<< Chapter < Page Chapter >> Page >

Appendicular control

The lateral corticospinal tract    is composed of the fibers that cross the midline at the pyramidal decussation (see [link] ). The axons cross over from the anterior position of the pyramids in the medulla to the lateral column of the spinal cord. These axons are responsible for controlling appendicular muscles.

This influence over the appendicular muscles means that the lateral corticospinal tract is responsible for moving the muscles of the arms and legs. The ventral horn in both the lower cervical spinal cord and the lumbar spinal cord both have wider ventral horns, representing the greater number of muscles controlled by these motor neurons. The cervical enlargement    is particularly large because there is greater control over the fine musculature of the upper limbs, particularly of the fingers. The lumbar enlargement    is not as significant in appearance because there is less fine motor control of the lower limbs.

Axial control

The anterior corticospinal tract    is responsible for controlling the muscles of the body trunk (see [link] ). These axons do not decussate in the medulla. Instead, they remain in an anterior position as they descend the brain stem and enter the spinal cord. These axons then travel to the spinal cord level at which they synapse with a lower motor neuron. Upon reaching the appropriate level, the axons decussate, entering the ventral horn on the opposite side of the spinal cord from which they entered. In the ventral horn, these axons synapse with their corresponding lower motor neurons. The lower motor neurons are located in the medial regions of the ventral horn, because they control the axial muscles of the trunk.

Because movements of the body trunk involve both sides of the body, the anterior corticospinal tract is not entirely contralateral. Some collateral branches of the tract will project into the ipsilateral ventral horn to control synergistic muscles on that side of the body, or to inhibit antagonistic muscles through interneurons within the ventral horn. Through the influence of both sides of the body, the anterior corticospinal tract can coordinate postural muscles in broad movements of the body. These coordinating axons in the anterior corticospinal tract are often considered bilateral, as they are both ipsilateral and contralateral.

Watch this video to learn more about the descending motor pathway for the somatic nervous system. The autonomic connections are mentioned, which are covered in another chapter. From this brief video, only some of the descending motor pathway of the somatic nervous system is described. Which division of the pathway is described and which division is left out?

Extrapyramidal controls

Other descending connections between the brain and the spinal cord are called the extrapyramidal system    . The name comes from the fact that this system is outside the corticospinal pathway, which includes the pyramids in the medulla. A few pathways originating from the brain stem contribute to this system.

Questions & Answers

the inflammation of spinal cord is called
Francis Reply
TM partial transver myelitis
Ayan
Transverse myelitis
Amit
transverse mylitis
Gopi
T M means transeverse myelitis
Ayan
what is anatomy
Bruce Reply
is the study of human structure or various parts of the body
Adoma
What is the chordae tendineae and where is located? Where is the Aorta located?
Sovilace Reply
What is the meaning of aponuerosis
Veronica Reply
a sheet of pearly white fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment.
Hassan
example of epitheliam tissue
Nirob Reply
what is systemic anatomy
Friday Reply
it's a study of organ structure
Amarachi
definition of anatomy and physiology
Kapil Reply
in anatomy we study about structure of human body........ in physiology we study about function
Zahid
Explain the anatomy
Junaid
structure of heart
Anusha
explain biology
saviour
biology is the science of life. biologists study the structure, function, growth, origin, evolution and distribution of living organisms.
Kadence
how is albino affected
Ujam Reply
what are the important stuff in the papillary layer
Ujam
Melanie's is responsible for the change in the color of the skin
Ujam
what happened when they are badly severed
Ujam
what happened when they are badly severed
Ujam
Examples of glial cells?
Nesh Reply
glial cell s help in the attractive foces of motion in the cellular network
Ujam
What is glial cell?
Esther
what is gland
Nirob
a gland is a group of cells or group of similar cells that secretes substances
Veronica
what is homeostasis
Laura Reply
homeostasis- The ability to maintain relatively stable internal conditions even though the outside world changes continuously. i,e, maintaining normal values in your body such as Adequate blood levels,blood pressure, heart activity and blood pressure.
Williams
thank you
Laura
Give atleast three reasons to study anatomy and physiology
George Reply
It helps to know about the body structure properly and administer proper care for the patient
Opeyemi
what's augmentin
Aphet Reply
augmentin is a type of combination antibiotic.
wintana
Can you explain to Heart anatomy in details please?
Handren Reply
definition of anatomy and physiology
Sardar Reply
Anatomy is the study structure of the body while physiology is the study of function of the body
Ayan
What is a dorsal cavity?
John Reply

Get the best Anatomy & Physiology course in your pocket!





Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask