Presentation on theme: "The Axial Skeleton Fun Facts About Bones"— Presentation transcript:
1 The Axial Skeleton Fun Facts About Bones Bone is made of the same type of minerals as limestone.Babies are born with 300 bones, but only have 206 by adulthood.Mice and giraffes have the same number of bones in their neck as a human: 7.The long horned ram can take a head butt at 25 mph. The human skull will fracture at 5 mph.
2 The Axial and Appendicular Skeleton About 206 bonesSesamoid bones range from (2-26)2 major divisions:AxialAppendicularEveryone has sesamoid bones making up their patella or kneecaps, but whether we have them in other locations varies.Many animals do without a skeleton of any kind. For example, earthworms, sea worms, and mollusks like octopuses have muscles and complex nervous systems, but have no rigid skeletal elements at all. This is because their bodies have no need to resist gravity. Humans, on the other hand, need to stand upright and walk in opposition to gravity, so our muscles need rigid structural elements to pull upon to produce movement.
3 The Axial Skeleton Head, neck, trunk Skull Hyoid bone Vertebral Column Thoracic Cage (12 pairs of ribs)Sternum
5 The Axial Skeleton Functions of the Axial Skeleton Supports and protects organs in body cavitiesAttaches to muscles ofHead, neck, and trunkRespirationAppendicular skeleton
6 The Skull The skull protects The skull contains 22 bones The brain Entrances to respiratory systemEntrance to digestive systemThe skull contains 22 bones8 cranial bones:Form the braincase or cranium14 facial bones:Protect and support entrances to digestive and respiratory tractsThe axial skeleton begins with the skull.
11 The SkullIn red we can see the 8 cranial bones that enclose the brain.In green, is another good view of the most of the 9 bones that form the nasal cavity – nasal, lacrimal, palatine, vomer, and inferior nasal conchae. The palatine bones form the posterior portion of the hard palate.In purple, we can some of the remaining 5 bones that form the face including the maxillary bone that forms the upper jaw and root the upper teeth, as well as the mandible that contains the lower teeth.Fig 7-4
12 The SkullSome special features within some of the bones of the cranial cavity.Fig 7-4
13 The Skull Superficial Facial Bones (for muscle attachment) Maxillae = maxillary bonesLacrimalNasalZygomaticMandibleDeep Facial Bones1. Separate the oral and nasal cavities2. Form the nasal septumPalatine bonesInferior nasal conchaeVomer
14 The Skull Sinuses Sutures Cavities that decrease the weight of the skullLined with mucous membranesProtect the entrances of the respiratory systemSuturesThe immovable joints of the skullThe four major suturesLambdoid sutureCoronal sutureSagittal sutureSquamous suture
15 The Skull __________________ Suture Between occipital & parietal bones May contain sutural (Wormian) bonesBetween frontal & parietal bonesThe calvaria (skullcap)Consists of occipital, parietal, and frontal bonesBetween the parietal bonesFrom lambdoid suture to coronal sutureFig 7-3
16 The Skull ___________________ Sutures During development, the skull organizes around the developing brain as both the brain and skull grow rapidly. Fontanelles, which are non-ossified areas b/n cranial bones allow for the skull and brain growth.The premature closing of one or more fontanelles is called craniostenosis.___________________ SuturesForm boundaries between temporal bones and parietal bonesFig 7-3
17 The Cranial Bones of the Skull Occipital boneParietal bonesFrontal boneTemporal bonesSphenoidEthmoidLet’s go through the 8 cranial bones in more detail.
