make up natural cara make up make up tutorial make up korea make up minimalis make up artis make up mata belajar make up make up wardah alat make up makeup forever indonesia makeup artist jakarta tips make up barbie make up natural make up make up wajah make up pesta make up syahrini makeup mata makeup minimalis peralatan make up make up cantik make up mac make up kit jual make up make up sederhana perlengkapan make up gambar make up vidio make up cara makeup minimalis wardah make up make up pac make up glamour cara memakai makeup make up panggung harga make up make up modern make up alami make up dasar pixy make up make up muslimah make up oriflame make up jepang makeover cosmetic make up ultima make up sariayu grosir make up makeup fantasi makeup pesta tas makeup langkah make up make up pria make up malam alat makeup tahapan make up produk make up shading make up mak up make up kebaya make up jilbab make up inez make up simpel contoh make up cara ber makeup makeup wajah tanpa make up make up terbaru toko make up mac makeup indonesia make up soft urutan make up trik make up makeover makeup brand gusnaldi make up paket make up panduan make up jual makeup brush make up bagus alat2 make up make up gusnaldi aplikasi make up alat alat makeup dasar make up inez make up peralatan makeup make up wanita make up berjilbab make up tebal sejarah make up make up maybeline make up branded make up siang tata cara makeup reseller make up make up muslim make up maybelin warna make up tips make up artist rias make up make up mata make up artis belajar make up make up artist kursus make up kuas make up make up forever indonesia jual make up mac indonesia make up make up artist indonesia harga make up forever jual make up online make up pac make up forever jakarta make up oriflame jual make up forever make up online shop indonesia harga make up sekolah make up grosir make up harga make up maybelline jual make up murah make up terbaru mak up mac make up indonesia sofia make up make up kit murah mac makeup indonesia produk make up jual make up kit make up store indonesia make up forever academy jakarta toko make up online jual make up set jual make up mac make up beauty jual make up branded produk make up mac make up forever harga make up mac indonesia produk make up artis jual make up palette produk make up forever make up palette murah before after make up pengantin before after make up sendiri before n after hasil makeup contoh make up karakter contoh riasan pengantin before n after harga make up wisuda harga make up artist harga make up forever make up wisuda rias wisuda di jogja Daftar harga make up forever daftar harga make up mac daftar harga kosmetik make up forever makeup wisuda harga makeup wisuda kursus make up di yogyakarta kursus make up di jogja kursus make up jogja kursus make up yogyakarta kursus kecantikan di yogyakarta kursus kecantikan di jogja kursus make up artist di jogja kursus rias pengantin di jogja kursus rias di yogyakarta kursus tata rias di yogyakarta rias pengantin muslim jogja jasa kreasi jilbab wisuda yogyakarta jasa rias make up wisuda murah bagus bisa dpanggil tempat make uf di jigja yang bagus rias wisuda murah dan berkualitas yogyakarta pakar kreasi jilbab di jogja make uper natural yogya make up wisuda hijab area jogja make up dan kreasi jilbab yang bagus di jogja jasa make up natural untuk wisuda jogja makeup jogja make up jogja makeup yogyakarta make up yogyakarta makeup wisuda jogja make up wisuda jogja make up wisuda yogyakarta makeup wisuda yogyakarta
Tuesday December 7, 2021

Itty Bitty Muscles

Written by James Rooney, D.V.M.
Category: Hoof Anatomy & Physiology
Hits: 4959

Being an anatomist at heart I became interested in small muscles of the fore and hind legs: the mm. interossei and the mm. lumbricales. Actually, pharmacy I was looking into the innervation of the musculature of the m. interosseus, malady the misnamed: suspensory ligament. Doing so I paid attention to the small interosseous muscles which lie on either side of the proximal end of the suspensory. That twigged me to the lumbricales muscles farther down the leg on the medial and lateral sides. The lumbricales are marginally larger in the hind legs than in the fore.

The usual statement in the anatomy texts is that these are rudimentary muscles with no mechanical function. It is certainly the case that the muscles are small and have no direct mechanical function. That they are rudimentary or vestigial and have absolutely no function may, however, be questioned and, of course, that is precisely what I intend to do! One may think, for example, of the human appendix, long thought to be rudimentary until investigation revealed its immunological importance.

While one tends to think of these small muscles as underdeveloped, it seems equally plausible that they are just the size they ought to be if the horse were still the size of Hyracotherium, 50 million years ago. That is to say that while the cat-size Hyracotherium became larger and larger over the centuries, the lumbricales and interossei simply remained the original size. The digits with which they were associated disappeared, but the muscles remained as they were.


The mm. lumbricales are paired, thin, slender muscles about 3-4 cm. long which lie in the deep fascia between the superficial and deep flexor tendons about 3-5 cm. proximal to the fetlock joint. Their tendons attach to the deep fascia in the general area of the proximal sesamoid bones, Figure 1.

The mm. interossei are paired, slender muscles about 3 cm. long lying on either side of the m. interosseus between the interosseus and the splint bones. Their long, slender tendons insert on an indistinct condensation of deep fascia between the distal end of the respective splint bones and the abaxial aspects of the proximal sesamoid bones, Figure 1.

Figure 1

Figure 1: Lateral view of fetlock region. Modified after Ellenberger and Baum 1927.


The mm. interossei receive nerve branches from the branch of the metacarpal/metatarsal nerve which also innervates the m. interosseus. As will be noted below the branches to the lumbricalis and interossei contain both sensory and motor components. In the foreleg, the nerve branch to the mm. interossei and the m. interosseus arises from the ulnar nerve component of the lateral palmar nerve. These muscles in the hind leg are innervated by a deep branch arising from the lateral plantar nerve.

Gross dissection of the lumbricalis of the foreleg with the assistance of basic fuchsin staining (Coleman’s Schiff reagent) showed the nerve pattern sketched in Figure 2. The proximal branch of the nerve connected with the abundant motor end plates; the middle branch connected to the muscle spindles concentrated along the equator of the muscle; and the distal branch was connected to the tendon end organs at the musculotendinous junction.

Figure 2

Figure 2: Schematic of lumbricales muscle. The red nerve fibers are motor and the blue sensory. The same basic pattern of innervation was found for the interossei.

So far… facts; now the speculation. I have no way to follow up these ideas, but perhaps someone looking for an interesting dissertation in physiology might be interested.

These small muscles are richly innervated, suggesting that they are active. Can one speculate that they are acting as peripheral proprioceptive sensors? With the evolution to monodactyly the muscular bodies of the forearm and gaskin are a long way from the insertions of their tendons. Perhaps the small muscles are better positioned to monitor proprioceptive data arising below the carpus and tarsus. No amount of anatomical speculation can answer that question. There is no help from pathology either since I have not seen or seen reports of damage to the small muscles with subsequent gait abnormality. Anesthesia and or extirpation of the lumbricales with sophisticated monitoring of gait on a treadmill offers one approach. Specific anesthesia or extirpation of the interossei would be quite difficult though the tendons could be transected near the fetlock.

Perhaps clinicians/practitioners who have used local anesthesia for help in diagnosing problems of the proximal end of the interosseus might have some salient observations. I am not sanguine, however, that any of those esteemed individuals will have read this far!

[1] I give fair warning that this essay will be of no practical interest to most of you. It is a rumination for possible consideration by anatomists and scholarly students of horse locomotion.

S5 Box



Fields marked with an asterisk (*) are required.