Chapter 8 *Lecture PowerPoint The Skeletal System *See separate FlexArt PowerPoint slides for all figures and tables preinserted into PowerPoint without notes.
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 Skull Pectoral girdle Thoracic cage Pelvis Frontal bone Maxilla Mandible Clavicle Scapula Sternum Ribs Costal cartilages Vertebral column Hip bone Sacrum Coccyx Carpus Metacarpal bones Phalanges Patella Parietal bone Occipital bone Mandible Clavicle Scapula Humerus Ulna Radius Femur Fibula Tibia Axial skeleton is colored tan Forms central supporting axis of the body Skull, vertebrae, sternum, ribs, sacrum, and hyoid Appendicular skeleton is colored green Pectoral girdle Upper extremity Pelvic girdle Lower extremity Tarsus Figure 8.1 (a) Anterior view Metatarsal bones Phalanges (b) Posterior view 8-3
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 Lines Crest Sinuses Fovea Meatus Process Condyle Spine Foramen Alveolus Foramen Head Trochanters Crest Head Tubercle (a) Skull (lateral view) Line Tuberosity Process Spine Fossae Epicondyles Fossae Condyles (b) Scapula (posterior view) Figure 8.2 (c) Femur (posterior view) (d) Humerus (anterior view) 8-6
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 Cranial cavity Frontal bone Ethmoid air cells Ethmoid bone Nasal conchae Vomer Superior Middle Inferior Orbit Zygomatic bone Maxilla Maxillary sinus Mandible Oral cavity Nasal cavity Figure 8.7 8-10
Cranial Bones Anterior cranial fossa Frontal lobe Temporal lobe Middle cranial fossa Cerebellum Posterior cranial fossa Figure 8.9 Posterior cranial fossa Middle cranial fossa 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 Figure 8.9 Anterior cranial fossa Frontal lobe Temporal lobe Middle cranial fossa Cerebellum Posterior cranial fossa Posterior cranial 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 Coronal suture posterior boundary of frontal bone Supraorbital margin forms roof of the orbit Supraorbital foramen provides passage for nerve, artery, and vein Glabella smooth area above root of the nose Frontal bone Glabella Coronal suture Lacrimal bone Squamous suture Sphenoid bone Nasal bone Middle nasal concha Infraorbital foramen Vomer Mandible Mental protuberance Supraorbital foramen Parietal bone Supraorbital margin Temporal bone Ethmoid bone Zygomatic bone Inferior nasal concha Maxilla Mental foramen Contains frontal sinus Figure 8.3 8-13
The Parietal Bones Parietal bone Lambdoid suture Sphenoid bone Occipital bone Squamous suture Temporal bone Zygomatic process External acoustic meatus Mastoid process Styloid process Mandibular condyle (a) Right lateral view Coronal suture Frontal bone Temporal lines Ethmoid bone Nasal bone Lacrimal bone Zygomaticofacial foramen Infraorbital foramen Zygomatic bone Maxilla Temporal process Mandible Mental foramen Frontal bone Coronal suture Anterior Figure 8.4a Form most of cranial roof and part of its lateral walls Bordered by four sutures Sagittal: between parietal bones Coronal: at anterior margin Lambdoid: at posterior margin Squamous: at lateral border Parietal bone Sagittal suture Sutural bone Two temporal lines serve as attachment of the temporalis muscle Parietal foramen Lambdoid suture Occipital bone Posterior Figure 8.6 8-14
The Temporal Bones Parietal bone Lambdoid suture Sphenoid bone Occipital bone Squamous suture Temporal bone Zygomatic process External acoustic meatus Mastoid process Styloid process Mandibular condyle (a) Right lateral view Figure 8.4a Coronal suture Frontal bone Temporal lines Ethmoid bone Nasal bone Lacrimal bone Zygomaticofacial foramen Infraorbital foramen Zygomatic bone Maxilla Temporal process Mandible Mental foramen Lateral wall and part of floor of cranial cavity Squamous part Encircled by squamous suture Zygomatic process Mandibular fossa Tympanic part External auditory meatus Styloid process 8-15
The Temporal Bones Parietal bone Lambdoid suture Sphenoid bone Occipital bone Squamous suture Temporal bone Zygomatic process External acoustic meatus Mastoid process Styloid process Mandibular condyle (a) Right lateral view Coronal suture Frontal bone Temporal lines Ethmoid bone Nasal bone Lacrimal bone Zygomaticofacial foramen Infraorbital foramen Zygomatic bone Maxilla Temporal process Mandible Mental foramen Mastoid part Mastoid process Mastoiditis from ear infection Mastoid notch Stylomastoid foramen Mastoid foramen Figure 8.4a 8-16
The Temporal Bones Diploe (spongy bone) Crista galli Cribriform foramina Optic foramen Foramen rotundum Foramen ovale Foramen spinosum Internal acoustic meatus Jugular foramen Groove for venous sinus Hypoglossal canal (b) Superior view of cranial floor Figure 8.5b Frontal bone Cribriform plate of ethmoid bone Sphenoid bone Sella turcica Temporal bone Petrous part of temporal bone Parietal bone Foramen magnum Occipital bone Petrous part Part of cranial floor Separates middle from posterior cranial fossa Houses middle- and innerear cavities Receptors for hearing and sense of balance Internal auditory meatus opening for CN VII (vestibulocochlear nerve) Carotid canal Jugular foramen 8-17
The Temporal Bones Squamous suture Squamous part Mastoid part Mastoid notch Mastoid process Styloid process Zygomatic process Mandibular fossa External acoustic meatus Tympanic part (a) Lateral surface Squamous suture Squamous part Zygomatic process Petrous part Internal acoustic meatus Styloid process (b) Medial surface Mastoid process Figure 8.10 8-18
The Occipital Bone Rear and base of skull Foramen magnum holds spinal cord Basilar part, thick median plate Skull rests on atlas at occipital condyles Condylar canal, posterior to each occipital condyle Hypoglossal canal transmits hypoglossal nerve (CN XII) supplying tongue muscles External occipital protuberance for nuchal ligament Superior and inferior nuchal lines mark neck muscles Incisive foramen Zygomatic bone Zygomatic arch Posterior nasal aperture Vomer Sphenoid bone Mandibular fossa Styloid process External acoustic meatus Occipital condyle Mastoid process Mastoid notch Temporal bone Condylar canal Parietal bone Inferior nuchal line Superior nuchal line Occipital bone (a) Inferior view Figure 8.5a Palatine process of maxilla Intermaxillary suture Palatine bone Greater palatine foramen Medial pterygoid plate Lateral pterygoid plate Foramen ovale Foramen spinosum Foramen lacerum Basilar part of occipital bone Carotid canal Stylomastoid foramen Jugular foramen Foramen magnum Mastoid foramen Lambdoid suture External occipital protuberance 8-19