18 The Cranial Bones of the Skull The _________________ BoneFunctions of the occipital boneForms the posterior and inferior surfaces of the craniumArticulations of the occipital boneParietal bonesTemporal bonesSphenoid (underneath)First cervical vertebra (atlas)Marks of the occipital boneExternal occipital protuberance (bulge)External occipital crest (prominent ridge):to attach ligaments
19 The Cranial Bones of the Skull The Occipital BoneMarks of the occipital boneOccipital ________: articulate with neckInferior and superior nuchal lines: attachment site of muscles and ligamentsForamina of the occipital bone____________________: connects cranial and spinal cavitiesJugular foramen: for jugular vein_________________________: for hypoglossal nervesHypoglossal nerves (CN 11) provide motor control to muscles of the tongue.Fig 7-5
20 The Cranial Bones of the Skull The ___________________ BonesFunctions of the parietal bonesForms part of the superior and lateral surfaces of the craniumArticulations of the parietal bonesOther parietal boneOccipital boneTemporal boneFrontal boneSphenoid
21 The Cranial Bones of the Skull The Parietal BonesMarks of the parietal bonesSuperior and inferior temporal lines:to attach temporalis muscleGrooves for cranial blood vesselsFig 7-5
22 The Cranial Bones of the Skull The __________________ boneFunctions of the frontal boneForms the anterior cranium and upper eye socketsContains frontal sinusesCavities lined with mucous membranes that protect the entrances of the respiratory systemArticulations of the frontal BoneParietal boneMaxillaMetopic sutureEthmoidLacrimal boneZygomatic boneSphenoidNasal bone
23 The Cranial Bones of the Skull The Frontal BoneMarks of the frontal boneFrontal squama (forehead)Supra-orbital margin (protects eye)_________________(for tear ducts)Frontal sinusesForamina of the frontal boneSupra-orbital foramen:for blood vessels of eyebrows, eyelids, and frontal sinusesSupra-orbital notch:an incomplete supra-orbital foramenFig 7-6
24 The Cranial Bones of the Skull The Temporal BonesFunctions of the temporal bonesPart of lateral walls of cranium and zygomatic archesArticulate with mandibleSurround and protect inner earAttach muscles of jaws and headArticulations of the temporal bonesZygomatic boneSphenoidParietal boneOccipital boneMandibleFig 7-7
25 The Cranial Bones of the Skull Marks of the Temporal BonesSquamous part: borders the squamous sutureMandibular fossa (depression): articulates with the mandible___________________ process (projection or bump)Inferior to the squamous portionArticulates with temporal process of zygomatic boneForms zygomatic arch (cheekbone)______________________ (canal): ends at tympanic membraneMastoid processFor muscle attachment
26 The Cranial Bones of the Skull Functions of the SphenoidPart of the floor of the craniumUnites cranial and facial bonesStrengthens sides of the skullContains sphenoidal sinusesArticulations of the SphenoidEthmoidFrontal boneOccipital boneParietal boneTemporal bonePalatine bonesZygomatic bonesMaxillaeVomerThe bottom of the brain is supported by a single sphenoid bone, which extends flat plates from the midline that resembles the wings of a butterfly.
27 The Cranial Bones of the Skull Aside from making the floor of the cranium and strengthening the sides, the sphenoid bone also has many other functions with its many foramina.The optical canals will allow passage for the optic nerves, the superior orbital fissure not viewed here for the blood vessels and nerves of the orbit, the foramen rotundum and ovale for blood vessels and nerves of the face, and the foramen spinosum for blood vessels and nerves of the jaw.Greater wing forms part of the cranial floorHypophyseal fossa of the sella turcica holds the ____________Foramens hold blood vessels & nerves of the face and jawsFig 7-8
28 The Cranial Bones of the Skull Functions of the ethmoidForms anteromedial floor of the craniumRoof of the nasal cavityPart of the nasal septum and medial orbital wallContains ethmoidal air cells (network of sinuses)If you get punched in the nose, this is the bone most likely to fracture.Fig 7-4
29 The Cranial Bones of the Skull Articulations of the EthmoidFrontal boneSphenoidMaxillary bonesNasal boneLacrimal bonePalatine boneInferior nasal conchaeVomerThe Ethmoid articulates with the frontal and sphenoid bones of the skull, the maxillary bones (upper jaw) of the face, and all of the nasal bones that form the nasal cavity except the zygomatic bones.
30 The Cranial Bones of the Skull Parts of the EthmoidThe _______________ plateFloor of the craniumRoof of the nasal cavityContains crista galliThe 2 lateral massesSuperior and middle nasal conchaeThe perpendicular platePart of the nasal septum__________________ foraminaIn the cribriform plateFor olfactory nervesFig 7-9
31 The Facial Bones of the Skull Maxillae (2 maxillary bones - upper jaw)Palatine bones (2, posterior portion of hard palate)Nasal bones (2, support bridge of nose & connect to cartilage)Vomer (1, forms inferior portion of the bony nasal septum)Inferior nasal conchae (2)1. Creates air turbulance in nasal cavity to warm and humidify inhaled air2. increases epithelial surface areaZygomatic bones (2, lateral wall of the orbit and cheeks)Lacrimal bones (2, medial wall of the orbit)Mandible (1, lower jaw)14 facial bones protect and support entrances to digestive and respiratory tracts.9 of which form the structure of the nasal cavity, which we said has a complicated anatomy that can only be viewed by dissecting the skull apart.The exception maybe being the palatine bones which we said form the posterior portion of the hard palate.Lacrimal bones are the smallest of the facial bones.The remaining bones are the maxillary bones that form the upper jaw, the zygomatic bones that form the cheeks, and the mandible or jawbone where the lower teeth insert.There are additional pictures of these in your textbook.
