7 The Skeleton.

7 The Skeleton

Section 1: Axial Skeleton
Learning Outcomes 7.1 Identify the bones of the cranium and face, and identify and locate the cranial sutures. 7.2 Explain the significance of the markings and locations of the anterior and posterior aspects of the facial and cranial bones. 7.3 Explain the significance of the markings and locations of the lateral and medial aspects of the facial and cranial bones. 7.4 Explain the significance of the markings and locations of the inferior and interior aspects of the facial and cranial bones.

Learning Outcomes 7.5 Describe and locate the surface features of the sphenoid, ethmoid, and palatine bones. 7.6 Describe the structure of the orbital complex and nasal complex and the functions of their individual bones. 7.7 Describe the mandible and the associated bones of the skull. 7.8 Describe key structural differences among the skulls of infants, children, and adults.

Learning Outcomes Identify and describe the curves of the spinal column and their functions, and identify the vertebral regions. 7.10 Describe the distinctive structural and functional characteristics of the cervical and thoracic vertebrae. 7.11 Describe the distinctive structural and functional characteristics of the lumbar vertebrae, sacrum, and coccyx. 7.12 Explain the significance of the articulations between the thoracic vertebrae and the ribs, and between the ribs and the sternum.

Forms longitudinal axis of body Includes: Skull and associated bones Thoracic cage Vertebral column Various supplemental cartilages Typically 80 bones ~40% of bones in body Animation : Whole Skeleton

Functions Protect (brain, spinal cord, and organs in ventral cavity) Permit limited movement but strong and reinforced with ligaments Provide attachment for muscles that Adjust positions of head, neck, and trunk Perform respiratory movements Stabilize or position parts of appendicular skeleton that support limbs Animation: Whole Axial Skeleton

The bones of the axial skeleton
SKELETAL SYSTEM 206 Cranium 8 APPENDICULAR SKELETON (see Section 2) Skull 126 Face 14 Skull and associated bones 29 Auditory ossicles 6 Associated bones Hyoid 1 AXIAL SKELETON Costal cartilages (cartilages of ribs) 80 Sternum 1 Thoracic cage 25 Ribs 24 Intervertebral discs (cartilage) Vertebrae 24 Vertebral column 26 Sacrum 1 Coccyx 1 Figure 7 Section 1 The Axial Skeleton Figure 7 Section 1 7

Module 7.1: Skull Skull 22 bones Cranium (8) Facial bones (22)
Cranial bones that form the cranial cavity (fluid-filled chamber that cushions and supports brain) Blood vessels, nerves, and membranes attach to brain Outer surface for muscles that move eyes, jaws, and head Facial bones (22) Protect and support entrances for digestive and respiratory tracts Provide attachment for muscles controlling facial expression and assist in manipulating food

Animation: Skull: Lateral View of the Adult Skull
Module 7.1: Skull Animation: Skull: Lateral View of the Adult Skull Animation: Skull: Skull Exploded Animation: Skull: Whole Skull

The 22 bones that form the skull, plus the seven
bones associated with the skull SKULL FACE 14 CRANIUM 8 ASSOCIATED BONES (see Module 7.7) 7 Maxillary bones 2 Occipital bone 1 Palatine bones 2 Parietel bones 2 Nasal bones 2 Frontal bone 1 Inferior nasal conchae Temporal bones 2 Hyoid bone 1 2 Auditory ossicles enclosed in temporal bones Sphenoid 1 6 Zygomatic bones 2 Ethmoid 1 Lacrimal bones 2 Figure The skull has cranial and facial components that are usually bound together by sutures Vomer 1 Mandible 1 Figure 10

Frontal bone Parietal bone Temporal bone
The facial and cranial bones of the skull Cranial Bones Frontal bone Parietal bone Temporal bone Sphenoid Ethmoid Figure The skull has cranial and facial components that are usually bound together by sutures Occipital bone Figure 11

Module 7.1: Skull Associated bones
Six auditory ossicles in temporal bones Three ear bones on each side Hyoid bone connected to inferior surfaces of temporal bones

Module 7.1: Skull Joints (articulations) Where two bones interconnect
Called sutures in the skull Immovable Bones tied together with dense fibrous connective tissue Four major sutures Coronal (frontal to parietal bones) Calvaria (skullcap formed by frontal, parietal, and occipital bones) Squamous (temporal to parietal bones) Sagittal (between parietal bones) Lambdoid (occipital to parietal bones)

The major sutures of the skull
Frontal bone Coronal suture Parietal bone Squamous suture Temporal bone Occipital bone Lambdoid suture Lateral view of skull Sagittal suture Figure The skull has cranial and facial components that are usually bound together by sutures Parietal bone Parietal bone Sutural bone Lambdoid suture Occipital bone Posterior view of skull Figure – 6 14

Module 7.1 Review a. Define suture.
b. Identify the bones of the cranium. c. Describe the functions of the facial bones.

Module 7.2: Facial and cranial bones
Facial bones Nasal bones Support superior portion of bridge of nose Attached to cartilages of distal portion of nose Lacrimal bones Form part of medial wall of orbit (eye socket) Palatine bones Form posterior portion of hard palate and contribute to floor of each orbit Zygomatic bones Contribute to rim and lateral wall of orbit Form part of cheekbone

Facial bones (continued) Maxillae Support upper teeth Form inferior rim, lateral margins of external nares, upper jaw, and most of hard palate Inferior nasal conchae Create turbulence in air entering nasal cavity Increase surface area to promote warming and humidification of incoming air Vomer Forms inferior portion of bony nasal septum

Facial bones (continued) Mandible Forms lower jaw Animation: Skull: Facial

Frontal bone Forms anterior portion of cranium and roof of orbits Frontal sinuses secrete mucus that helps flush nasal cavities Sphenoid Forms part of floor of cranium Unites facial and cranial bones Acts as crossbridge to strengthen skull Ethmoid Forms anteromedial floor of cranium and roof of nasal cavity, and part of nasal septum and medial orbit wall

The bones of the skull in anterior view
Facial Bones Cranial Bones Nasal bone Parietal bone Frontal bone Lacrimal bone Palatine bone Sphenoid Zygomatic bone Maxilla Ethmoid Figure Facial bones dominate the anterior aspect of the skull, and cranial bones dominate the posterior surface Inferior nasal concha Vomer Mandible Figure 20

Cranial bones (continued) Parietal bones Form part of superior and lateral surfaces of cranium Occipital bone Contributes to posterior, lateral, and inferior surfaces of cranium External occipital crest Helps stabilize vertebrae of neck

Cranial bones (continued) Temporal bones Form part of lateral wall of cranium Articulate with facial bones and form articulations with mandible Surround and protect sense organs of inner ear Attachment site for muscles closing jaw and moving head Mastoid process Attachment for muscles that rotate or extend head Styloid process Attached to ligaments supporting hyoid bone and tendons of several muscles

The bones of the skull in posterior view
Cranial Bones Sagittal suture Parietal bones Occipital bone Lambdoid suture Temporal bone Squamous suture Mastoid process Figure Facial bones dominate the anterior aspect of the skull, and cranial bones dominate the posterior surface Styloid process External occipital crest Mandible Figure 23

Module 7.2 Review a. Identify the facial bones.
b. Quincy suffers a hit to the skull that fractures the right superior lateral surface of his cranium. Which bone is fractured? c. Identify the following bones as either a facial bone or a cranial bone: vomer, ethmoid, sphenoid, temporal, and inferior nasal conchae.

Module 7.3: Lateral and medial aspects of skull
Lateral aspect Frontal squama (forehead) Forms anterior, superior portion of cranium Provides surface for attachment for facial muscles Alveolar processes Support upper and lower teeth in mandible and maxillae Mental protuberance (mentalis, chin) Attachment site for several facial muscles Mandibular angle Posterior, inferior corner of lower jaw

Lateral aspect (continued) Zygomatic process Articulates with zygomatic bone to form zygomatic arch (cheekbone) External acoustic meatus Ends at tympanic membrane Squamous part of temporal bone Convex, irregular surface bordering squamous suture Superior and inferior temporal lines Mark attachment of temporalis muscle

Frontal bone Parietal bone Temporal bone Zygomatic bone Occipital bone
The skull in lateral view Coronal suture Superior and inferior temporal lines Frontal squama (forehead) Squamous part (of temporal bone) Squamous suture Sphenoid Frontal bone Parietal bone External acoustic meatus Ethmoid Lacrimal bone Temporal bone Nasal bone Maxilla Lambdoid suture Zygomatic bone Alveolar processes Occipital bone Figure The lateral and medial aspects of the skull share many surface features Mastoid process Styloid process Mandible Zygomatic arch (cheekbone) Mental protuberance Mandibular angle Figure 27

Frontal sinuses Variable in size and appearance Hypoglossal fossa Recess that supports/protects pituitary gland Bony wall called sella turcica Petrous part of temporal bone Encloses structures of inner ear and auditory ossicles in middle ear

Medial aspect (continued) Internal acoustic meatus Medial surface of petrous portion of temporal bone Carries blood vessels and nerves to inner ear Conveys facial nerve to stylomastoid foramen Hypoglossal canal Lateral base of occipital condyle to inner surface of occipital bone near foramen magnum Hypoglossal nerves pass through

The interior of the skull, as revealed by sagittal
section that passes just to the left of the midline Frontal bone Coronal suture Sphenoidal sinus (right) Sphenoid Sella turcica Petrous part (of temporal bone) Frontal sinuses Parietal bone Squamous suture Lambdoid suture Nasal bone Temporal bone Ethmoid Vomer Figure The lateral and medial aspects of the skull share many surface features Internal acoustic meatus Occipital bone Palatine bone Hypoglossal canal Maxilla Mandible Styloid process Figure 30

Module 7.3 Review a. Name the meatuses found in the temporal bone.
b. What is the function of the internal acoustic meatus? c. The alveolar processes perform what functions in which bones?

Module 7.4: Interior and inferior surface of skull
Foramina Foramen lacerum (lacerare, to tear) Jagged slit between sphenoid and petrous portion of temporal bone Contains cartilage and small arteries for inner cranium Foramen ovale Passage of nerves for jaws Carotid canal Passage of carotid artery

Foramina (continued) Jugular foramen Between occipital and temporal bone Passage of jugular vein Stylomastoid foramen Posterior to base of styloid process Passage of facial nerve to facial muscles Foramen magnum Connects cranial cavity and vertebral canal

Other features Mandibular fossa Inferior surface of temporal bone Articulation site with mandible Occipital condyles Articulation sites for first vertebra Inferior and superior nuchal lines Attachment sites for muscles and ligaments that stabilize head with neck vertebrae Internal occipital crest Ridge that anchors blood vessels and membranes that stabilize brain

External occipital crest
An inferior view of the skull Zygomatic bone Frontal bone Palatine bone Maxilla Vomer Foramina Foramen lacerum Sphenoid Foramen ovale Zygomatic arch Styloid process Carotid canal Mandibular fossa Jugular foramen Temporal bone Figure The foramina on the inferior surface of the skull lead into the interior of the cranium Occipital condyle Stylomastoid foramen Occipital bone Lambdoid suture Foramen magnum Inferior and superior nuchal lines External occipital crest Figure 35

Internal occipital crest
The interior of the skull, as revealed by horizontal section Nasal bones Frontal bone Crista galli Ethmoid Cribriform plate Sella turcica Foramen rotundum Sphenoid Foramen lacerum Temporal bone Foramen ovale Foramen spinosum Carotid canal Internal acoustic meatus Figure The foramina on the inferior surface of the skull lead into the interior of the cranium Mastoid foramen Parietal bone Jugular foramen Hypoglossal canal Occipital bone Internal occipital crest Figure 36

Module 7.4 Review a. Identify the bone containing the carotid canal, and name the structure that runs through this passageway. b. Which foramen provides a passageway for nerves innervating the jaw? c. In which bone is the foramen magnum located, and what is significant about this opening?

Module 7.5: Sphenoid, ethmoid, and palatine bones
Optic canals Passage of optic nerves from eyes to brain Lesser wings Extend horizontally anterior to sella turcica Greater wings Extend laterally Form part of cranial floor and posterior wall of orbit

Sphenoid (continued) Sella turcica Saddle-shaped enclosure Hypophyseal fossa Depression within sella turcica Occupied by pituitary gland Sphenoidal spine Posterior, lateral corner of each greater wing

Sphenoid (continued) Foramina (penetrate greater wing and carry blood vessels and nerves) Foramen spinosum (to orbit) Foramen ovale (to face) Foramen rotundum (to jaws) Superior orbital fissure (to cranial cavity membranes)

Two views of the sphenoid
Greater wing Optic canal Lesser wing Superior surface of the sphenoid Hypophyseal fossa Figure The shapes and landmarks of the sphenoid, ethmoid, and palatine bones can best be seen in the isolated bones Sella turcica Foramen spinosum Foramen ovale Foramen rotundum Superior orbital fissure Sphenoidal spine Figure 41

Cribriform plate (cribrum, sieve) Forms anteromedial floor of cranium and roof of nasal cavity Olfactory foramina permit passage of olfactory nerves for sense of smell Crista galli (crista, crest + gallus, chicken; cock’s comb) Bony ridge that projects superior to cribiform plate Attachment of falx cerebri, which stabilizes brain

