Growth and development of sheep

Transcription

1 New Zealand Journal of Agricultural Research ISSN: (Print) (Online) Journal homepage: Growth and development of sheep P. D. Fourie To cite this article: P. D. Fourie (1962) Growth and development of sheep, New Zealand Journal of Agricultural Research, 5:1-2, , DOI: / To link to this article: Published online: 06 Jan Submit your article to this journal Article views: 275 View related articles Citing articles: 9 View citing articles Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 20 December 2017, At: 15:54

2 190 TECHNOLOGY GROWTH AND DEVELOPMENT OF SHEEP I. A carcass dissection technique By P. D. FOURIE Ruakura Animal Research Station, Department of Agriculture, Hamilton * (ReceitJed 23 January 1962) ABSTRACT A dissection technique for the study of sheep carcasses is described. A series of photograps taken at various stages during the dissection process shows the position of the different muscles. Illustrations of the muscle groups from different regions of the body show the shape and relative size of individual muscles. An attempt has been made to describe the location of each muscle to assist in its easy recognition. This paper is the first of a series concerning growth and development in sheep. lntroduction The quality of a carcass on any market, or when used in experimental work, is dependent fundamentally upon its relative proportions in terms of bone, muscle, fat, and offals. It has been clearly shown that with increase in liveweight the relative development in the proportions of the different parts of the body and its principal tissues is not the same. The value of a meat carcass at any stage depends mainly on the differential growth and development that has taken place within the body. Differences in rate, order, and extent of development of particular parts and tissues are responsible for the variation in form, in anatomical and chemical composition, and in conformation of animals of different weights and of different breeds. The growth pattern of an animal is further influenced by heredity and environmental factors. It is thus desirable that the general trends of growth of the different parts and tissues of an animal body should be known, in order to select the best breeding material, or to plan sound experimental trials. * Seconded from the Division of Animal Husbandry and Dairying, Department of Agricultural Technical Services, Pretoria, South Africa. N.Z. f. agric. Res. 5:

3 P. D. FOURIE 191 In studying the growth and development of farm animals, many workers have made use of various dissection techniques in the process of separating the different main tissues of the body (Hammond 1932; Palsson 1939, 1940; McMeekan 1940, 1941; Walker and McMeekan 1944a, b; Joubert 1956; Walker 1961). The importance of fat lamb production in many countries and the important role that sheep playas experimental animals emphasizes the necessity for more fundamental knowledge of the anatomy of these animals. In order to study growth and development in sheep on a sound scientific basis, an anatomical dissection method has been applied. The initial study in which it has been used concerns the growth and development of Romney, South Down, and South Down X Romney ewes. Results of this work will be published in due course. The object of this paper is to describe the technique used. Basically, the method follows that described by Walker (1961) for cattle, but an attempt has been made to provide more specific details regarding the origin and insertion of individual muscles. To achieve this, reference has been made to various published texts (Sisson and Grossman 1940; May 1955), and the material colla ted. DISSECTION PROCEDURE The method involves the removal of individual muscles and bones, as well as the separation of inter-muscular fat and tendons from them. This is necessarily a time-consuming procedure, and every effort is made to avoid moisture losses. The work is done as quickly as possible and with a minimum of handling-forceps, scalpels, and scissors being used, except where handling is absolutely essential. The carcass and its parts are kept covered with towels which have been soaked in cold water and wrung damp dry. Muscles and bones awaiting cleaning are laid on and covered with damp towels, and placed in stainless steel trays. As soon as a muscle or bone has been cleaned, it is weighed, again covered, and set aside for check weighing at a later stage of the day. The fat, tendon, etc., removed during the cleaning process is weighed at frequent intervals. A sheep carcass (one side) can be completely dissected in about hr. by a team composed of a leader and 2 skilled technicians, assisted by 8 casual workers working from 8 a.m. to 4 p.m. cleaning -muscles and bones. This also includes the time spent at the abattoir to separate and clean the organs, and the time spent on measuring the bones. The technician required to supervise work done by the "cleaning" staff is also placed in charge of weighing. ABATTOIR PROCEDURE Before slaughter the animal is weighed, then confined without food for from 8-24 hr. (depending on age). It is re-weighed immediately prior to killing, which takes place at 3 p.m. the day before dissection. T ext continued on page 203

