Chapter 7 Axial Anatomy PDF

Functional Anatomy HHSC 105 Instructor: Dr. Farnaz Gooya, MD (Doctor of Medicine) , MSc in Immunology & Allergy, MEd in Health Professions Education School of Health Sciences, University of Northern British Columbia  Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien...

Functional Anatomy HHSC 105 Instructor: Dr. Farnaz Gooya, MD (Doctor of Medicine) , MSc in Immunology & Allergy, MEd in Health Professions Education School of Health Sciences, University of Northern British Columbia  Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Sixth Edition @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Chapter 7 Axial Skeleton @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Outline  Skull  Sex Differences in the Skull  Aging of the Skull  Vertebral Column  Thoracic Cage Aging of the Axial Skeleton  Development of the Axial Skeleton @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Introduction The bones of the skeleton form an internal framework to ❖ support soft tissues ❖ protect vital organs ❖ bear the body’s weight ❖ help us move Typically, 206 bones in the adult skeleton. The total number decreases with growth and maturity. Why ? Bones differ in size, shape, weight, and even composition @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Introduction Skeletal system is divided into two parts: Axial skeleton: skull vertebral column thoracic cage Appendicular skeleton: a-pən-ˈdi-kyə-lər shoulder + those of the upper limbs hip bones + lower extremities @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Introduction: Function The main function of the axial skeleton is to form a framework that supports and protects the organs. It houses special sense organs (the organs for hearing, balance, taste, smell, and vision) It provides areas for the attachment of skeletal muscles. It involves in hematopoiesis: hi-ˌma-tə-pȯi-ˈē- səs ❖ The spongy bone of most of the axial skeleton contains hematopoietic hi-ˌma-tə-pȯ- ˈy-e-tik tissue, which is responsible for blood cell formation. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Skull  The skull is composed of cranial and facial bones Cranial bones ˈkrā-nē-əl : eight bones that surround and enclose the brain Unpaired: ethmoid ˈeth-ˌmȯid , frontal ˈfran- tᵊl , occipital äk-ˈsi-pə-tᵊl , and sphenoid ˈsfē-ˌnȯid Paired: parietal pə-ˈrī-ə-tᵊl and temporal ˈtem-p(ə-)rəl @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Skull Facial ˈfā-shəl bones: 14 bones that form the face and have no brain contact Unpaired: vomer ˈvo-mər and mandible ˈman-də-bəl Paired: maxillae mak-ˈsi-lə , nasal ˈnā-zəl , lacrimal ˈla-krə-məl , zygomatic ˌzī-gə-ˈma-tik , palatine ˈpa- lə-ˌtīn , and inferior nasal conchae ˈkäŋ-kə @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Major Cavities of the Skull  Skull contains many cavities  The largest being the cranial cavity which houses the brain  adult volume of about 1300 to 1500 cubic  The orbits (eye sockets), the oral cavity (mouth), the nasal (nā′zăl) cavity, and the paranasal sinuses @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Anterior View of the Skull  The frontal bone forms the forehead.  (Eye sockets) are formed from a complex articulation of multiple skull bones.  Within the orbits are two large openings, called the superior orbital fissure and the inferior orbital fissure.  Superior to the orbits are the superciliary arches, (the brow ridges).  The left and right nasal bones form the bony “bridge” of the nose.  Superior to the nasal bones and between the orbits is a landmark area called the glabella. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Anterior View of the Skull  The left and right maxillae join to form most of the upper jaw and the lateral boundaries of the nasal cavity.  The maxillae also help form the floor of each orbit.  Inferior to each orbit, within each maxilla, is an infraorbital foramen fə-ˈrā-mən , which conducts blood vessels and nerves to the face.  The lower jaw is formed by the mandible. The prominent “chin” of the mandible is called the mental protuberance prō-ˈtü-b(ə-)rən(t)s. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Anterior View of the Skull  An anterior view also shows the nasal cavity.  Its inferior border is marked by a prominent, anterior nasal spine.  The thin ridge of bone that subdivides the nasal cavity into left and right halves helps form the nasal septum.  Along the lateral walls of the nasal cavity are two scroll-shaped bones called the inferior nasal conchae ˈkäŋ-ˌkē. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Superior and Posterior Views of the Skull  Shows four of the cranial bones:  the frontal bone, both parietal bones, and the occipital bone.  The articulation between the frontal and parietal bones is the coronal suture, so named because it runs along a coronal plane.  The sagittal suture connects the left and right parietal bones almost exactly in the midline of the skull. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Superior and Posterior Views of the Skull  Along the posterior one-third of the sagittal suture are either a single parietal foramen or paired parietal foramina. These foramina conduct tiny emissary veins from the veins of the brain to the veins of the scalp.  The superior part of the lambdoid ˈlam- ˌdȯid suture represents the articulation of the occipital bone with both parietal bones.  The external occipital protuberance is a bump on the back of the head @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Lateral View of the Skull  Shows:  one parietal, one temporal, one zygomatic, one maxilla, the frontal bone, sphenoid (greater wing) the mandible, and portions of the occipital bone.  The tiny lacrimal bone articulates with the nasal bone anteriorly and with the ethmoid bone posteriorly.  A portion of the sphenoid bone articulates with the frontal, parietal, and temporal bones. The region called the pterion. teh·ree·aan @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Lateral View of the Skull  The temporal process of the zygomatic bone and the zygomatic process of the temporal bone fuse to form the zygomatic arch.  The zygomatic arch terminates superior to the point where the mandible articulates with the mandibular fossa of the temporal bone. This articulation is called the TMJ, temporomandibular joint. ˈtem-pə-rō-man-ˈdi-byə-lər  The external ear opening overlies the external acoustic meatus of the skull. ə-ˈkü-stik mē-ˈā- təs  Posterior to this canal is the mastoid process, the bump you feel posterior to your ear lobe. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sagittal Section of the Skull  The perpendicular plate of the ethmoid bone  The vomer  The frontal sinus (a space in the frontal bone) and  the sphenoidal sinus (a space in the sphenoid bone)  are better visible. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Inferior or Basal View of the Skull  The hard palate,  sphenoid bone,  parts of the temporal bone,  and the occipital bone  with its foramen magnum  are readily visible when the mandible is removed in this inferior view. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Superior View of the Endocranial Cavity of the Skull  When the calvarium is removed, the endocranial cavity of the skull may be seen in a superior view these parts are prominent:  frontal,  ethmoid,  sphenoid,  temporal,  and occipital bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Suture  Immovable joints between skull bones  Four major sutures: Coronal suture: junction between frontal and parietal bones Lambdoid suture: junction between occipital and parietal bones Sagittal suture: junction between parietal bones Squamous suture: junction between temporal and parietal bones  May contain sutural bones variable in size, number, and location @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Suture  During adulthood, sutures start to disappear as bones fuse  the coronal suture typically is the first to fuse, usually in the late 20s to early 30s,  followed by the sagittal suture and then the lambdoid suture (usually in the 40s).  The squamous suture usually does not fuse until late adulthood (60+ years), or it  may not fuse at all. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Bones of the Cranium  The cranium consists of a roof and a base.  The roof, called the calvaria or skullcap, is composed of the eight bones that protect the brain kal-ˈver-ē-ə Made of parietal bones and parts of frontal and occipital bones  Base of cranium: floor Made of parts of ethmoid, sphenoid, occipital and temporal bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Anterior View of the Frontal Bone  The frontal bone forms part of the calvaria, the forehead, and the roof of the orbits. Includes the:  Squamous part; the vertical flattened region, ends at the supraorbital margins  Supraorbital foramen, or notch.  Superciliary arches, which are the brow ridges. Male skulls have more pronounced arches  Glabella sandwiched between the superciliary arches @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Anterior View of the Frontal Bone  Orbital part: inferior portion that forms the roof of the orbit  zygomatic process; articulates with the frontal process of the zygomatic bone.  Frontal sinuses :appear at the 6  frontal crest; serves as a point of attachment for the falx cerebri, a protective connective tissue sheet that helps support the brain @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Lateral View of the Parietal Bone  Form the lateral walls and roof of the Cranium  Each parietal bone is bordered by four sutures that unite it to the neighboring bones.  On the lateral surface, each parietal bone exhibits a pair of faint ridges called the superior and inferior temporal lines  Superior to these lines, the rounded, smooth parietal surface is called the parietal eminence.  