The Sphenoid Bone Lesser wing Greater wing Body Foramen ovale Lateral pterygoid plate Medial pterygoid plate (b) Posterior view Dorsum sellae Superior orbital fissure Foramen rotundum Pterygoid processes Figure 8.11b Body Greater wing Diploe (spongy bone) Crista galli Cribriform foramina Optic foramen Foramen rotundum Foramen ovale Foramen spinosum Internal acoustic meatus Jugular foramen Groove for venous sinus Hypoglossal canal (b) Superior view of cranial floor Frontal bone Cribriform plate of ethmoid bone Sphenoid bone Sella turcica Temporal bone Petrous part of temporal bone Parietal bone Foramen magnum Occipital bone Figure 8.5b Lesser wing Optic foramen Anterior clinoid processes Superior orbital fissure 8-20
The Sphenoid Bone Optic foramen Lesser wing Greater wing Sella turcica Dorsum sellae (a) Superior view Hypophyseal fossa Foramen rotundum Anterior clinoid process Foramen ovale Foramen spinosum Figure 8.11a Diploe (spongy bone) Crista galli Cribriform foramina Optic foramen Foramen rotundum Foramen ovale Foramen spinosum Internal acoustic meatus Jugular foramen Groove for venous sinus Hypoglossal canal (b) Superior view of cranial floor Frontal bone Cribriform plate of ethmoid bone Sphenoid bone Sella turcica Temporal bone Petrous part of temporal bone Parietal bone Foramen magnum Occipital bone Figure 8.5b Foramen rotundum Foramen ovale Foramen lacerum Posterior nasal apertures or choanae Medial pterygoid plate Lateral pterygoid plate Sphenoid sinus 8-21
The Sphenoid Bone Coronal suture Parietal bone Squamous suture Frontal bone Sphenoid sinus Frontal sinus Incisive foramen Zygomatic bone Palatine process of maxilla Intermaxillary suture Occipital bone Temporal bone Sella turcica Lambdoid suture Internal acoustic meatus Jugular foramen Hypoglossal canal Styloid process Mandibular foramen Crista galli Cribriform plate of ethmoid bone Perpendicular plate of ethmoid bone Nasal bone Vomer Palatine process of maxilla Maxilla Palatine bone Mandible Mental spines Zygomatic arch Posterior nasal aperture Vomer Sphenoid bone Mandibular fossa Styloid process External acoustic meatus Occipital condyle Mastoid process Mastoid notch Temporal bone Condylar canal Palatine bone Greater palatine foramen Medial pterygoid plate Lateral pterygoid plate Foramen ovale Foramen spinosum Foramen lacerum Basilar part of occipital bone Carotid canal Stylomastoid foramen Jugular foramen Foramen magnum Mastoid foramen (b) Median section Parietal bone Lambdoid suture Figure 8.4b Inferior nuchal line Superior nuchal line Occipital bone External occipital protuberance Sphenoid sinus (a) Inferior view Figure 8.5a 8-22
The Ethmoid Bone Supraorbital foramen Roof of orbit Orbital plate of frontal bone Lesser wing of sphenoid bone Zygomatic process of frontal bone Medial wall Floor of orbit Optic foramen Orbital plate of ethmoid bone Lacrimal bone Frontal process of maxilla Orbital process of palatine bone Orbital surface of maxilla Figure 8.14 Greater wing of sphenoid bone Orbital surface of zygomatic bone Superior orbital fissure Inferior orbital fissure Infraorbital foramen Cribriform plate Cribriform foramina Orbital plate Ethmoidal cells Perpendicular plate Crista galli Superior nasal concha Middle nasal concha Lateral wall of orbit Anterior cranial bones located between the eyes Contributes to medial wall of orbit Lateral walls and roof of nasal cavity, and nasal septum Three major portions of this porous, delicate bone Perpendicular plate forms superior two-thirds of nasal septum Figure 8.12 8-23
The Ethmoid Bone Parietal bone Squamous suture Occipital bone Temporal bone Sella turcica Lambdoid suture Internal acoustic meatus Jugular foramen Hypoglossal canal Styloid process Mandibular foramen Figure 8.4b (b) Median section Coronal suture Frontal bone Sphenoid sinus Frontal sinus Crista galli Cribriform plate of ethmoid bone Perpendicular plate of ethmoid bone Nasal bone Vomer Palatine process of maxilla Maxilla Palatine bone Mandible Mental spines Sella turcica Sphenoid sinus Occipital bone Sphenoid bone Crista galli Cribriform plate Cribriform foramina Palatine bone Lacrimal bone Maxilla Frontal bone Frontal sinus Nasal bone Nasal conchae: Superior Middle Inferior Nasal cartilages Anterior nasal spine Incisive foramen Figure 8.13 Cribriform plate forms roof of nasal cavity Crista galli: attachment point for meninges Cribriform (olfactory) foramina Labyrinth large mass on each side of perpendicular plate Ethmoidal cells make up the ethmoid sinus Orbital plate 8-24 Lip Incisor
The Ethmoid Bone Coronal suture Parietal bone Squamous suture Occipital bone Temporal bone Sella turcica Lambdoid suture Internal acoustic meatus Jugular foramen Hypoglossal canal Styloid process Mandibular foramen Frontal bone Sphenoid sinus Frontal sinus Crista galli Cribriform plate of ethmoid bone Perpendicular plate of ethmoid bone Nasal bone Vomer Palatine process of maxilla Maxilla Palatine bone Mandible Mental spines Crista galli Cribriform plate Cribriform foramina Sella turcica Sphenoid sinus Occipital bone Sphenoid bone Palatine bone Lacrimal bone Maxilla Frontal bone Frontal sinus Nasal bone Nasal conchae: Superior Middle Inferior Nasal cartilages Anterior nasal spine Incisive foramen Lip Incisor (b) Median section Figure 8.4b Figure 8.13 Superior and middle nasal conchae scroll-like plates project into the nasal fossa Inferior nasal concha separate bone Three chonchae occupy most of the nasal cavity, create turbulence of airflow, humidify air before it reaches the lungs 8-25
Facial Bones Facial bones (14) those that have no direct contact with the brain or meninges Support the teeth Give shape and individuality to the face Form part of the orbital and nasal cavities Provide attachments for muscles of facial expression and mastication 2 maxillae 2 nasal bones 2 palatine bones 2 inferior nasal conchae 2 zygomatic bones 1 vomer 2 lacrimal bones 1 mandible 8-26
The Maxillae Frontal bone Glabella Supraorbital foramen Largest facial bones Forms upper jaw and meets at median intermaxillary suture Alveolar processes: bony points between teeth Alveolus: sockets that hold teeth Coronal suture Squamous suture Sphenoid bone Lacrimal bone Nasal bone Middle nasal concha Infraorbital foramen Vomer Mandible Mental protuberance Parietal bone Supraorbital margin Temporal bone Ethmoid bone Zygomatic bone Inferior nasal concha Maxilla Figure 8.3 Mental foramen Incisive foramen Zygomatic bone Zygomatic arch Posterior nasal aperture Vomer Sphenoid bone Mandibular fossa Styloid process External acoustic meatus Occipital condyle Mastoid process Mastoid notch Temporal bone Condylar canal Parietal bone Inferior nuchal line Superior nuchal line Occipital bone Figure 8.5a (a) Inferior view Palatine process of maxilla Intermaxillary suture Palatine bone Greater palatine foramen Medial pterygoid plate Lateral pterygoid plate Foramen ovale Foramen spinosum Foramen lacerum Basilar part of occipital bone Carotid canal Stylomastoid foramen Jugular foramen Foramen magnum Mastoid foramen Lambdoid suture External occipital protuberance 8-27
The Maxillae Cont. Forms inferomedial wall of orbit Infraorbital foramen Inferior orbital fissure Forms most of the hard palate Palatine process Palate: forms roof of mouth and floor of nasal cavity Incisive foramen Palate allows us to chew while breathing Cleft palate and cleft lip 8-28
The Maxillae Sphenoid sinus Frontal sinus Ethmoid sinus Maxillary sinus Figure 8.8 Figure 8.8 Maxillary sinus fills maxillae bone Larger in volume than frontal, sphenoid, and ethmoid sinuses 8-29
The Palatine Bones L-shaped bone Form the posterior portion of the hard palate Crista galli Cribriform plate Cribriform foramina Sella turcica Sphenoid sinus Occipital bone Frontal bone Frontal sinus Nasal bone Nasal conchae: Superior Middle Inferior Nasal cartilages Part of lateral nasal cavity wall Part of the orbital floor Greater palatine foramina Roof of orbit Medial wall Floor of orbit Supraorbital foramen Orbital plate of frontal bone Lesser wing of sphenoid bone Optic foramen Orbital plate of ethmoid bone Lacrimal bone Sphenoid bone Frontal process of maxilla Orbital process of palatine bone Orbital surface of maxilla Palatine bone Lacrimal bone Maxilla Zygomatic process of frontal bone Greater wing of sphenoid bone Orbital surface of zygomatic bone Superior orbital fissure Inferior orbital fissure Infraorbital foramen Anterior nasal spine Incisive foramen Lip Incisor Figure 8.13 Lateral wall of orbit Figure 8.14 8-30
The Zygomatic Bones Coronal suture Forms angles of the cheekbones and part of lateral orbital wall Parietal bone Lambdoid suture Sphenoid bone Occipital bone Squamous suture Temporal bone Zygomatic process External acoustic meatus Mastoid process Styloid process Mandibular condyle (a) Right lateral view Figure 8.4a Frontal bone Temporal lines Ethmoid bone Nasal bone Lacrimal bone Zygomaticofacial foramen Infraorbital foramen Zygomatic bone Maxilla Temporal process Mandible Mental foramen Zygomaticofacial foramen Zygomatic arch is formed from temporal process of zygomatic bone and zygomatic process of temporal bone 8-31
The Lacrimal Bones Parietal bone Coronal suture Frontal bone Temporal lines Form part of medial wall of each orbit Smallest bone of skull Lambdoid suture Sphenoid bone Occipital bone Squamous suture Temporal bone Zygomatic process External acoustic meatus Mastoid process Styloid process Mandibular condyle (a) Right lateral view Figure 8.4a Ethmoid bone Nasal bone Lacrimal bone Zygomaticofacial foramen Infraorbital foramen Zygomatic bone Maxilla Temporal process Mandible Mental foramen Lacrimal fossa houses lacrimal sac in life Tears collect in lacrimal sac and drain into nasal cavity 8-32
The Nasal Bones Forms bridge of nose Supports cartilages that shape lower portion of the nose Often fractured by blow to the nose Frontal bone Glabella Coronal suture Lacrimal bone Squamous suture Sphenoid bone Nasal bone Middle nasal concha Infraorbital foramen Vomer Mandible Supraorbital foramen Parietal bone Supraorbital margin Temporal bone Ethmoid bone Zygomatic bone Inferior nasal concha Maxilla Mental protuberance Mental foramen Figure 8.3 8-33
The Inferior Nasal Conchae Three conchae in the nasal cavity Superior and middle are part of the ethmoid bone Inferior nasal concha is a separate bone Largest of the three Crista galli Frontal bone Cribriform plate Frontal sinus Cribriform foramina Nasal bone Sella turcica Nasal conchae: Superior Middle Sphenoid sinus Inferior Nasal cartilages Occipital bone Sphenoid bone Anterior nasal spine Palatine bone Incisive foramen Lacrimal bone Lip Maxilla Incisor Figure 8.13 8-34
The Vomer Parietal bone Squamous suture Occipital bone Temporal bone Sella turcica Lambdoid suture Internal acoustic meatus Jugular foramen Hypoglossal canal Styloid process Mandibular foramen (b) Median section Figure 8.4b Coronal suture Frontal bone Sphenoid sinus Frontal sinus Crista galli Cribriform plate of ethmoid bone Perpendicular plate of ethmoid bone Nasal bone Vomer Palatine process of maxilla Maxilla Palatine bone Mandible Mental spines Inferior half of the nasal septum Superior half formed by perpendicular plate of ethmoid Supports cartilage that forms the anterior part of the nasal septum 8-35
Strongest bone of the skull Only bone of skull that moves noticeably Supports lower teeth Provides attachments for muscles of facial expression and mastication Mental symphysis median cartilaginous joint in fetus Develops as two separate bones in fetus Ossifies in early childhood The Mandible Incisive foramen Zygomatic bone Zygomatic arch Posterior nasal aperture Vomer Sphenoid bone Mandibular fossa Styloid process External acoustic meatus Occipital condyle Mastoid process Mastoid notch Temporal bone Condylar canal Parietal bone Inferior nuchal line Superior nuchal line Occipital bone Condylar process Coronoid process Mandibular notch Mandibular foramen Alveolar process Mental foramen (a) Inferior view Figure 8.5a Palatine process of maxilla Intermaxillary suture Palatine bone Greater palatine foramen Medial pterygoid plate Lateral pterygoid plate Foramen ovale Foramen spinosum Foramen lacerum Basilar part of occipital bone Carotid canal Stylomastoid foramen Jugular foramen Foramen magnum Mastoid foramen Lambdoid suture External occipital protuberance Mandibular condyles Ramus Mental protuberance Figure 8.15 Body Angle 8-36
Mental protuberance point of chin Two major parts on each side Body: supports teeth Ramus: articulates with cranium Angle where body and ramus meet Alveolar processes between teeth Mental foramen permits passage of nerves and BVs Mental spines The Mandible Incisive foramen Zygomatic bone Zygomatic arch Posterior nasal aperture Vomer Sphenoid bone Mandibular fossa Styloid process External acoustic meatus Occipital condyle Mastoid process Mastoid notch Temporal bone Condylar canal Parietal bone Inferior nuchal line Superior nuchal line Occipital bone Condylar process Coronoid process Mandibular notch Mandibular foramen Alveolar process Mental foramen Mental protuberance Figure 8.15 (a) Inferior view Body Figure 8.5a Palatine process of maxilla Intermaxillary suture Palatine bone Greater palatine foramen Medial pterygoid plate Lateral pterygoid plate Foramen ovale Foramen spinosum Foramen lacerum Basilar part of occipital bone Carotid canal Stylomastoid foramen Jugular foramen Foramen magnum Mastoid foramen Lambdoid suture External occipital protuberance Mandibular condyles Angle Ramus 8-37
The Mandible Mandibular condyles Condylar process Coronoid process Mandibular notch Mandibular foramen Condylar process bears the mandibular condyle oval knob that articulates with the mandibular fossa of the temporal bone forming the hinge temporomandibular joint (TMJ) Alveolar process Mental foramen Mental protuberance Body Figure 8.15 Angle Ramus Coronoid process point of insertion of temporalis muscle Mandibular notch Mandibular foramen BVs, nerves supply lower teeth 8-38