Ethmoid (continued) Lateral masses Ethmoidal labyrinth Interconnected air cells that connect to nasal cavity Superior nasal conchae (projections) Middle nasal conchae (projections) Perpendicular plate Forms part of nasal septum

The ethmoid Cribriform plate Crista galli Lateral masses Figure The shapes and landmarks of the sphenoid, ethmoid, and palatine bones can best be seen in the isolated bones Superior and middle nasal conchae Perpendicular plate Superior surface Posterior surface Figure 44

Forms posterior portion of hard palate and contributes to floor of each orbit Orbital process Forms part of floor of orbit Normally contains small sinus that opens into sphenoidal sinus Horizontal plate Forms posterior part of hard palate Perpendicular plate Extends from horizontal plate to orbital process

The palatine bones Orbital process Perpendicular plate
of the palatine bone Nasal crest Figure The shapes and landmarks of the sphenoid, ethmoid, and palatine bones can best be seen in the isolated bones Horizontal plate Figure 46

Module 7.5 Review a. Identify the bone containing the optic canal, and cite the structures using this passageway. b. Which bone contains the sella turcica? What structure is in the depression (fossa) within the sella turcica? c. Identify the bone containing the cribriform plate. What is significant about this structure?

Module 7.6: Orbital and nasal complexes
Contains eye Formed by seven bones of the orbital complex Frontal (roof) Zygomatic (lateral wall) Maxilla (most of floor) Lacrimal (medial wall) Ethmoid (medial wall) Sphenoid (posterior wall) Palatine (posterior wall)

Bony features of orbit Lacrimal fossa Shallow depression in frontal bone Lacrimal (tear) gland location Supra-orbital margin Thickening of frontal bone to help protect eye Supra-orbital notch Passage of blood vessels to eyebrow, eyelids, and frontal sinuses Also occurs as supra-orbital foramen when fully enclosed

Bony features of orbit (continued) Lacrimal sulcus Groove along anterior, lateral surface of lacrimal bone Location of lacrimal sac Leads to nasolacrimal canal Nasolacrimal canal Formed by maxilla and lacrimal bone Protects lacrimal sac and nasolacrimal duct (carries tears to nasal cavity)

Bony features of orbit (continued) Infra-orbital foramen Passage of major sensory nerve that reaches brain through foramen rotundum Zygomaticofacial foramen Anterior surface of zygomatic bone Carries sensory nerve innervating cheek

The bones of the orbital complex
Supra-orbital margin Lacrimal fossa Supra-orbital notch Frontal bone Palatine bone Ethmoid Lacrimal sulcus Sphenoid Temporal bone Figure Each orbital complex contains one eye, and the nasal complex encloses the nasal cavities Nasolacrimal canal Zygomatic bone Middle nasal concha Zygomaticofacial foramen Intra-orbital foramen Inferior nasal concha Maxilla Figure 52

Bones that enclose the nasal cavities and paranasal sinuses (secretions flush nasal cavities) Paranasal sinuses Sphenoidal sinuses Ethmoid air cells Frontal sinuses Palatine Maxillary sinuses Lighten skull and provide area of mucous epithelium

The bones of the nasal complex
Cranial cavity Frontal bone Ethmoidal air cells Orbit Zygomatic bone Maxillary sinus Maxilla Frontal section Figure Each orbital complex contains one eye, and the nasal complex encloses the nasal cavities Mandible Nasal cavities Figure 54

Nasal cavity bones Superior wall Frontal Sphenoid Ethmoid Lateral walls Maxillae Lacrimal bones Inferior nasal conchae

The bones that form and surround the nasal cavity, as
revealed by a sagittal section with nasal septum removed Frontal sinuses Frontal bone Sphenoidal sinus Sphenoid Nasal bone Ethmoid Lacrimal bone Superior nasal concha Inferior nasal concha Middle nasal concha Perpendicular plate of palatine bone Pterygoid plates Figure Each orbital complex contains one eye, and the nasal complex encloses the nasal cavities Maxilla Hard palate Figure 56

Module 7.6 Review a. Identify the bones of the orbital complex.
b. Describe the frontal sinuses. c. To which complex—nasal, orbital, or both—does each of the following bones contribute? frontal, maxilla, palatine, nasal

Module 7.7: Mandible and associated skull bones
Condylar process Articulates with temporal bone at temporomandibular joint Coronoid process Insertion point for temporalis muscle Mandibular notch Depression that separates condylar and coronoid processes Alveolar process Supports lower teeth

Mandible (continued) Body Horizontal portion of bone Ramus Ascending part that begins at mandibular angle Mylohyoid line Insertion of mylohyoid muscle (supports mouth floor) Mandibular foramen Passageway for blood vessels and nerves that service the lower teeth

The mandible in lateral view
Coronoid process Teeth (molars) Condylar process Alveolar process Figure The mandible forms the lower jaw, and the associated bones of the skull perform specialized functions Mental foramen Mandibular notch Body of the mandible Ramus of the mandible Figure 60

The medial surface of the mandible
Coronoid process Condylar process Mylohyoid line Head Mandibular foramen Alveolar part Figure The mandible forms the lower jaw, and the associated bones of the skull perform specialized functions Position of the submandibular salivary gland Figure 61

Hyoid bone Supports larynx Attachment site for muscles of larynx, pharynx, and tongue Greater horns Help support larynx Attachment point for tongue muscles Lesser horns Attachment point for hyoid and laryngeal ligaments

The hyoid bone Greater horn Lesser horn Body of the hyoid
Figure The mandible forms the lower jaw, and the associated bones of the skull perform specialized functions Figure 63

Associated skull bones (continued) Auditory ossicles In middle ear within petrous portion of temporal bone Conduct sound wave vibrations from tympanic membrane to hearing receptors of inner ear

The auditory ossicles, bones associated
with the skull SKULL ASSOCIATED BONES 7 FACE 14 CRANIUM 8 Maxillary bones 2 Occipital bone 1 Palatine bones 2 Parietal bones 2 Auditory ossicles enclosed in temporal bones (see Chapter 15) Nasal bones 2 Frontal bone 1 Hyoid bone 1 6 Inferior nasal conchae 2 Temporal bones 2 Sphenoid 1 Zygomatic bones 2 Ethmoid 1 Lacrimal bones 2 Vomer 1 Mandible 1 Figure The mandible forms the lower jaw, and the associated bones of the skull perform specialized functions Figure 65

Module 7.7 Review a. Name the foramina of the mandible.
b. Describe the location and function of the auditory ossicles. c. ls your lab partner correct when she claims that the hyoid bone does not directly join (articulate with) any other bone?

