Author: Kenneth S. Saladin
Edition: Sixth Edition
Publisher: McGraw-Hill Education (2020)
Cervical
Thoracic
Lumbar
Sacral
Cervical Enlargement: Responsible for innervating the arms.
Lumbosacral Enlargement: Responsible for innervating the lower limbs.
Medullary Cone: Tapered end of the spinal cord.
Cauda Equina: Bundle of spinal nerve roots extended beyond the spinal cord.
Terminal Filum: Fibrous extension anchoring the spinal cord.
Dura Mater (Dural Sheath)
Tough, outer layer.
Contains the epidural space.
Arachnoid Mater
Middle layer.
Subarachnoid Space: Contains cerebrospinal fluid (CSF).
Pia Mater
Delicate, inner layer, supports blood vessels to the spinal cord.
Denticulate Ligaments: Anchors spinal cord to vertebrae.
Regions:
Posterior Horn
Lateral Horn (only in thoracic region)
Anterior Horn
Gray Commissure: Connects left and right sides.
Characteristics: Contains few myelinated axons.
Columns (Funiculi):
Posterior Funiculus
Lateral Funiculus
Anterior Funiculus
Contains the myelinated axons; connected by the white commissure.
Ascending Tracts: Carry sensory information to the brain.
Descending Tracts: Carry motor information from the brain.
Decussation: Many tracts cross midline, which means origin and destination are on opposite sides of the body.
Some tract connections remain ipsilateral (same side).
Components:
Epineurium: wraps the entire nerve.
Perineurium: wraps a fascicle of axons.
Endoneurium: wraps around a single axon.
Ganglion: Cluster of cell bodies outside of the CNS.
Total of 31 pairs:
Cervical: C1–C8
Thoracic: T1–T12
Lumbar: L1–L5
Sacral: S1–S5
Coccygeal: Co1
Posterior Dorsal Root: Sensory input.
Dorsal Root Ganglion: Contains sensory neuron cell bodies.
Anterior Ventral Root: Motor output.
Posterior Dorsal Ramus: Innervates deep muscles and skin of the back.
Anterior Ventral Ramus: Larger, innervates front and limbs, gives rise to plexuses, especially intercostal nerves.
Cervical Plexus: Includes innervation of neck and diaphragm (phrenic nerve).
Brachial Plexus: Supplies upper limbs (includes musculocutaneous, radial, median, and ulnar nerves).
Lumbar Plexus: Innervates lower back and legs (includes femoral and obturator nerves).
Sacral Plexus: Supplies lower body, includes sciatic nerve.
Coccygeal Plexus: Innervates lower sacrum and coccyx.
Nerves:
Hypoglossal, Lesser Occipital, Great Auricular, Transverse Cervical, Phrenic Nerve.
Complexity of branches serving shoulder and arm:
Dorsal Scapular, Suprascapular, Musculocutaneous, Median, Ulnar, Radial Nerves.
Important branches include:
Iliohypogastric, Ilioinguinal, Genitofemoral, Obturator, Femoral Nerves.
Key Nerves: Sciatic nerve (Common Fibular and Tibial branches), pudenal nerve.
Dermatome: Area of skin innervated by specific spinal nerve.
Maps show the skin areas corresponding to spinal nerves.
Paraplegia: Paralysis of both lower limbs (lesions from T1 to L1).
Quadriplegia: Paralysis of all four limbs (lesions above C5 requiring ventilation support).
Hemiplegia: Paralysis on one side of the body, often due to stroke.
End of Chapter 14: Comprehensive overview of the anatomy and functions of the spinal cord and spinal nerves.