Chapter 12 Spinal nerves & spinal cord
The coccygeal plexus is formed by the anterior rami S4 and S5 and the coccygeal nerves. What area in the body does the plexus service?
Formed by the anterior rami of S4-S5 and the coccygeal nerves. Supplies a small area of skin in the coccygeal region. Medial aspect above the buttocks.
The cervical plexus is formed by the anterior rami C1-C5 and the phrenic nerves are one of the important nerves from the cervical plexuses.
Location: Cervical plexus Function: Runs to diaphragm: responsible for diaphragm contraction in breathing. The brachial plexus is formed by the anterior rami C5-C8 and T1 and supplies the shoulder and upper extremities. The path of the brachial plexus begins with the roots (C5-C8 and T1), then to the trunks, then subdivides into cords and finally nerves.
5 components of a reflex arc. Provide a basic drawing of a reflex arc
The pathway followed by nerve impulses that produce a reflex is a reflex arc. A reflex arc includes: sensory receptor; detects change of stimulus sensory neuron integrating center; process center motor neuron; carry out a response effector; target
A reflex is an automatic, sudden, involuntary, and rapid response to a stimulus. What is a spinal reflex? What is an example of a spinal reflex?
A reflex is an automatic, sudden, involuntary response to a stimulus. We don't think about this. Its innate. EX: patellar reflex, tapped the patellar ligament which causes reflex. When the integration takes place in the spinal cord, the reflex is a spinal reflex.
Discuss the type of stimuli relayed by the fasciculus gracilis and cuneatus as well as the lateral and anterior spinothalamic tracts
Fasciculi cuneatus and gracilis - fine touch and pressure Lateral and anterior spinothalamic tracts - pain, temperature, deep
The lumbar plexus is formed by the anterior rami L1-L4 and supplies the anterolateral abdominal wall, external genitalia, and part of the lower extremities.
Formed by the anterior rami of L1-L4. Supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs. Femoral nerves, obturator nerves. Femoral, transects the thigh. Supplies skin of upper thigh, and the inner leg Obturator, supply the lower leg
The sacral plexus is formed by the anterior rami L4-L5 and S1-S4 and supplies the buttocks, perineum, and lower extremities. What nerve does this plexus give rise to?
Formed by the anterior rami of L4-L5 and S1-S4. Supplies the buttocks, perineum, and lower limbs. Gives rise to the largest nerve in the body- the sciatic nerve. Upon compression, this root cause of much back pain & lower limb spasms
Ascending tracts (sensory) vs. Descending tracts (motor) The name of the tract (root, followed from PNS to CNS, and from CNS back to PNS) often indicates its location in the white matter and where it begins and ends. The white matter contains both sensory and motor tracts.
• Ascending tracts: Carry sensory info to the brain (with three neurons), from receptor to the somatosensory cortex. Consist of: Posterior (Dorsal) Column, Spinothalamic Tracts, and Spinocerebellar Tracts. • Descending tracts: Upper motor neurons (that originate in brain) descend through tracts in spinal cord to synapse in the lateral and ventral horns of gray matter to lower motor neurons. Consist of: Pyramidal System and Extrapyramidal System.
Important nerves that arise from the brachial plexuses are
• Branches off the posterior cord and runs posterior to the surgical neck of the humerus and innervates the deltoid and teres minor muscles and the skin/joint capsule of the shoulder
Spinal nerves C2-C8 (anterior view) provide sensory input from dermatomes from what part of the body?
• C2: back of head; • C3- neck; • C4- collar; • C5: -lateral shoulder; • C6: -lateral forearm and hand (thumb) • C7: -middle of hand; • C8: -medial hand; pinky
Spinal nerves L1-L2 (posterior view) provide sensory input from dermatomes from what part of the body?
• L1-L2: end of the spinal cord located at Conus Medullaris • L1: inguinal area • L2: upper 1/3 of anterior thigh
Spinal nerves S1-S5 (posterior view) provide sensory input from dermatomes from what part of the body?
• S1: -lateral foot (little toe) and proximal posterior calf • S2: -back of thigh and upper calf • S3-S5:-perineum; -saddle, sex organs, butt cheeks
Spinal nerves T1-T12 (anterior view) provide sensory input from dermatomes from what part of the body?
• T1: upper thorax and anterior surface of upper extremity • T2-T12: -produce the intercostal nerves, roughly correspond with ribs • T4: -nipple • T5: inferior angle of scapula • T10: -belly button
