1. THE SKELETON

2. THE SKELETON
Composed of bones, cartilages, joints, and ligaments, accounts for about 20% of body mass (30 pounds in a 160 pound person)
Bones make up most of the skeleton
Cartilages occur only in isolated areas
Nose, parts of the ribs, and the joints
Ligaments connect bones and reinforce joints, allowing required movements while restricting motions in other directions
Joints, the junction between bones, provide for the remarkable mobility of the skeleton

3. Axial Skeleton
Structured from 80 bones segregated into three major regions:
Skull
Vertebral column
Bony thorax
Supports the head, neck, and trunk, and protects the brain, spinal cord, and organs in the thorax

4. AXIAL SKELETON

5. The Skull
The skull consists of 22 cranial and facial bones that form the framework of the face, contain cavities for special sense organs, provide openings for air and food passage, secure the teeth, and anchor muscles of facial expression
The cranial bones (cranium) enclose and protect the fragile brain and furnish a site for attachment of head and neck muscles
Facial bones:
Form the framework of the face
Contain cavities for the special sense organs of sight, taste, and smell
Provide openings for air and food passage
Secure the teeth
Anchor the facial muscles of expression, which we use to show our feelings

6. The Skull
Except for the mandible, which is joined to the skull by a freely movable joint, most skull bones are flat bones joined by interlocking joints called sutures
Suture lines have a saw-toothed or serrated appearance
Major sutures that connect cranial bones are:
Coronal
Sagittal
Squamous
Lambdoid

7. EXTERNAL LATERAL SKULL

8. POSTERIOR SKULL

9. The Skull
Most other skull sutures connect facial bones and are named according to the specific bones they connect
Examples:
Frontonasal suture
Occipitomastoid suture

10. ANTERIOR SKULL

11. POSTERIOR SKULL

12. Overview of Skull Geography
The anterior aspect of the skull is formed by facial bones, and the remainder is formed by a cranium, which is divided into:
1. Cranial vault (calvaria):
Forms the superior, lateral, and posterior aspects of the skull, as well as the forehead

13. EXTERNAL LATERAL SKULL

14. The Skull 2. Cranial base (floor) (a): inferior superficial view
Forms the skull’s inferior aspect
Internally (b+c):
(b): superior view of the floor of cranial cavity
(c): schematic view of the cranial cavity floor
prominent bony ridges divide the base into three distinct “steps” or fossa:
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa

15. INFERIOR SKULL

16. SUPERIOR SKULL

17. The Skull The cavities of the skull include: Cranial cavity:
Houses the brain
Ear cavities
Nasal cavity
Orbit cavities:
House the eyeballs
Air-filled sinuses:
Lighten the skull

18. SKULL CAVITIES

19. The Skull
The skull has about 85 named openings that provide passageways for the spinal cord, major blood vessels serving the brain, and the cranial nerves
Named:
Foramina
Canals
Fissures

20. Cranium Consists of eight strong, superiorly curved bones
1. Frontal bone:
Forms the anterior cranium
Most anterior part of the frontal bone is the vertical frontal squama (forehead)
Articulates posteriorly with the parietal bones via the coronal suture, extends forward to the supraorbital margins, and extends posteriorly to form the superior wall of the orbits and most of the anterior cranial fossa

21. ANTERIOR SKULL

22. EXTERNAL LATERAL SKULL

23. Parietal Bone
2. Two large, rectangular bones on the superior and lateral aspects of the skull
Form the bulk of the cranial vault
The four largest sutures of the skull are located where the parietal bones articulate with other bones:
Coronal: parietal bones meet the frontal anteriorly
Sagittal: the parietal bones meet superiorly at the cranial midline
Lambdoid: parietal bones meet the occipital bone posteriorly
Squamous: where a parietal and temporal bone meet on the lateral aspect of the skull

24. POSTERIOR SKULL

25. EXTERNAL LATERAL SKULL

26. Occipital Bone
Articulates with the parietal, temporal, and sphenoid bones
Forms most of the posterior wall and base of the skull
The foramen magnum, a large opening through which the brain connects to the spinal cord, is located in the base of the occipital bone
Rockerlike occipital condyles articulate with the first vertebra of the spinal column in a way that permits a nodding movement of the head

27. POSTERIOR SKULL

28. EXTERNAL LATERAL SKULL

29. Temporal Bone Lateral skull surface
Articulate with the parietal bones and form the inferolateral aspects of the skull and parts of the cranial floor
The temporal bone is characterized by the small, oval mandibular fossa on the inferior surface of the zygomatic process
It receives the condyle of the mandible (lower jawbone) forming the freely movable temporomandibular joint

30. EXTERNAL LATERAL SKULL

31. MID SAGITTAL SKULL

32. INFERIOR SKULL

33. Temporal Bone
Tympanic region surrounds the external acoustic meatus (external ear canal)
Housed in the petrous region are the middle and inner ear cavities, which contain sensory receptors for hearing and balance

34. TEMPORAL BONE

35. Temporal Bone
Jugular foramen: passage of internal jugular vein and three cranial nerves
Carotid canal: passage of the internal carotid arteries (both supply 80% of blood to the brain)
Closeness to the inner ear cavities explains why, during excitement or exertion, we sometimes hear our rapid pulse as a thundering sound in the head
Mastoid process: felt as a bump just posterior to the ear
Anchoring site for some neck muscles
Full of air cavities (mastoid sinuses: air cells)
Position adjacent to the middle ear cavity (high-risk area for infections spreading from the throat) puts it at risk for infection itself
Mastoid sinus infection (mastoiditis) is difficult to treat
Separated from the brain by only a very thin bony plate
Infections may spread to the brain

36. INFERIOR SKULL

37. TEMPORAL BONE

38. TEMPORAL BONE

39. Sphenoid Bone
Spans the width of the middle cranial fossa (furrow or shallow depression)
Keystone of the cranium because it articulates with all other cranial bones
Pterygoid processes anchor the pterygoid muscles which are important in chewing
Optic canals: allow passage of optic nerve

40. SUPERIOR SKULL

41. SPHENOID BONE

42. SPHENOID BONE

43. Ethmoid Bone Lies between the sphenoid and nasal bones
Forms most of the bony area between the nasal cavity and the orbits
Superior surface (cribriform plate) helps form the roof of the nasal cavities and the floor of the anterior cranial fossa
Olfactory foramina: allows passage of the olfactory nerve
Perpendicular plate: forms superior part of the nasal septum, which divides the nasal cavity into right and left halves

