NSC 4130 Lab

Spinal nerves (numbers & divisions)

8 cervical (lots of connections, wide)

12 thoracic (fewer connections, smallest)

5 lumbar (lots of connections, round)

5 sacral (lots of connections)

1 coccygeal

2 types of tracts

ascending → periphery to spinal cord & brain

descending → cortex to periphery & exterior

DC/ML tract

ascending → decussates at medulls, terminates in VPL thalamus

carries info for fine touch, vibration, proprioception

• fasciculus gracilis (medial) = lower limbs

• fasciculus cuneatus (lateral) = upper limbs

spinocerebellar tract

ascending

carries unconscious proprioceptive info from body to cerebellum

• dorsal = fine coordination of posture, individual muscle movement

• ventral = impulses from lower extremity

spinothalamic / anterolateral tract

ascending

lateral = pain & temp

• injury affects opposite side of body one spinal cord segment below lesion (contralateral)

anterior = light touch

• injury produces little disturbance

corticospinal tracts

descending → 85% decussates at pyramids → voluntary, skilled movement

lateral = primary motor cortex → terminates throughout spinal cord

• movement of contralateral limbs

ventral = primary motor cortex → cervical/upper thoracic spine, doesn’t decussate

• control of bilateral axial & girdle muscles

rubrospinal tract

descending: red nucleus → decussates in ventral tegmentum → terminates in cervical cord

muscle tone

vestibulospinal tract

descending: vestibular nuclei → entire cord (lateral) or cervical/upper thoracic (medial)

lateral: maintain balance

medial: head/neck position

reticulospinal tract

descending: reticular formation → entire cord

pontine = automatic posture/gait-related movements, axial & limb muscles

medullary = automatic posture/gait-related movements

medulla function (4 types)

AUTONOMIC

• cardiac → sympathetic/parasympathetic function

• respiratory → chemoreceptors detect variation of oxygen concentration in blood

• reflexes → vomiting, coughing, sneezing, and swallowing

• vasomotor → baroreceptors, change in blood pressure

where do medulla sensory fibers decussate

obex

pons function (4 types)

AUTONOMIC & info integration

• respiratory regulation

• involuntary actions

• SENSORY: hearing, taste, facial sensations

• MOTOR: eye movement, face expressions, chewing, swallowing, tear/saliva secretion

corticospinal tract (PYRAMIDAL)

motor cortex → spinal cord (LMN in ventral horn)

function: voluntary motor control of limbs & voluntary posture adjustments

corticobulbar tract (PYRAMIDAL)

motor cortex → medulla & pons

function: swallowing, tongue movement, face/jaw muscles

colliculospinal/tectospinal tract

superior colliculus → LMN

function: involuntary head movements

rubrospinal tract

red nucleus → LMN

function: involuntary arm movements, body support

vestibulospinal tract

vestibular nucleus → LMN

function: posture and balance

reticulospinal tract

reticular formation → LMN

function: involuntary motor movements that assist with balance

2 main parts of pons

basilar part of pons

pontine tegmentum