What Is the Anterior Horn?

Anterior horn: The enlarged part of the front of the gray matter on each side of the spinal cord is called the anterior horn. The anterior horn contains motor cells and other small cells.

Anterior horn: The enlarged part of the front of the gray matter on each side of the spinal cord is called the anterior horn. The anterior horn contains motor cells and other small cells.

Chinese name

Front angle

Foreign name

tool orthogonal rake

Category

theorem

Big small

The larger the rake angle, the sharper the tool

Front angle overview:

1. Fetal spinal cord anterior horn motor neurons:

Fetal spinal cord anterior horn motor neurons include cell nuclei, nucleoli, Golgi complex, rough endoplasmic reticulum, free ribosomes, axons, microfilaments, and synapses.

2. Spinal anterior horn cells:

Spinal anterior horn cell line is a part of spinal cord cells. There are many larger motor cells in the anterior horn of the spinal gray matter. The axis of this cell protrudes from the anterolateral groove, forms the anterior root, and reaches the skeletal muscle directly. The anterior horn cells are divided into two groups: the inner group is small, which governs the intrinsic muscles of the back, and is found in the full length of the spinal cord; the outer group is large, which controls the muscles of the anterior, lateral and limbs of the body. If the anterior horn cells are damaged, the muscles dominated by them are paralyzed, showing muscle tension loss and muscle atrophy. Polio is caused by a virus that attacks these cells.

Anterior anatomical structure:

Anterior horn: The anterior horn of gray matter is mostly composed of the cell body group of multipolar motor neurons, including alpha motor neurons, gamma motor neurons, and many intermediate neurons. The anterior horn motor neurons are divided into two groups, the medial group is called the medial nucleus, but it is smaller and governs the muscle movements of the trunk; the lateral group is called the lateral nucleus, which is relatively large and mainly governs the muscle movements of the limbs.

The neurites of the anterior horn motor cells exit the spinal cord through the anterolateral groove, forming the anterior root of the spinal nerve.

Spinal gray matter anterior horn motor cells are the primary centers of trunk and limb skeletal muscle reflexes and are the lower motor units of the pyramidal conduction channel. They are the last link of the various reflex arcs in the spinal cord, the final road. Therefore, when the front horn motor cells are damaged, all reflex activity disappears.

The classification and morphological structure of the anterior horn

The anterior horn contains motor cells and other small cells. Motor cells are also called anterior horn motor cells, including large alpha cells and small gamma cells. The axis of the anterior horn motor cells protrudes from the anterolateral sulcus and forms the anterior root, which constitutes the body movement component of the spinal nerve. They directly reach the skeletal muscles and govern the movement of skeletal muscles. Alpha cells are large multipolar nerve cells. Their axons account for about two-thirds of the anterior root motor fibers, and they are distributed to the fusiform muscle fibers of the skeletal muscle, which mainly transmit impulses of voluntary movement. Gamma cells are small multipolar nerve cells. Scattered between alpha cells, their axons account for about 1/3 of the anterior root, and they are distributed to the intrafusal fibers of skeletal muscles, which play an important role in maintaining muscle tension.

Anterior horn motor cells can be roughly divided into two groups, the inside and the outside. The medial group, also called the medial nucleus, is smaller and can be divided into two groups, the anterior and posterior group. They can be seen almost over the entire length of the spinal cord and control the muscles of the trunk. The lateral group, also called the lateral nucleus, is larger and can be divided into several groups. The lateral nucleus is not seen in the thoracic spine, and the neck and lumbar swollen areas are the most developed, mainly dominating the muscles of the limbs. The medial motor cells in the anterior horn dominate the muscles near the midline, and the lateral cells dominate the distal muscles of the limb. Specifically, anterior horn cells dominate the trunk muscle, shoulder strap or hip muscle, gluteal or thigh muscle, forearm or calf muscle, hand muscle or foot muscle in order from the inside to the outside. The cells that govern the extensors of the limbs line the periphery of the anterior horn, while the cells that govern the flexors are arranged deep inside them.

Anterior horn related diseases:

Sequela of anterior poliomyelitis:

Anterior poliomyelitis is an acute infectious disease caused by a group of neurotropic viruses. The virus has particular affinity for the anterior horn of the spinal cord and some motor nuclei of the brainstem. Neurons of the anterior horn are necrotic and lose motor control. Not all patients remain paralyzed, only a small percentage remain. Due to the use of oral vaccines, the incidence has been greatly reduced in China in recent years, but the deformity cases left over from the past are still routinely learned by orthopedic workers. Chronic sequelae can be treated with orthopedic surgery for the purpose of: correcting soft tissue contractures; using muscle (tendon) displacement and stabilization surgery to improve function and correct deformities; correcting unequal lengths of lower limbs