44. ETHMOID BONE

45. ETHMOID BONE

46. Sutural Bones
Sutural, or Wormian, bones are groups of irregularly shaped bones or bone clusters located within sutures (most often in the lambdoid suture) that vary in number and are not present on all skulls
Formed during fetal development
Structurally unimportant

47. POSTERIOR SKULL

48. Facial Bones Mandible U-shaped bone Lower jawbone
Largest, strongest bone of the face
Body forms the chin
Two upright rami
Each ramus meets the body posteriorly at a mandibular angle
Superior margin of each ramus are two processes separated by the mandibular notch
The anterior coronoid process is an insertion point for the large temporalis muscle that elevates the lower jaw during chewing
The posterior mandibular condyle articulates with the mandibular fossa of the temporal bone, forming the temporomandibular joint on the same side

49. FACIAL BONES Mandible

50. Facial Bones Mandible Mandibular body anchors the lower teeth:
Its superior border, called the alveolar margin, contains the sockets (alveoli) in which the teeth are embedded
In the midline of the mandibular body is a slight depression, the mandibular symphysis, indicating where the two mandibular bones fused during infancy

51. FACIAL BONES Mandible

52. ANTERIOR SKULL

53. Facial Bones Mandible Large mandibular foramina: Mental foramina:
One on the medial surface of each ramus
Permit the nerves responsible for tooth sensation to pass to the teeth in the lower jaw
Dentist inject Novocain into these foramina to prevent pain while working on the lower teeth
Mental foramina:
Openings on the lateral aspects of the mandibular body
Allow blood vessels and nerves to pass to the skin of the chin and lower lips

54. FACIAL BONES Mandible

55. Facial Bones Maxillary Bones
Maxillae (b)
Form the upper jaw and central portion of the face
Articulates with all other facial bones except the mandible
Hence the maxillae are considered the keystone bones of the facial skeleton
Maxillae carry the upper teeth in their alveolar margins
Just inferior to the nose the maxillae meet medially, forming the pointed anterior nasal spine at their junction

56. Facial Bones Maxillary Bones

57. Facial Bones Maxillary Bones
Palatine processes of the maxillae project posteriorly from the alveolar margins and fuse medially, forming the anterior 2/3 of the hard palate, or bony roof of the mouth
Posterior to the teeth is a midline foramen, called the incisive fossa
Serves as a passageway for blood vessels and nerves

58. MID SAGITTAL SKULL

59. INFERIOR SKULL

60. Facial Bones Maxillary Bones
Frontal processes extend superiorly to the frontal bone, forming part of the lateral aspects of the bridge of the nose
Regions that flank the nasal cavity laterally contain the maxillary sinuses, the largest of the paranasal sinuses
They extend from the orbits to the upper teeth

61. Facial Bones Maxillary Bones

62. SINUSES

63. Facial Bones Maxillary Bones
Laterally, the maxillae articulates with the zygomatic bones via their zygomatic processes

64. ANTERIOR SKULL

65. EXTERNAL LATERAL SKULL

66. Facial Bones Maxillary Bones
Inferior orbital fissure is located deep within the orbit at the junction of the maxilla with the greater wing of the sphenoid
Permits the zygomatic nerve, the maxillary nerve (branch of cranial nerve V), and blood vessels to pass to the face
Just below the eye socket on each side is an infraorbital foramen that allows the infraorbital nerve and artery to reach the face

67. ANTERIOR SKULL

68. Facial Bones Zygomatic Bones
Commonly called cheek bones
They articulate with the zygomatic process of the temporal bones posteriorly, the zygomatic process of the frontal bone superiorly, and with the zygomatic processes of the maxillary bones anteriorly
Form the prominences of the cheeks and parts of the inferolateral margins of the orbits

69. ANTERIOR SKULL

70. EXTERNAL LATERAL SKULL

71. Facial Bones Nasal Bones
Form the bridge of the nose
Articulate with the frontal bone superiorly, the maxillary bones laterally, and the perpendicular plate of the ethmoid bones posteriorly
Inferiorly they attach to the cartilages that form most of the skeleton of the external nose

72. ANTERIOR SKULL

73. EXTERNAL LATERAL SKULL

74. Facial Bones Lacrimal Bones
Located in the medial wall of the orbits
Articulate with the frontal bone superiorly, ethmoid bone posteriorly, and maxillae anteriorly
Contains a deep groove that helps form a lacrimal fossa
Houses the lacrimal sac, part of the passageway that allows tears to drain from the eye surface into the nasal cavity

75. ANTERIOR SKULL

76. EXTERNAL LATERAL SKULL

77. Facial Bones Palatine Bones
Consist of bony plates that complete the posterior portion of the hard palate
Form part of the posterolateral walls of the nasal cavity, and small parts of the orbits

78. INFERIOR SKULL

79. NASAL CAVITY

80. Facial Bones Vomer
Lies in the nasal cavity, where it forms part of the nasal septum
Plow-shaped

81. ANTERIOR SKULL

82. Facial Bones Inferior Nasal Conchae
Paired thin, curved bones in the nasal cavity
Project medially from the lateral walls of the nasal cavity, just inferior to the middle nasal conchae of the ethmoid bone
Largest of the three pairs of conchae and, like the others, they form part of the lateral walls of the nasal cavity

83. ANTERIOR SKULL

84. NASAL CAVITY

85. Special Characteristics of the Orbits and Nasal Cavity
The orbits are bony cavities that contain:
The eyes which are firmly encased and cushioned by fatty tissue
Muscles that move the eyes
Tear-producing glands lacrimal glands
The walls of each orbit are formed by parts of seven bones—the frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid bones
Superior and inferior orbital fissures
Optic canals

86. ORBIT

87. ORBIT

88. Facial Bones Nasal Cavity
Constructed of bone and hyaline cartilage
Roof of the nasal cavity is formed by the cribriform plate of the ethmoid
Lateral walls are largely shaped by the superior and middle conchae of the ethmoid bone, the perpendicular plates of the palatine bones, and the inferior nasal conchae
The depressions under cover of the conchae on the lateral walls are called meatuses (superior, middle, inferior)

89. NASAL CAVITY

90. Facial Bones Nasal Cavity
It is divided into right and left parts by the nasal septum, which consists of portions of the ethmoid bone and vomer
A sheet of cartilage called the septal cartilage completes the septum anteriorly