The internal surfaces of the parietal bones exhibit many grooves that accommodate some of the blood vessels within the cranium @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Temporal Bone  Each temporal bone has a complex structure composed of three parts: the petrous ˈpe-trəs , squamous, and tympanic parts.  The thick petrous part, houses sensory structures of the inner ear that provide information about hearing and balance  Externally, the prominent bulge is the mastoid process,  it is filled with many small, interconnected air cells (called mastoid air cells) that communicate with the middle ear.  A thin, pointed projection of bone, called the styloid stī′loyd @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Occipital Bone  The occipital bone forms the posterior portion of the skull. Two parts:  1. Squamous  2. Basilar: includes ˈba-zə-lər  a large, circular opening called the foramen magnum  smooth knobs called occipital condyles ˈkän-ˌdī(-ə)l  (a) External (inferior) view shows the nuchal lines and the external occipital protuberance. prō-ˈtü-b(ə- )rən(t)s  (b) Internal (superior) view shows the internal occipital protuberance and grooves for the venous sinuses @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sphenoid Bone, Superior View  Has a complex shape, resembling that of a butterfly, forms the centerpiece of the base of the cranium.  It is often referred to as a “bridging bone,” or the “keystone of the skull,” because it unites the cranial and facial bones and articulates with almost every other bone of the skull.  Main Parts:  Body  Greater & Lesser wings  Much of it hidden by other bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sphenoid Bone Posterior View Pterygoid Process & Canal ˈter-ə- ˌgȯid @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Ethmoid Bone  The anterior view of the ethmoid highlights:  Ethmoidal Labyrinth  Perpendicular plate, forms the superior part of the nasal septum.  Crista Galli,  Superior nasal conchae,  Middle nasal conchae  Orbital plate  Superior View:  Cribriform plate  Ethmoidal sinus or cells @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Articulations of Sphenoid and Ethmoid Bones  Ethmoid bone is positioned between the orbits  It forms:  the anteromedial floor of the cranium,  the roof of the nasal cavity,  part of the medial wall of each orbit,  and part of the nasal septum @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Cranial Fossae  A fossa is a depression in a bone  The floor of the cranial cavity contains three cranial fossae: Anterior cranial fossa, the shallowest, made by frontal bone, the ethmoid bone, and the lesser wings of the sphenoid bone. Middle cranial fossa made from the parietal, sphenoid, and temporal bones. Posterior cranial fossa made from occipital, temporal, and parietal bones. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Foramen of the skulls:  Foramen Cecum ˈsē-kəm  Foramen Lacerum -ˈlas-ər-əm  Foramen Magnum ˈmag-nəm  Jugular Foamen: ˈjü-gyə-lər  Foramen Ovale -ō-ˈva-lē  Foramen Spinosum: -spin-ˈō-səm  Foramen Rotundum rō-ˈtən-dəm @Mc Graw Hill-Human An atomy, McKin ely, o’Loughlin, Pen nefather- O, Brie n  Incisive Foramen: in-ˈsī-siv  Infraorbital Foramen: ˌin-frə-ˈȯr-bət-ᵊl  Mental Foramen : ˌin-frə-ˈȯr-bət-ᵊl  Hypoglossal Canal: ˌhī-pə-ˈglä-səl  Mandibular Fossa: man-ˈdi-byə-lər  Optic Canal @Mc G raw Hill-Human An atomy, McKin ely, o’Loughlin, Pen nefather- O, Brie n  Bones of the Face  Fourteen facial bones give shape to the face  Form part of the orbital and nasal cavities  Support teeth  Serve as attachment sites for muscles of expression and chewing @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Facial Bones and Selected Features 1 @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Facial Bones and Selected Features 2 @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Zygomatic Bone  “Cheekbones,”  Has:  Temporal process makes zygomatic arch  maxillary (mak′si-lār-ē) process  frontal process  orbital surface @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Vomer  Has a triangular shape, and when viewed laterally, resembles a farming plow  articulates along its midline with both the maxillae and the palatine  ala, meaning “wing,”  Vertical plate: articulates with the perpendicular plate of the ethmoid bone.  Anteriorly, both the vomer and the perpendicular plate of the ethmoid bone form the bony nasal septum. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Inferior Nasal Conchae  Something shaped like a shell  They are in the inferolateral wall of the nasal cavity  They are similar to the superior and middle nasal conchae of the ethmoid bone  They help create turbulence in inhaled air.  inferior nasal conchae are separate bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Palatine Bone paləˌtīn  small bones with a distinct L shape  They form part of the hard palate, nasal cavity, and eye orbit.  