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HUMAN ANATOMY LECTURE SEVEN SKELETAL SYSTEM ANATOMIC BONE FEATURES General Terms • • • • • • • • Head - enlarged end Neck - constriction (narrowing) between head and body Margin or border - edge Angle - bend Body - main part Condyle - smooth rounded articular surface Epicondyle - near or above condyle Facet - small flattened atricular surface Ridges • Line or linea - low ridge • Crest or cristae - prominent ridge • Spine - very high ridge Projections • • • • Process - prominent projection Tubercle - small rounded bump Tuberosity - knob Trochanter - tuberosities on proximal femur Openings • • • • Foramen - hole Canal or meatus - tunnel Fissure - cleft Sinus or labyrinthe – cavity Depressions • • • • Fossa - depression Notch - depression in bone margin Fovea - little pit Groove or sulcus - deeper, narrow depression DIVISIONS OF THE SKELETAL SYSTEM Axial Skeleton • • • • Skull Hyoid bone Vertebral column Thoracic (rib) cage Appendicular Skeleton • Limbs • Girdles THE COMPLETE SKELETON THE SKULL/CRANIUM Functions • Protects brain • Supports special sense organs • Provides foundation for structures that take air, food, water into body Superior View • Parietal bone - sides • Frontal bone - forehead • Occipital bone - back BONES OF THE SKULL • 22 bones plus 6 auditory ossicles (bones of ear) • Divided into 2 sections: (1) Neurocranium (braincase) - surround and protect brain - parietals, temporals, frontal, occipital, sphenoid, ethmoid bones (2) Viscerocranium (facial bones) - protect major sensory organs: eyes, ears, nose, tongue - provide attachment sites for muscles of mastication, facial expression, eye movement - maxillae, zygomatics, lacrimals, nasals, inferior nasal conchae, mandible POSTERIOR VIEW OF THE SKULL • • • • • Parietal bones – sides of head Occipital bone – back of head Temporal bone - near ears Mastoid process - bump behind ear Occipital condyles – points of articulation between skull and vertebral column • Zygomatic arch - cheekbones LATERAL VIEW OF THE SKULL • Parietal bones • Frontal bone - forehead • Temporal bone - external auditory meatus into eardrum - mastoid process - zygomatic process of zygomatic arch • Maxilla - upper jaw • Mandible - lower jaw - coronoid process FRONTAL VIEW OF THE SKULL • • • • Frontal bone Zygomatic bones Maxillae Mandible - tooth sockets • Nasal bones • Orbits - eye sockets THE ORBIT • • • • • • Sphenoid bone - behind eye Frontal bone Maxilla Zygomatic bone Ethmoid bone - inner eye Lacrimal bone - next to nose NASAL CAVITY • Nasal Septum - divides cavity into right and left halves - perpendicular plate of ethmoid - anterior is hyaline cartilage • Nasal conchae - lateral walls that increase surface area (warm and moisten air) - inferior is separate bone - middle and superior are projections from ethmoid bone PARANASAL SINUSES • Associated with bones of nasal cavity • Function: - decrease skull weight - resonating chambers for voice - secrete mucous to clean out nasal cavity • Named for bones in which they are found: – – – – Frontal Maxillary Ethmoidal Sphenoidal INTERIOR OF CRANIAL CAVITY • Cribriform plate of ethnoid bone - forms floor of olfactory fossa (olfactory nerves pass through foramina of cribriform plate) • Sphenoid bone – floor of cranium (joins cranium and facial bones) • Sella turcica of sphenoid bone - houses the pituitary gland • Foramen Magnum - opening for spinal cord INFERIOR VIEW OF THE SKULL • Foramen magnum • Occipital condyles • Styloid processes – processes off temporal bone for attachment of muscles • Occipital bone • Temporal bone • Zygomatic bone • Maxilla • Spheniod bones BONES OF THE EAR • Malleus • Incus • Stapes HYOID BONE • No direct bony attachment to skull • Attachment point for some tongue muscles • Attachment point for neck muscles that elevate larynx during speech and swallowing VERTEBRAL COLUMN Functions • • • • • Supports weight of head and trunk Protects spinal cord Allows spinal nerves to exit spinal cord Provides site of muscle attachment Permits movement of head and trunk 26 bones in adults, 34 in fetus • 5 fuse to form sacrum • 4 or 5 coccygeal fuse to form the coccyx Regions • • • • • Cervical (7 vertebrae) Thoracic (12 vertebrae) Lumbar (5 vertebrae) Sacral bone (1) Coccygeal bone (1) Four major curvatures • • • • Cervical - anterior Thoracic - posterior Lumbar - anterior Sacral and coccygeal - posterior VERTEBRAE 4 basic parts: 1) body - weight bearing portion 2) arch - surrounds vertebral foramen (spinal cord runs through) - sides are pedicles - lamina make up the roof 3) processes - transverse processes extend laterally from sides of arch - spinous process projects dorsally - articular processes are smooth surfaces where vertebrae meet 4) foramen - vertebral foramen - intervertebral foramen where nerves run through to spinal cord CERVICAL VERTEBRAE • Superior 7 vertebrae • Very small bodies with bifid spinous process and transverse foramina • Atlas - first cervical vertebra - articulates with skull and allows “yes” movement and tilting side to side - no body and no spinous process • Axis - second cervical vertebra - considerable rotation - dens extends into vertebral foramen of atlas - lends to rotation of atlas for “no” THORACIC VERTEBRAE • 12 middle vertebrae • Long, thin spinous processes directed inferiorly • Long transverse processes • Articular facets on transverse processed for connection with ribs (on 1st 10) • Facets on body for articulation with ribs LUMBAR VERTEBRAE • Large, thick bodies • Heavy, rectangular transverse and spinous processes • Superior articular facets face medially and inferior facets face laterally - allows for locking to adjacent vertebrae - limits rotation - adds strength SACRUM AND COCCYX Sacrum - attaches pelvic girdle to • • • • • axial skeleton Fusion of 5 sacral vertebrae Median sacral crest - fusion of spinous processes of 1st 4 Sacral hiatus - spinous process of 5th vertebrae Sacroiliac articulating surface articulates with last lumbar Sacral foramina - intervertebral foramina Coccyx - tailbone • 4 vertebrae fused into a single bone THORACIC OR RIB CAGE Functions • Protects vital organs • Forms semi-rigid structure for respiration Parts • Thoracic vertebrae • Ribs (12 pairs) - superior 7 “true” ribs attach directly to sternum via costal cartilages - inferior 5 “false” ribs - 3 attach to sternum via common cartilage - 2 floating do not attach to sternum - head articulates with transverse facets of thoracic vertebrae STERNUM Divided into 1) Manubrium - articulates with 1st rib and clavicle at jugular notch 2) Body - ribs 3 – 7 articulate 3) Xiphoid process - attachment of diaphragm and rectus abdominus muscles APPENDICULAR SKELETON 126 supporting bones and girdles Girdles • Pectoral/shoulder • Pelvic Upper Limbs • • • • Arm Forearm Wrist Hand Lower Limbs • Thigh • Leg • foot PECTORAL GIRDLE • Scapula (shoulder blade) - acromion process - coracoid process - glenoid fossa -spine - supra spinous fossa • Clavicle (collarbone) - articulates with acromion and manubrium of sternum - acromial (lateral end) - sternal (medial end) HUMERUS (Upper arm) • • • • • • Head - articulates with scapula Greater tubercle - lateral bump Lesser tubercle - medial bump Intertubercular groove Deltoid tuberosity Capitulum - articulates with radius • Trochlea - articulates with ulna RADIUS (Forearm) Lateral bone of forearm • Head - articulates with capitulum of humerus • Neck • Radial tuberosity • Styloid process ULNA (Forearm) Medial bone of forearm • Olecranon process • Trochlear notch - articulates with capitulum of humerus • Head - articulates with carpals of wrist • Styloid process WRIST AND HAND • Wrist - 8 carpals arranged in 2 rows of 4 - all are concave anteriorly • Hand - 5 metacarpals (palm) articulate with distal carpals of wrist - 3 phalanges on each digit (proximal, middle, distal positions) - thumb only has 2 phalanges PELVIC GIRDLE Main features: • Coxal (pelvic) bones and sacrum form a sturdy ring • Pelvis - pelvic girdle and coccyx • Sacrum • Coxae - right and left - ilium - pubis - ischium • Acetabulum - articulates with head of femur • Obturator foramen COXAE • Formed by the fusion of the: 1) ilium - articulates with the sacrum - iliac crest - anterior superior iliac spine 2) pubis - pubic symphysis - superior and inferior pubic ramis 3) ischium - ischial spine MALE AND FEMALE PELVIS FEMUR AND PATELLA Femur (thigh bone) • Head - articulates with pelvis at acetabulum • Neck • Greater and lesser trochanters • Medial and lateral condyles – articulate with tibia Patella (knee cap) • Located within quadricep tendon of anterior thigh muscle (quadricep femoris) also patellar ligament TIBIA AND FIBULA (lower leg) Tibia (shin) • Medial and lateral condyles articulate with condyles of femur • Tibial tuberosity • Medial malleolus (inner ankle) Fibula • Head - articulates with tibia • Lateral malleolus (outer ankle) ANKLE AND FOOT Ankle • 7 tarsals make up ankle and heel • Talus - articulates with tibia • Calcaneus (heel) Foot • 5 metatarsals (sole) • Phalanges (toes) ARCH OF FOOT Distributes weight of body between heel and ball of foot • weight is transferred from the tibia and fibula to the talus • through to the calcaneus • through arch system along lateral side of foot to the ball (head of metatarsals) ie/ footprint in wet sand - imprint of heel, lateral margin, ball and toes