91. NASAL CAVITY

92. Nasal Cavity
Nasal septum and conchae are covered with a mucus-secreting mucosa that moistens and warms the entering air and helps cleanse it of debris
The scroll-shaped conchae increase the turbulence of air flowing through the nasal cavity
This swirling forces more of the inhaled air into contact with the warm, damp mucosa and encourages trapping of airborne particles (dust, pollen, bacteria) in the sticky mucus

93. Paranasal Sinuses
Five skull bones—frontal, sphenoid, ethmoid, and paired maxillary bones—contain mucosa-lined, air-filled sinuses that cause them to look rather moth-eaten in an X-ray image
Are air-filled sinuses that cluster around the nasal cavity
Small openings connect the sinuses to the nasal cavity and act as “two-way streets”
Air enters the sinuses from the nasal cavity
Sinus mucosae:
Forms mucus which drains into the nasal cavity
Helps to warm and humidify inspired air
Lightens the skull
Enhances resonance of the voice

94. SINUSES

95. Hyoid Bone Not really part of the skull U-shaped
Lies inferior to the mandible in the anterior neck
It is the only bone of the body that does not articulate directly with any other bone
Anchored by the narrow stylohyoid ligaments to the styloid processes of the temporal bones
Acts as a movable base for the tongue:
Its body and greater horns are attachment points for neck muscles that raise and lower the larynx during swallowing and speech

96. HYOID BONE

97. THE VERTEBRAL COLUMN General Characteristics:
The vertebral column consists of 26 irregular bones (vertebrae)
Separated by intervertebral discs
Forms a flexible, curved structure extending from the skull to the pelvis
Surrounds and protects the spinal cord
Provides attachment for ribs and muscles of the neck and back
Divisions and Curvatures:
The vertebrae of the spine fall in five major divisions:
7 cervical
12 thoracic
5 lumbar
5 fused vertebrae of the sacrum
4 fused vertebrae of the coccyx

98. VERTEBRAL COLUMN

99. Curvatures Right lateral view
Cervical and lumber curvatures are concave (spherically depressed: bowl like) posteriorly
Thoracic and sacral curvatures are convex (curved sphere like) posteriorly
Curvatures of the spine increase resiliency and flexibility of the spine allowing it to function like a spring rather than as a rigid rod

100. VERTEBRAL COLUMN

101. Homeostatic Imbalance
There are several types of abnormal spinal curvatures caused by:
Congenital (present at birth)
Disease
Poor posture
Unequal muscle pull on the spine
Scoliosis: twisted disease
Abnormal lateral curvature that occurs most often in the thoracic region
Quite common during late childhood, particularly in girls, for some unknown reason
Sever cases result from abnormal vertebral structure, lower limbs of unequal length, or muscle paralysis
If muscles on one side of the body are nonfunctional, those of the opposite side exert an unopposed pull on the spine and force it out of alignment
Treated (with braces or surgery) before growth ends
Prevents permanent deformity and breathing difficulties due to compressed lung

102. Homeostatic Imbalance
Kyphosis: hunchback
Dorsally exaggerated thoracic curvature
Common in aged individuals because of osteoporosis (loss of bone mass), but may also reflect tuberculosis of the spine, rickets, or osteomalacia (vitamin D deficiency, loss of calcium salts)
Lordosis: swayback
Accentuated lumbar curvature
Can result from spinal tuberculosis or osteomalacia
Temporary lordosis common in people with:
Pot bellies
Pregnant woman
In an attempt to preserve their center of gravity, these individuals automatically throw back their shoulders, accentuating their lumbar curvature

103. Ligaments The vertebral column cannot possibly stand upright by itself
It must be held in place by an elaborate system of cablelike supports
Straplike ligaments and the trunk muscles assume this role
Ligaments: band of regular fibrous tissue that connects bones
The major supporting ligaments of the spine are the anterior and posterior longitudinal ligaments, which run as continuous bands down the front (anterior) and back (posterior) surfaces of the spine from the neck to the sacrum

104. VERTEBRAL DISC

105. Ligaments Anterior ligament: Posterior ligament:
Strongly attached to both the bony vertebrae and the disc
Broad and strong
Along with its supporting role, it prevents hyperextension of the spine (bending too far backward)
Posterior ligament:
Attaches only to discs
Narrow and relatively weak
Resists hyperflexion of the spine (bending too sharply forward)
However:
The ligamentum flavum, which contains elastic connective tissue, is especially strong
Stretches on bending forward and recoils when we resume an erect posture
Short ligaments connect each vertebra to those immediately above and below

106. VERTEBRAL DISC

107. Intervertebral Discs Cushionlike pads: Composed of two parts:
Inner gelatinous nucleus pulposus
Acts like a rubber ball, giving the disc its elasticity and compressibility
Annulus fibrosus:
Surrounds the nucleus pulposus
Strong collar composed of collagen fibers superficially and internally fibrocartilage
Limits the expansion of the nucleus pulposus when the spine is compressed
Holds together successive vertebrae and resists tension in the spine
Act as shock absorbers and allow the spine to flex, extend, and bend laterally
At points of compression, the discs flatten and bulge out a bit between the vertebrae
Flattened somewhat during the course of the day, so we are always a few centimeters shorter at night than when we awake in the morning

108. VERTEBRAL DISC

109. Homeostatic Imbalance
Severe or sudden physical trauma to the spine—for example, from bending forward while lifting a heavy object—may result in herniation of one or more discs
Herinated (prolapsed) disc:
Slipped disc
Usually involves rupture of the annulus fibrosus followed by protrusion of the spongy nucleus through the annulus
If protrusion presses on the spinal cord or on spinal nerves exiting from the cord, numbness or excruciating pain may result
Treatment:
Moderate exercise
Heat therapy
Painkillers
Surgical removal followed by a bone graft to fuse the adjoining vertebrae
Partial vaporization with a laser
Outpatient procedure

110. VERTEBRAL DISC

111. General Structure of Vertebrae
Each vertebra consists of an anterior body (centrum) and a posterior vertebral arch
Disc-shaped body is the weight-bearing region
Together, the body and vertebral arch enclose an opening called the vertebral foramen
Successive vertebral foramina of the articulated vertebrae form the long vertebral canal, through which the spinal cord passes

112. General Structure of Vertebrae
The vertebral arch consists of two pedicles and two laminae, which collectively give rise to several projections
Pedicles (little feet):
Short bony pillars projecting posteriorly from the vertebral body
Form the sides of the arch
Laminae:
Flattened plates that fuse in the median plane
Complete the arch posteriorly

113. General Structure of Vertebrae
The pedicles have notches on their superior and inferior borders, providing lateral openings between adjacent vertebrae called intervertebral foramen
Provide openings for the passage of spinal nerves

114. General Structure of Vertebrae
Seven processes project from the vertebral arch
Spinous process (1): median posterior projection arising at the junction of the two laminae
Attachments sites for muscles that move the vertebral column and for ligaments that stabilize it
Transverse processes (2): extends laterally from each side of the vertebral arch

115. THORACIC VERTEBRAE

116. General Structure of Vertebrae
Paired superior and inferior articular processes (2):
Protrude superiorly and inferiorly, respectively, from the pedicle-lamina junctions
The smooth joint surfaces of the articular processes, called facets (little faces), are covered with hyaline cartilage
The inferior articular processes of each vertebra form movable joints with the superior articular processes of the vertebra immediately below
Thus, successive vertebrae join both at their bodies and at their articular processes

117. THORACIC VERTEBRAE

118. VERTEBRA

119. Cervical Vertebrae Smallest vertebrae Identified as C1-C7
They typically have:
An oval body: wider from side to side than in the anteroposterior dimension
Except in C7, the spinous process is short, projects directly back, and is bifid (split at its tip)
Vertebral foramen is large and generally triangular
Each transverse process contains a transverse foramen through which the vertebral arteries pass to service the brain

120. Cervical Vertebrae
The spinous process of C7 is not bifid and is much larger than those of the other cervical vertebrae
Its spinous process is visible through the skin
Used as a landmark for counting the vertebrae and is called the vertebra prominens (prominent vertebra)

121. CERVICAL VERTEBRAE

122. Cervical Vertebrae The first two cervical vertebrae are unusual
Atlas and Axis
Have no intervertebral disc between them
Have special functions
Atlas (C1) has no body or spinous process
Essentially, it is a ring of bone consisting of anterior and posterior arches and a lateral mass on each side
Each lateral mass has articular facets on its superior and inferior surfaces
The superior articular facets articulate with the occipital condyles of the skull
They carry the skull just as Atlas supported the heavens in greek mythology
These joints allow you to nod “YES”
The inferior articular surfaces form joints with the axis below (inferiorly)

123. Cervical Vertebrae
Axis (C2) has a body, spine, and other typical vertebral processes
Not as special as the atlas
Its only unusual feature is the knoblike dens (tooth), or odontoid process, projecting superiorly from its body
Acts as a pivot for the rotation of the atlas
Hence, this joint allows you to rotate your head from side to side to indicate “NO”

124. CERVICAL VERTEBRAE

125. Thoracic Vertebrae 12 thoracic vertebrae (T1-T12)
All articulate with ribs
Gradually transition between cervical structure at the top, and lumbar structure toward the bottom
Thoracic vertebrae have a roughly heart-shaped body
Typically bears (demifacets: half-facets), on each side, one at the superior edge and the other at the inferior edge
The demifacets articuale with the ribs
Circular vertebral foramen
Spinous process is long and points sharply downward

126. THORACIC VERTEBRAE

127. Lumbar Vertebrae 5 Lumbar vertebrae (L1-L5) Receives the most stress
The enhanced weight-bearing function is reflected in their sturdier structure
Large vertebrae that have kidney-shaped bodies
Triangular vertebral foramen
Short, thick pedicles and laminae
Short, flat, hatchet-shaped spinous processes

128. LUMBAR VERTEBRAE

129. Sacrum Forms the posterior wall of the pelvis
It is formed by five, fused vertebrae in adults, and articulates with the fifth lumbar vertebra superiorly, the coccyx inferiorly, and the hip bones laterally via the sacroiliac joint
The vertebral canal continues through the sacrum, often ending at a large external opening, the sacral hiatus
Body’s center of gravity

130. SACRUM/COCCYX VERTEBRAE

131. Coccyx
The coccyx (tailbone) is a small bone consisting of four, fused vertebrae that articulate superiorly with the sacrum
Except for the slight support it affords the pelvic organs, it is a nearly useless bone
Occasionally, a baby is born with an unusually long coccyx
Snipped off

132. SACRUM/COCCYX VERTEBRAE

133. THE BONY THORAX The bony thorax (thoracic cage)
Consists of the thoracic vertebrae dorsally, the ribs laterally, and the sternum and costal cartilages anteriorly
Costal cartilage secure the ribs to the sternum
It forms a protective cage around the organs of the thoracic cavity, and provides support for the shoulder girdles (pectoral) and upper limbs
Provides attachment points for many muscles of the neck, back, chest, and shoulders
Intercostal spaces between the ribs are occupied by the intercostal muscles, which lift and depress the thorax during breathing

134. BONY THORAX

135. Sternum
The sternum (breastbone) lies in the anterior midline of the thorax
Is a flat bone resulting from the fusion of three bones: the manubrium, body, and xiphoid process
The manubrium (superior portion) articulates with the clavicles and the first two pairs of ribs
The body (midportion) articulates with the cartilage of ribs two through seven
The xiphoid process (inferior portion) forms the inferior end, articulating only with the body
Serves as an attachment point for some abdominal muscles

136. BONY THORAX

137. Ribs
The sides of the thoracic cage are formed by twelve pairs of ribs that attach posteriorly to the thoracic vertebrae and curve inferiorly toward the anterior body surface
The superior seven pairs of ribs are called true, or vertebrosternal, ribs
They attach directly to the sternum via individual costal cartilages
The lower five pairs of ribs are called false ribs
They either attach indirectly to the sternum or lack a sternal attachment entirely

138. BONY THORAX

139. Rib A typical rib is a bowed flat bone
Bulk of a rib is simply called the shaft
Wedged shaped head articulates with the vertebral bodies by two facets:
One joins the body of the same-numbered thoracic vertebra
The other articulates with the body of the vertebra immediately superior
Neck is the constricted portion of the rib just beyond the head
Knoblike tubercle articulates with the transverse process of the same-numbered thoracic vertebra
Costal cartilages provide secure but flexible rib attachments to the sternum

140. TRUE RIB

141. Appendicular Skeleton
Bones of the limbs and their girdles
They are appended to the axial skeleton that forms the longitudinal axis of the body
Pectoral girdles attach the upper limbs to the body trunk
Pelvic girdle secures the lower limbs