Module 7.8: Fontanelles Fontanelles
Large fibrous areas between cranial bones of infants and small children Ease passage of head through birth canal Allow for cranial growth to keep pace with brain growth and later fetal stages Over time, fontanelles are replaced with sutures Occipital, sphenoidal, and mastoid fontanelles disappear a month or two after birth All fontanelles replaced before age 5 when brain stops growing

Module 7.8: Fontanelles Fontanelles Anterior Sphenoidal Mastoid
Largest fontanelle At intersection of frontal, sagittal, and coronal sutures Sphenoidal Junction of squamous and coronal sutures Mastoid Junction of squamous and lambdoid sutures Occipital Junction of lambdoid and sagittal sutures

Right parietal bone Left parietal bone
The anterior fontanelle (“soft spot”) and associated sutures in the skull of an infant Sagittal suture Right parietal bone Left parietal bone Anterior fontanelle Coronal suture Frontal suture Figure Fontanelles permit cranial growth in infants and small children Frontal bone Frontal suture Figure 69

Left parietal bone Right parietal bone
The occipital fontanelle and associated sutures in a posterior view of the skull of an infant Left parietal bone Right parietal bone Sagittal suture Occipital fontanelle Figure Fontanelles permit cranial growth in infants and small children Lambdoid suture Occipital bone Figure 70

Frontal bone Parietal bone Temporal bone
A lateral view of the skull of an infant Sphenoidal fontanelle Coronal suture Frontal bone Parietal bone Sphenoid Squamous suture Mastoid fontanelle Nasal bone Temporal bone Maxilla Figure Fontanelles permit cranial growth in infants and small children Mandible Lambdoid suture Occipital bone Figure 71

Parietal bone Frontal bone Sagittal suture Frontal bone Parietal bone
A superior view of the skull of an infant Parietal bone Lambdoid suture Frontal bone Frontal suture Sagittal suture Occipital fontanelle Anterior fontanelle Frontal bone Parietal bone Occipital bone Figure Fontanelles permit cranial growth in infants and small children Coronal suture Figure 72

Module 7.8 Review a. Define fontanelle.
b. Identify the major fontanelles. c. What purposes do fontanelles serve?

Module 7.9: Vertebral column
Consists of 26 bones (24 vertebrae, 1 sacrum, 1 coccyx) Average adult length is 71 cm (28 in.) Functions Provides a column of support to bear weight of head, neck, and trunk Transfers weight to lower limbs Protects spinal column Helps maintain upright position Animation: The Division and Curvatures of the Vertebral Column

Spinal curves Primary (before birth) and secondary (after birth) Cervical curve (secondary) Develops as infant learns to balance head on vertebrae Thoracic curve (primary) Accommodation of thoracic organs Lumbar curve (secondary) Develops with ability to stand to balance trunk over limbs Sacral curve (primary) Accommodates abdominopelvic organs

The spinal curves and vertebral regions in the adult vertebral column
Primary curves develop before birth, and secondary curves after birth. Regions are defined by anatomical characteristics of individual vertebrae. C1 C2 Cervical curve (a secondary curve) C3 C4 Cervical (7 vertebrae) C5 C6 C7 T1 T2 T3 T4 T5 Thoracic curve (a primary curve) T6 T7 Thoracic (12 vertebrae) T8 T9 T10 T11 T12 Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences L1 L2 Lumbar curve (a secondary curve) L3 Lumbar (5 vertebrae) L4 L5 Sacral Sacral curve (a primary curve) Coccygeal Figure 76

Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Figure 77

Vertebral regions (defined by anatomical characteristics of individual vertebrae) Cervical (7 vertebrae) Thoracic (12 vertebrae) Lumbar (5 vertebrae) Sacral Coccygeal

The parts of a typical vertebra Parts of a Vertebra
Articular processes Vertebral arch Vertebral body Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Superior view Figure 79

Parts of typical vertebra Articular processes Extend superiorly and inferiorly to articulate with adjacent vertebrae Have smooth, concave surface (articular facet) Superior articular process Inferior articular process Vertebral body Transfers weight along vertebral column axis

Parts of typical vertebra (continued) Vertebral arch Spinous process (projects posteriorly) Laminae (form “roof” of vertebral foramen) Transverse processes (project laterally) Pedicles (form sides of vertebral arch) Vertebral foramen Formed by vertebral body and arch

The parts of the vertebral arch The Vertebral Arch
Spinous process Vertebral foramen Laminae Transverse process Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Pedicles Inferior view Figure 82

Characteristics of articulated vertebrae Intervertebral discs Pads of fibrous cartilage found between bodies of adjacent vertebrae Intervertebral foramina Spaces between successive pedicles Passage of nerves and blood vessels Vertebral canal Encloses spinal cord

A lateral view of three vertebrae
Pedicle Intervertebral disc Intervertebral foramina Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Vertebral body Vertebral canal Figure 84

Superior articular process Inferior articular process
A posterior view of two vertebrae Articular facet Superior articular process Inferior articular process Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Figure 85

Referencing individual vertebrae One capital letter designator according to region Examples: C, T, L, S, and Co Subscript number designates relative position within region Example: C3 = 3rd cervical vertebra

Module 7.9 Review a. Name the major components of a typical vertebra.
b. What is the importance of the secondary curves of the spine? c. To which part of the vertebra do the intervertebral discs attach?

Module 7.10: Cervical and thoracic vertebrae
Cervical vertebrae Characteristics Smallest of vertebral column Extend from occipital bone to thorax Large vertebral foramen Spinal cord here has many axons connecting to brain Vertebral body is small and light Only supports weight of head Bifid (split) spinous process Transverse foramen Protects vertebral arteries and veins serving brain Costal process (extends anterolaterally from body)

A typical cervical vertebra
Bifid spinous process Vertebral foramen Transverse foramen Transverse process Figure There are seven cervical vertebrae and twelve thoracic vertebrae Vertebral body Costal process Figure 89

First two cervical vertebrae Specialized to stabilize cranium while permitting head movement Atlas (C1) (named after Greek god who holds world) No spinous process No vertebral body Large round vertebral foramen Axis (C2) Prominent dens or odontoid (odontos, tooth) process of body Animation: Vertebral Column: Axis Atlas

First two cervical vertebrae (continued) Articulation between occipital condyles and atlas Forms joint permitting “nodding yes” movement Articulation between atlas and axis Transverse ligament binds dens to anterior arch of atlas Forms joint permitting rotation (shaking your head “no”)

The first two cervical vertebrae: the atlas and the axis Anterior
arch of atlas Atlas Dens (odontoid process) Ligament that enables rotation (as in shaking the head to indicate “no”) Joint that permits nodding (as in indicating “yes”) Figure There are seven cervical vertebrae and twelve thoracic vertebrae Axis Posterior arch of atlas Figure 92

