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Page 1: The Spine & Thorax Bones
Cervical Vertebrae: C1 is rostral to C7
Costal Relation: C7 is costal to C1
Vertebral Column: Structure comprising multiple vertebrae.
Page 2: Overview of the Vertebral Column
Often referred to as the spinal column or spine.
Composition: Consists of 33 vertebrae.
Functions:
Supports the trunk.
Protects the spinal cord.
Movements: Includes flexion, extension, lateral flexion, and rotation.
Intervertebral Discs: Found between adjacent vertebrae; primarily composed of water.
Page 3: Spinal Development
Fetal Stage: Vertebral column is C-shaped (convex).
Newborn Stage: Slight flexure occurs between lumbar and sacral areas.
Adult Stage:
Thoracic & sacral curvatures persist from original curve.
Cervical & lumbar concavities are posteriorly directed (lordotic).
These adaptations enhance weight balance on the vertebral column.
Cervical Lordosis: Develops when a child attempts head control.
Lumbar Lordosis: Develops during stages of standing and walking.
Page 4: Structure of a Typical Vertebra
Body: Cylindrical, heavy; made of spongy bone and covered with a thin cortical bone layer.
Pedicles: Two on the posterior side; extend back and connect to laminae, forming the vertebral arch.
Vertebral Foramen: Space between arch and the body that houses the spinal cord.
Vertebral Canal: Formed by successive vertebral foramina.
Transverse Process: Projects laterally where the pedicle and lamina meet; offers attachment for muscles and articulation with ribs.
Page 5: Key Features of Vertebrae
Notches: Inferior and superior vertebral notches of lower pedicle form the intervertebral foramen, through which spinal nerves exit from the vertebral canal.
Zygapophyses (Z joints): Connect pedicle and lamina to form facets for articulation with adjacent vertebrae.
Spinous Process: Midline posterior projection providing muscle attachment.
Page 6: Cervical Vertebrae
Transverse Foramen: Present in each transverse process.
Delicate Bodies: Larger diameter laterally.
Articular Processes:
Superior face upward and backward.
Inferior face forward and downward.
Size increases caudally, with C7 marking the transition to thoracic vertebrae.
Page 7: Atlas (C1)
Articular Facets: Superior facets are concave, articulating with the occipital condyles of the skull; inferior facets flatter and articulate with the axis.
Page 8: Axis (C2)
Dens: Projects upward and articulates with the anterior arch of the atlas, allowing rotation.
Page 9: Thoracic Vertebrae
Articular Facets: Superior and inferior facets are aligned almost in a frontal plane.
Costal Facets: Points of articulation with ribs; spinous processes are long and directed downward.
Page 10: Lumbar Vertebrae
Structure: Massive bodies; heavy and broad spinous processes; shorter laminae than body; long and slender transverse processes.
Page 11: Sacrum & Coccyx
Pelvic Sacral Foramina: Ventral rami of S1-S4 exit through these openings.
Median Crest: Comprises rudimentary spinous processes.
Page 12: Dorsal Sacral Foramina
Function: Dorsal rami of S1-S4 exit here.
Coccyx: Usually composed of 3 or 4 vertebrae, with the first typically separate.
Terminology:
Vertebral foramen = sacral foramen
Canal of sacrum = sacral canal
Sacral hiatus = deficient caudal portion of the canal.
Page 13: Functions of Vertebral Column
Composed of 33 bones:
7 cervical
12 thoracic
5 lumbar
5 sacral
3-4 coccygeal.
Key function: Support for the trunk and spinal cord protection.
Movements: flexion, extension, lateral flexion, and rotation.
Page 14: Intervertebral Discs
Role in weight bearing; not primarily for movement.
Size & thickness vary across different spinal regions.
Structure is related to the spine's curvature.
Most prominent discs between C2-C3 and L5-S1.
Comprised of annulus fibrosus surrounding nucleus pulposus.
Page 15: Annulus Fibrosus & Nucleus Pulposus
Annulus Fibrosus: Inserts into smooth rims on the vertebral bodies’ articular surface.
Nucleus Pulposus: High water content, more posterior than central, acts as a shock absorber and is avascular.
Page 16: Anterior Longitudinal Ligament
Broad fibrous band connecting anterior vertebral bodies and intervertebral discs from sacrum to C1.