142. APPENDICULAR SKELETON

143. Pectoral Girdle
The pectoral (shoulder) girdle consists of the clavicle, which joins the sternum anteriorly, and the scapula, which is attached to the posterior thorax and vertebrae via muscular attachments
The pectoral girdles are very light and have a high degree of mobility due to the openness of the shoulder joint and the free movement of the scapula across the thorax

144. Pectoral Girdle
The paired pectoral girdles and their associated muscles form your shoulders
Although the term girdle usually signifies a beltlike structure encircling the body, a single pectoral girdle, or even the pair, does not quite satisfy this description
Anteriorly, the medial end of each clavicle joins the sternum; the distal ends of the clavicles meet the scapulae laterally
However, the scapulae fail to complete the ring posteriorly, because their medial borders do not join each other or the axial skeleton
Instead, the scapulae are attached to the thorax and vertebral column only by the muscles that cover their surfaces

145. PECTORAL GIRDLE

146. Pectoral Girdle The mobility is due to the following factors:
1. Only the clavicle attaches to the axial skeleton, the scapula can move quite freely across the thorax, allowing the arm to move with it
2. The socket of the shoulder joint (the scapula’s glenoid cavity) is shallow and poorly reinforced, so it does not restrict the movement of the humerus (arm bone)
Although this arrangement is good for flexibility, it is bad for stability
Shoulder dislocations are fairly common

147. PECTORAL GIRDLE

148. Clavicle
The clavicles (collarbones) extend horizontally across the thorax (a)
Articulating medially with the axial skeleton (sternum), and laterally with the scapula, bracing the arms and scapulae laterally
(b+c):Each clavicle is cone shaped at its medial sternal end, which attaches to the sternal manubrium, and flattened at its lateral acromial end, which articulates with the scapula

149. PECTORAL GIRDLE

150. Clavicle Anchors many muscles in the shoulder region
Braces and holds the scapulae and arms out laterally, away from the narrower superior part of the thorax
This bracing function becomes obvious when a clavicle is fractured: the entire shoulder region collapses medially

151. APPENDICULAR SKELETON

152. Clavicle Not very strong and are likely to fracture Example:
When a person uses outstretched arms to break a fall
The curves in the clavicle ensure that it usually fractures anteriorly (outward)
If it were to collapse posteriorly (inward), bone splinters would damage the subclavian artery, which passes just deep to the clavicle to serve the upper limb

153. PECTORAL GIRDLE

154. Scapulae
The scapulae (shoulder blades) are thin, triangular flat bones that lie on the dorsal surface of the ribcage between ribs 2 + 7
Derived from words Spade/Shovel
Each scapula has three borders:
Superior border:
Shortest, sharpest
Medial (vertebral) border:
Parallels the vertebral column
Lateral (axillary) border:
Thick
Abuts the armpit and ends superiorly in a small, shallow fossa (glenoid cavity)
Articulating with the humerus via the glenoid cavity, and the clavicle via the acromion forming the shoulder joint

155. Scapula

156. SCAPULA

157. Scapula Like all triangle, the scapula has three corners or angles
Superior scapular border meets the medial at the superior angle
Superior scapular border meets the lateral border at the lateral angle
The medial and lateral borders join at the inferior angle
The inferior angle moves extensively as the arm is raised and lowered

158. PECTORAL GIRDLE

159. SCAPULA

160. Scapula
The anterior, or costal, surface is concave (depression) and relatively featureless
Posterior surface bears a prominent spine that is easily felt through the skin
Spine ends laterally in an enlarged, roughened triangular projection called the acromion (point of shoulder)
Acromion articulates with the acromial end of the clavicle, forming the acromioclavicular joint

161. PECTORAL GIRDLE

162. Scapula

163. Scapula
Projecting anteriorly from the superior scapular border is the coracoid (beadlike) process
Looks like a little bend finger
Anchors the biceps muscle of the arm
Bounded by the suprascapular notch (a nerve passage) medially and by the glenoid cavity laterally

164. Scapula

165. Scapula

166. Scapula
Several large fossae appear on both sides of the scapula and are named according to location:
Infraspinous fossa: inferior to the spine
Supraspinous fossa: superior to the spine
Subscapular fossa: shallow concavity formed by the entire anterior scapular surface

167. Scapula

168. Scapula

169. Upper Limb
30 separate bones form the bony framework of each upper limb
Each of these bones may be described regionally as a bone of the arm (anatomically is the part of the upper limb between the shoulder and elbow), forearm, or hand

170. Arm: Humerus Sole bone of the arm Typical long bone
Largest, longest bone of the upper limb
Articulates with the scapula at the shoulder and with the radius and ulna (forearm bones) at the elbow

171. APPENDICULAR SKELETON

172. Humerus Proximal end is its smooth, hemispherical head
Fits into the glenoid cavity of the scapula in a manner that allows the arm to hang freely at one’s side
Tubercles (greater, inter, lesser) are sites where muscles attach
Distal to the tubercles is the surgical neck
Named because it is the most frequently fractured part of the humerus
Midway down the shaft on its lateral side is the deltoid tuberosity
Attachment site for the deltoid muscle of the shoulder

173. HUMERUS ARM

174. HUMERUS

175. Humerus Distal end are two condyles
Medial trochlea (pulley):
Articulates with the ulna
Lateral capitulum (ball-like):
Articulates with the radius
Condyle pair (medial trochlea and lateral capitulum) are flanked by the medial and lateral epicondyles:
Muscle attachment
Directly above these epicondyles are the supracondylar ridges
Ulnar nerve runs behind the medial epicondyle and is responsible for the painful, tingling sensation you experience when you hit your “funny bone” (medial epicondyle of the humerus)

176. HUMERUS ARM

177. Humerus
Superior to the trochlea on the anterior surface is the coronoid fossa
Posterior surface is the deeper olecranon fossa
These two depressions allow the corresponding processes of the ulna to move freely when the elbow is flexed and extended
Small radial fossa, lateral to the coronoid fossa, receives the head of the radius when the elbow is flexed

178. HUMERUS ARM

179. Forearm The forearm is the region between the elbow and wrist
It consist of two bones, the ulna and the radius

180. FOREARM BONES

181. Ulna The ulna: Proximal end forms the elbow joint with the humerus
Distal end forms joints with the wrist
Articulates with the bones of the wrist via a cartilage disc at the distal end
It articulates with the radius both proximally and distally at small radioulnar joints
Ulna and radius are connected along their entire length by a flexible interosseous membrane
In the anatomical position, the radius lies laterally (on the thumb side) and the ulna medially
However, when you rotate your forearm so that the palm faces posteriorly (a movement called pronation), the distal end of the radius crosses over the ulna and the two bones form an X