Bones Associated with the Skull Auditory ossicles Three in each middle-ear cavity Malleus, incus, and stapes Hyoid bone Slender U-shaped bone between the chin and larynx Does not articulate with any other bone Suspended from styloid process of skull by muscle and ligament Body and greater and lesser horns (cornua) Fractured hyoid bone is evidence of strangulation Hyoid Larynx Figure 8.16 Styloid process Stylohyoid muscle Lesser horn Greater horn Body 8-39
The Skull in Infancy and Childhood Parietal bone Lambdoid suture Squamous suture Occipital bone Mastoid fontanel Temporal bone Frontal bone Anterior fontanel Sagittal suture Parietal bone Posterior fontanel (a) Lateral view Sphenoid bone Coronal suture Frontal bone Sphenoid fontanel Nasal bone Maxilla Zygomatic bone Mandible Fontanels spaces between unfused bones Filled with fibrous membrane Allow shifting of bones during birth and growth of brain Anterior, posterior, sphenoid (anterolateral), and mastoid (posterolateral) fontanels Two frontal bones fuse by age 6 (metopic suture) Skull reaches adult size by 8 or 9 years of age (b) Superior view Figure 8.17 8-40
The Vertebral Column and Thoracic Cage Expected Learning Outcomes Describe the general features of the vertebral column and those of a typical vertebra. Describe the structure of the intervertebral discs and their relationship to the vertebrae. Describe the special features of vertebrae in different regions of the vertebral column, and discuss the functional significance of the regional differences. Describe the anatomy of the sternum and ribs and how the ribs articulate with the thoracic vertebrae. 8-41
General Features of the Functions Supports the skull and trunk Allows for their movement Protects the spinal cord Absorbs stress of walking, running, and lifting Provides attachments for limbs, thoracic cage, and postural muscles Vertebral Column Anterior view Atlas (C1) Axis (C2) C7 T1 T12 L1 Posterior view Cervical vertebrae Thoracic vertebrae 33 vertebrae with intervertebral discs of fibrocartilage between most of them L5 S1 Lumbar vertebrae Sacrum S5 Coccyx Figure 8.18 Coccyx 8-42
General Features of the Vertebral Column Anterior view Posterior view Adult vertebral column averages 71 cm (28 in.) long Intervertebral discs account for about onequarter of its length Person is 1% shorter when in bed Compression squeezes water out during the day and absorbs water when compression is removed during sleep Atlas (C1) Axis (C2) C7 T1 T12 L1 L5 S1 Cervical vertebrae Thoracic vertebrae Lumbar vertebrae Sacrum S5 Coccyx Figure 8.18 Coccyx 8-43
General Features of the Vertebral Column Five vertebral groups 7 cervical in the neck 12 thoracic in the chest 5 lumbar in lower back 5 fused sacral at base of spine 4 fused coccygeal Variations in number of lumbar and sacral vertebrae occur in 1 in 20 people Anterior view Atlas (C1) Axis (C2) C7 T1 T12 L1 L5 S1 Posterior view Cervical vertebrae Thoracic vertebrae Lumbar vertebrae Sacrum S5 Coccyx Figure 8.18 Coccyx 8-44
General Features of the Vertebral Column Spine exhibits one continuous C-shaped curve at birth Known as primary curvature The McGraw-Hill Companies, Inc./Bob Coyle, photographer Figure 8.20 8-45
General Features of the Vertebral Column C1 C7 T1 Cervical curvature Thoracic curvature T12 L1 S-shaped vertebral column with four normal curvatures Cervical Thoracic Lumbar Pelvic Lumbar curvature L5 S1 Pelvic curvature Figure 8.19 8-46
General Features of the Vertebral Column Primary curvatures present at birth Thoracic and pelvic Secondary curvatures develop later Cervical and lumbar Lifting head as it begins to crawl develops cervical curvature Walking upright develops lumbar curvature 8-47
Abnormal Spinal Curvatures From disease, paralysis of trunk muscles, poor posture, pregnancy, or congenital defect (a) Scoliosis Key Normal Pathological (b) Kyphosis ( hunchback ) Figure 8.21 (c) Lordosis ( hunchback ) Scoliosis abnormal lateral curvature Most common Usually in thoracic region Particularly of adolescent girls Developmental abnormality in which the body and arch fail to develop on one side of the vertebrae 8-48
Abnormal Spinal Curvatures Kyphosis (hunchback) exaggerated thoracic curvature Usually from osteoporosis, also osteomalacia or spinal tuberculosis, or wrestling or weight lifting in young boys Lordosis (swayback) exaggerated lumbar curvature From pregnancy or obesity 8-49
General Structure of Vertebra Posterior Body (centrum) Mass of spongy bone that contains red bone marrow Covered with thin shell of compact bone Weight-bearing portion Rough superior and inferior surfaces provide firm attachment for intervertebral discs Spinous process Superior articular facet Transverse process Vertebral foramen Body (a) 2nd lumbar vertebra (L2) Anterior Lamina Pedicle Vertebral arch Vertebral foramina Collectively form vertebral canal for spinal cord Nucleus pulposus Anulus fibrosus (b) Intervertebral disc Figure 8.22a,b 8-50
General Structure of Vertebra Vertebral arch Composed of two parts on each side Pedicle: pillarlike and lamina: platelike Spinous process Projection extending from the apex of arch Extends posteriorly and downward Transverse process Extends laterally from point where pedicel and lamina meet Superior articular processes Project upward from one vertebra and meets inferior articular processes from the vertebra above Facets Flat articular surfaces covered with hyaline cartilage 8-51
General Structure of Vertebra L1 L2 L3 (b) Left lateral view Figure 8.23b Superior articular process of L1 Inferior vertebral notch of L1 Superior vertebral notch of L2 Spinous process Intervertebral disc Inferior articular process of L3 Intervertebral foramen Intervertebral foramen When two vertebrae are joined they exhibit an opening between their pedicles Passageway for spinal nerves Inferior vertebral notch in the pedicle of the upper vertebra Superior vertebral notch in the pedicle of the lower vertebra 8-52
General Structure of Vertebra Intervertebral discs (23) First one between C2 and C3 Last one between L5 and sacrum Pad consisting of: Nucleus pulposus inner gelatinous mass Anulus fibrosus outer ring of fibrocartilage Bind vertebrae together Support weight of the body Absorb shock Herniated disc ( ruptured or slipped disc) puts painful pressure on spinal nerve or spinal cord 8-53
The Cervical Vertebrae Transverse process Body (centrum) Intervertebral disc Inferior articular process of L2 Superior articular process of L3 Lamina L2 L3 (a) Posterior (dorsal) view Figure 8.23a Cervical vertebrae atlas (C1) Supports the head Has no body Delicate ring surrounding a large vertebral foramen Lateral masses with superior articular facets Articulates with occipital condyles Allows nodding motion of skull gesturing yes Inferior articular facets articulate with C2 Anterior and posterior arches Anterior and posterior tubercles 8-54