Last cervical vertebra (C7) Has very robust spinous process with tubercle that can be felt through the skin Known as vertebra prominens Ligamentum nuchae (nucha, nape) Stout elastic ligament extending from vertebra prominens to external occipital crest on skull Acts like bowstring to maintain cervical curvature without muscular effort Animation: Vertebral Column: Cervical Vertebrae

A lateral view of the seven cervical vertebrae
prominens Figure There are seven cervical vertebrae and twelve thoracic vertebrae Figure 94

Twelve thoracic vertebrae Body of each (moving inferior) is more robust than the one superior due to bearing of increasing weight Each has costal facets on the dorsolateral surfaces of vertebral body that articulate with ribs First 10 vertebrae have transverse costal facets as well Ribs 11 and 12 are known as floating ribs accordingly

Characteristics Distinctive heart-shaped body Smaller vertebral foramen Long, slender, inferiorly pointing spinous process Animation: Vertebral Column: Thoracic Vertebrae

Figure 7.10.4 There are seven cervical vertebrae and twelve thoracic vertebrae
97

A typical thoracic vertebra in superior view
Transverse process Spinous process Superior articular facet Vertebral foramen Superior costal facet Figure There are seven cervical vertebrae and twelve thoracic vertebrae Vertebral body Figure 98

A typical thoracic vertebra in lateral view
Superior costal facet Transverse costal facet Vertebral body Spinous process Inferior costal facet Figure There are seven cervical vertebrae and twelve thoracic vertebrae Transverse process Figure 99

Module 7.10 Review a. Joe suffered a hairline fracture at the base of the dens. Which bone is fractured and where is the fractured bone located? b. Examining a human vertebra, you notice that, in addition to the large foramen for the spinal cord, two smaller foramina are on either side of the bone in the region of the transverse processes. From which region of the vertebral column is this vertebra? c. When you run your finger down the middle of a person's spine, what part of each vertebra are you feeling just beneath the skin?

Module 7.11: Lumbar vertebrae, sacrum, and coccyx
Five lumbar vertebrae Largest and transmit most weight Characteristics Do not have costal facets Have slender transverse processes Triangular vertebral foramen Stumpy spinous process Superior articular processes face medially Inferior articular processes face laterally Animation: Vertebral Column: Lumbar Vertebrae

Five fused vertebrae Completely fused by ~25–30 years old Anterior surface concave/posterior surface convex Characteristics Ala (bony wing extending laterally) Base (broad superior surface) Sacral promontory (important landmark in females) Sacral foramina (intervertebral foramina of fused vertebrae) Apex (narrow inferior portion)

Characteristics (continued) Sacral canal (passageway extending length of sacrum containing nerves and membranes of spinal cord) Auricular surface (thickened, flattened lateral surfaces; sacral part of sacro-iliac joint) Sacral tuberosity (roughened area dorsal to auricular surface; attachment site for ligaments of sacro-iliac joint) Lateral sacral crest (ridge from transverse processes of fused sacral vertebrae)

Characteristics (continued) Superior articular process (forms articulation with last lumbar vertebra) Median sacral crest (ridge formed by spinous processes of fused sacral vertebrae) Sacral hiatus (inferior opening of sacral canal) Coccyx Three to five fused vertebrae Begin fusing about age 2 Animation: Vertebral Column: Sacrum Coccyx

Module 7.11 Review a. How many vertebrae are present in the lumbar region? In the sacrum? b. What structure forms the posterior wall of the pelvic girdle? c. Why are the bodies of the lumbar vertebrae so large?

Module 7.12: Thoracic cage Thoracic cage
Provides bony support to thoracic cavity walls Protects heart, lungs, thymus, and other thoracic cavity organs Attachment for muscles involved in Respiration Maintenance of vertebral column position Movements of pectoral girdle and upper limbs

Module 7.12: Thoracic cage Thoracic cage components Ribs
Reinforce posterior and lateral thoracic walls Very mobile and flexible bones Types Vertebrocostal ribs (ribs 1–7) Connect to sternum via individual costal cartilages Vertebrochondral ribs (ribs 8–10) Connect to sternum via shared costal cartilages Floating ribs (ribs 11 and 12) No connection to sternum Also known as vertebral ribs

Module 7.12: Thoracic cage Thoracic cage components (continued)
Sternum Forms anterior midline of thoracic wall Three regions Manubrium (superior portion that articulates with clavicles and first pair of ribs) Body (attaches inferiorly to manubrium and to ribs –7) Xiphoid process (smallest, most inferior region)

An anterior view of the thoracic cage
Jugular notch T1 1 2 3 Sternum Manubrium 4 5 Ribs Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Vertebrosternal ribs (ribs 1–7) 6 Body 11 T11 Vertebrosternal ribs (ribs 8–10) 7 T12 12 8 9 Floating ribs (ribs 11 and 12) Xiphoid process 10 Costal cartilages Figure 109

Module 7.12: Thoracic cage Thoracic cage Rib landmarks
Head or capitulum (attachment to vertebra) Articular facts (specific attachment points) Angle (bend connecting head to shaft) Shaft (tubular body) Typical ribs act as bucket handles Pushing down moves ribs inward Pulling up moves ribs outward Sternum moves accordingly Movements affect width and depth of thoracic cage

Posterior view of a representative rib (ribs 2–9)
Articular facets on head Capitulum Tubercle Angle of the rib Shaft Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Superficial surface Costal groove Figure 111

The action of a typical rib, which can be likened to the movement
of a bucket’s handle Sternum Ribs Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Figure 112

Module 7.12: Thoracic cage Thoracic cage (continued)
Costal-vertebral articulations Heads of ribs 2–9 articulate on two adjacent vertebrae at costal facets Heads of ribs 1, 10, 11, and 12 articulate with individual vertebrae Tubercular facets attach to transverse costal facts

Superior view of a representative rib
Transverse process Tubercular facet Superior articular facet Transverse costal facet Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Inferior articular facet Figure 114

Module 7.12 Review a. How are vertebrosternal ribs distinguished from vertebrochondral ribs? b. Improper chest compressions during cardiopulmonary resuscitation (CPR) can result in fractures of which bones? c. In addition to the ribs and sternum, what other bones make up the thoracic cage?

Section 2: Appendicular Skeleton
Learning Outcomes 7.13 Identify the bones that form the pectoral girdle, their functions, and their superficial features. 7.14 Identify the bones of the arm and forearm, their functions, and their superficial features. 7.15 Identify the bones of the wrist and hand, and describe their locations using anatomical terminology. 7.16 Describe the hip bones that form the pelvic girdle, their functions, and their superficial features.