182. FOREARM BONES

183. Ulna Main responsibility for forming the elbow joint with the humerus
Proximally bears two prominent processes
Olecranon process (elbow):
Coronoid process
Separated by a deep concavity: trochlear notch
Together these two processes grip the trochlea of the humerus, forming a hinge joint that allows the forearm to be bent upon the arm (flexed), then straightened again (extended)
On the lateral side of the coronoid process is a small depression, the radial notch, where the ulna articulates with the head of the radius
Distally the ulna ends in a knoblike head:
Separated from the bones of the wrist by a disc of fibrocartilage
Plays no role in hand movement
Medial to the head is a styloid process, from which a ligament runs to the wrist

184. FOREARM BONES

185. Radius Head is shaped like the head of a nail
Superior surface of this head is concave, and it articulates with the capitulum of the humerus
Medially, the head articulates with the radial notch of the ulna
Inferior to the head is the rough radial tuberosity, which anchors the biceps muscle of the arm
While the ulna contributes more heavily to the elbow joint, the radius is the major forearm bone contributing to the wrist joint
When the radius moves, the hand moves with it
It articulates with the carpels of the wrist and the ulna medially at the distal end

186. FOREARM BONES

187. RADIUS/ULNA

188. HOMEOSTATIC IMBALANCE
Colle’s fracture is a break in the distal end of the radius
Common fracture when a falling person attempts to break his or her fall with outstretched hands

189. FOREARM BONES

190. Hand Skeleton of the hand includes the bones of: The carpus (wrist)
The metacarpus (palm)
The phalanges (bones of the fingers)

191. Carpus
The carpus (wrist) consists of eight marble-size short bones (carpals), arranged in two irregular rows of four bones each, closely united by ligaments:
Gliding movements occur between these bones
Quite flexible
Proximal row (lateral to medial):
Scaphoid: articulates with the radius to form the wrist
Lunate: articulates with the radius to form the wrist
Triquetral
Pisiform Trapezium
Distal row (lateral to medial):
Trapezium
Trapezoid
Capitate
Hamate
Sally left the party to take Cathy home

192. HAND BONES

193. HOMEOSTATIC IMBALANCE
The carpus is concave anteriorly and a ligament roofs over this concavity, forming the notorious carpal tunnel
Besides the median nerve (which supplies the lateral side of the hand), several long muscle tendons crowd into this tunnel
Overuse and inflammation of the tendons cause them to swell, compressing the median nerve, which causes numbness of the areas served
Carpal tunnel syndrome

194. Metacarpus (Palm)
Radiate from the wrist like spokes to form the palm of the hand
Not named but numbered
1 to 5 from thumb to little finger
Bases articulate with the carpals proximally and each other medially and laterally
Bulbous heads articulate with the proximal phalanges of the fingers
When you clench your fist, the heads of the metacarpals become prominent as your knuckles

195. HAND BONES

196. Phalanges Fingers (digits)
Numbered from 1 to 5 beginning with the thumb (pollex)
There are 14 phalanges (miniature bones) of the fingers:
Thumb (pollex) is digit 1, and has two phalanges
The other fingers (digits), numbered 2-5 have three phalanges each
Distal
Middle
Proximal

197. HAND BONES

198. HAND BONES

199. PELVIC (HIP) GIRDLE Attaches the lower limbs to the axial skeleton
Transmits the weight of the upper body to the lower limbs
Supports the visceral organs of the pelvis
Whereas the pectoral girdle is sparingly attached to the thoracic cage, the pelvic girdle is secured to the axial skeleton by some of the strongest ligaments in the body
Lacks the mobility of the pectoral girdle but is far more stable

200. PELVIC (HIP) GIRDLE
It is formed by a pair of coxal bones, each consisting of three fused bones; the ischium, ilium, and pubis
Each coxal bone unites with its partner anteriorly and with the sacrum posteriorly

201. BONY PELVIS

202. PELVIC (HIP) GIRDLE
At the point of fusion of the ilium, ischium, and pubis is a deep hemispherical socket called the acetabulum on the lateral surface of the pelvis
The acetabulum receives the head of the femur, or thigh bone, at this hip joint
The deep, basinlike structure formed by the hip bones, together with the sacrum and coccyx, is called the bony pelvis

203. BONY PELVIS

204. ILIUM (b): Lateral view of right hip (c): medial view of right hip
Large flaring bone that forms the superior region of the coxal bone
It consists of a body and a superior winglike portion called the ala
When you rest your hands on your hips, you are resting them on the thickened superior margins of the alae, the tubercle of the iliac crests

205. ILIUM

206. ILIUM (b): lateral right (c): medial right
Each iliac crest ends anteriorly in the blunt anterior superior iliac spine and posteriorly in the sharp posterior superior iliac spine
Anterior superior iliac spine is easily felt through the skin and is visible in thin people
Posterior superior iliac spine is revealed by a skin dimple in the sacral region
Located below these are the less prominent anterior and posterior inferior iliac spines
All of these spines are attachment points for the muscles of the trunk, hip, and thigh

207. ILIUM

208. ILIUM
Inferior to the posterior inferior iliac spine, the ilium indents deeply to form the greater sciatic notch, through which the thick cordlike sciatic nerve passes to enter the thigh

209. ILIUM

210. ILIUM
Internal surface of the iliac ala exhibits a concavity called the iliac fossa
It articulates with the sacrum, forming the sacroiliac joint, and also with the ischium and pubis anteriorly
Weight of the body is transmitted from the spine to the pelvis through the sacroiliac joints

211. BONY PELVIS

212. Ischium
(b): lateral right
(c): medial right
The ischium forms the posteroinferior portion of the coxa (hip bone)
Roughly L-shaped or arc-shaped
It has a thicker, superior body adjoining the ilium and a thinner, inferior ramus
Joins the pubis anteriorly

213. Ischium

214. Ischium Ischial spine:
(b): lateral right / (c): medial right
Three important markings:
Ischial spine:
Projects medially into the pelvic cavity and serves as a point of attachment of the sacrospinous ligament from the sacrum
Lesser sciatic notch:
Inferior to the ischial spine
A number of nerves and blood vessels pass through this notch to supply the anogenital area
Ischial tuberosity:
Inferior surface of the ischial body
Rough and thickened
When we sit, our weight is borne entirely by the ischial tuberosities
Strongest parts of the hip bones

