Chapter 8 *Lecture PowerPoint The Skeletal System *See separate FlexArt PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction • Many organs are named for their relationships to nearby bones • Understanding muscle movements also depends on knowledge of skeletal anatomy • Positions, shapes, and processes of bones can serve as landmarks for clinicians 7-2 Overview of the Skeleton Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Frontal bone Parietal bone • Axial skeleton is Occipital bone Skull Maxilla colored tan Mandible Mandible – Forms central Clavicle Clavicle Pectoral girdle Scapula Scapula supporting axis of the Sternum body Thoracic Ribs Humerus cage Costal cartilages – Skull, vertebrae, sternum, ribs, Vertebral column sacrum, and hyoid Hip bone Pelvis Sacrum Ulna Coccyx Radius Carpus • Appendicular Metacarpal bones Phalanges skeleton is colored green Femur – Pectoral girdle Patella – Upper extremity Fibula – Pelvic girdle Tibia – Lower extremity Metatarsal bones Tarsus Phalanges 8-3 Figure 8.1 (a) Anterior view (b) Posterior view Bones of the Skeletal System • Number of bones – 206 in typical adult skeleton • Varies with development of sesamoid bones (patella) – Bones that form within some tendons in response to stress • Varies with presence of sutural (wormian) bones in skull – Extra bones that develop in skull suture lines – 270 bones at birth, decreases with fusion • Surface markings – Ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces 8-4 Anatomical Features of Bones • Bone markings—ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces • Ways to study bones – Articulated skeleton: held together by wire and rods, show spatial relationship to each other – Disarticulated bones: bones taken apart so their surface features can be studied in more detail 8-5 Anatomical Features of Bones Copyright © The McGraw-Hill Companies, Inc. 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Lines Crest Sinuses Fovea Head Foramen Meatus Crest Head Trochanters Tubercle Process Condyle Alveolus Spine Foramen Tuberosity (a) Skull (lateral view) Line Process Spine Fossae Epicondyles Fossae Condyles (c) Femur (d) Humerus 8-6 (b) Scapula (posterior view) Figure 8.2 (posterior view) (anterior view) The Skull • Expected Learning Outcomes – Distinguish between cranial and facial bones. – Name the bones of the skull and the anatomical features. – Identify the cavities in the skull and in some of its individual bones. – Name the principal sutures that join the bones of the skull. – Describe some bones that are closely associated with the skull. – Describe the development of the skull from infancy through childhood. 8-7 The Skull • Skull—the most complex part of the skeleton • 22 bones joined together by sutures (immovable joints) • 8 cranial bones surround cranial cavity which encloses the brain • Other cavities—orbits, nasal cavity, oral (buccal) cavity, middle- and inner-ear cavities, and paranasal sinuses 8-8 The Skull • Paranasal sinuses—frontal, sphenoid, ethmoid, and maxillary – Lined by mucous membrane and air-filled – Lighten the anterior portion of the skull – Act as chambers that add resonance to the voice • Foramina—holes that allow passage for nerves and blood vessels • 14 facial bones support teeth, facial, and jaw muscles 8-9 The Skull Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cranial cavity Ethmoid Frontal bone air cells Ethmoid bone Orbit Superior Zygomatic Nasal Middle bone conchae Inferior Maxilla Maxillary Vomer sinus Nasal cavity Oral cavity Mandible Figure 8.7 8-10 Cranial Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior cranial Frontal lobe fossa Temporal lobe Middle cranial fossa Cerebellum Posterior cranial Posterior cranial fossa fossa Middle cranial fossa Figure 8.9 Anterior cranial fossa (a) Superior view (b) Lateral view • Cranium (braincase)—protects the brain and associated sense organs – Meninges separates brain from direct contact with bones—that is, dura mater – Swelling of the brain inside the rigid cranium may force tissue through foramen magnum (large hole, exit for spinal cord) resulting in death – Consists of two parts: calvaria (skullcap) and cranial base 8-11 Cranial Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 8.9 Anterior cranial Frontal lobe fossa Temporal lobe Middle cranial fossa Cerebellum Posterior cranial Posterior cranial fossa fossa Middle cranial fossa Anterior cranial fossa (a) Superior view (b) Lateral