The bones of the axial skeleton

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Section 1: Axial Skeleton Forms longitudinal axis of body Includes: Skull and associated bones Thoracic cage Vertebral column Various supplemental cartilages Typically 80 bones

Transcript of The bones of the axial skeleton

The bones of the axial skeleton
SKELETAL SYSTEM 206 Cranium 8 APPENDICULAR SKELETON (see Section 2) Skull 126 Face 14 Skull and associated bones 29 Auditory ossicles 6 Associated bones Hyoid 1 AXIAL SKELETON Costal cartilages (cartilages of ribs) 80 Sternum 1 Thoracic cage 25 Ribs 24 Intervertebral discs (cartilage) Vertebrae 24 Vertebral column 26 Sacrum 1 Coccyx 1 Figure 7 Section 1 The Axial Skeleton Figure 7 Section 1 1 Section 1: Axial Skeleton
Forms longitudinal axis of body Includes: Skull and associated bones Thoracic cage Vertebral column Various supplemental cartilages Typically 80 bones Module 7.9: Vertebral column
Consists of 26 bones (24 vertebrae, 1 sacrum, 1 coccyx) Functions Provides a column of support Transfers weight to lower limbs Protects spinal column Helps maintain upright position Module 7.9: Vertebral column
Spinal curves Primary (before birth) and secondary (after birth) Cervical curve (secondary) Develops as infant learns to balance head on vertebrae Thoracic curve (primary) Accommodation of thoracic organs Lumbar curve (secondary) Develops with ability to stand to balance trunk over limbs Sacral curve (primary) Accommodates abdominopelvic organs The spinal curves and vertebral regions in the adult vertebral column
Primary curves develop before birth, and secondary curves after birth. Regions are defined by anatomical characteristics of individual vertebrae. C1 C2 Cervical curve (a secondary curve) C3 C4 Cervical (7 vertebrae) C5 C6 C7 T1 T2 T3 T4 T5 Thoracic curve (a primary curve) T6 T7 Thoracic (12 vertebrae) T8 T9 T10 T11 T12 Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences L1 L2 Lumbar curve (a secondary curve) L3 Lumbar (5 vertebrae) L4 L5 Sacral Sacral curve (a primary curve) Coccygeal Figure 5 Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Figure 6 Module 7.9: Vertebral column
Vertebral regions (defined by anatomical characteristics of individual vertebrae) Cervical (7 vertebrae) Thoracic (12 vertebrae) Lumbar (5 vertebrae) Sacral Coccygeal The parts of a typical vertebra Parts of a Vertebra
Articular processes Vertebral arch Vertebral body Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Superior view Figure 8 Module 7.9: Vertebral column
Parts of typical vertebra Articular processes Extend superiorly and inferiorly to articulate with adjacent vertebrae Vertebral body Transfers weight along vertebral column axis Vertebral arch (next slide) Vertebral foramen Formed by vertebral body and arch The parts of the vertebral arch The Vertebral Arch
Spinous process Vertebral foramen Laminae Transverse process Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Pedicles Inferior view Figure 10 Module 7.9: Vertebral column
Characteristics of articulated vertebrae Intervertebral discs Pads of fibrous cartilage found between bodies of adjacent vertebrae Intervertebral foramina Spaces between successive pedicles Passage of nerves and blood vessels Vertebral canal Encloses spinal cord A lateral view of three vertebrae
Pedicle Intervertebral disc Intervertebral foramina Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Vertebral body Vertebral canal Figure 12 Superior articular process Inferior articular process
A posterior view of two vertebrae Articular facet Superior articular process Inferior articular process Figure The vertebral column has four spinal curves, and vertebrae have both anatomical similarities and regional differences Figure 13 Module 7.9 Review a. Name the major components of a typical vertebra.
b.What is the importance of the secondary curves of the spine? c.To which part of the vertebra do the intervertebral discs attach? Module 7.10: Cervical and thoracic vertebrae
Cervical vertebrae Characteristics Smallest of vertebral column Extend from occipital bone to thorax Large vertebral foramen Spinal cord here has many axons connecting to brain Vertebral body is small and light Only supports weight of head A typical cervical vertebra
Bifid spinous process Vertebral foramen Transverse foramen Transverse process Figure There are seven cervical vertebrae and twelve thoracic vertebrae Vertebral body Costal process Figure 16 Module 7.10: Cervical and thoracic vertebrae
First two cervical vertebrae Specialized to stabilize cranium while permitting head movement Atlas (C1) (named after Greek god who holds world) No spinous process No vertebral body Large round vertebral foramen Axis (C2) Prominent dens or odontoid (odontos, tooth) process of body The first two cervical vertebrae: the atlas and the axis Anterior
