Bones and Organization of the Postcranial Axial Skeleton (Biology 2230)

NO PHOTOGRAPHY or VIDEOS Bones and Organization of the Postcranial Axial Skeleton Biology 2230 FA24 Lecture 7.0 m....

NO PHOTOGRAPHY or VIDEOS Bones and Organization of the Postcranial Axial Skeleton Biology 2230 FA24 Lecture 7.0 m. iyengar  Axial Skeleton and Regions Cranial / Cephalic Clavicle Clavicle Cervical Scapula Scapula Brachium Thoracic Upper Vertebral limb Humerus Humerus Vertebra Antebrachium Radius Lumbar Ulna Radius Ulna Lumbar Sacral Carpals Carpals Sacral Manus Femoral Phalanges Phalanges Bones of Metacarpals Metacarpals pelvic girdle Femur Femur Patella Lower limb Tibia Tibia Fibular Fibula Fibula *Crual ^notice this *notice this region Fibular ^Sural region is is anterior only posterior only Pes Tarsals Metatarsals Anterior view Posterior view Phalanges Axial Skeleton - Thoracic Cage The ribs, sternum, and thoracic Sternum vertebrae create a cylindrical cage. – Protects the vital organs in the thoracic cavity. Which ones? ribs Heart, lungs – Provides thoracic cavity movement for breathing. How? Expansion and contraction of the ribs by the diaphragm. Bones are made to be flexible enough to allow for the expansion and then recontraction. – Attachment site for neck, back, and shoulder muscles. Why the Thoracic Cage is Bean-shaped. The lower limbs are lateral and in contact with the ground. – Less stability on two limb. – The thorax is “bean-shaped” or wider laterally (side-to-side) to provide stability. The upper limbs are dorsal. – Counterbalances the weight that is ventral from chests, breasts, and beer bellies. The Thoracic Cage Twelve pairs of ribs. – True ribs attach to sternum via an individual costal cartilage – False ribs are not directly attached to sternum. Costal cartilage merges together and then to the last true rib’s costal cartilage. – Floating ribs are not attached to the sternum – Intercostal spaces are gaps between successive ribs, allowing for flexibility during movement and breathing. A Typical Rib Each rib is curved into a C-shape but varies in size. – The shaft is the flat region that makes up most of the rib. The costal groove is the indent on the internal surface that supports nerves and blood vessels. Rib 2 Rib 1 The Vertebrocostal Joints The head, neck, and tubercle of each rib articulates posteriorly with the thoracic vertebrae’s transverse processes. Transverse costal Tubercle of rib facet Tubercle of rib Neck of rib Head of ribs Inferior costal facet Superior costal facet Curve inferiorly The Sternum It is a “T-shaped” bone that is flat and slightly curved. – The manubrium is the superior portion where the clavicle and ribs 1-2 articulate. – The body is where the costal cartilage of ribs 2-7 articulate and the pectoral muscles attach. – The xiphoid process is the small inferior portion and indirectly attaches costal cartilage to the sternum. Clinical Implications – Why We Study Anatomy Cardiopulmonary Resuscitation (CPR). – Keeps oxygen-rich blood flowing to the brain and other organs until the typical heart rhythm is restored. – Chest compressions of 100 to 120 a minute. – Hand placement is important. Why? NO PHOTOGRAPHY or VIDEOS Joints of the Thorax The sternoclavicular joint allows for the pectoral girdle to articulate with the axial skeleton Sternal end of the clavicle Clavicular notch Of manibrium The costosternal joints Sternum bring the ribs to the Anterior end sternum anteriorly using Of rib hyaline cartilage. Costal cartilage – What type of joint is this? Synchondroses Axial Skeleton – Vertebral column Vertebrae (plural), vertebra (singular) – Protects the spinal cord – Supports the posture – Attachment for back muscles. Allows for flexion, extension, and rotation of the torso – Attachment of the pelvic girdle and lower limbs. – What specific embryonic tissue creates the vertebrae and ribs? The Vertebral Column A series of single vertebrae (24), given a letter that signifies its region and a number that indicates its position. – Seven (7) cervical (C1-7) – Twelve (12) Thoracic (T1-12) Articulate with the 12 pairs of ribs – Five (5) Lumbar (L1-5) – Sacrum a fusion of 5 vertebrae – Coccyx is a short region that can be 2-6 segments Where the pelvic floor musculature attaches. The Vertebral Column It appears “straight” in anterior (ventral) and posterior (dorsal) views. In lateral view vertebral column is a series of curves, from cranial to caudal. – Primary curvatures of the thoracic and sacral regions are present at birth. – Secondary curvatures of the cervical and lumbar regions develop within the 1st yr after birth. Why? – Cervical – to hold up your own head – Lumbar – starts to walk A Typical Vertebra The body is on the anterior aspect of each vertebra and the primary weight-bearing area. The Verterbal foramen is a large opening posterior to the body that surrounds the spinal cord. The spinous process projects posteriorly and provides attachment sites for muscles. The transverse processes project laterally and provide attachment Intervertebral Joints Joints between the vertebral bodies and intervertebral discs support the superior vertebrae and proper alignment. – Do not provide much movement. The intervertebral discs (23) are fibrocartilage