Vet Prep Structural and Functional Biology Axial Skeleton Spring 2024 PDF

Vet Prep Structural and Functional Biology Axial Skeleton Dr. Melissa Kehl Courtesy of Dr. Terri Clark Learning Goals Describe the vertebral formula for the dog. Describe the features of a typical vertebra. Describe the difference between vertebral foramen, vertebral canal, and the intervertebral fo...

Vet Prep Structural and Functional Biology Axial Skeleton Dr. Melissa Kehl Courtesy of Dr. Terri Clark Learning Goals Describe the vertebral formula for the dog. Describe the features of a typical vertebra. Describe the difference between vertebral foramen, vertebral canal, and the intervertebral foramen. Describe the distinguishing features of vertebrae in each region of the body. Describe the joints and ligaments associated with the vertebrae. Describe the articulation of ribs with vertebrae. Define axial muscles and explain the difference between epaxial and hypaxial muscles including their general location and function. Skull and mandibles Vertebrae Ribs Sternum Hyoid apparatus Axial skeleton Vertebral formula for the dog: C7 T13 L7 S3 Ca 20-23 Features of a typical vertebra C7, Caudal view Vertebral body Intervertebral discs are located between adjacent bodies Vertebral arch Consists of pedicles (walls) and laminae (roof) Vertebral foramen surrounded by arch and dorsal surface of body Processes (Dorsal) spinous process Transverse processes – bilateral Articular processes – cranial and caudal pairs Articular process Vertebral canal and intervertebral foramen Vertebral canal Intervertebral foramen Formed by the vertebral foramen Houses spinal cord Intervertebral foramen Located laterally between adjacent vertebrae Spinal nerves and blood vessels course through Intervertebral foramen Vertebral canal Lateral view, thoracolumbar region Cervical vertebrae C1 and C2 are NOT typical vertebrae! Atlas, dorsal view C1 (Atlas) Large transverse processes, referred to as wings No spinous process C2 (Axis) Prominent spinous process Dens articulates with atlas Axis, left lateral view C1 and C2 craniolateral view Joints associated with the Atlas Atlanto-occipital joint Between occipital condyles of skull and the atlas (C1) Allows extension and flexion only (nodding “yes” joint) Atlantoaxial joint Between the atlas (C1) and the axis (C2) Rotary movement along the long axis (“no” joint) www.reddit.com Ligaments associated with the atlas and axis Several ligaments stabilize the atlas and axis. Transverse ligament of the atlas - holds dens against the atlas Cervical vertebrae C3-C6 C5, Craniolateral view More typical Short spinous processes Transverse foramen present in transverse processes of C1C6 for vertebral artery, vein, nerve C7 No transverse foramen Has a costal fovea for articulation with the 1st rib C7, Caudal view Vertebral a. Thoracic vertebrae Long spinous processes Short transverse processes due to articulation with ribs Costal foveae on bodies and transverse processes for articulation with ribs T6, craniolateral view Ribs and Sternum 13 pairs of ribs in the dog 8 sternebrae in the dog Costochondral junction Costal Cartilage Tubercle of rib Rib articulation T4 T5 Head of rib The head of the rib articulates with the body of the thoracic vertebrae cranial to that rib for ribs 1-10. For ribs 1-13, the head of the rib articulates with the body of the same number. The tubercles of the ribs articulate with the transverse processes of the corresponding thoracic vertebrae for all ribs. Transverse process Body Rib 5 Lumbar vertebrae Large bodies Large transverse processes Prominent spinous processes T13 Sacrum Extra processes for muscle attachment You do not need to memorize the names of these processes. Sacrum Fused S1, S2, S3 vertebrae Articulates with ilium The cranial ventral lip of the body is called the sacral promontory Fused transverse processes Sacral foramen for nerves instead of intervertebral foramina (3, 3’) Ventral view Dorsal view Cranial view 1. Sacral promontory 2. Articular surface 3. Ventral (3’ dorsal) sacral foramina 4. Spinous process 6. Vertebral canal 7. Body Caudal/coccygeal vertebrae First few caudal vertebrae look like typical vertebrae and then they become more rod-shaped Hemal arch located on Ca4-Ca6 - Protects tail vessels Ca5 Intervertebral disc ▪ Located between vertebral bodies (except at C1-C2 and in the sacrum) ▪ Fibrocartilaginous structure ▪ Two parts: 1. Anulus fibrosus Outer circumferential collagenous fibers Thicker ventrally 2. Nucleus pulposus Inner gelatinous core ▪ Shock absorber, spreads the load evenly between bones Vertebral ligaments Supraspinous ligament Courses dorsally along the spinous processes of T1 – Ca3 vertebrae Nuchal ligament Cranial extension of the supraspinous ligament Courses between the spinous processes of the axis (C2) and T1 in the dog (more extensive in large animals!) Not present in the cat or pig Nuchal ligament Supraspinous ligament Vertebral ligaments Interspinous ligament Dorsal longitudinal ligament (A) Located on the dorsal surface of the vertebral bodies, ventral to the spinal cord Ventral longitudinal ligament (J) Located on the ventral surface of the vertebral bodies Interspinous and intertransverse ligaments A Intertransverse ligament Broad bands between spinous processes and between transverse processes J