Learning Outcomes 7.17 Identify the bones of the pelvis, and discuss the structural and functional differences between the pelvis in males and the pelvis in females. 7.18 Identify the bones of the thigh and leg, their functions, and their superficial features. 7.19 Identify the bones of the ankle and foot, and describe their locations using anatomical terminology.

Consists of bones of the limbs and supporting elements (or girdles) that connect them to trunk 126 bones Pectoral girdle (4) Upper limbs (60) Pelvic girdle (2) Lower limbs (60)

The bones of the appendicular skeleton
SKELETAL SYSTEM 206 AXIAL SKELETON 80 Clavicle 2 Pectoral girdle 4 Scapula 2 Humerus 2 Radius 2 Ulna 2 Upper limbs 60 Carpal bones 16 Metacarpal bones 10 APPENDICULAR SKELETON 126 Phalanges (proximal, middle, distal) 28 Hip bone (coxal bone) 2 Pelvic girdle 2 Figure 7 Section 2 The Appendicular Skeleton Femur 2 Patella 2 Tibia 2 Fibula 2 Lower limbs 60 Tarsal bones 14 Metatarsal bones 10 Phalanges 28 Figure 7 Section 2 119

Module 7.13: Pectoral girdle
Pectoral (shoulder) girdle Joins arm to trunk Consists of clavicle and scapula

The relationship of the clavicle to adjacent bones
Jugular notch Scapula Humerus Figure The pectoral girdles—the clavicles and scapulae—connect the upper limbs to the axial skeleton Anterior view Figure 121

Clavicle Originates at superior, lateral border of manubrium Articulates with acromion of scapula Characteristics Sternal end Pyramid-shaped Acromial end Flatter, broader than sternal end Rough interior surface bearing lines and tubercles

Two views of the right clavicle
Superior view LATERAL MEDIAL Acromial end Sternal end Figure The pectoral girdles—the clavicles and scapulae—connect the upper limbs to the axial skeleton LATERAL Inferior view MEDIAL Figure 123

Scapula Body Broad, smooth triangle Sides Superior border Medial border Lateral border Corners Superior angle Inferior angle Lateral angle

Scapula (continued) Subscapular fossa Anterior surface depression Glenoid cavity Cup-shaped Articulates with humerus Scapular spine Ridge on posterior surface

Scapula (continued) Supraspinous fossa (supra, above) Infraspinous fossa (infra, below) Acromion process End of spine Coracoid process Anterior, superior to glenoid cavity

Two views of the right scapula
Scapular spine Acromion Coracoid process Superior border Superior angle Acromion Supraspinous fossa Subscapular fossa Process that supports the cup-shaped glenoid cavity Figure The pectoral girdles—the clavicles and scapulae—connect the upper limbs to the axial skeleton Medial border Infraspinous fossa Lateral border Anterior view Posterior view Inferior angle Figure – 4 127

A lateral view of the right scapula
Coracoid process Glenoid cavity Acromion Figure The pectoral girdles—the clavicles and scapulae—connect the upper limbs to the axial skeleton Figure 128

Module 7.13 Review a. Name the bones of the pectoral girdle.
b. How would a broken clavicle affect the mobility and stability of the scapula? c. Which bone articulates with the scapula at the glenoid cavity?

Module 7.14: Humerus, radius, ulna
Skeleton of upper limbs includes those of arms, forearms, wrists, and hands Arm = shoulder to elbow Forearm = elbow to wrist Animation: Pectoral Girdle: Upper Limb

Head Proximal end that articulates with glenoid cavity (scapula) Lesser tubercle Smaller projection on anterior, medial epiphyseal surface Greater tubercle Rounded projection on lateral epiphyseal surface Establishes lateral contour of shoulder Intertubercular groove Between tubercles Important for muscle attachment

Humerus (continued) Anatomical neck Marks extent of joint capsule Surgical neck Fractures typically occur here Deltoid tuberosity Large, rough elevation on lateral surface Attachment of deltoid muscle Radial groove Crosses inferior end of deltoid tuberosity Depression marking path of radial nerve

Humerus (continued) Radial fossa Accommodates portion of radial head Condyle Capitulum Lateral surface of condyle Trochlea (trochlea, pulley) Medial surface of condyle Extends from olecranon fossa (posterior) to coronoid fossa (anterior) These depressions accept projections of ulna

Surface features of the right humerus
Anterior view Posterior view Head Greater tubercle Greater tubercle Lesser tubercle Intertubercular groove Anatomical neck Surgical neck Radial groove Shaft Deltoid tuberosity Figure The humerus of the arm articulates with the radius and ulna of the forearm Radial fossa Coronoid fossa Olecranon fossa Lateral epicondyle Medial epicondyle Trochlea Capitulum Trochlea Figure 134

Ulna and radius Parallel bones that support forearm In anatomical position, ulna is medial to radius Shafts connected via interosseus membrane Proximal radio-ulnar joint Radial notch on ulna with radial head Distal radio-ulnar joint Lateral surface of ulnar head with distal end of radius

Surface features of the right ulna and radius
Posterior view Anterior view Radial head Trochlear notch Olecranon Neck of the radius Coronoid process Proximal radio-ulnar joint Radial notch at proximal radio-ulnar joint Radial tuberosity Ulna Radius Radius Ulna Figure The humerus of the arm articulates with the radius and ulna of the forearm Interosseous membrane Ulnar notch Distal radio-ulnar joint Ulnar head Styloid process of the radius Ulnar head Styloid process of the ulna Figure 136

Olecranon Superior end of ulna Point of elbow Ulnar head Distal, slender, rounded end Styloid process (styloid, long and pointed) Posterior, lateral surface of head Radial notch Accommodates head of radius

Ulna (continued) Trochlear notch Articulates with trochlea of humerus at elbow joint Coronoid process Inferior lip of trochlear notch

Radial head Articulates with capitulum of humerus During flexion, swings into radial fossa of humerus Neck From radial head to tuberosity Radial tuberosity Marks attachment site of biceps brachii muscle Ulnar notch Site of articulation with ulnar head Styloid process Distal radius that articulates with bones of wrist

Module 7.14 Review a. Identify the bones of the arm and forearm.
b. Identify the two rounded projections on either side of the elbow, and state to which bone they belong. c. Which bone of the forearm is positioned laterally while in anatomical position?

Module 7.15: Carpal bones, metacarpals, and phalanges
Carpus Eight carpal bones arranged in two rows of four bones Proximal carpal bones Scaphoid (skaphe, boat) Lateral border of wrist Closest to styloid process of radius Lunate (luna, moon) Medial to scaphoid Articulates with radius Pisiform (pisum, pea) Anterior to triquetrum Triquetrum (triquetrus, three-cornered) Articulates with disc separating ulna from wrist

Carpus (continued) Distal carpal bones Trapezium (trapezion, four sided with no parallel sides) Lateral bone that articulates with scaphoid Trapezoid Medial to trapezium Proximal articulation with scaphoid Capitate (caput, head) Largest carpal bone Between trapezoid and hamate Hamate Medial carpal bone

The bones of the carpus (wrist)
Proximal Carpal Bones Scaphoid Lunate Pisiform Triquetrum Right wrist and hand, anterior (palmar) view Radius Ulna I II III IV V Metacarpal bones Figure The wrist is composed of carpal bones, and the hand consists of metacarpal bones and phalanges Proximal phalanx Distal Carpal Bones Trapezium Trapezoid Capitate Hamate Middle phalanx Distal phalanx Figure 143

Metacarpals (metacarpus, hand) Articulate with distal carpal bones and support hand Identified by Roman numerals I–V, from lateral to medial Distally articulate with proximal finger bones Phalanges 14 phalanges per hand Pollex (thumb) has 2 phalanges (proximal and distal) All other fingers have 3 phalanges (proximal, middle, and distal) Animation: Pectoral Girdle: Wrist Hand

The metacarpal bones (designated I–V) and the phalanges of the hand Radius Ulna Proximal Carpal Bones Scaphoid Lunate Triquetrum Distal Carpal Bones Pisiform Trapezium Trapezoid Capitate Hamate I V III II IV Proximal phalanx of pollex Metacarpal bones Proximal phalanx Distal phalanx of pollex Figure The wrist is composed of carpal bones, and the hand consists of metacarpal bones and phalanges Middle phalanx Right wrist and hand, posterior (dorsal) view Distal phalanx Figure 145

Module 7.15 Review a. Define phalanges. b. Name the carpal bones.
c. Bill accidentally fractures his first distal phalanx with a hammer. Which finger is broken?

Module 7.16: Pelvic girdle Pelvic girdle
Consists of paired hip bones (coxal bones) Hip bone formed by fusion of three bones Ilium Ischium Pubis Acetabulum (acetabulum, vinegar cup) Concave socket formed by all three fused bones Articulates with head of femur Has smooth, cup-shaped surface (lunate surface) Has superior gap in bony rim (acetabular notch)

Module 7.16: Pelvic girdle Ilium Iliac spines Gluteal lines
Attachment of important muscles and ligaments Gluteal lines Mark attachment of large hip muscles Greater sciatic notch Passage of sciatic nerve to lower limb Iliac crest Important ridge for muscle attachment

Module 7.16: Pelvic girdle Ilium (continued) Iliac fossa
Shallow depression that supports abdominal organs and some muscle attachment Auricular surface Surface that articulates with sacrum Iliac tuberosity Roughened area superior to auricular surface Has attached ligaments that stabilize sacro-iliac joint Arcuate line Continuous with pectineal line of pubis

Module 7.16: Pelvic girdle Ischium Ischial spine Ischial tuberosity
Projects superior to sciatic notch Passage of blood vessels, nerves, and small muscle Ischial tuberosity Roughened projection Supports body weight when seated Ischial ramus Bony extension that borders obturator foramen

Module 7.16: Pelvic girdle Pubis Pectineal line Pubic symphysis
Ridge that ends in pubic tubercle Pubic symphysis Connects pubic bones via fibrous cartilage pad Superior and inferior pubic rami (singular, ramus) Bony extensions that border obturator foramen

A hip bone, which consists of an
ilium, an ischium, and a pubis Ilium A lateral view of the right hip bone POSTERIOR ANTERIOR Pubis Ischium Iliac crest Gluteal Lines Anterior Inferior Anterior superior iliac spine Posterior Posterior superior iliac spine Lunate surface Posterior inferior iliac spine Figure The hip bone forms by the fusion of the ilium, ischium, and pubis Greater sciatic notch Acetabulum Ischial spine Ischial ramus Ischial tuberosity Acetabular notch Figure – 2 152

A medial view of the right hip bone
Ilium ANTERIOR POSTERIOR Pubis Ischium Iliac crest Iliac tuberosity Iliac fossa Auricular surface of the ilium Arcuate line of the ilium Figure The hip bone forms by the fusion of the ilium, ischium, and pubis Greater sciatic notch Pectineal line Obturator foramen Superior pubic ramus Pubic symphysis Ischial ramus Inferior pubic ramus Figure 153

Module 7.16 Review a. Describe the acetabulum.
b. Which three bones fuse to make up a hip bone? c. When you are seated, which part of the hip bone bears your body’s weight?

Module 7.17: Pelvis Consists of two hip bones, sacrum, and coccyx
Has extensive network of ligaments connecting sacrum with: Iliac crest Ischial tuberosity Ischial spine Arcuate line Other ligaments tie ilia to lumbar vertebrae

The structures of the pelvis
Sacrum Hip Bone Ilium Coccyx Pubis Ischium L5 Iliac crest Iliac fossa Ilium Sacrum Figure The pelvis consists of the two hip bones plus the sacrum and the coccyx Sacro-iliac joint Acetabulum Pubic tubercle Obturator foramen Ischium Pubic symphysis Figure 156

Module 7.17: Pelvis May be divided into: True (lesser) pelvis
Encloses pelvic cavity Superior limit extends from base of sacrum, along arcuate line and pectineal line, to pubic symphysis = Pelvic brim Encloses pelvic inlet Pelvic outlet bounded by coccyx, ischial tuberosities, ischial spines, and inferior pubic symphysis False (greater) pelvis Consists of area enclosed by bladelike portions of ilia superior to pelvic brim

Superior view Inferior view
The locations and extents of the true (lesser) pelvis (in purple) and the false (greater) pelvis Superior view Inferior view Pelvic outlet False pelvis Ischial spine Figure The pelvis consists of the two hip bones plus the sacrum and the coccyx Pelvic inlet Pelvic brim Pelvic outlet Figure 158

Module 7.17: Pelvis Sexual differences in pelvic structure
Most related to adaptations for childbearing Female (compared to male) Generally smoother and lighter with less prominent markings Enlarged pelvic outlet Broader pubic angle, greater than 100° Less curvature on sacrum and coccyx Wider, more circular pelvic inlet Relatively broad, low pelvis Ilia project farther laterally but not as far superiorly

The shapes of the pelvis in females and males
The pelvis of a female The pelvis of a male Female Male Ischial spine Ischial spine Figure The pelvis consists of the two hip bones plus the sacrum and the coccyx 100° or more 90° or less Figure 160

Module 7.17 Review a. Name the bones of the pelvis.
b. The pubic bones are joined anteriorly by what structure? c. How is the pelvis of females adapted for childbearing?

Module 7.18: Femur, tibia, and fibula
Skeleton of lower limb consists of: Femur (thigh) Patella (kneecap) Tibia and fibula (leg) Connected with interosseus membrane Metatarsal bones and phalanges (foot) Same number of bones as upper limb Functional anatomy is different due to weight-bearing properties Animation: Pelvic Girdle: Lower Limb

Longest and heaviest bone in body Articulates with hip at hip joint Articulates with tibia at knee joint Characteristics Femoral head Articulates with pelvis at acetabulum Fovea capitis Small pit containing ligament attaching head to acetabulum Neck Joins shaft at about 125°

Femur (continued) Characteristics Greater trochanter Large, rough projection that extends laterally Attachment site for large tendons Lesser trochanter Smaller process that projects posteriorly and medially Intertrochanteric line Marks edge of articular capsule on anterior femur Gluteal tuberosity Attachment of gluteus maximus muscle

Femur (continued) Characteristics Linea aspera (aspera, rough) Attachment of powerful hip muscles Popliteal surface (poples, hollow of knee) Flattened triangular area on posterior Medial and lateral condyles Participate in knee joint at distal end Separated by: Patellar surface (anterior) Intercondylar fossa (posterior)

Figure 7.18.1-2 The femur articulates with the patella and tibia
Landmarks of the right femur Neck Fovea capitis Greater trochanter Greater trochanter Femoral head Intertrochanteric crest Gluteal tuberosity Intertrochanteric line Linea aspera Lesser trochanter Anterior view Posterior view Figure The femur articulates with the patella and tibia Shaft Lateral supracondylar ridge Popliteal surface Adductor tubercle Patellar surface Lateral epicondyle Medial epicondyle Intercondylar fossa Lateral condyle Medial condyle Lateral epicondyle Lateral condyle Figure 166

Patella Large sesamoid bone that forms in quadriceps tendon Characteristics Base Attachment of quadriceps tendon Apex Attachment of patellar ligament (patella to tibia) Lateral facet For lateral condyle of femur Medial facet For medial condyle of femur

Anterior view Posterior view
The surface features of the patella Base of patella Lateral facet, for lateral condyle of femur Attachment area for quadriceps tendon Medial facet, for medial condyle of femur Attachment area for the patellar ligament, which attaches the patella to the tibia Articular surface of patella Apex of patella Figure The femur articulates with the patella and tibia Anterior view Posterior view Figure 168

Tibia (shinbone) Large medial bone of leg Characteristics Intercondylar eminence Ridge separating lateral and medial tibial condyles Tibial tuberosity Attachment of patellar ligament Anterior margin Ridge beginning at tibial tuberosity, extending along anterior surface Medial malleolus (malleolus, hammer) Medial projection of ankle that supports joint

Attachment of muscles that move foot and toes Provides lateral stability to ankle joint Characteristics Head Articulates with tibia proximally Lateral malleolus

Anterior view Posterior view
The features of the right tibia and fibula Superior tibiofibular joint Articular surface of medial tibial condyle Intercondylar eminence Lateral tibial condyle Articular surface of lateral tibial condyle Medial tibial condyle Head of the fibula Lateral tibial condyle Tibial tuberosity Head of fibula Interosseous membrane Anterior view Posterior view Anterior margin of the tibia Figure The femur articulates with the patella and tibia Tibia Fibula Fibula Medial malleolus of the tibia Inferior tibiofibular joint Lateral malleolus of the fibula Lateral malleolus (fibula) Inferior articular surface Figure 171

Module 7.18 Review a. Identify the bones of the lower limb.
b. Which structure articulates with the acetabulum? c. The fibula neither participates in the knee joint nor bears weight. Yet, when it is fractured, walking becomes difficult. Why?

Module 7.19: Tarsals, metatarsals, and phalanges
Angle bones accept body weight from leg and transfer to the ground, distributing through foot bones Need to be strong yet flexible to deal with locomotive movements Animation: Pelvic Girdle and Lower Limbs: Ankle and Foot

Tarsals (7 bones) Calcaneus (heel bone) Largest of tarsal bones Most weight transmitted from tibia to ground through it Posterior portion is attachment site for calcaneal tendon (Achilles tendon) Talus Transmits weight from tibia toward toes Trochlea of talus bone forms articulation between tibia and talus

Tarsals (continued) Navicular Articulates with talus and three cuneiform bones Cuboid Articulates with anterior surface of calcaneus 5–7. Cuneiform bones Medial, intermediate, lateral

Articulate with distal surfaces of cuboid and cuneiforms and phalanges Form distal portion of foot Identified by Roman numerals I–V from medial to lateral I–III articulate with cuneiform bones IV & V articulate with cuboid Phalanges (toe bones) Same anatomical organization as fingers (14 bones) Hallux (great toe) has two bones (proximal and distal) All other toes have three bones (proximal, middle, distal)

The Ankle (Tarsus) The bones of the ankle and foot The ankle consists of seven tarsal bones. Calcaneus Talus Navicular Trochlea Cuboid Cuneiform bones Metatarsals Articulations of the cuboid and the cuneiform bones with the metatarsal bones V IV III II I Figure 7.19 The ankle and foot contain tarsal bones, metatarsal bones, and phalanges Metatarsal bones (designated I–V) Proximal phalanx Phalanges Distal phalanx Proximal, middle, and distal phalanges Hallux Figure 177

Arches of the foot Longitudinal arch Transfers weight between toes and calcaneus Present because of ligaments and tendons connecting calcaneus to distal portions of metatarsals Lateral (calcaneal) portion has much less curvature than medial (talar) portion Therefore, medial plantar surface elevated to allow passage of inferior surface muscles, blood vessels, and nerves Creates transverse arch

A lateral view of the right ankle and foot
Cuboid bone Navicular bone Cuneiform bones Metatarsal bones (I–V) Lateral surface of the trochlea Phalanges Lateral view I II Attachment site for the calcaneal tendon (Achilles tendon) III IV V Figure The ankle and foot contain tarsal bones, metatarsal bones, and phalanges Figure 179

A medial view of the right ankle and foot
Phalanges Metatarsal bones Medial cuneiform bone Navicular bone Talus Medial view I Calcaneus Figure The ankle and foot contain tarsal bones, metatarsal bones, and phalanges Longitudinal arch Transverse arch Figure 180

Arches of the foot (continued) Congenital talipes equinovarus (clubfoot) Arches fail to develop properly due to abnormal muscle development Tibia, ankle, and foot are affected Longitudinal arches are exaggerated Feet turn medially and inverted Affects 1 in 1000 births Twice as common in boys Prompt treatment with casts or other supports can alleviate

Module 7.19 Review a. Identify the tarsal bones.
b. Which foot bone transmits the weight of the body from the tibia toward the toes? c. While jumping off the back steps at his house, 10-year-old Joey lands on his right heel and breaks his foot. Which foot bone is most likely broken?

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