Include:  Orbital Process: forms a small part of the medial floor of the orbit  Perpendicular plate: forms part of the lateral wall of the nasal cavity  Horizontal plate: forms posterior portion of the hard palate @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Maxilla  Form the central part of the facial skeleton  Left and right maxillae unite to form the upper jaw.  The inferior portions of the maxillae contain the alveolar processes that house the upper teeth.  Most of the hard palate is formed anteriorly by horizontal medial extensions of both maxillae, called palatine processes @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Maxilla  Lateral to the nasal cavity, each maxilla contains a large, spacious cavity called the maxillary sinus  Laterally, each maxilla articulates with a zygomatic bone via a zygomatic process. Superiorly, the maxillae articulate with the frontal bones via frontal processes @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Mandible  Forms the entire lower jaw  It supports the inferior teeth and provides attachment for the muscles of mastication.  The mandible has a horizontal body and two ramus ˈrā-məs  vertical-to-oblique ascending posterior regions called the ramus.  Each ramus intersects the body at a “corner” called the angle of the mandible.  The teeth are supported by the alveolar process of the mandibular body. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Mandible  The point of the chin is the mental (mentum = chin) protuberance.  Posterior projection of mandibular ramus: condylar (kon.di-l.r) process  temporomandibular joint (TMJ), each articulation of the head of the mandible with the mandibular fossa of the temporal bone @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Mandible  The anterior projection of the ramus, the coronoid (k.r..noyd) process  Mandibular notch: Th U shape depression between two process  Mandibular Foramen  Mental Foramen @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Nasal Complex  The nasal complex is composed of bones and cartilages forming the nasal cavities and paranasal sinuses  Superior border: cribriform ˈkri-brə-ˌfȯrm plate of ethmoid, parts of frontal and sphenoid  Inferior border: maxillae and palatine bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Nasal Complex  Lateral walls: ethmoid, maxillae, inferior nasal conchae, palatine bones, and lacrimal bones  Most of the anterior walls of the nasal cavity are formed by cartilage and the soft tissues of the nose, but the bridge of the nose is supported by the maxillae and the nasal bones @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Paranasal Sinuses  The paranasal sinuses are air-filled spaces within the skull bones surrounding the nasal cavity  Functions: Mucous lining humidifies and warms inhaled air Lighten skull Resonant chambers for sound production while speaking The maxillary sinus becomes a bit more prominent beginning at age 5, and by age10 the frontal sinus is becoming well formed. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Orbital Complex/ Left Orbit  The orbits are bony cavities in skull that hold and protect the eyes, and the orbital complex consists of multiple bones that form each orbit  Borders: Roof of orbit: frontal bone and lesser wing of sphenoid bone Floor: mainly the maxilla bone Medial wall: maxilla, lacrimal, and ethmoid bones Lateral wall: zygomatic, greater wing of sphenoid, and frontal bones Posterior wall: mainly the sphenoid bone @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Bones Associated with the Skull  The auditory ossicles and the hyoid bone are bones of the axial skeleton associated with the skull.  Auditory ossicles: Three tiny bones in petrous part of each temporal bone are for hearing: Malleus ma·lee·uhs Incus in·kuhs Stapes staypz @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Hyoid Bone ˈhī-ˌȯid  Hyoid bone: located between the mandible and larynx Does not articulate with another bone Contains a midline body and two hornlike processes, the greater cornu and lesser cornu The hyoid serves as an attachment site for tongue and muscles of larynx ler- iŋ(k)s used in swallowing @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sex Differences in the Skull  Human male and female skulls show differences in shape and size; this is called sexual dimorphism dī-ˈmȯr-ˌfi-zəm  Typical female features are delicate and small, whereas typical male features are larger, sturdier, and bulkier, however human skulls vary along a continuum.  Features on the skull and rest of skeleton make it possible to determine the sex of an individual.  Impossible to determine the sex of infant and juvenile remains, because skull @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien characteristics appear female-like until well after puberty. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Sexually Dimorphic Features  Male skulls:  have more pronounced superciliary arches  Blunter supraorbital margin  Sloping frontal bone  Less obtuse äb-ˈtüs mandibular angel  Prominent external occipital protuberance  Squarish Mental protuberance @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Fetal Skull  Infant cranial bones are connected by flexible areas of dense regular connective tissue called fontanelles  soft spots  Major fontanelles: Mastoid fontanelle Sphenoidal fontanelle Posterior fontanelle (closed at age 9 months) Anterior fontanelle (closed at age of 15 months)  These allow for the flexibility of the skull during birth and  the growth of the brain after birth.  (a) The mastoid and sphenoid fontanelles are best seen in lateral view,  while (b) the anterior and posterior fontanelles are best seen in superior view. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Fetal Skull  The most significant growth in the skull occurs before age 5,  When the brain is still growing and exerting pressure against the internal surface of the developing skull bones.  Brain growth is 90% to 95% complete by age 5, at which time cranial bone growth is also nearly complete, and the cranial sutures are almost fully developed.  Early in life, the skull grows at a much faster rate than the rest of the body.  Thus, a young child’s cranium is relatively larger than that of an adult. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Vertebral Column  The vertebral column is composed of 26 bones, including 24 individual vertebrae  Functions of the vertebral column: Provide vertical support for the body Supporting the weight of the head Help maintain upright body position Transfer weight of upper body to lower limbs Protection of spinal cord Provide passageways for spinal nerves  The vertebral column is partitioned into five regions identified by a capital letter that denotes their region, followed by a numerical subscript that indicates their sequence, going from superior to inferior @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Division of the Vertebral Column  Seven cervical vertebrae (C1-C7) form the bones of the neck.  C1 articulates superiorly with the occipital condyles of the occipital bone of the skull.  The seventh cervical vertebra C7) articulates inferiorly with the first thoracic vertebra.  Twelve thoracic vertebrae (T1-T12) form the superior regions of the back Each thoracic vertebra articulates with a pair of ribs  Five lumbar vertebrae (L1-L5) form the lower back  The sacrum (S1-S5) is formed from five fused sacral vertebrae  The coccyx (“tailbone”) is formed from four coccygeal /käkˈsijēəl/vertebrae (Co1-Co4) Begin to fuse during puberty @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Spinal Curvatures  Four spinal curvatures present in adult: Cervical curvature ˈkər-və-ˌchu̇r Thoracic curvature Lumbar curvature Sacral curvature  Primary curves appear in fetal development Thoracic and sacral curvatures. In the newborn, only these primary curves are present, and the vertebral column is C- shaped. Secondary curves appear at 3–4 months of age including: Cervical and lumbar curvatures Called compensation curves as they help shift trunk’s weight over the legs @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Vertebral Anatomy  Most vertebrae have the following features:  Body: weight-bearing region, rounded or cylindric, called also Centrum  Adjacent bodies separated by pad of fibrocartilage (intervertebral disc) with gelatinous consistency. One-quarter of the entire vertebral column. Shock absorber & let the column bend.  Vertebral or neural arch attaches to body to form vertebral foramen  Pedicles: feet of the arch  Laminae: posterior extensions of the arch  Stacked vertebral foramina form vertebral canal (contains spinal cord) and intervertebral foramina (passage for spinal nerves) @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Vertebral Anatomy  Processes:  Spinous processes project posteriorly  Transverse processes project laterally  Inferior articular processes of each vertebra attach to the superior articular processes of the vertebra immediately inferior to it  Each articular process has smooth articular facet @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Characteristic Features of Cervical, Thoracic, and Lumbar Vertebrae  In general, the vertebrae are smallest near the skull and become gradually larger moving inferiorly through the body trunk as weight bearing increases.  Thus, the cervical vertebrae are the smallest, followed by the thoracic, lumbar, and sacral vertebrae.  Because cervical vertebrae support only the weight of the head, their vertebral bodies are relatively small and light.  Also, the vertebral foramen is largest in the cervical vertebrae and smallest in the sacral vertebrae. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Atlas: C1  The atlas is the first cervical vertebra, which articulates with the occipital condyles of the skull and functions in supporting the head.  