Marrow

MARROW. The soft tissue in the cavities of bones (Job.21.24; Heb.4.12). It is used figuratively of richness (Ps.63.5 kjv) and good things (Isa.25.6 kjv).

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MARROW (מֵחַ, H4671, חֵ֫לֶב, H2693, μυελός, G3678) is found in the cavities of the bones. It produces blood platelets to aid in blood clotting, red blood cells for carrying oxygen, and white blood cells for combating infection. There are two kinds of bone marrow, red and yellow. Red marrow preponderates in childhood and represents a more active phase of blood cell formation. Yellow marrow, characterized by more fat tissue, is increased in the healthy adult (Ps 63:5). The marrow in adults reverts to red marrow following serious blood loss or body stress. The marrow cavity of long bones ends at the joints so that it is completely surrounded by bone cortex. This clear demarcation is referred to in Hebrews 4:12.

International Standard Bible Encyclopedia (1915)

Marrow is the nourisher and strengthener of the bones; it is said to moisten the bones: "The marrow (moach) of his bones is moistened" (Job 21:24). The fear of Yahweh "will be health to thy navel, and marrow (shiqquy, margin "refreshing, Hebrew moistening") to thy bones" (Pr 3:8). Thus, the expression is used figuratively of the things which alone can satisfy the soul: "My soul shall be satisfied as with marrow (chelebh, "fat") and fatness" (Ps 63:5); "In this mountain will Yahweh of hosts make unto all peoples a feast of fat things, a feast of wines on the lees, of fat things full of marrow (memuchayim, particle, plural, Pual of machah), of wines on the lees well refined" (Isa 25:6). In the Epistle to the Hebrews the writer speaks of the word of God, which is "living, and active, and sharper than any two-edged sword, and piercing even to the dividing of soul and spirit, of both joints and marrow" (Heb 4:12).