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Biology 231 Human Anatomy and Physiology Chapter 7 Lecture Outline Divisions of the Skeletal System (total 206 bones) Axial Skeleton (80 bones) – bones arranged around body’s longitudinal axis Skull – cranium and facial bones Spine (vertebral column) Thoracic cage – breastbone and ribs Hyoid and Auditory ossicles Appendicular Skeleton (126 bones) – upper and lower limbs and bony girdles (pelvis, shoulder blades, collar bone) that connect them with axial skeleton Types of Bones – based on general shape Long bones – greater length than width; mainly compact bone with spongy bone in ends; levers for body motion (thigh, leg, arm, forearm, hands and feet, fingers and toes) Short bones – nearly equal length and width; spongy bone except at surface (wrists and ankles) Flat bones – 2 thin layers of compact bone enclosing spongy bone; enclose structures providing protection and provide large surface area for muscle attachment (cranium, breastbone and ribs, shoulder blades) Irregular bones – don’t fit other categories; complex shapes and variable composition (vertebrae, some facial bones) Sesamoid bones (shaped like sesame seed) – develop in tendons where they provide strength to areas of unusual mechanical stress; variable in individuals (kneecaps are largest) (Sutural bones – small bones which may occur within sutures between cranial bones in some individuals) Bone Surface Markings – develop in response to mechanical forces on bone surfaces depressions and openings – result from compressive force; allow passage of soft tissues, form joints fissure – crack foramen – hole meatus – tunnel fossa – pocket or cup sulcus – groove 1 processes – prominences on bones; result from tension (pulling)forces; attachment points for tendons and ligaments, form joints joints – condyle facet head sites of attachment line crest spinous process tubercle tuberosity trochanter epicondyle Vertebral Column (spine) – 26 vertebrae in adult; strong, flexible rod that can flex and extend in 2 planes and rotate around axis; encloses and protects spinal cord; attachment site for head, ribs, pelvic girdle and back muscles Divisions: Cervical vertebrae (7) – neck Thoracic vertebrae (12) – chest Lumbar vertebrae (5) – lower back Sacrum (5 fused vertebrae) – attachment site for pelvic girdle Coccyx (4 fused vertebrae) – tailbone Spinal curvature – primary curve seen in fetus 4 normal curves in adult: thoracic curve – primary curve sacral curve – primary curve cervical curve – secondary to lifting head lumbar curve – secondary to standing upright abnormal curves: kyphosis (humpback) lordosis (swayback) scoliosis – lateral curvature Parts of Typical Vertebra vertebral body – anterior portion; thick disc that bears weight; have intervertebral discs between vertebral arch – extends posteriorly from body and surrounds spinal cord pedicles – form anterior margin of arch laminae – form posterior margin of arch vertebral foramen – contains spinal cord, connective tissue, and blood vessels vertebral canal – formed by all vertebral foramina 2 intervertebral foramina – openings in vertebral canal between 2 adjoining vertebrae; allows passage of spinal nerves processes – 7 total transverse processes (2) – lateral; muscle attachment sites spinous process (1) – posterior; muscle attachment site superior and inferior articular processes (2 of each) – sites of vertebral articulation; joint surfaces called facets Intervertebral Discs (C2-sacrum) – cartilaginous discs between bodies of vertebrae which absorb shock and can compress to allow flexion of the vertebral column annulus fibrosus – outer fibrocartilage ring nucleus pulposus – inner soft, pulpy connective tissue herniated (slipped) disc – annulus fibrosus ruptures and nucleus pulposus herniates, compressing spinal nerve or cord; laminectomy relieves pressure Cervical vertebrae (C1-C7) Atlas (C1) – supports head; ring of bone with large vertebral foramen; articulates with occipital condyles of skull = nodding head Axis (C2) – dens (odontoid process) makes pivot joint with atlas = shaking head no; first intervertebral disc between C2-C3 C3-C7 – small body, large vertebral foramen, superior and inferior articular facets; transverse foramina for vertebral nerves and vessels; spinous processes often bifid (split in 2); C7 (vertebra prominens) – large spinous process Thoracic vertebrae (T1-T12) – large body with facets for articulation with rib heads; long, flat spinous processes directed inferiorly; transverse processes with facets for articulation with rib superior and inferior articular facets Lumbar vertebrae (L1-L5) – largest, thickest body; thick, rectangular spinous processes; articular facets directed medially and laterally Sacrum (S1-S5) – fuse by age 30 base – wide superior end; articulates with L5 apex – narrow inferior end; articulates with coccyx transverse lines – fused bodies median sacral crest – fused spinous processes sacral canal – fused vertebral foramina sacral foramina – nerves and vessels pass through auricular surface – articulates with pelvis (sacroiliac joint) 3 Coccyx (Co1-Co4) – fuse by age 30 coccygeal cornua – dorsal processes attached to sacrum by ligaments; apex points inferiorly in females, anteriorly in males Thoracic Cage – encloses and protects organs of thoracic and upper abdominal cavities; supports shoulder girdle and upper limbs; includes bodies of thoracic vertebrae, sternum, ribs and costal cartilages Sternum (breastbone) – anterior midline 3 parts: manubrium – superior part; articulates with collar bones and costal cartilages of ribs 1 and 2 body – largest, middle part; articulates directly or indirectly with costal cartilages of ribs 2-10 xiphoid process – inferior part; hyaline cartilage that doesn’t fully ossify until about age 40; no ribs attached; attachment site for abdominal muscles CPR done improperly can fracture xiphoid and puncture organs Ribs (12 pairs) – articulate with corresponding thoracic vertebrae true ribs (1-7) – attach directly to sternum via costal cartilages false ribs - don’t attach directly to sternum 8-10 attach to other costal cartilages 11 and 12 (floating ribs) no anterior attachment Parts of Typical Rib: head – posterior end; facets articulate with vertebral body tubercle – articulates with transverse process body – long, curved portion; has groove for nerve & vessels intercostal spaces – spaces between ribs SKULL – consists of 22 bones; forms several cavities; outer surfaces are attachment site for muscles cranium (braincase) – protects brain; inner surface is attachment site for membranes (meninges) facial bones – create cavities containing special sense organs (nasal cavity, eye sockets, mouth); assist in intake of foods CRANIUM – 8 bones; joined at sutures Frontal bone – forehead, roof of orbits, anterior cranial floor frontal squama supraorbital foramen frontal sinuses Parietal bones (2) – sides and roof of cranium sagittal suture 4 Temporal bones (2) – lateral cranium and cranial floor squamous portion zygomatic process – part of zygomatic arch, mandibular fossa of temporomandibular (TMJ) joint external auditory meatus (ear canal) mastoid portion - mastoiditis (inflammation of mastoid air cells) mastoid process styloid process petrous portion – middle and inner ear internal auditory meatus Occipital bone – posterior cranium and cranial floor foramen magnum – spinal cord passes through to brainstem occipital condyles external occipital protruberance – ligamentum nuchae Sphenoid bone – central cranial floor; articulates with all cranial bones sphenoid sinuses sella turcica – hypophyseal fossa (pituitary) greater wings – foramen ovale, foramen rotundum lesser wings – optic foramen Ethmoid bone – cranial floor and nasal cavity lateral masses – ethmoid sinuses, superior and middle superior and middle nasal conchae (turbinates) – circulate air perpendicular plate – nasal septum cribriform plate – olfactory foramina crista galli FACIAL BONES – 14 bones; grow until about age 16 Nasal bones (2) – bridge of nose Maxillae (2) – upper jaw maxillary sinus alveolar margin(process) – alveoli(sockets) for teeth palatine process – hard palate (cleft palate) Zygomatic bones (2) – cheekbones, part of orbit temporal process – part of zygomatic arch Lacrimal bones (2) – medial orbits lacrimal fossa – lacrimal sac (collects tears from eye) Palatine bones (2) – posterioir hard palate Inferior nasal conchae (2) – turbinates Vomer – floor of nasal cavity, part of nasal septum Mandible – lower jaw, only movable skull bone (auditory ossicles excluded) body – alveolar margin(process) ramus (2) – angle mandibular foramen and canal coronoid process mandibular condyle – TMJ joint 5 Hyoid Bone – no bony articulation; suspended from styloid processes by ligaments and muscles; U-shaped; site of attachment for muscles of tongue, pharynx, and neck; supports tongue body – anterior part greater and lesser horns – project posteriorly Auditory Ossicles – tiny bones of middle ear (3 in each); located in petrous portion of temporal bone; to be discussed with special senses SPECIAL FEATURES OF SKULL Sutures – immovable joints between skull bones coronal suture – between frontal and parietal bones sagittal suture – between 2 parietal bones lamboidal suture – between occipital and parietal bones squamous sutures – between parietal and temporal bones Fontanels – in infant; fibrous connective tissue membranes between cranial bones not yet fully ossified; provide flexibility of skull anterior fontanel – largest; between frontal and parietal bones; closes 18-24 months after birth posterior fontanel anterolateral fontanels posterolateral fontanels Paranasal sinuses – cavities in cranial and facial bones lined with mucous membranes continuous with nasal cavity (frontal, sphenoid, ethmoid, maxillary bones) produce mucus; act as resonating chambers sinusitis – inflammation of sinus membranes Nasal septum – midsagittal division of nasal cavity composed of vomer and ethmoid bones and septal cartilage deviated septum – deflected laterally Orbits – eye sockets 7 bones: cranial – frontal, sphenoid, ethmoid facial – palatine, zygomatic, lacrimal, maxillae 5 openings: optic foramen, superior and inferior orbital fissures, supraorbital foramen, lacrimal fossa 6 7