Axial Skeleton: The Skull Slides by Vince Austin; HESC310 4/14/2017 Axial Skeleton: The Skull Slides by Vince Austin; figures from Marieb & Hoehn 8th ed.; modifications and some slides by W. Rose Portions copyright Pearson Education Axial Skeleton

The Axial Skeleton Eighty bones segregated into three regions Skull Vertebral column Bony thorax

Figure 7.1 The human skeleton. Cranium Skull Facial bones Bones of pectoral girdle Clavicle Thoracic cage (ribs and sternum) Scapula Sternum Upper limb Rib Humerus Vertebra Vertebral column Radius Bones of pelvic girdle Ulna Sacrum Carpals Phalanges Metacarpals Femur Patella Lower limb Tibia Fibula Tarsals (a) Anterior view Metatarsals (b) Posterior view Phalanges

The Skull Skull Body’s most complex bony structure Formed by the cranium and facial bones Cranium – protects brain; site of attachment for head and neck muscles Facial bones Framework for the face, sense organs, and teeth Provide openings for passage of air and food Anchor facial muscles of expression

Figure 7.2a The skull: Cranial and facial divisions and fossae. Bones of cranium (cranial vault) Coronal suture Squamous suture Lambdoid suture Facial bones (a) Cranial and facial divisions of the skull

Anatomy of the Cranium Eight cranial bones – two parietal, two temporal, frontal, occipital, sphenoid, and ethmoid Cranial bones thin and strong for their weight

Figure 7.2b The skull: Cranial and facial divisons and fossae. Anterior cranial fossa Middle cranial fossa Posterior cranial fossa (b) Superior view of the cranial fossae

Figure 7.2c The skull: Cranial and facial divisions and fossae. Temporal lobe of cerebrum Frontal lobe of cerebrum Cerebellum Posterior Cranial fossae Middle Anterior (c) Lateral view of cranial fossae showing the contained brain regions

Figure 7.3 Major cavities of the skull, frontal section. bone Cranial cavity Frontal sinus Zygomatic bone Orbit Orbit Ethmoid sinuses Ethmoid bone Maxillary sinus Inferior nasal concha Nasal cavity Maxilla Oral cavity Vomer Mandible

Frontal Bone Anterior portion of the cranium Articulates posteriorly with the parietal bones via the coronal suture Major markings include: supraorbital margins, anterior cranial fossa, frontal sinuses (internal and lateral to the glabella)

Frontal Bone Figure 7.2a

Parietal Bones and associated sutures Form most of the superior and lateral aspects of the skull Coronal, sagittal, lambdoid, squamous sutures Figure 7.3a

Forms most of skull’s posterior wall and base Occipital Bone Sagittal suture Parietal bone Sutural (Wormian) bone Lambdoid suture Occipital bone Forms most of skull’s posterior wall and base Mastoid process Occipital condyle

Cranial cavity floor Anterior cranial fossa Middle cranial fossa Jugular foramen Foramen magnum (spinal cord) Posterior cranial fossa View Occipital bone

Temporal Bones Form the inferolateral aspects of the skull and parts of the cranial floor Divided into four major regions – squamous, tympanic, mastoid, and petrous Major markings include: zygomatic, styloid, and mastoid processes, middle cranial fossa Major openings include: external auditory meatus, internal auditory meatus, stylomastoid and jugular foramina, carotid canal

Figure 7.8 Right temporal bone, lateral view Squamous region External acoustic meatus Mastoid region Zygomatic process Mastoid process Tympanic region Styloid process

Sphenoid Bone Butterfly-shaped bone that spans the width of the middle cranial fossa Forms the central wedge that articulates with all other cranial bones Central body, greater wings, lesser wings, and pterygoid processes Major markings: sella turcica, hypophyseal fossa, pterygoid processes, sphenoid sinuses, middle cranial fossa Major openings include: optic canals, superior orbital fissure

Figure 7.7a Cranial cavity floor Frontal bone Optic canal (cn 2) Lesser wing Sphenoid Greater wing Hypophyseal fossa of sella turcica Middle cranial fossa View Superior view of cranial interior

Lesser wing Optic canal (cn2) Superior orbital Figure 7.9 Sphenoid bone Lesser wing Optic canal (cn2) Superior orbital fissure (cn 3, 4, part5, 6) Greater wing Hypophyseal fossa of sella turcica Body of sphenoid Superior view Body of sphenoid Lesser wing Greater wing Superior orbital fissure (cn 3,4, part5, 6) Pterygoid process Posterior view

Ethmoid Bone Deepest skull bone; lies between the sphenoid and nasal bones Forms most of the bony area between the nasal cavity and the orbits Major markings include: cribriform plate, crista galli, perpendicular plate, superior & middle nasal conchae, ethmoid sinuses

Crista galli Olfactory foramina Cribriform plate Orbital plate Figure 7.10 Ethmoid bone Crista galli Olfactory foramina Cribriform plate Orbital plate Left lateral mass Ethmoidal air cells Perpendicular plate Middle nasal concha

Figure 7.7a Cranial cavity floor Cribriform plate Frontal bone Ethmoid bone Crista galli Olfactory foramina Anterior cranial fossa View

Facial Bones Fourteen bones Only mandible and vomer are unpaired Paired bones: maxillae, zygomatics, nasals, lacrimals, palatines, inferior conchae

Mandible Maxillary Bones Lower jawbone; largest, strongest bone of face Major markings include: coronoid process, mandibular condyle, alveolar margin, mandibular angle, mandibular and mental foramina Maxillary Bones Medially fused bones make up upper jaw and central portion of the facial skeleton Facial keystone bones that articulate with all other facial bones except mandible Major markings include: palatine, frontal, and zygomatic processes (artic. w/ respective bones), alveolar margins, maxillary sinuses

Figure 7.11 Mandible and maxilla right lateral view Temporomandibular joint Coronoid process Mandibular condyle Mandibular foramen Alveolar margin Ramus of mandible Mental foramen Mandibular angle Body of mandible Articulates with frontal bone Orbital surface Zygomatic process (cut) Alveolar margin Maxilla, right lateral view

Facial Bones Zygomatic Bones - irregularly shaped bones (cheekbones), form prominences of cheeks and inferolateral margins of orbits Nasal bones – thin medially fused bones, form bridge of nose Lacrimal bones – contribute to medial walls of orbits; contain lacrimal fossae which house lacrimal sacs Palatine bones – two bone plates, form portions of hard palate, posterolateral walls of nasal cavity, and small parts of orbits Vomer – plow-shaped bone, forms part of nasal septum Inferior nasal conchae – paired, curved bones in nasal cavity, form part of lateral walls of nasal cavity

Figure 7.4a Anterior aspect of skull Frontal bone Parietal bone Supraorbital margin Nasal bone Superior orbital fissure Sphenoid bone Optic canal Temporal bone Inferior orbital fissure Ethmoid bone Lacrimal bone Ethmoid bone Zygomatic bone Maxilla Inferior nasal concha Mandible Vomer Mental foramen

Figure 7.5a Lateral aspect of skull, external view Coronal suture Frontal bone Sphenoid bone (greater wing) Parietal bone Ethmoid bone Temporal bone Lacrimal bone Lambdoid suture Squamous suture Nasal bone Occipital bone Zygomatic bone Zygomatic process Maxilla External acoustic meatus Mastoid process Alveolar margins Styloid process Mandibular condyle Mandible Mental foramen Mandibular ramus Mandibular angle Coronoid process (a) External anatomy of the right side of the skull

Figure 7.5b Lateral aspect of skull, internal view Parietal bone Coronal suture Frontal bone Sphenoid bone Squamous suture Frontal sinus Temporal bone Crista galli Nasal bone Lambdoid suture Sphenoid sinus Ethmoid bone Occipital bone (perpendicular plate) Vomer Maxilla Alveolar margins Pterygoid process of sphenoid bone Sella turcica of sphenoid bone Mandible Mandibular foramen Palatine bone Midsagittal section showing the internal anatomy of left half of skull