The articulation called the atlanto- occipital joint, permits us to nod our heads “yes.”  The atlas is readily distinguished from the other vertebrae because it lacks a body and a spinous process. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  C2: Axis:  The axis is the second cervical vertebra, which contains a process called the dens  The dens of axis serves as a pivot point for atlas, permitting rotation of the head as when you shake your head to say “no.”  The articulation of the atlas and axis, called the atlantoaxial joint. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Vertebra Prominens (C7)  The seventh cervical vertebra represents a transition to the thoracic vertebral region and has some features of thoracic vertebrae.  The spinous process of C7 is typically not bifurcated, Art of Medicine and it is much larger and longer than the spinous processes of the other cervical vertebrae.  This large spinous process is easily discerned and palpated through the skin,  If you drop your head forward (place your chin to your chest) and run your fingers down the back of your neck, it is the first bony lump you feel. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Art of Medicine  Thoracic Vertebra There are 12 thoracic vertebrae, designated T1–T12, and each vertebra articulates with the ribs. The thoracic vertebrae lack the mobility of the other vertebrae due to their stabilizing articulation with the ribs. The thoracic vertebrae also lack the transverse foramina and bifid spinous processes of the cervical vertebrae, @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Thoracic Vertebra A thoracic vertebra has a heart-shaped body that is larger and more massive than the body of a cervical vertebra. Its spinous process is relatively pointed and long and can be angled inferiorly Thoracic vertebrae are distinguished from all other types of vertebrae by the presence of costal facets or costal demifacets (dem′ē; half) on the lateral side of the body and on the sides of the transverse processes. @Mc G raw Hill-Human An atomy, McKin ely, o’Loughlin, Pen nefather- O, Brie n @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Lumbar Vertebrae  The largest vertebrae  Bear most of the weight of the body  Distinguished by the features they lack:  A lumbar vertebra has neither transverse foramina nor costal facets. @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sacrum and Coccyx  Sacrum: triangular bone forming posterior wall of pelvic cavity Apex: points inferiorly; base is broad superior surface Transverse ridges mark fusion points of the five vertebrae Sacral canal is continuation of vertebral canal Sacral hiatus in inferior opening Anterior and posterior sacral foramina allow nerves to exit Has an auricular surface at sacroiliac joint @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sacrum and Coccyx Coccyx: fusion of four small vertebrae Attachment site for ligaments and muscles Coccygeal cornu are the laminae of the first coccygeal vertebrae @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Thoracic Cage  The bony framework of the chest is called the thoracic cage, which is composed of: Thoracic vertebrae posteriorly Ribs laterally Sternum anteriorly  Protects heart, lungs, trachea, esophagus, and other thoracic organs @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Sternum  Adult sternum: the “breastbone” in anterior midline of thoracic wall  Composed of three major parts: Manubrium mə-ˈnü-brē-əm Body Xiphoid process ˈzī-ˌfȯid Clavicle articulate with the manubrium @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Ribs  Elongated, curved, flat bones that articulate posteriorly with thoracic vertebrae and end in the anterior wall of the thorax  Articular facets on the head and tubercle ˈtü-bər-kəl of each rib articulate with vertebral body and transverse process, respectively @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien  Ribs  12 pairs total True ribs: ribs 1–7; articulate anteriorly with the sternum via costal cartilages False ribs: ribs 8–12; their costal cartilages do not attach directly to the sternum Floating ribs: false ribs (pairs 11 and 12) that do not articulate with the sternum @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Aging of the Axial Skeleton  Many bones fuse as we age  Skeletal mass and density become reduced  Bones can become more porous and brittle (osteoporosis), ˌä-stē-ō- pə-ˈrō-səs enhancing chance of fracture  Articulating surfaces deteriorate, contributing to arthritic conditions @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien Extra references:  1. The Art of Medicine  https://theartofmed.wordpress.com/2 015/05/23/what-is-this-blog-about/  2. Teach Me Anatomy  https://teachmeanatomy.info/abdome n/bones/lumbar-spine/ @Mc Graw Hill-Human Anatomy, McKinely, o’Loughlin, Pennefather- O, Brien