215. Ischium

216. Ischium
A massive ligament runs from the sacrum to each ischial tuberosity
This sacrotuberous ligament (not illustrated) helps hold the pelvis together

217. Pubis The pubic bones form the anterior portion of the coxae
They are joined by a fibrocartilage disc, forming the midline pubic symphysis joint
In the anatomical position, it lies nearly horizontally and the urinary bladder rests upon it
As the two rami of the pubic bone run laterally to join with the body and ramus of the ischium, they define a large opening in the hip bone, the obturator foramen through which a few blood vessels and nerves pass
Although it is large, it is nearly closed by a fibrous membrane in life

218. Pubis
Inferior to the pubic symphysis joint, the inferior pubic rami angle laterally, forming an inverted V-shaped arch called the pubic arch
The acuteness of the pubic arch helps to differentiate the male and female pelvis
More acute in the males
Less than 90O (50O-60O)
Females: 80O – 90O

219. Pubis

220. Pelvic Structure and Childbearing
The female pelvis is modified for childbearing. It tends to be wider, shallower, lighter, and rounder than the male pelvis
Not only accommodates a growing fetus, but it must be large enough to allow the infant’s relatively large head to exit at birth

221. Pelvic Structure and Childbearing
Pelvic brim:
Continuous oval ridge that runs from the pubic crest through the arcuate line and sacral promontory
Separates: false and true pelvis
The false (greater) pelvis superior to the pelvic brim
Really part of the abdomen and helps support the abdominal viscera
Does not restrict child birth
The true (lesser) pelvis inferior to the pelvic brim
Almost entirely surrounded by bone
Its dimensions (inlet and outlet) are critical to the uncomplicated delivery of a baby
Carefully measured by an obstetrician

222. Pelvic Brim

223. Pelvic Inlet/Outlet Pelvic Inlet is the Pelvic Brim
Widest dimension is from right to left along the frontal plane
As labor begins, an infant’s head typically enters the inlet:
Forehead facing one ilium and the occiput (back part of the skull) facing the other ilium
A sacral promontory that is particularly large can impair the infant’s entry into the true pelvis

224. Pelvic Inlet/Outlet Pelvic Outlet:
Is the inferior margin of the true pelvis
Bounded anteriorly by the pubic arch, laterally by the ischia, and posteriorly by the sacrum and coccyx
Both the coccyx and the ischial spines protrude into the outlet opening
A sharply angled coccyx or unusually large ischial spines can interfere with delivery
Generally, after the baby’s head passes through the inlet, it rotates so that the forehead faces posteriorly and the occiput anteriorly
Thus, during birth, the infant’s head makes a quarter turn to follow the widest dimensions of the true pelvis

225. Pelvic Structure and Childbearing
Female:
Tilted forward
Adapted for childbearing
True pelvis defines the birth canal
Cavity of true pelvis is broad, shallow, and has a greater capacity
Bone thickness:
Less
Lighter
Thinner
Smoother
Acetabula:
Smaller
Farther apart
Pubic arch/angle:
Broader: 80-90O
More rounded
Sacrum:
Wider
Shorter
Sacral curvature is accentuated
Coccyx:
More movable
straighter
Male:
Tilted less forward
Adapted for support of a heavier build and stronger muscles
Cavity of the true pelvis is narrow and deep
Bone thickness:
Greater
Heavier
Thicker
Markings more prominent
Acetabula:
Larger
Closer
Pubic arch/angle:
More acute: 50-60O
Sacrum:
Narrow
Longer
Sacral promontory more ventral
Coccyx:
Less movable
Curves ventrally

226. HIP BONE

227. Thigh Is the region between the hip and knee
It has one bone, the femur
The femur is the largest, longest, and strongest bone in the body
It articulates proximally with the hip via a ball-like head, and distally with the knee at the lateral and medial condyles

228. Femur
The ball-like head of the femur has a small central pit called the fovea capitis
The short ligament of the head of the femur (ligamentum teres) runs from this pit to the acetabulum, where it helps secure the femur
The ball-like head is carried on a neck that angles laterally to join the shaft
The neck is the weakest part of the femur and is often fractured, an injury commonly called a broken hip

229. THIGH BONE

230. Femur
At the junction of the shaft and neck are the lateral greater trochanter and posteromedial lesser trochanter
These projections serve as sites of attachment for thigh and buttock muscles

231. Femur
Distally , the femur broadens and ends in the wheel-like lateral and medial condyles, which articulate with the tibia of the leg
Medial and lateral epicondyles (sites of muscle attachment) flank the condyles superiorly
The smooth patellar surface, between the condyles on the anterior femoral surface, articulates with the patella, or kneecap

232. Patella
Is a triangular sesamoid (short bones embedded in tendons) bone enclosed in the (quadriceps) tendon that secures the anterior thigh muscles to the tibia
It protects the knee joint anteriorly and improves the leverage of the thigh muscles acting across the knee

233. KNEE BONE

234. THIGH BONE

235. FEMUR

236. LOWER LIMB
Leg: The leg is the region between the knee and ankle. It has two bones, the tibia and fibula
These two bones are connected by an interosseous membrane and articulate with each other both proximally and distally
But unlike the joints between the radius and ulna of the forearm, the tibiofibular joints of the leg allow essentially NO movement
The medial tibia articulates proximally with the femur to form the modified hinge joint of the knee and distally with the talus bone of the foot at the ankle
The fibula, by contrast, does not contribute to the knee joint and merely helps stabilize the ankle joint

237. TIBIA/FIBULA

238. Tibia
The tibia (shinbone) receives the weight of the body from the femur and transmits it to the foot
It is second only to the femur in size and strength
At its broad proximal end are the concave medial and lateral condyles, which look like two huge checkers lying side by side
These are separated by an irregular projection, the intercondylar eminence
The tibial condyles articulate with the corresponding condyles of the femur
Inferior to the condyles, the tibia’s anterior surface displays the rough tibial tuberosity, to which the patellar ligament attaches

239. Tibia Shaft is triangular in cross section
Its anterior border is the sharp anterior crest
Neither this crest nor the tibia’s medial surface is covered by muscles, so they can be felt just deep to the skin along their entire length
The anguish of a “bumped” shin is an experience familiar to nearly everyone