32 The Facial Bones of the Skull The Hyoid BoneFunctions of the hyoid boneSupports the ______Attaches muscles of the larynx, pharynx, and tongueThe hyoid bone is unusual because it doesn’t contact another bone.Fig 7-12
33 The Orbital Complex Fig 7-13 The frontal bone forms the roof. The maxilla forms the floor.The maxillary, lacrimal, and ethmoid bones form the orbital rim and medial wall.Fig 7-13
34 The Vertebral Column The spine or vertebral column Protects the spinal cordSupports the head and body26 bones24 vertebrae, the sacrum, and the coccyxThe vertebral column forms the next portion of the axial skeleton.Fig 7-16
35 The Vertebral Column Vertebrae The neck The upper back (T1-T12) C1 (superior) to C7 (inferior)C1 articulates with the skullThe upper back (T1-T12)12 __________________ vertebraeEach articulates with one or more pair of ribsThe lower back (L1-L5)5 ___________________ vertebraeL5 articulates with the sacrumHumans and most other mammals have 7 bones in the neck (cervical vertebrae), 12 bones in the thorax (thoracic vertebrae), and 5 bones in the lower back (lumbar vertebrae). The vertebrae are numbered by region from top to bottom so that C1 is the most superior vertebrae and it articulates with the skull. The cervical vertebrae are then numbered C1-C7. The thoracic from T1-T12. Each of these will articulate with one or more pair of ribs. And the lower back is made up of L1-L5. L5 will articulate with the sacrum. A good anatomist can easily distinguish which region of the body a vertebral bone comes from, because they have different structures to fulfill different tasks.
36 The Vertebral Column The Sacrum (S) and Coccyx (Co) The fifth lumbar vertebra articulates with the ____________________The sacrum articulates with the ____________________
37 The Vertebral Column Structure of a Vertebra The vertebral body (________)Transfers weight along the spineIntravertebral discs provide flexibility and protectionThe vertebral archVertebral foramen encloses the _______________________The articular processesLateral projections between laminae and pediclesThe vertebral column is composed of individual vertebral bones that vary considerably in shape and function. All vertebrae have 2 main parts: a hollow, dorsal neural arch, the vertebral canal, that encloses the spinal cord, and a sturdy, solid, ventral spool-shaped centrum. The weight of the body is supported by the vertebral centra, which are stacked up upon each other to form a flexible column. This column is flexible because pliable intravertebral discs form cushions between each vertebral bone.The third and more variable part you see are the articular processes.Fig 7-18
38 The Vertebral Column Intervertebral discs are pads of cartilage that Here we see a stack of vertebrae coming together with the superior articular facets coming in contact with the inferior articular facets of the vertebrae above them.Notice that separating the vertebrae are intervertebral discs.These are pads of fibrous cartilage that (1) separate the vertebral bodies, (2) absorb shock, and (3) provide flexibility.Intervertebral discs are pads of cartilage that(1) separate the ________________________(2) absorb shock(3) provide flexibilityFig 7-18
39 Vertebral Regions Distinctive features: Cervical vertebrae are distinctive because they possess small holes on each side of the centrum. These holes are for the passage up the neck of vertebral arteries that supply blood to the brain.They also all have a small vertebral body because they only have to support the head.The small vertebral body make cervical vertebrae more delicate and likely to have dislocations or fractures than the other vertebrae.In contrast to the small bodies, they have large vertebral foramen because they allow passage of the largest part of the spinal cord.They also have prominent dorsal spinous processes; the largest one is on the cervical vertebra number 7 (C7), which is responsible for the bump you can feel on the back of your neck. This is where we’ll transition to the thoracic vertebrae.Distinctive features:_____________________ for passage of vertebral arteries to brain.Prominent dorsal spinous processes___________ vertebral body (only have to support the head)Large vertebral ________ (passage of largest part of spinal cord)Fig 7-19