view • Base is divided into three basins that comprise the cranial floor – Anterior cranial fossa holds the frontal lobe of the brain – Middle cranial fossa holds the temporal lobes of the brain – Posterior cranial fossa contains the cerebellum • 8 cranial bones: 1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, 1 ethmoid 8-12 The Frontal Bone • Forms forehead and part of the roof of the cranium Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Frontal bone Supraorbital • Coronal suture—posterior Glabella foramen Parietal bone boundary of frontal bone Coronal suture Supraorbital margin Squamous suture • Supraorbital margin forms Temporal bone Sphenoid bone roof of the orbit Lacrimal bone Ethmoid bone Nasal bone Middle nasal • Supraorbital foramen concha Zygomatic bone Infraorbital foramen Inferior nasal concha provides passage for nerve, Maxilla artery, and vein Vomer Mandible • Glabella—smooth area Mental protuberance Mental foramen above root of the nose • Contains frontal sinus Figure 8.3 8-13 The Parietal Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Coronal suture Frontal bone Parietal bone Temporal lines • Form most of cranial roof and Lambdoid suture Ethmoid bone part of its lateral walls Sphenoid bone Nasal bone Occipital bone Lacrimal bone Squamous suture Zygomaticofacial foramen Temporal bone • Bordered by four sutures Infraorbital foramen Zygomatic process External acoustic meatus Zygomatic bone Maxilla – Sagittal: between parietal Mastoid process Temporal process Styloid process Mandible bones Mandibular condyle Mental foramen (a) Right lateral view Figure 8.4a – Coronal: at anterior margin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. – Lambdoid: at posterior Anterior margin Frontal bone – Squamous: at lateral border Coronal suture Parietal bone • Two temporal lines serve as Sagittal suture attachment of the temporalis Sutural bone muscle Parietal foramen Lambdoid suture Occipital bone Figure 8.6 8-14 Posterior The Temporal Bones • Lateral wall and part of floor Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. of cranial cavity Coronal suture Frontal bone – Squamous part Parietal bone Temporal lines • Encircled by squamous Lambdoid suture Ethmoid bone Sphenoid bone Nasal bone suture Occipital bone Lacrimal bone Squamous suture Zygomaticofacial foramen Temporal bone • Zygomatic process Infraorbital foramen Zygomatic process External acoustic meatus Zygomatic bone Maxilla • Mandibular fossa Mastoid process Temporal process Styloid process Mandible Mandibular condyle Mental foramen (a) Right lateral view – Tympanic part Figure 8.4a • External auditory meatus • Styloid process 8-15 The Temporal Bones – Mastoid part Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Coronal suture • Mastoid process Frontal bone Parietal bone Temporal lines – Mastoiditis from ear Lambdoid suture Ethmoid bone infection Sphenoid bone Nasal bone Occipital bone Lacrimal bone Squamous suture Zygomaticofacial foramen • Mastoid notch Temporal bone Infraorbital foramen Zygomatic process External acoustic meatus Zygomatic bone Maxilla • Stylomastoid foramen Mastoid process Temporal process Styloid process Mandible Mandibular condyle Mental foramen • Mastoid foramen (a) Right lateral view Figure 8.4a 8-16 The Temporal Bones – Petrous part Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Part of cranial floor Diploe (spongy bone) Frontal bone Crista galli • Separates middle from Cribriform plate Cribriform foramina of ethmoid bone posterior cranial fossa Sphenoid bone Optic foramen • Houses middle- and inner- Foramen rotundum Sella turcica Foramen ovale ear cavities Foramen spinosum Temporal bone Internal acoustic meatus Petrous part of temporal bone • Receptors for hearing and Jugular foramen Parietal bone Groove for Foramen magnum sense of balance venous sinus Occipital bone Hypoglossal canal • Internal auditory meatus—opening for CN (b) Superior view of cranial floor VII (vestibulocochlear Figure 8.5b nerve) • Carotid canal • Jugular foramen 8-17 The Temporal Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Squamous suture Squamous part Mastoid part Zygomatic process Mandibular fossa Mastoid notch External acoustic Mastoid process meatus Styloid process Tympanic part (a) Lateral surface Squamous suture Squamous part Zygomatic Petrous part process Internal acoustic meatus Mastoid process Styloid process 8-18 (b) Medial surface Figure 8.10 The Occipital Bone