The Cervical Vertebrae Dens (odontoid process) Superior articular facet Transverse foramen Transverse process Inferior articular process Lamina Spinous process (b) Axis Figure 8.24b Cervical vertebrae axis (C2) Allows rotation of the head gesturing no Dens or odontoid process prominent knob on its anterosuperior side Body Pedicle Forms as an independent ossification center during first year of life Fuses with axis by age 3 to 6 years Projects into vertebral foramen of the atlas Held in place by a transverse ligament Atlanto occipital joint: between atlas and cranium Atlantoaxial joint: between atlas and axis 8-55
Atlas and Axis Articulation Axis of rotation Dens Atlas Transverse ligament Axis Figure 8.24c (c) Atlantoaxial joint 8-56
The Cervical Vertebrae Superior views Lateral views Spinous process Lamina Superior articular facet Figure 8.25a Transverse foramen Transverse process (a) Cervical vertebrae C1 to C7 are smallest and lightest vertebrae, other than the coccygeals Bifid or forked spinous processes in C2 to C6 Small body and larger vertebral foramen Transverse foramen in each short transverse process Body Provides passage and protection for vertebral arteries (supply blood to brain) and vertebral veins (drain blood from various neck structures) Transverse foramen only found in cervical vertebrae Spinous process Inferior articular process C7 vertebra prominens spinous process not bifid and especially long Prominent bump on lower back of neck; convenient landmark for counting vertebrae 8-57
The Thoracic Vertebrae Spinous process Lamina Superior articular facet Transverse process Figure 8.25b Transverse costal facet (b) Thoracic vertebrae Superior costal facet Inferior costal facet Body Transverse costal facet Inferior articular facet Spinous process 12 thoracic vertebrae (T1 T12) Corresponds to the 12 pairs of ribs attached to them Spinous processes pointed and angled sharply downward Larger body than cervical, but smaller than lumbar Costal facets for attachment of ribs On body as small, smooth, slightly concave spots Transverse costal facets at end of each transverse process T1 T10 Provide second point of articulation for ribs 1 10 Inferior and superior costal facets on vertebral body In most cases, ribs insert between the two vertebra 8-58
The Lumbar Vertebrae Spinous process Superior articular facet Superior articular process Figure 8.25c Transverse process Pedicle Body Spinous process (c) Lumbar vertebrae Inferior articular facet Five lumbar vertebrae (L1 L5) Thick, stout body Blunt, squarish spinous process Superior articular processes face medially Lumbar region resistant to twisting movements 8-59
The Sacrum Sacrum bony plate that forms posterior wall of pelvic cavity Once considered seat of the Ala Transverse lines Anterior sacral foramina Coccyx S1 S2 S3 S4 S5 Co1 Co2 Co3 Co4 (a) Anterior view Figure 8.26a Superior articular process Sacral promontory soul In children, five separate sacral vertebrae (S1 S5) Begin fusion around age 16 and complete fusion by age 26 Anterior surface Smooth and concave Four transverse lines indicate line of fusion of vertebrae Four pairs of large anterior sacral (pelvic) foramina Allow for passage of nerves and arteries into pelvic organs Sacral promontory on S1 supports L5 8-60
The Sacrum Posterior surface very rough Median sacral crest Formed from fusion of spinous processes Lateral sacral crest Less prominent, and on either side of Superior articular process Horn Transverse process (b) Posterior view Coccyx Sacral canal Median sacral crest Auricular surface Lateral sacral crest Posterior sacral foramina Sacral hiatus median sacral crest Formed from the fusion of the transverse processes Posterior sacral foramina Four pairs of openings for spinal nerves that supply gluteal region and lower limbs Sacral canal runs through sacrum and ends as sacral hiatus Contains spinal nerve roots Auricular surface is part of sacroiliac (SI) joint formed with hip bone Superior articular processes on S1; articulates with L5 Alae pair of large, rough, winglike extensions lateral to the superior articular processes Figure 8.26b 8-61
Superior articular process Horn Transverse process (b) Posterior view Figure 8.26b The Coccyx Coccyx Sacral canal Median sacral crest Auricular surface Lateral sacral crest Posterior sacral foramina Sacral hiatus Coccyx usually consists of four small vertebrae (Co1 Co4); sometimes five Fuse into a single, triangular bone by age 20 to 30 Horns (cornua) on Co1 Serve as attachment points for ligaments that bind the coccyx to the sacrum Fractured during difficult childbirth or by hard fall on buttocks Provide attachment for muscles of the pelvic floor 8-62
Sternoclavicular joint Acromioclavicular joint Pectoral girdle: Clavicle Scapula True ribs (1 7) False ribs (8 12) The Thoracic Cage Consists of thoracic vertebrae, sternum, ribs Floating ribs (11 12) 6 7 8 9 10 5 4 3 2 1 11 T1 12 T12 L1 Figure 8.27 Sternum: Suprasternal notch Clavicular notch Manubrium Angle Body Xiphoid process Costal cartilages Costal margin Forms conical enclosure for lungs and heart Provides attachment for pectoral girdle and upper limbs Broad base and narrower apex Rhythmically expanded by respiratory muscles to draw air into lungs Costal margin inferior border of thoracic cage formed by downward arc of ribs Protect thoracic organs, but also spleen, most of liver, and to some extent the kidneys 8-63
The Sternum Sternum (breastbone) bony plate anterior to the heart Divided into three regions Manubrium Broad superior portion Suprasternal (jugular) notch medially Clavicular notches articulate with clavicle Ribs attach along scalloped lateral margins Body (gladiolus) Longest part of sternum Sternal angle point where body joins manubrium Ribs attach along scalloped lateral margins Xiphoid Inferior end of sternum Attachment for some abdominal muscles In cardiopulmonary resuscitation, improperly performed chest compressions can drive xiphoid process into the liver and cause a fatal hemorrhage 8-64
The Ribs Angle Costal groove (b) Ribs 2 10 Figure 8.28b Superior articular facet Superior costal facet for rib 6 Shaft T6 Tubercle Articular facet for transverse process (b) Superior view Neck Tubercle Neck Head Head Superior Transverse costal facet for rib 6 Inferior Articular facets for vertebral bodies Rib 6 Figure 8.29b 12 pairs of ribs No difference between sexes Posterior (proximal) end attached to vertebral column Anterior (distal) ends mostly attached to the sternum Costal cartilages composed of hyaline cartilage attach anterior ends to sternum Head portion of rib that articulates with thoracic vertebrae Superior articular facet Inferior articular facet 8-65