240. Tibia
Distally the tibia is flat where it articulates with the talus bone of the foot
Medial to that joint surface is an inferior projection, the medial malleolus, which forms the medial bulge of the ankle
The fibular notch, on the lateral surface of the tibia, participates in the distal tibiofibular joint

241. Fibula Is a sticklike, non-weight-bearing bone
It has expanded ends that articulate proximally via the head and distally via the lateral malleolus with the lateral aspects of the tibia
The lateral malleolus forms the conspicuous lateral ankle bulge and articulates with the talus

242. TIBIA/FIBULA

243. HOMEOSTATIC IMBALANCE
Pott’s fracture occurs at the distal end of the fibula, the tibia, or both
Common sports injury

244. TIBIA/FIBULA

245. TIBIA/FIBULA

246. Foot Skeleton of the foot includes the bones of the:
Tarsus
Metatarsus
Phalanges (toe bones)
Two important functions:
1. Supports our body weight
2. Acts as a lever to propel the body forward when we walk and run

247. Tarsus
Consists of seven tarsal bones that make up the posterior half of the foot
Body weight is carried primarily by the two largest, most posterior tarsals
Talus: ankle
Articulates with the tibia and fibula superiorly
Calcaneus: heel bone
Forms the heel of the foot and carries the talus on its superior surface
The thick calcaneal (Achilles) tendon of the calf muscles attaches to the posterior surface of the calcaneus
The part of the calcaneus that touches the ground is the tuber calcanei

248. FOOT BONES

249. Tarsus
Tarsal bones:
Posterior Talus
Inferior Calcaneus
Lateral Cuboid
Medial Navicular
Anterior medial cunieform
Anterior intermediate cunieform
Anterior lateral cunieform
The cuboid and cunieform bones articulate with the metatarsal bones anteriorly

250. FOOT BONES

251. Metatarsus
The metatarsus consists of five small, long bones called metatarsal bones which number 1 to 5 beginning on the medial (great toe) side of the foot
First metatarsal is short and thick and plays an important role in supporting body weight
Distally, where the metatarsals articulate with the proximal phalanges of the toes, the enlarged head of the first metatarsal forms the “ball” of the foot

252. FOOT BONES

253. Phalanges (Toes) There are 14 phalanges of the toes:
Smaller than those of the fingers and thus are less nimble
There are three phalanges in each digit except for the great toe (hallux)
The great big toe (hallux) is digit 1 and has two phalanges
The other toes, numbered 2-5, have three phalanges each

254. FOOT BONES

255. Arches of the Foot
A segmented structure can hold up weight ONLY if it is arched
Foot has three arches: account for its awesome strength
Two longitudinal:
Medial arch
Lateral arch
One transverse arch
The arches of the foot are maintained by:
Interlocking shapes of the foot bones
Strong ligaments
Pull of some tendons during muscle activity

256. FOOT ARCHES

257. Arches of the Foot
Ligaments and muscle tendons provide a certain amount of springiness
Arches give or stretch slightly when weight is applied to the foot and spring back when the weight is removed, which makes walking and running more economical in terms of energy use than would otherwise be the case

258. Arches of the Foot
If you examine your wet footprint, you will see that the medial margin from the heel to the head of the first metatarsal leaves no print
This is because the MEDIAL LONGITUDINAL ARCH curves well above the ground
The talus is the keystone of this arch, which originates at the calcaneus, rises to the talus, and then descends to the three medial metatarsals

259. FOOT ARCHES

260. FOOT BONES

261. Arches of the Foot Lateral longitudinal arch: Is very low
It elevates the lateral part of the foot just enough to redistribute some of the weight to the calcaneus and the head of the fifth (5) metatarsal (to the ends of the arch)
Cuboid is the keystone bone of this arch

262. FOOT ARCHES

263. FOOT BONES

264. Arches of the Foot
The two longitudinal arches (medial and lateral) serve as pillars for the transverse arch, which runs obliquely from one side of the foot to the other, following the line of the joints between the tarsals and metatarsals

265. Arches of the Foot
Together, the arches of the foot form a half-dome that distributes about half our standing and walking weight to the heel bones and half to the heads of the metatarsals

266. HOMEOSTATIC IMBALANCE
Standing immobile for extended periods places excessive strain on the tendons and ligaments of the feet (because muscles are inactive) and can result in fallen arches, or “flat feet,” particularly if one is overweight
Running on hard surfaces can also cause arches to fall unless one wears shoes that give proper arch support

267. DEVELOPMENTAL ASPECTS OF THE SKELETON
Membrane bones of the skull begin to ossify late in the second month of development
At birth, skull bones are connected by fontanels, unossified remnants of fibrous membranes
Changes in cranial-facial proportions and fusion of bones occur throughout childhood
At birth, the cranium is much larger than the face, and several bones are still unfused
By nine months, the cranium is half the adult size due to rapid brain growth
By age 8-9, the cranium has reached almost adult proportions
Between ages 6-13, the jaws, cheekbones, and nose become more prominent, due to expansion of the nose, paranasal sinuses, and development of permanent teeth

268. FETAL SKULL

269. DEVELOPMENTAL ASPECTS OF THE SKELETON
Curvatures of the Spine
The primary curvatures (thoracic and sacral curvatures) are convex posteriorly and are present at birth
The secondary curvatures (cervical and lumbar curvatures) are convex anteriorly and are associated with the child’s development
The secondary curvatures result from reshaping the intervertebral disc

270. DEVELOPMENTAL ASPECTS OF THE SKELETON
Changes in body height and proportion occur throughout childhood
At birth, the head and trunk are roughly 1 ½ times the length of the lower limbs
The lower limbs grow more rapidly than the trunk, and by age 10, the head and trunk are about the same length as the lower limbs
During puberty, the female pelvis widens and the male skeleton becomes more robust

271. GROWTH RATES

272. DEVELOPMENTAL ASPECTS OF THE SKELETON
Effects of age on the skeleton
The intervertebral discs become thinner, less hydrated, and less elastic
The thorax becomes more rigid, due to calcification of the costal cartilages
All bones lose bone mass

273. HOMEOSTATIC IMBALANCE
Cleft Palate:
Condition in which the right and left halves of the palate fail to fuse medially
Dysplasia of the hip:
Acetabulum forms incompletely or the ligaments of the hip joint are loose, so the head of the femur slips out of its socket