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Bone Diversity Dr. Anderson GCIT Bone Diversity • There are normally 206 bones in the adult human body • Each bone is derived from connective tissue and grows to articulate with other bones to form the functional human skeleton The Axial Skeleton • Composed of the skull, vertebrae, ribs (thoracic cage) and coccyx The Skull • Cranium – Made of multiple bones that are immovable (as adult) and connect in sutures, houses the brain Cranium – Frontal Bone (#1) • Shell-shaped frontal bone, anterior to parietal (coronal) sutures • Makes up superior wall of orbits Cranium – Parietal Bone (#2) • Form most of the superior and lateral aspects of the skull and articulate with other skull bones Cranium - Occipital Bone (#4) • Forms most of the skull’s posterior walls and base • Foramen magnum occurs in the inferior surface of this bone, allowing the spinal cord to pass through Cranium - Temporal Bone (#3) • Inferior to parietal bones (3 regions) – Squamous region • Produces the zygomatic process anteriorly to meet the zygomatic bone (makes up the “cheekbone”) and contains the mandibular fossa (meets the mandible to articulate the lower jaw) – Tympanic Region • Contains acoustic meatus and styloid process – Mastoid region • Exhibits mastoid process (anchors some neck musculature) and has the stylomastoid foramen (allows cranial nerve VII to exit the skull) Cranium - Temporal Bone (#3) (con’d) Cranium - Sphenoid Bone (#5) • Very complex, but articulates with almost all other bones – Spans the width of the middle cranial fossa Cranium - Sphenoid Bone (#5) (con’d) Cranium - Sphenoid Bone (#5) - con’d • Openings in sphenoid include – Optic canals – anterior to the sella turcica, allow cranial nerves to pass to the eyes – Superior Orbital Fissure • Allows cranial nerves that control eye movements to exit Facial Bones - Mandible • Lower Jawbone – articulates with mandibular fossa (on temporal bone) • Two main parts – Body (chin) – Ramus (vertical part) Maxillary Bones • Bilateral maxillary bones are fused medially – form the upper jaw and the central part of the face Smaller Facial Bones (pg 213) • • • • • Zygomatic bones – form cheek bones Nasal Bones – forms bridge of nose Lacrimal Bones – medial orbit walls Palatine Bones – posterior part of hard palate Inferior nasal conchae – lateral walls of nasal cavity All of the Aforementioned Bones are Summarized on pp. 214-215 The Vertebral Column • Consists of 33 irregular (in shape) bones • Segmentation = flexibility! • Prone to damage under heavy and/or chronic forces Vertebral Function • Transmits force from upper body to legs • Houses and protects the spinal cord • Attachment points for ribs, and for muscles/ ligaments of the back and neck Spinal Divisions • 7 cervical (neck) vertebrae • 12 Thoracic vertebrae • 5 Lumbar vertebrae • 5 Sacral (fused) vertebrae • 4 Vertebrae in Coccyx Scoliosis • Abnormal curvature of the spine • Leads to gait problems, pain and disability, breathing difficulties • Can be corrected early by bracing, in extreme cases- surgery Spinal Arrangement • Alternating arrangement of vertebrae and discs • Peripheral nerves from spinal cord extend from each vertebral “level” Intervertebral Discs • Serves as a shock absorber between vertebrae- composed of collagen and fibrocartilage • Composed of 2 layers – Inner, gel-like layer (nucleus pulposus) – Annulus fibrosus – tough outer covering that resists compression Herniated Discs • Injury leads to rupture of the anulus fibrosis leading to a “bulge” which may press on the spinal nerves causing intense pain, numbness or loss of motor fuction Vertebra (Dorsal View) • Centrum bears the weight of the body (interspersed by discs) • Spinal cord passes through the vertebral foramen • Spinous process and transverse process are for