The Ribs Angle Costal groove (b) Ribs 2 10 Figure 8.28b Superior articular facet Superior costal facet for rib 6 Shaft T6 Tubercle Articular facet for transverse process (b) Superior view Neck Transverse costal facet for rib 6 Tubercle Neck Head Head Superior Inferior Articular facets for vertebral bodies Rib 6 Figure 8.29b Neck narrow portion distal to the head Tubercle wider rough area distal to the neck Articulates with transverse costal facet of vertebra Angle lateral curve of rib Shaft long, gentle sloping, bladelike portion of rib Costal groove on inferior margin of shaft 8-66
The Ribs Rib 6 Vertebral body T5 Vertebral body T6 (a) Anterior view Inferior costal facet of T5 Superior articular facet of rib 6 Inferior articular facet of rib 6 Superior costal facet of T6 Superior articular facet Transverse costal facet for rib 6 Tubercle Figure 8.29 Superior costal facet for rib 6 T6 Neck Head Rib 6 (b) Superior view 8-67
The Ribs Sternoclavicular joint Acromioclavicular joint T1 Sternum: Suprasternal notch Pectoral girdle: Clavicle Scapula 2 1 Clavicular notch Manubrium Angle 3 True ribs (1 7) 4 Body 6 5 Xiphoid process Costal cartilages 7 11 8 False ribs (8 12) Floating ribs (11 12) 9 10 12 T12 L1 Costal margin Figure 8.27 8-68
The Ribs True ribs (ribs 1 7) Each has own costal cartilage connecting to sternum False ribs (ribs 8 12) Lack independent cartilaginous connection to sternum Floating ribs (ribs 11 12) Articulate with bodies of vertebrae T11 and T12 Do not have tubercles Do not attach to transverse processes of the vertebra No cartilaginous connection to the sternum or any of the higher costal cartilages 8-69
The Pectoral Girdle and Upper Limb Expected Learning Outcome Identify and describe the features of the clavicle, scapula, humerus, radius, ulna, and bones of the wrist and hand. 8-70
The Pectoral Girdle Pectoral girdle (shoulder girdle) supports the arm Consists of two bones on each side of the body Clavicle (collarbone) and scapula (shoulder blade) Clavicle articulates medially to the sternum and laterally to the scapula Sternoclavicular joint Acromioclavicular joint Scapula articulates with the humerus Glenohumeral joint: shoulder joint Easily dislocated due to loose attachment 8-71
The Clavicle Sternal end Conoid tubercle (a) Superior view Acromial end Figure 8.30 Sternal end Conoid tubercle (b) Inferior view Acromial end Clavicle S-shaped, somewhat flattened bone Inferior grooves and ridges for muscle attachment Sternal end rounded head 8-72
The Clavicle Acromial end flattened Conoid tubercle: roughened tuberosity near acromial end; ligament attachment Braces shoulder, keeping upper limb away from midline of body Most frequently fractured bone in the body 8-73
The Scapula Scapula named for its resemblance to a spade or shovel Triangular plate that posteriorly overlies ribs 2 to 7 Three sides: superior, medial (vertebral), and lateral (axillary) borders Three angles: superior, inferior, and lateral angles 8-74
The Scapula Suprascapular notch conspicuous notch on superior border Provides passage for a nerve Spine transverse ridge on posterior surface Supraspinous fossa: indentation superior to the spine Infraspinous fossa: broad surface inferior to the spine 8-75
The Scapula Subscapular fossa concave, anterior surface of scapula Complex lateral angle of scapula has three main features Acromion: platelike extension of the spine Forms apex of the shoulder Articulates with the clavicle the sole point of attachment of the scapula and the upper limb to the rest of the skeleton 8-76
The Scapula Cont. Coracoid process: shaped like a bent finger Provides attachment for tendons of the biceps brachii and other arm muscles Glenoid cavity: shallow socket that articulates with the head of the humerus Forming glenohumeral joint 8-77
The Scapula Suprascapular notch Superior border Superior angle Acromion Acromion Coracoid process Glenoid cavity Supraspinous fossa Spine Lateral angle Subscapular fossa Infraspinous fossa Lateral border Medial border Inferior angle (a) Anterior view (b) Posterior view Figure 8.31 8-78
The Upper Limb Upper limb is divided into four regions containing a total of 30 bones per limb Brachium (arm proper): extends from shoulder to elbow Contains only 1 bone humerus Antebrachium (forearm): extends from elbow to wrist Contains 2 bones radius and ulna Carpus (wrist) Contains 8 small bones arranged in two rows Manus (hand) 19 bones in two groups 5 metacarpals in palm 14 phalanges in fingers 8-79
Greater tubercle Lesser tubercle Intertubercular sulcus Deltoid tuberosity Coronoid fossa Radial fossa Capitulum Head Trochlea (a) Anterior view The Humerus Lateral epicondyle Surgical neck Medial supracondylar ridge Medial epicondyle Greater tubercle Anatomical neck Nutrient foramen Deltoid tuberosity Lateral supracondylar ridge Lateral epicondyle Olecranon fossa (b) Posterior view Proximal end Figure 8.32 Hemispherical head that articulates with the glenoid cavity of scapula Anatomical neck Greater and lesser tubercles and deltoid tuberosity Intertubercular sulcus holds biceps tendon Surgical neck 8-80
Greater tubercle Lesser tubercle Intertubercular sulcus Deltoid tuberosity Coronoid fossa Radial fossa Capitulum Head Trochlea (a) Anterior view The Humerus Lateral epicondyle Figure 8.32 Surgical neck Medial supracondylar ridge Medial epicondyle Greater tubercle Anatomical neck Nutrient foramen Deltoid tuberosity Lateral supracondylar ridge Lateral epicondyle Olecranon fossa (b) Posterior view Distal end Rounded capitulum articulates with head of radius Trochlea articulates with ulna Lateral and medial epicondyles Lateral and medial supracondylar ridges Olecranon fossa holds olecranon process of ulna Coronoid fossa Radial fossa 8-81
The Radius Olecranon Olecranon Trochlear notch Radial notch of ulna Head of radius Neck of radius Radial tuberosity Styloid process (a) Anterior view Coronoid process Ulnar tuberosity Ulna Radius Interosseous borders Interosseous membrane Ulnar notch of radius Head of ulna Styloid process Articular facets Figure 8.33 (b) Posterior view Head of radius Neck of radius Styloid process Radius Head: disc-shaped, allows for rotation around the longitudinal axis of the bone during pronation and supination of hand Superior surface articulates with capitulum on humerus Side of disc spins on radial notch on ulna Neck Radial tuberosity for biceps muscle Styloid process can be palpated near thumb Ulnar notch 8-82
The Ulna Olecranon Olecranon Trochlear notch Radial notch of ulna Head of radius Neck of radius Radial tuberosity Coronoid process Ulnar tuberosity Ulna Radius Interosseous borders Head of radius Neck of radius Ulna Trochlear notch articulates with trochlea of humerus Olecranon: bony point at back of elbow Coronoid process Radial notch holds head of radius Styloid process Styloid process (a) Anterior view Interosseous membrane Ulnar notch of radius Head of ulna Styloid process Articular facets Figure 8.33 (b) Posterior view Styloid process Interosseous membrane Ligament attaches radius to ulna along interosseous margin of each bone Enables the two elbow joints to share the load 8-83