Stabilizes joints, prevents hyperextension of the spine, and is involved in whiplash injuries.
Page 17: Posterior Longitudinal Ligament
Narrower and weaker than the anterior ligament, runs posteriorly along the vertebral bodies.
Prevents hyperflexion and posterior protrusion of nucleus pulposus.
Page 18: Zygapophyseal (Z) Joints
Synovial joints between superior and inferior articular processes allow gliding movements.
Orientation in cervical region permits increased flexibility for movement.
Page 19: Ligaments of Intervertebral Joints
Ligamenta Flava: Joins laminae of adjacent vertebral arches and helps maintain spinal curvature.
Interspinous Ligaments: Connect adjacent spinous processes (weak).
Supraspinous Ligament: Strong, supports attached spinous processes.
Page 20: Atlantooccipital Joint
Joint between the skull and C1 allows nodding of the head.
Atlantoaxial Joint: Joint between C1 and C2 facilitates head rotation.
Page 21: Transverse Ligaments of Axis
Hold the dens in position against the anterior arch of the atlas with additional support from the cruciform ligament and alar ligaments.
Page 22: Tectorial Membrane
Extends from the body of the atlas to the occipital bone, covering alar and transverse ligaments.
Page 23: Extrinsic Back Muscles
Divided into superficial (e.g., trapezius, latissimus dorsi, levator scapulae) which help with limb movements and intermediate muscles (serratus posterior) which are primarily proprioceptive.
Page 24: Serratus Posterior Muscles
Superior:
Origin: Ligamentum nuchae, spinous processes of C7-T2/3
Insertion: 2nd-5th ribs
Action: Assists in elevating ribs.
Page 25: Serratus Posterior Inferior
Origin: Spinous processes of T11-L2.
Insertion: 9th-12th ribs.
Action: Draw lower ribs downward and stabilize them.
Page 26: Intrinsic (Deep) Back Muscles
Maintain posture and control spine movements, extending from pelvis to cranium, composed of multiple layers distinguished by fiber direction and length.
Page 27: Splenius Muscles
Splenius Capitis & Cervicis:
Origins: Ligamentum nuchae and spinous processes from C7 & T1-T3/4.
Insertions: Occipital bone and transverse processes of cervical vertebrae.
Actions: Rotate head and assist in extension of neck.
Page 28: Erector Spinae Group
Origin: Posterior sacrum, iliac crest, spinous processes of T11-L5.
Actions: Extends the thoracic vertebral column.
Page 29: Erector Spinae Subgroups
Consists of three groups moving from largest to smallest.
Page 30: Iliocostalis System
Origins: From iliac crest to lower ribs.
Insertions: Lower ribs to transverse processes.
Page 31: Longissimus System
Origins: Common tendon of erector spinae to cervical and thoracic vertebrae.
Insertions: Transverse processes and mastoid process.
Page 32: Spinalis System
Origins: Spinous processes of lumbar and thoracic vertebrae.
Insertions: Upper thoracic and axis spinous processes.
Page 33: Deep Layer: Transversospinalis Muscles
Includes Semispinalis (deep to erector spinae), Multifidus, and Rotators.
Function: Extend and rotate the spine.
Page 34: Semispinalis Muscles
Origins: Transverse processes of thoracic and cervical vertebrae.
Insertions: Occipital bone and spinous processes of cervical vertebrae.
Page 35: Multifidus
This muscle assists in extending the spine bilaterally and rotates the spine unilaterally.
Page 36: Rotatores
Short muscles that help in rotation and extension of the spine.
Page 37: Quadratus Lumborum
Origin: Posterior iliac crest, Insertion: Last rib and lumbar vertebrae transverse processes; acts to stabilize lumbar region and supports lateral flexion.
Page 38: Lecture Notes Summary
Discussed common muscle groups in various spinal regions:
Cervical Region: Notable flexibility due to disc structure.
Thoracic Region: More restricted movements; rib attachment influences motion.
Lumbar Region: Facilitates flexion and extension, limited by structure.
Page 39: General Anatomy Notes of Muscles
Muscle Fibers: Arrangement and layers contribute to strength and movement.
Longer muscles are superficial; short muscles lie directly against vertebrae.