.2a

Posterior Aspects of the Skull Sagittal suture Parietal bone Sutural bone Lambdoid suture Occipital bone Superior nuchal line External occipital protuberance Mastoid process Inferior nuchal line Occipitomastoid suture External occipital crest Occipital condyle (b) Figure 7.2b

External Lateral Aspects of the Skull Coronal suture Frontal bone Sphenoid bone (greater wing) Parietal bone Ethmoid bone Temporal bone Lacrimal bone Lambdoid suture Lacrimal fossa Squamous suture Nasal bone Occipital bone Zygomatic process Zygomatic bone Occipitomastoid suture Maxilla External acoustic meatus Mastoid process Alveolar margins Styloid process Mandibular condyle Mandible Mandibular notch Mental foramen Mandibular ramus (a) Mandibular angle Coronoid process Figure 7.3a

Midsagittal Lateral Aspects of the Skull (b) Parietal bone Coronal suture Frontal bone Frontal sinus Sphenoid bone (greater wing) Crista galli Nasal bone Sphenoid sinus Ethmoid bone (perpendicular plate) Vomer bone Maxilla Mandible Alveolar margins Incisive fossa Lambdoid suture Occipital bone Occipitomastoid suture External occipital protuberance Internal acoustic meatus Sella turcica of sphenoid Pterygoid process of sphenoid Mandibular foramen Palatine Squamous Temporal maxilla Figure 7.3b

Inferior Portion of the Skull Maxilla (palatine process) Incisive fossa Medial palatine suture Hard palate Infraorbital foramen Palatine bone (horizontal plate) Maxilla Zygomatic bone Sphenoid bone (greater wing) Temporal bone (zygomatic process) Foramen ovale Vomer Foramen lacerum Mandibular fossa Carotid canal External acoustic meatus Styloid process Stylomastoid foramen Mastoid process Jugular foramen Temporal bone (petrous part) Occipital condyle Pharyngeal tubercle of basioccipital Inferior nuchal line Parietal bone Superior nuchal line External occipital crest External occipital protuberance Foramen magnum (a) Figure 7.4a

Inferior Portion of the Skull Olfactory foramina Frontal bone Anterior cranial fossa Cribriform plate Ethmoid bone Crista galli Lesser wing Sphenoid Optic canal Greater wing Anterior clinoid process Tuberculum sellae Foramen rotundum Hypophyseal fossa Foramen ovale Sella turcica Dorsum sellae Posterior clinoid process Foramen spinosum Middle cranial fossa Foramen lacerum Temporal bone (petrous part) Jugular foramen Hypoglossal canal Internal acoustic meatus Posterior cranial fossa Anterior cranial fossa Parietal bone Occipital bone Middle cranial fossa (b) Foramen magnum Posterior cranial fossa (c) Figure 7.4b