Figure 7.6a Inferior aspect of skull, mandible removed Maxilla Hard palate Palatine bone Maxilla Zygomatic bone Sphenoid bone (greater wing) Temporal bone (zygomatic process) Vomer External acoustic meatus Styloid process Mastoid process Temporal bone (petrous part) Occipital condyle Parietal bone Foramen magnum

Orbits Bony cavities in which the eyes are firmly encased and cushioned by fatty tissue Formed by parts of seven bones – frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid

Orbits (cn 3,4,part5,6) (cn 2) frontal temporal maxilla

Nasal Cavity Constructed of bone and hyaline cartilage Roof – formed by cribiform plate of ethmoid Lateral walls – formed by superior and middle conchae of ethmoid, perpendicular plate of palatine, and inferior nasal conchae Floor – formed by palatine process of the maxillae and by palatine

Nasal cavity: left lateral wall Nasal septum removed. Frontal sinus Superior, middle, and inferior meatus Superior nasal concha Ethmoid bone Middle nasal concha Inferior nasal concha Nasal bone Sphenoid sinus Maxillary bone (palatine process) Sphenoid bone Pterygoid process Palatine bone Palatine bone Nasal cavity: left lateral wall Nasal septum removed.

Nasal cavity: Midline structures. Crista galli Ethmoid bone Cribriform plate Frontal sinus Sella turcica Nasal bone Perpendicular plate of ethmoid bone Sphenoid sinus Septal cartilage Palatine bone Vomer Alveolar margin of maxilla Hard palate Palatine process of maxilla Nasal cavity: Midline structures. Septum in place; note contributions of ethmoid bone, vomer, septal cartilage

Paranasal Sinuses Mucosa-lined, air-filled sacs found in five skull bones: frontal, sphenoid, ethmoid, and paired maxillary bones Named for bones in which they reside Air enters paranasal sinuses from nasal cavity Mucus drains into nasal cavity from paranasal sinuses Lighten skull; enhance resonance of the voice

Figure 7.15 Paranasal sinuses. Frontal sinus Frontal sinus Ethmoidal air cells (sinus) Ethmoidal air cells Sphenoid sinus Sphenoid sinus Maxillary sinus Maxillary sinus (a) Anterior aspect (b) Medial aspect

Hyoid Bone Not actually part of the skull Lies just inferior to mandible in anterior neck Only bone that does not articulate with another bone Attachment point for neck muscles that raise and lower larynx during swallowing and speech

Anterior aspects of skull Frontal bone Parietal bone Supraorbital margin Nasal bone Superior orbital fissure Sphenoid bone Optic canal Temporal bone Inferior orbital fissure Ethmoid bone Lacrimal bone Ethmoid bone Zygomatic bone Maxilla Inferior nasal concha Mandible Vomer Mental foramen

Right side of skull Frontal bone Coronal suture Sphenoid bone (greater wing) Parietal bone Ethmoid bone Temporal bone Lacrimal bone Lambdoid suture Lacrimal fossa Squamous suture Nasal bone Occipital bone Zygomatic bone Zygomatic process Maxilla Alveolar margins Mandible Mental foramen Mandibular ramus Mandibular angle Coronoid process

Internal anatomy of left half of skull (midsagittal section) Parietal bone Frontal bone Sphenoid bone Frontal sinus Temporal bone Crista galli Nasal bone Lambdoid suture Sphenoid sinus Ethmoid bone Occipital bone Vomer Maxilla Alveolar margins Sella turcica of sphenoid bone Mandible Mandibular foramen Palatine bone Maxilla

Figure 7.7a Cranial cavity floor Cribriform plate Frontal bone Ethmoid bone Crista galli Olfactory foramina Anterior cranial fossa Optic canal Lesser wing Sphenoid Greater wing Hypophyseal fossa of sella turcica Middle cranial fossa Temporal bone Hypoglossal canal Posterior cranial fossa Foramen magnum View Parietal bone Occipital bone

Inferior view of skull (mandible removed) Maxilla Hard palate Palatine bone Maxilla Zygomatic bone Sphenoid bone (greater wing) Temporal bone (zygomatic process) Vomer Carotid canal Temporal bone Occipital condyle Parietal bone Foramen magnum