Page 98 - Headlines Histology2024_Neat

• They consist of delicate connective capsule surrounding highly coiled non-
myelinated terminal branches that form a ball-like mass (glomerulus).

• They are sensitive to touch and pressure sensation.
Golgi tendon organs (Neurotendineous spindles)

• They are found at muscle-tendon junctions and are sensitive to tension of
muscles.

• They consist of thin connective tissue capsule surrounding unmyelinated
axon that forms spray-like branches ending in small dilatations.

Ruffini corpuscles

• They are found in dermis, fascia, ligaments and joint capsule.
• They are similar to neurotendinious junction and are sensitive to mechanical

distortion of the limbs.
Neuromuscular spindle (muscle spindle)

• They are large (up to 6 mm long and less than 1 mm in diameter),
encapsulated, lymph-filled, fusiform structures found within skeletal
muscles. Each spindle contains from 2-10 modified skeletal muscle fibers
called intrafusal fibers, in contrast to extrafusal fibers located outside the
spindle.

• Two types of intrafusal fibers are recognized: Nuclear bag fibers: have
dilated non-striated middle zone filled with nuclei. Nuclear chain fibers:
are smaller than nuclear bag fibers and their nuclei are arranged in a single
row.

Two types of sensory receptors are associated with the intrafusal fibers:
1. Annulo-spiral endings: where the non-myelinated endings of large myelinated
sensory fibers are wrapped around the nuclear region of the intrafusal muscle
fibers.
2. Flower-spray endings: of smaller myelinated sensory fibers and are located on
the striated portion of the intrafusal fibers.

98