discs found between adjacent vertebrae. – Absorbs shock and binds vertebral columns together, giving vertebrae proper alignment. – The nucleus pulposus is what remains of the notocord from embryonic development. Intervertebral Joints Superior and inferior articular facets of Intervertebra successive vertebrae determine foramen movement of the vertebral column. Intervertebral foramen are the lateral spaces between adjacent vertebrae. Superior and inferior articular – A segmental spinal nerves pass through processes each foramen on their way toward the body. Eight (8) pairs of cervical Twelve (12) pairs of thoracic Five (5) pairs of lumbar Five (5) pairs of sacral One (1) pair of coccygeal Clinical Implications – Why We Study Anatomy Herniated (prolapsed) disc or a slipped disc. The middle portion of the disc Presses against the (nucleus pulposus) slips away spinal nerve cord, from the outer fibrous portion. resulting in pain Why does this result in pain? Treatments include exercise, heat therapy, painkillers, or removal. NO PHOTOGRAPHY or VIDEOS Comparison of the Vertebrae Breakfast at 7am Lunch at 12pm 5 Dinner at 5pm Comparison of the Vertebrae You are not expected to be able to recognize each vertebra (C2 from C3 or T1 from T5), but you should know what region (cervical, thoracic, lumbar) it belongs to and how to place them in order. – You should be able to recognize the atlas (C1) and axis (C2) Cervical Vertebrae (C2-C7) Smallest, lightest vertebrae with an oval-shaped body. The vertebral foramen is large and triangular. The spinous process is short, projects directly posteriorly, and is usually split (bifid), except C7 The Transverse Foramen is found within the transverse process it allows for the passage of the vertebral artery and vein. Atlas (C1) Has no spinous process Has no body The superior articular facet is deeper than the inferior articular facet. What does it look like? Ass end of a jet yoda Stewie Axis (C2) What does it look like? Leviathan (Subnautica) Dens is a large Kaiju superior projection that articulates with the axis. Joints of the Head The atlanto-occipital joint is between the superior articular facets of the atlas and occipital condyles. Occipital condyles – Allows for flexion/extension of the Superior head. articular – Shaking your head to indicate YES facet The atlanto-axial joint is between the Atlas atlas and the dens. Dens – Allows for Rotation of the head. – Shaking your head to indicate NO Thoracic Vertebrae (T1-T12) Are larger than cervical vertebrae with a heart shaped body. The vertebral foramen is circular The spinous processes is long and points inferiorly. Costal facets are the three points of articulation with the ribs for the vertebrocostal joints. Lumbar Vertebrae (L1-L5) Largest and heaviest vertebrae to support the weight of the trunk, arms, and head. Large, kidney shaped bodies. Thick, flat spinous processes that point posteriorly. Vertebral foramen have a flattened triangle shape. The cervical and lumbar regions have the greatest potential flexion/extension of the torso. The Sacrum The sacral canal is the opening continuous with the vertebral canal. – It allows for the passage of the spinal nerve to the lower limb. Sacral foramina (smaller foramen) are the 4 pairs of holes found on either side of the median sacral nerves – Serve as the passageway for spinal nerves to the lower limb. The auricular surface on the lateral surface articulates with the aricular Sexual Dimorphism of the Sacrum Female Male Short and wide Long and Narrow Curves posterior Curves Anterior (backwards) Check your understanding List all the joints associated with the torso. What bones and bone parts come together to create each of the joints you listed? Compare the atlas, axis, and the other cervical vertebrae. Compare the cervical, thoracic, and lumbar vertebrae. You are out on a paleontology dig and come across a sacrum. What features would you used to determine if it was from a male or female? A single vertebra is place on a desk for you to identify. What features would you use to determine if it from the cervical, thoracic, or lumbar region? Check your understanding The T11 and T12 vertebrae look very similar to the L1 and L2 vertebrae. How would you distinguish them from each other? The C7 vertebra looks very similar to the T1 vertebra. How would you distinguish one from the other? Describe the development of the axial skeleton? What specific embryonic structure is it derived from? Is it segmental or trans-segmental? Created via endochondral or intramembranous ossification? Compare the number of cervical vertebrae to the number of cervical nerves, are they the same? Why or why not? What joints allow you to use your head to indicate “yes” or “no”? Which vertebral curvatures are formed after birth? Why? Check your understanding Why is the rib cage wider laterally than the anterior/posterior direction? What distinguishing features will help you determine rib one and two? Compare the three different types of ribs. Where is each located in the rib cage. What are the three parts of the sternum? Why is proper hand placement over the sternum during CPR important? During heart surgery should the surgeon cut through the sternum or costal cartilage? Explain why.