Anatomy & Histology


Human skull – frontal, lateral, and inferior projections

Schematic representation of section across top of skull, showing membranes (based on plate 769 from Gray’s Anatomy, 1918)

Arousal and consciousness


Major areas involved in controlling movement
Area Location Function
Ventral horn Spinal cord Contains motor neurons that directly activate muscles[94]
Oculomotor nuclei Midbrain Contains motor neurons that directly activate the eye muscles[95]
Cerebellum Hindbrain Calibrates precision and timing of movements[7]
Basal ganglia Forebrain Action selection on the basis of motivation[96]
Motor cortex Frontal lobe Direct cortical activation of spinal motor circuits
Premotor cortex Frontal lobe Groups elementary movements into coordinated patterns[7]
Supplementary motor area Frontal lobe Sequences movements into temporal patterns[97]
Prefrontal cortex Frontal lobe Planning and other executive functions[98]

Language & Voice


Hearing & Balance



Spinal Cord

Spinal cord tracts [Wikimedia Commons]

Spinal Nerve

Actions of the spinal nerves
Level Motor Function
C1C6 Neck flexors
C1T1 Neck extensors
C3, C4, C5 Supply diaphragm (mostly C4)
C5, C6 Move shoulder, raise arm (deltoid); flex elbow (biceps)
C6 externally rotate (supinate) the arm
C6, C7 Extend elbow and wrist (triceps and wrist extensors); pronate wrist
C7, C8 Flex wrist; supply small muscles of the hand
T1T6 Intercostals and trunk above the waist
T7L1 Abdominal muscles
L1L4 Flex thigh
L2, L3, L4 Adduct thigh; Extend leg at the knee (quadriceps femoris)
L4, L5, S1 abduct thigh; Flex leg at the knee (hamstrings); Dorsiflex foot (tibialis anterior); Extend toes
L5, S1, S2 Extend leg at the hip (gluteus maximus); Plantar flex foot and flex toes

Note: Unless otherwise indicated, images are in the Public Domain (for the most part, Wikimedia Commons).