Sacrum and Coccyx.pptx

Sacrum & Coccyx Vertebral Column • Consists of: • Vertebrae • Interve rtebral (IV) discs •4 curvature s: • 2 primary – present at birth; concave anteriorly Erect Standing Position • The line of gravity passes thru the junctions of the curvatures • Preserves the normal curvatures of the vertebr...

Sacrum & Coccyx Vertebral Column • Consists of: • Vertebrae • Interve rtebral (IV) discs •4 curvature s: • 2 primary – present at birth; concave anteriorly Erect Standing Position • The line of gravity passes thru the junctions of the curvatures • Preserves the normal curvatures of the vertebral column • Passes • Posterior to the hip joint • Anterior to the knee and ankle joints • Very little muscular activity is needed in a quiet standing position • Deep back muscles, hip flexors and plantarflexors Sacru m • Wedge-shaped bone • Base is superior • Apex is inferior • Consists of 5 fused sacral vertebrae • Latin for “sacred” • Provides strength and stability to the pelvis • Supports the body weight from the vertebral column • Posterior wall of the true pelvis Sacru m • Anterior or pelvic surface • Smooth and concave • Ala (Latin for wing) • Laterally flared region of the base • Anterior (ventral) foramina • 4 paired foramina • Transmit the ventral rami of spinal nerves S1 – S4 • 4 transverse ridges • Remnants of the intervertebral discs • Sacral promontory • Body of S1 that projects The General Structure of Vertebrae • Body • Supports body weight • Vertebral arch • 2 pedicles • 2 laminae Vertebral foramen •7 • 1 spinous process Processe • 2 superior s articular • • processes 2 2 inferior articular transve processes rse Intervertebral Joints • Joints of the vertebral bodies • Symphyses • Designed for WB and strength • Articulating surfaces of adjacent vertebrae • Connected by IV discs • Facet joints • Planar, synovial joints • Between superior and inferior articular processes of adjacent vertebrae • More detail In Human Sacru m • Sacral promontory S1 • Superior aspect of the body of S1 that projects anteriorly S2 • Sacral canal S3 S4 S 5 Lateral view Midsagittal (cut thru the midline) section • Triangular shaped opening within the sacrum • Continuous with the vertebral canal • Contain spinal nerve roots (cauda equina) • Ventral rami exit thru the ventral foramina • Dorsal rami exit thru dorsal foramina Sacru m • Posterior (dorsal) surface • Rough and convex surface • 4 pairs of dorsal (posterior) foramina • Median sacral crest • Represents fused spinous processes of vertebrae S1 – S4 • Lateral sacral crests • Represents the fused transverse processes of S1 – S5 • Superior articular Sacru m • Sacral hiatus (hio = to yawn) • Upside down V or U shaped opening inferior to the median sacral crest • Where laminae of S5 did not fuse • Sacral cornu (horn) • Boney projections on either side of the sacral hiatus • Auricular surface • Ear-shaped area that Lateral View of Sacrum • Auricular surface • Smooth ear-shaped articular surface • Forms a planar synovial joint with the auricular surface of the ilium • Sacral tuberosity • Roughened area just posterior to the auricular surface • Where interosseous sacroiliac ligament attaches • Massive, very strong Cocc yx • Tailbone • Vestigial remnant of the embryonic tail • Consists of 3-5 rudimentary vertebrae • Wedge-shaped bone • Base located superiorly • Articulates with the sacrum at the sacrococcygeal joint • No weight is transferred • It is a symphysis until middle or old age • Becomes a synostosis when it ossifies Cocc yx • Coccygeal cornua (horns) • Connect to the sacral cornua • By intercornual ligaments sacral angleprocess by the • Transverse of lateral Co1 sacrococcygeal • • S 5 Co 1 Transverse process ligament Connected to the inferior Creates lateral a foramen for S5 spinal nerve, ventral rami • Superficial and deep dorsal sacrococcygeal (Nata l) Spinal Cord • The spinal cord is located in the vertebral canal • The spinal cord ends at the conus medullaris • L1/L2 vertebra level • The dural sac ends at • S2 vertebral level; within the sacral canal • Contains cerebral Dural sac: Spinal Nerves • Cauda equina (horse’s tail) • Group of spinal nerve roots distal to the end of spinal cord • Each spinal nerve branches into: • Ventral rami • Supply muscles and skin of the extremities • Dorsal rami • Supply deep back muscles and skin of the back and gluteal region Coronal section through the pelvis and Posterior View of the Sacrum Left dorsal roof of the spinal canal has been removed. (Dural sac) Dorsal rami of S3 spinal nerve Ventral rami of S4 Superior View of the Sacrum Al a Ala Body of S1 Middle of body S2 Caudal Anesthesia • Epidural (extradural) anesthesia • Delivered thru the sacral hiatus • Provides anesthesia below the umbilicus • Uses: (ligame nt) • Surgery in infants/children/ad ults • Pain management for LE trauma • Sympathetic nerve block for the LE Caudal Anesthesia Cerebral spinal fluid (CSF) Spina Bifida • Congenital condition • Failure of the neural arch to close posteriorly • Can occur at any level of the vertebral column • Sacrum in the photo on the right • The sacral hiatus extends farther superior than normal • There are two prominent ridges instead of just one Lumbosacral Joint L5 L 5 • Articulation between L5 and sacrum • Symphysis • 2 •facet joints Intervertebral • disc Between the articular processes • Ligaments • Lumbosacral • Iliolumbar • Lumbosacral angle • Varies from 130o - 160o Bones of the Pelvis • Sacrum and coccyx • Located posteriorly • Right and left os coxae (hip bones) • Located anterolaterally • Composed of 3 separate bones in childhood • Joined to one another by cartilage (synchondroses) • After puberty the bones begin to fuse together (synostoses) • Iliac tuberosi ty Medial View of the Left Os CoxaIliac • crest Ilium • Superior 2/3s of the os coxa • Articulates with the sacrum at the sacroiliac joint • Smooth auricular surface •• Attachment interosseous Planar synovial joint ligamen sacroiliaciliac tuberosity • Roughened ts • Ischiu m• Posteroinferior • Pubis aspect Auricul ar surface Ischial tuberosi Symphys eal surface • Anteroinferior • Articulates with the aspect at the pubic pubis contralateral symphysis X-ray of the Sacrum • Bone appears white on Xrays • Air and joints appear black on X- rays • Radiolucent • i.e. sacral foramina, sacroiliac (SI) joint, gas in the rectum Al a Ilium • Radiopaque • You see a superimposition of all the bones from anterior to posterior Sacral foram en SI joint C Anterior posterior (AP) radiograph X-ray of the Sacrum L 5 • Radiolucent • Sacral canal • Intervertebral disc (cartilage) • Lumbosacral joint • Sacrococcygeal joint Sacr al cana l S P • Gas in the rectum • Radiopaque (bone) • Sacrum • Sacral promontory (SP) • Coccyx • Not completely fused • L5 vertebra cocc yx Lateral AP X-ray of the Pelvis (AP is anterior to Iliu m posterior) Isc h. P Iliu m