arch of atlas Atlas Dens (odontoid process) Ligament that enables rotation (as in shaking the head to indicate no) Joint that permits nodding (as in indicating yes) Figure There are seven cervical vertebrae and twelve thoracic vertebrae Axis Posterior arch of atlas Figure 18 A lateral view of the seven cervical vertebrae
prominens Figure There are seven cervical vertebrae and twelve thoracic vertebrae Figure 20 Module 7.10: thoracic vertebrae
Twelve thoracic vertebrae Body of each (moving inferior) is more robust than the one superior due to bearing of increasing weight Each has costal facets that articulate with ribs Characteristics Distinctive heart-shaped body Smaller vertebral foramen Long, slender, inferiorly pointing spinous process Figure 7.10.4 There are seven cervical vertebrae and twelve thoracic vertebrae
22 A typical thoracic vertebra in superior view
Transverse process Spinous process Superior articular facet Vertebral foramen Superior costal facet Figure There are seven cervical vertebrae and twelve thoracic vertebrae Vertebral body Figure 23 A typical thoracic vertebra in lateral view
Superior costal facet Transverse costal facet Vertebral body Spinous process Inferior costal facet Figure There are seven cervical vertebrae and twelve thoracic vertebrae Transverse process Figure 24 Lumbar vertebrae Five lumbar vertebrae
Largest and transmit most weight Characteristics Do not have costal facets Have slender transverse processes Triangular vertebral foramen Module 7.11: Lumbar vertebrae, sacrum, and coccyx
Five fused vertebrae Completely fused by ~2530 years old Module 7.11: Lumbar vertebrae, sacrum, and coccyx
Three to five fused vertebrae Begin fusing about age 2 Module 7.11 Review a.How many vertebrae are present in the lumbar region? In the sacrum? b.What structure forms the posterior wall of the pelvic girdle?We have not gone over this yet but what do you think it would be? c.Why are the bodies of the lumbar vertebrae so large? Module 7.12: Thoracic cage Thoracic cage
Provides bony support to thoracic cavity walls Protects heart, lungs, thymus, and other thoracic cavity organs Attachment for muscles involved in Respiration Maintenance of vertebral column position Movements of pectoral girdle and upper limbs An anterior view of the thoracic cage
Jugular notch T1 1 2 3 Sternum Manubrium 4 5 Ribs Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Vertebrosternal ribs (ribs 17) 6 Body 11 T11 Vertebrosternal ribs (ribs 810) 7 T12 12 8 9 Floating ribs (ribs 11 and 12) Xiphoid process 10 Costal cartilages Figure 30 Module 7.12: Thoracic cage Thoracic cage components Ribs
Very mobile and flexible bones Types Vertebrocostal ribs (ribs 17) Connect to sternum via individual costal cartilages Vertebrochondral ribs (ribs 810) Connect to sternum via shared costal cartilages Floating ribs (ribs 11 and 12) No connection to sternum Also known as vertebral ribs Module 7.12: Thoracic cage Thoracic cage components (continued)
Sternum Forms anterior midline of thoracic wall Three regions Manubrium (superior portion that articulates with clavicles and first pair of ribs) Body (attaches inferiorly to manubrium and to ribs 7) Xiphoid process (smallest, most inferior region) Ribs: Head or capitulum (attachment to vertebra)
Angle (bend connecting head to shaft) Shaft (tubular body) Posterior view of a representative rib (ribs 29) Articular facets on head Capitulum Tubercle Angle of the rib Shaft Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Superficial surface Costal groove Figure 33 The action of a typical rib, which can be likened to the movement
of a buckets handle Sternum Ribs Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Figure 34 Superior view of a representative rib
Transverse process Tubercular facet Superior articular facet Transverse costal facet Figure The thoracic cage protects organs in the chest and provides sites for muscle attachment Inferior articular facet Figure 35 Section 2: Appendicular Skeleton
Consists of bones of the limbs and supporting elements (or girdles) that connect them to trunk 126 bones Pectoral girdle (4) Upper limbs (60) Pelvic girdle (2) Lower limbs (60) The bones of the appendicular skeleton
SKELETAL SYSTEM 206 AXIAL SKELETON 80 Clavicle 2 Pectoral girdle 4 Scapula 2 Humerus 2 Radius 2 Ulna 2 Upper limbs 60 Carpal bones 16 Metacarpal bones 10 APPENDICULAR SKELETON 126 Phalanges (proximal, middle, distal) 28 Hip bone (coxal bone) 2 Pelvic girdle 2 Figure 7 Section 2 The Appendicular Skeleton Femur 2 Patella 2 Tibia 2 Fibula 2 Lower limbs 60 Tarsal bones 14 Metatarsal bones 10 Phalanges 28 Figure 7 Section 2 37 Pectoral (shoulder) girdle Joins arm to trunk
Consists of clavicle and scapula The relationship of the clavicle to adjacent bones Clavicle Jugular not