40 Vertebral Regions The Cervical Vertebrae Atlas (_________) Articulates with occipital condyles of skullHas no body or spinous process (the others do)Has a large, round foramen within anterior and posterior archesBecause joints between all the bones of the vertebral column are flexible, you can rotate your shoulders forwards and backwards a bit. Your head, however, can be rotated from side to side much more dramatically than your shoulders. What accounts for this unusual freedom of rotation of the skull? The rotation of the skull is due to the first 2 cervical vertebrae. The first one is in direct contact with the skull and is called the atlas, after the Greek god who held the earth in his arms. This bone has a normal neural arch that encloses the spinal cord; however, the centrum for this bone is missing. So the spinal canal in this area is enclosed by a roof of bone and a floor formed only by a tough ligament that spans the middle of the atlas, which looks like a hollow circle divided in two by the ligament. The second cervical vertebrae is called the axis. It supports the atlas. It has a more normal appearance, except for an addition to its centrum. The upper face of the C2 centrum has a large spike or dens, which projects upwards from it. This dens of the axis fits into the ventral opening of the atlas above it. When you turn your head, the atlas freely rotates around the dens, allowing this easy movement. Fish and amphibians don’t have these special features and can’t rotate their heads as freely as mammals or reptiles.Fig 7-19
41 Vertebral Regions Thoracic vertebrae (T1–T12) Have heart-shaped bodies ________bodies than in C1–C7Smaller vertebral _________ than in C1–C7Long, slender spinous processesDorsolateral surfaces of body have costal facets:Which articulate with heads of ribsRemember a facet is a smooth flat articular surface.Thoracic vertebrae possess stout transverse processes that attach to and buttress the 12 ribs that join to the vertebral column. Ribs attach to the thoracic vertebrae by articulating with the transverse processes of the vertebrae, curve around to the ventral side of the body, and terminate on the breastbone, or sternum.Fig 7-20
42 Vertebral Regions Thoracic vertebrae (T1–T12) Ribs at T1–T10 Contact costal and transverse costal facetsT1–T8 articulate with two pairs of ribsAt superior and inferior costal facetsT9–T11 articulate with one pair of ribsT10–T12 transition to lumbar vertebraeThe thoracic vertebrae can be distinguished from other vertebrae by the presence of these facets for the articulation of ribs.The other distinctive features of the thoracic vertebrae are the heart-shaped bodies, and the long spinous processes.Fig 7-20
43 Vertebral Regions Lumbar vertebrae (L1–L5) ___________ vertebrae Thicker bodies than T1–T12Transverse processesSlenderProject dorsolaterallySpinous process:Short, heavyFor attachment of lower back musclesFig 7-21
44 Vertebral Regions Lumbar vertebrae (L1–L5) Oval-shaped bodies No costal or transverse costal facets (Why?)Triangular vertebral foramenSuperior articular processesFace up and inInferior articular processesFace down and outLarger _______ (supporting weight of upper skeleton)Lumbar vertebrae are larger and have larger centra, which are needed to support all the weight of the upper skeleton.The are the most massive, the widest and least mobile of the vertebrae.Ruptured intervertebral discs are more common here because the lumbar vertebrae carry so much weight.Fig 7-21
48 The Vertebral Column Figure 7–17 Abnormal Curvatures of the Spine. One common problem with the vertebral column is scoliosis. In scoliosis, the spine, as seen from the dorsal surface, develops an s-shaped curve rather than forming a straight line from pelvis to neck. About 2% of the population will develop scoliosis, which may sometimes require surgery to straighten the spine. There is a tendency to inherit this condition. Recently, a gene called CHD7 that affects the function of homeotic proteins has been found to contribute to the development of scoliosis. (Homeotic proteins are DNA-binding proteins expressed in stripes along the body during embryogenesis and force the cells that they control to become structures appropriate for that segment). This has got to be a future target for RNAi therapeutics.
49 Vertebral Regions The __________________ Is curved, more in males than in femalesProtects reproductive, urinary, and digestive organsAttachesThe axial skeleton to pelvic girdle of appendicular skeletonBroad muscles that move the thighThe adult sacrumConsists of five fused sacral vertebraeFuses between puberty and ages 25–30Leaving transverse lines
50 Vertebral Regions The __________________ Attaches ligaments and a constricting muscle of the anusMature coccyxConsists of three to five fused coccygeal vertebraeSo unlike the other vertebrae the vertebrae of both the sacum and coccyx are fused.Fig 7-21
51 Vertebral Regions Ilium Ischial bone Pubis Acetabulum Ishial tuberosityPubisAcetabulumThe axial skeleton ends here. The sacrum is a triangle-shaped mass of bone that arises from the fusion of 5 sacral vertebrae. It is connected on each side by ligaments to fan-shaped bones of the pelvis called the iliac bones. This arrangement is ingenious, since a great load on the sacrum wedges it harder into the pelvis and causes the iliac bones to move closer together for better load-bearing. The iliac bones are joined to two other pelvic bones. The ischial bones on each side have downward-projecting, rounded processes called ishial tuberosities (these are what we sit on). More ventrally, the pubic bones of each side come together to form the front of the pelvic basin. The bones of the thighs insert into a cup-shaped depression, the acetabulum (ass-ah-tab-u-lum), that transmits forces from the six pelvic bones to the two thigh bones.
52 The Thoracic Cage The skeleton of the chest The Rib Cage Supports the thoracic cavityConsists of:thoracic vertebraeribssternum (breastbone)The Rib CageFormed of ribs and sternumRibs 1–7 (true ribs) They are connected to the sternum by costal cartilagesRibs 8–12 (false ribs) They do not attach directly to the sternumWe can see that ribs 8-10 fuse together and merge with cartilage before reaching the sterumWe can also see that ribs only connect to the vertebrae and back muscles. They do not connect with the sternum.Fig 7-23a
53 The Thoracic Cage Functions of the Thoracic Cage Protects organs of the thoracic cavityHeart, lungs, and thymusAttaches musclesFor respirationOf the vertebral columnOf the pectoral girdleOf the upper limbsFig 7-23b
54 The Thoracic Cage Ribs Are mobile Can absorb shock Functions of ribs Rib movements (breathing):affect width and depth of thoracic cagechanging its volumeFig 7-24c
55 The Thoracic Cage Ribs 1–7 (true ribs) Ribs 8–12 (false ribs) Vertebrosternal ribsConnected to the sternum by __________ cartilagesRibs 8–12 (false ribs)Do not attach directly to the sternum_________________________ribs (ribs 8–10)Fuse togetherMerge with cartilage before reaching the sternum___________________ or vertebral ribs (ribs 11–12)Connect only to the vertebrae and back musclesHave no connection with the sternumRibs 1–7 (true ribs) They are connected to the sternum by costal cartilages. Costal is Latin for rib.Ribs 8–12 (false ribs) They do not attach directly to the sternumWe can see that ribs 8-10 fuse together and merge with cartilage before reaching the sterumWe can also see that ribs only connect to the vertebrae and back muscles. They do not connect with the sternum.
56 The Thoracic Cage Structures of the Ribs The head (capitulum) The neck At the vertebral end of the ribHas superior and inferior articular facetsThe neckThe short area between the head and the tubercle
57 The Thoracic Cage Structures of the Ribs The tubercle (tuberculum) A small dorsal elevationHas an auricular facet that contacts the facet of its thoracic vertebra (at T1–T10 only)The tubercular body (shaft)Attaches muscles of the pectoral girdle and trunkAttaches to the intercostal muscles that move the ribs
58 The Thoracic CageLet’s talk about some structures of the ribs.Notice the head is at the vertebral end of the rib and it has superior and inferior articular facets.The neck is the short area between the head and the tubercle (the small rounded projection where a tendon or ligament can attach).The tubercle has a facet that contacts the facet of its thoracic vertebra in T1-10.The body or shaft attaches muscles of the pectoral girdle and trunk and the muscles that move the ribs.Fig 7-24
59 The Thoracic Cage The sternum A flat bone In the midline of the thoracic wallThree parts of the sternumThe __________The sternal bodyThe xiphoid processMah-new-bree-umThe sternum doesn’t completely fuse or ossify until about age 25 and the xiphoid process is the last part to fuse.The xiphoid process is also the easiest to break which can cause injury to nearby organs, so position those hands correctly while doing CPR.- articulates with the clavicles & 1st ribs- attaches to costal cartilages of ribs 2-7- attaches to diaphragm and rectus abdominis muscles