Spinal Cord branches
Come off of the spinal cord as a Dorsal root (6-8 rootlets) and Ventral root (6-8 rootlets) 31 total spinal nerves.
- Sensory - Afferent
- Motor - Efferent
- Dorsal - Afferent
- Ventral - Efferent
Dorsal Root and Ventral root combine to form Dorsal root ganglion. This becomes/is Spinal nerve and Dorsal/Ventral rami branch off later.
Area of skin innervated by sensory fibers of a single spinal nerve. There is considerable overlap between adjacent dermatomes.
Paired bundle of nerve fibers that are situated on both sides of the vertebral column. They run longitudinally down the vertebral column from the base of the skull to the coccyx where they join together at the ganglion impar.
Important part of innervating autonomic nervous system. Involuntary muscle control etc.
Throught the ganglia, it innervates various motor muscles.
Sympathetic Chain Ganglia
They deliver motor innervation to the dilator pupillae (muscle that dilates iris), arrectorpili muscles (muscles attached to hair follicles that cause the hairs to stand upright - we learned about these in the skin module), sweat glands, suprarenal medulla, heart, respiratory system, and the digestive system.
Thoracic Dorsal Spinal Rami
supply sensory innervation to the skin overlying the thoracic spinous processes. They supply motor innervation to the semispinalis thoracis, multifidus, levatores costarum, longissimus thoracis, iliocostalis cervicis, and interspinales, which are muscles of the spine.
Ventral Spinal Rami
contribute to the lower trunks (with ventral rami of C8) of the brachial plexus and the anterior and lateral cutaneous branches.
The ventral spinal rami supply sensory innervation and are distributed along the anterior and lateral cutaneous branches. They supply motor innervation to the muscles of the upper limb (via brachial plexus).
The Intervertebral Discs
designed to separate and support the vertebrae.