muscle attachment Vertebral Names • Cervical Vertebrae (C1-C7) • Thoracic Vertebrae (T1-T12) • Lumbar Vertebrae (L1-L5) • Sacral Vertebrae (S1-S5) Superior-Inferior Changes • Centra of each vertebrae tend to thicken inferiorly • Vertebral foramen narrows inferiorly • No rib articulation past T12 The Thoracic (Rib) Cage • Roughly cone-shaped • Protects the heart, lungs • Provides a solid foundation for muscles to pull and push against for inhalation and exhalation Sternum • Articulates with the costal cartilages of the ribs (anteriorly) Ribs • Serve to protect the organs of the thoracic cavity (heart, lungs) • 12 pairs (in both genders) – 7 pairs are “true” ribs that articulate directly with sternum – 5 pairs are “false” ribs that articulate indirectly with the sternum Posterior Rib Articulation Appendicular Skeleton • Peripheral to axial skeleton • Includes limb bones (arms and legs) and pelvic a shoulder girdles Shoulder (Pectoral) Girdle • Attach upper limbs to the axial skeleton • Major bones – Scapula (shoulder blade) • Posterior aspect – Clavicle (collar bone) • Anterior aspect Scapula • Bilateral and posterior • Does NOT articulate directly with the axial skeleton – held in place by muscles – This articulation allows for flexibility at the cost of stability Scapula - Anatomy • Triangular bone • Notable features – Glenoid cavity (fossa) articulates with the humerus on lateral border Upper Limb (Arm) Bones • Humerus – Upper Arm • Radius, Ulna – Forearm • Carpal bones – wrists • Metacarpals – palm • Phalanges - Fingers Ulna • Forms elbow joint with humerus • Longer forearm bone (on pinky side), thicker proximally • Notable features – Olecranon (elbow) – Coronoid Process – Trochlear notch Grips trochlea of humerus, forming articulation proximally – Distal head (forms articulation with wrist) Radius • Thicker distally • Notable features – Proximal head – articulates with capitulum of humerus – Radial tuberosity – provides attachment for bicep – Styloid process – provides attachment for wrist ligament Proximal Distal Ulna – Detailed Structure The Hand • Carpals – (8 bones total) • Metacarpals (5 bones) labeled 1-5 (thumb to pinky) • Phalanges – multiple bones each – Two in thumb – Three in all other fingers • Distal, middle, proximal The Hand The Pelvic (Hip) Girdle • Attaches lower limbs to the axial skeleton • More stable but less flexible than shoulder girdle • “Pelvis” is actually three separate bones Pelvic Function • Attaches lower appendicular skeleton to the axial skeleton • Firmly attached with ligaments • Provides a strong foundation for femur articulation and muscle attachment Pelvic Bones • 3 main parts – Ilium (superior) – Ischium (inferior and posterior) – Pubis (inferior and anterior) • The acetabulum (hip socket) is where all three hip bones fuse and where the femur articulates Medial view Lateral view Ischium and Pubis • Ischium – Ischial tuberosity • Bears all weight when sitting • Pubis – Forms anterior part of hip bone – Pubic symphysis (cartilaginous disc connects pubic bones medially) Gender Differences in Pelvic Anatomy • What are the major differences in hip morphology between men and women? The Lower Limb (Leg) Bones • • • • • • Femur – thigh bone Tibia – shin bone 1 Fibula – shin bone 2 Tarsals – ankle bones Metatarsals – foot bones Phalanges - toes Femur • Largest and strongest bone in the body • Transfers all weight from the pelvis to the legs Tibia • Tibia transmits weight of femur to the foot – Lateral and medial condyle articulate with femur (proximal end) • Medial malleolus (distal end) – “bulge” on inside of ankle Fibula • Primarily for muscle attachment – Does not bear weight • Lateral Malleolus – “Outside” bump of ankle Ankle and Foot Bones • Tarsals – ankle bones • Metatarsals – proximal foot bones – Calcaneus – heel bone • Phalanges - Toes