The Carpal Bones Eight bones form wrist Allow movements of flexion, extension, abduction, and adduction Two rows (four bones each) Proximal row: scaphoid, lunate, triquetrum, and pisiform Pisiform is a sesamoid developed by age 9 to12 in tendon of flexor carpi ulnaris muscle Distal row: trapezium, trapezoid, capitate, and hamate 8-84
The Right Wrist and Hand Distal phalanx II Middle phalanx II Key to carpal bones Distal row Proximal row Proximal phalanx II Head IV III II Distal phalanx I Phalanges Body Base Head V I Proximal phalanx I Metacarpal bones Body Base First metacarpal Carpal bones Hamulus of hamate Hamate Pisiform Triquetrum Lunate Trapezoid Trapezium Capitate Scaphoid Carpal bones (a) Anterior view Figure 8.34a 8-85
The Metacarpal Bones and the Phalanges Metacarpals bones of the palm Metacarpal I proximal to base of thumb Metacarpal V proximal to base of little finger Proximal base, body, and distal head Phalanges bones of the fingers Thumb or pollex has two phalanges Proximal, distal phalanx Fingers have three phalanges Proximal, middle, distal phalanx 8-86
The Pelvic Girdle and Lower Limb Expected Learning Outcomes Identify and describe the features of the pelvic girdle, femur, patella, tibia, fibula, and bones of the foot. Compare the anatomy of the male and female pelvic girdles and explain the functional significance of the differences. 8-87
The Pelvic Girdle Pelvic girdle consists of a complete ring composed of three bones Two hip (coxal) bones, also called ossa coxae or innominate bones Sacrum is also part of the vertebral column Ilium Ischium Pubis Iliac crest Iliac fossa Anterior superior iliac spine Anterior inferior iliac spine Spine Body Ramus Superior ramus Inferior ramus Body Pubic symphysis (a) Anterosuperior view Figure 8.35a Base of sacrum Sacroiliac joint Pelvic surface of sacrum Pelvic inlet Coccyx Acetabulum Interpubic disc Obturator foramen 8-88
The Pelvic Girdle Pelvis bowl-shaped structure composed of the two coxal bones and sacrum as well as their ligaments and muscles that line the pelvic cavity and form its floor Supports trunk on the lower limbs and protects viscera, lower colon, urinary bladder, and internal reproductive organs Sacroiliac joint joins hipbone to the vertebral column Auricular surface of ileum to auricular surface of sacrum 8-89
The Pelvic Girdle Anteriorly, interpubic disc pad of fibrocartilage joins pubic bones Ilium Iliac crest Iliac fossa Anterior superior iliac spine Anterior inferior iliac spine Spine Base of sacrum Sacroiliac joint Pelvic surface of sacrum Pelvic inlet Coccyx Pubic symphysis the interpubic disc and adjacent regions of the pubic bone on each side Ischium Body Ramus Superior ramus Pubis Inferior ramus Body Pubic symphysis (a) Anterosuperior view Figure 8.35a Acetabulum Interpubic disc Obturator foramen 8-90
The Pelvic Girdle Iliac crest Ilium Iliac fossa Base of sacrum Greater pelvis Anterior superior iliac spine Anterior inferior iliac spine Spine Sacroiliac joint Pelvic surface of sacrum Pelvic inlet Coccyx Pelvic brim Pelvic inlet Ischium Body Ramus Acetabulum Interpubic disc Lesser pelvis Pubis Superior ramus Inferior ramus Body Pubic symphysis Obturator foramen (a) Anterosuperior view Figure 8.35a Pelvic outlet (b) Median section Figure 8.35b Greater (false) pelvis between flare of the hips Lesser (true) pelvis narrower and below Pelvic brim round margin that separates the two Pelvic inlet opening circumscribed by brim that infant s head must pass during birth Pelvic outlet lower margin of the lesser pelvis 8-91
The Pelvic Girdle Three distinct features of hip bone Iliac crest: superior crest of hip Acetabulum: hip socket Obturator foramen: large hole below acetabulum Ilium Ischium Pubis Inferior gluteal line Posterior gluteal line Posterior superior Iliac spine Posterior inferior Iliac spine Greater sciatic notch Acetabulum Ischial spine Lesser sciatic notch Body of ischium Iliac crest Anterior gluteal line Anterior superior iliac spine Anterior r inferior iliac spine Body of ilium Superior ramus of pubis Body of pubis Inferior ramus of pubis Ischial tuberosity Obturator foramen Ramus of ischium (a) Lateral view Figure 8.36a 8-92
The Pelvic Girdle Each adult hip bone is formed by the fusion of three childhood bones: illeum, ishchium, pubis Ileum Largest Extends from the iliac crest to the center of the acetabulum Anterior and posterior superior spine Anterior and posterior inferior spines Greater sciatic notch and iliac fossa 8-93
The Pelvic Girdle Ischium Inferioposterior portion of hip Heavy body with prominent spine Lesser sciatic notch Ischial tuberosity Ramus Pubis (pubic bone) Most anterior portion of the hip bone Body, superior, and inferior ramus 8-94
The Pelvic Girdle Narrow subpubic angle (a) Male, anterior view Triangular pubic body Large, oval obturator foramen Wide subpubic angle (c) Female, anterior view Rectangular pubic body Triangular obturator foramen Preauricular sulcus Wide greater sciatic notch Narrow greater sciatic notch (b) Male, medial view Figure 8.37 (d) Female, medial view (a): David Hunt/specimens from the National Museum of Natural History, Smithsonian Institution; (b-c): L. Bassett/Visuals Unlimited; (d): David Hunt/specimens from the National Museum of Natural History, Smithsonian Institution Male heavier and thicker due to forces exerted by stronger muscles Female wider and shallower, and adapted to the needs of pregnancy and childbirth, larger pelvic inlet and outlet for passage of infant s head 8-95
The Lower Limb Lower limb divided into four regions containing 30 bones per limb Femoral region (thigh): extends from hip to knee region Contains the femur and patella Crural region (leg proper): extends from knee to ankle Contains medial tibia and lateral fibula Tarsal region (tarsus): ankle the union of the crural region with the foot Tarsal bones are considered part of the foot Pedal region (pes): foot Composed of 7 tarsal bones, 5 metatarsals, and 14 phalanges in the toes 8-96
The Femur Greater trochanter Intertrochanteric line Lateral epicondyle Patellar surface Base of patella Apex of patella Fovea capitis Head Neck Lesser trochanter Spiral line Shaft Medial supracondylar line Popliteal surface Medial epicondyle Medial condyle (a) Anterior view (b) Posterior view Greater trochanter Intertrochanteric crest Gluteal tuberosity Linea aspera Lateral supracondylar line Lateral epicondyle Lateral condyle Intercondylar fossa Articular facets Longest and strongest bone of the body Hemispherical head that articulates with the acetabulum of the pelvis Forms ball-and-socket joint Fovea capitis: pit in head of femur for attachment of a ligament Greater and lesser trochanters for muscle attachment Intertrochanteric crest thick oblique ridge on the posterior surface that connects the trochanters Figure 8.38 8-97
The Femur Greater trochanter Intertrochanteric line Fovea capitis Head Neck Lesser trochanter Spiral line Greater trochanter Intertrochanteric crest Gluteal tuberosity Intertrochanteric line more delicate ridge on the anterior surface that connects trochanters Linea aspera Linea aspera ridge on posterior of the shaft Shaft Spiral (pectineal) line and gluteal tuberosity Lateral epicondyle Patellar surface Base of patella Apex of patella Medial supracondylar line Popliteal surface Medial epicondyle Medial condyle (a) Anterior view Figure 8.38 (b) Posterior view Lateral supracondylar line Lateral epicondyle Lateral condyle Intercondylar fossa Articular facets Medial and lateral condyles and epicondyles found distally Intercondylar fossa Patellar and popliteal surface 8-98
Greater trochanter Intertrochanteric line Lateral epicondyle Patellar surface Base of patella Apex of patella The Patella Patella triangular sesamoid bone embedded (a) Anterior view Fovea capitis Head Neck Lesser trochanter Spiral line Shaft Medial supracondylar line Popliteal surface Medial epicondyle Medial condyle Figure 8.38 (b) Posterior view Greater trochanter Intertrochanteric crest Gluteal tuberosity Linea aspera Lateral supracondylar line Lateral epicondyle Lateral condyle Intercondylar fossa Articular facets in tendon of knee Cartilaginous at birth Ossifies at age 3 to 6 years Base broad, superior portion Apex pointed, inferior portion Articular facets shallow, posterior portion Quadriceps femoris tendon extends from anterior muscle of thigh to patella Continues as the patellar ligament from patella to tibia 8-99
Intercondylar eminence Proximal tibiofibular joint Lateral surface Distal tibiofibular joint Lateral malleolus (a) Anterior view Medial condyle Tibial tuberosity Interosseous membrane Anterior crest Tibia Fibula Medial malleolus Figure 8.39 (b) Posterior view Tibia Lateral condyle Apex Head of fibula Lateral malleolus Tibia thick, medial, weightbearing bone Only weight-bearing bone of the crural region Broad superior head Medial and lateral condyles Fairly flat articular surfaces Articulate with condyle of femur Intercondylar eminence ridge separating condyles Tibial tuberosity attachment of quadricep muscles Anterior crest sharp, angular Medial malleolus bony knob on inside of ankle 8-100
The Fibula Intercondylar eminence Proximal tibiofibular joint Lateral surface Medial condyle Tibial tuberosity Interosseous membrane Anterior crest Tibia Lateral condyle Apex Head of fibula Fibula slender, lateral strut that helps stabilizes ankle Does not bear any body weight Spare bone tissue for grafts Head proximal end Apex point of the head Distal tibiofibular joint Lateral malleolus (a) Anterior view Fibula Medial malleolus Figure 8.39 (b) Posterior view Lateral malleolus Lateral malleolus distal expansion, bony knob on lateral side of ankle Joined to tibia by interosseous membrane 8-101
The Ankle and Foot Distal phalanx I Proximal phalanx I Metatarsal Medial cuneiform Intermediate cuneiform Lateral cuneiform Navicular Talus Trochlear surface of talus I II (a) Superior (dorsal) view Figure 8.40a III IV V Distal phalanx V Middle phalanx V Proximal phalanx V Cuboid Calcaneus Tuberosity of calcaneus Key to tarsal bones Distal group Proximal group Tarsal bones arranged in proximal and distal groups Tarsal bones are shaped and arranged differently from carpal bones due to loadbearing role of the ankle Calcaneus largest tarsal bone Forms heel Distal portion is point of attachment for calcaneal (Achilles) tendon Talus is most superior tarsal bone Forms ankle joint with tibia and fibula Sits upon calcaneus and articulates with navicular Proximal row of tarsal bones Talus, calcaneus, navicular Distal row of tarsal bones Medial, intermediate, lateral cuneiforms and cuboid 8-
The Ankle and Foot Remaining bones of foot are similar in name and arrangement to the hand Distal phalanx I Proximal phalanx I Metatarsal Medial cuneiform Intermediate cuneiform Lateral cuneiform Navicular I II III IV V Distal phalanx V Middle phalanx V Proximal phalanx V Cuboid Metatarsals Metatarsal I is proximal to the great toe (hallux) Metatarsal V is proximal to the little toe Proximal base, intermediate shaft, and distal head Talus Trochlear surface of talus Calcaneus Tuberosity of calcaneus (a) Superior (dorsal) view Figure 8.40a Key to tarsal bones Distal group Proximal group Phalanges Two in great toe Proximal and distal phalanx Three in all other toes Proximal, middle, distal phalanx 8-103
The Ankle and Foot Future thumb Thumb Elbow (a) Seven weeks Future great toe (b) Eight weeks Rotation of upper and lower limbs in opposite directions Starts seventh week of embryonic development Largest digit medial in foot and lateral in hand Each limb rotates about 90 in opposite directions Figure 8.41 Rotation also explains why elbow flexes posteriorly and knee flexes anteriorly Knee Great toe 8-104
The Ankle and Foot Medial longitudinal arch Transverse arch Lateral longitudinal arch Figure 8.42a Sole of foot is not flat on ground Three springy arches absorb stress Medial longitudinal arch From heel to hallux Formed from the calcaneus, talus, navicular, cuneiforms, and metatarsals I and III Lateral longitudinal arch From heel to little toe Includes calcaneus, cuboid, and metatarsals IV and V (a) Inferior (plantar) view 8-105
The Ankle and Foot Medial longitudinal arch Transverse arch Lateral longitudinal arch Figure 8.42a Transverse arch Across middle of foot Includes the cuboid, cuneiforms, and proximal heads of metatarsals Arches held together by short, strong ligaments Pes planus (flat feet) excessive weight, repetitious stress, or congenital weakness (a) Inferior (plantar) view 8-106
Skeletal Adaptations for Bipedalism Humans are only animals habitually bipedal 3.6-million-year-old human footprints indicate upright walking Adaptations Strong, springy foot arches Great toe not opposable Femurs angle inward so knees are closer together erect posture requires less muscular effort Viscera supported in bowl-shaped pelvis Insertions of gluteal muscles differ from other primates 8-107
Skeletal Adaptations for Bipedalism (a) Foot (b) Knee Chimpanzee Human Figure 8.43a,b Chimpanzee Human 8-108
Skeletal Adaptations for Bipedalism (c) Gluteal muscles (d) Pelvis (e) Vertebral column Chimpanzee Chimpanzee Chimpanzee Human Human Figure 8.43c,d,e Human 8-109
Skeletal Adaptations for Bipedalism (f) Skull Supraorbital ridge Pivot Foramen magnum Chimpanzee Pivot Human Foramen magnum Figure 8.43f 8-110