4 Fig. 2.-The carcass stripped of subcutaneous fat and ready for dissection. I-Trapezius. 2-Brachiocephalicus. 3-Omo-transversarius. 5-Latissimus dorsi. 6A-Superficial Pectoral. 6B-Deep Pectoral. IO-Sterno-cephalicus. lob-sterno-thyro-hyoideus. II-Splenius. 14-0mo-hyoideus. 19-Deltoid. 20-Tensor fasciae antibrachii. 2 I-Infraspinatus. 22-Supraspinatus. 25-Triceps brachii. 2S-Tensor fasciae latae. 29-Biceps femoris. 30-Gluteus medius. 3 I-Semitendinosus. 32-Quadriceps femoris. 33-Gastrocnemius. 35-Lateral extensor. 36- Peroneus longus. 37-Peroneus tertius and long extensor group. 43-Flexor group (hind). 45-Serratus dorsalis posterior. 46-0bliquus abdominis externus. 47-Rectus abdominis (and aponeurosis). 4S-0bliquus abdominis internus. 5S-Scmimembranosus. 61-Longissimus dorsi. 69-Flexor group (fore). 70-Extensor group (fore). Fig. 3.-Carcass with some first-layer muscles remov(;d. 3-0mo-transversarius. 4-Subclavius. 6A-Superficial Pectoral. 6B-Deep Pectoral. 7-Rhomboideus. SB-Serratus ventralis-thoracic part. IO-Sterno-cephalicus. IOB-Sterno-thyro-hyoideus. II-Splenius. 14-0mo-hyoideus. IS-Longissimus capitis et atlantis. 16-Complexus. 19-Deltoid. 20-Tensor fasciae antibrachii. 2 I-Infraspinatus. 22-Suprasphinatus. 24-Teres major. 25-Triceps brachii. 30-Gluteus medius. 3 I-Semitendinosus. 32-Quadriceps femoris. 33-Gastrocnemius. 35-Lateral extensor. 36-Peroneus longus. 37-Peroneus tertius and long extensor group. 4 I-Gemellus. 42- Quadratus femoris. 43-Flexor group (hind). 45-Serratus dorsalis posterior. 46-0bliquus abdominis externus. 47-Rectus abdominis (aponeurosis removed). 4S-0bliquus abdominis internus. 52A-Iliacus (Ilia-psoas major). 5S-Semim~mbranosus. 59-Adductor femoris. 60-Longissimus costarum. 61-Longissimus dorsi. 63-Intertransversales colli. 66-Mulrifidus dorsi. 67-Intercostais. 70-Extensor group (fore). Fig. 4.-The carcass with the shoulder removed. 6A-Superficial Pectoral. 6B-Deep Pectoral. 7-Rhomboideus. 8A-Serratus ventralis-cervical part. 8B-Serratus ventralis-thoracic part. 9-Scalenus dorsalis. IOB-Sterno-thyro-hyoideus. 12-Scalenus ventralis. 14-Omo-hyoideus. 15- Longissimus capitis et atlantis. 16-Complexus. 32-Quadriceps femoris. 33-Gastrocnemius. 37-Peroneus tertius and long extensor group. 38-Tibialis anterior. 39-Gluteus accessorius. 40-Gluteus profundus. 4 I-Gemellus. 42-Quadratus femoris. 43-Flexor group (hind). 44-Serratus dorsalis anterior. 45-Serratus dorsalis posterior. 46-0bliquus abdominis externus. 48-0bliquus abdominis internus. 52A-Iliacus (IIi-psoas major). 58-Semimembranosus. 59-Adductor femoris. 60-Longissimus costarum. 61-Longissimus dorsi. 63-Intertransversales colli. 67-Intercostals. Fig. 5.-Carcass showing deeper muscle layers. SA-Serratus ventralis-cervical part. 8B-Serratus ventralis-thoracic part. 9-Scalenus dorsalis. 12-Scalenus ventrars. 13-Rectus capitis ventralis major. IS-Longissimus capitis et atlantis. 16-Complexus. 34-Soleus. 38-Tibialis anterior. 40-Gluteus profundus. 41-Gemellus. 42-Quadratus femoris. 43-Flexor group (hind). 44-Serratus dorsalis anterior. 43-0bliquus abdominis internus. 50-Rectus thoracis. 51-Transversus abdominis. 52A-Iliacus (Ilio-psoas major). 56- Sartorius. 57-Pectineus. 58-Semimembranosus. 59-Adductor femoris. 60-Longissimus costarum. 61-Longissimus dorsi. 63-Intertransversales colli. 66-Multifidus dorsi. 67-Intercostals. -<.a t-:l 41 ~ ~ ~.,. ;:! ~ ~ '" ~ '" -.. <:> ~ ~ '" ~ <:> - '"' ~ ~ '" :--

5 Fig. 6.-Carcass showing the deepest muscles. 17-Rectus capitis dorsalis major. 18-0bliquus capitis posterior. 38-Tibialis anterior. 40-Gluteus profundus 41- Gemellus. 42-Quadratus femoris. 43-Flexor group (hind) 44-Serratus dorsalis anterior. 50-Rectus thoracis. 51- Transversus abdominis. 52A-Iliacus (Ilio-psoas major). 56-Sartorius. 57-Pectineus. 58-Semimembranosus. 59-Adductor femoris. 60-Longissimus costarum. 61-Longissimus dorsi. 61 A-Longissimus dorsi-cervical part. 63-Inter:ransversales colli. 65-Multifidus cervicis. 66-Miltifidus dorsi. 67-Intercostals. Fig. 7.-Carcass showing medial thigh, sublumbar, and deep neck muscles. N-Ligamentum nuchae. 4-Subclavius. 12-Scalenus,entralis. 18-0bliquus capitis posterior. 28-Tensor fasciae latae. 31-Semitendinosus. 32-Quadriceps femoris. 33-Gastroenemius. 37-Peroneus tertius and long extensor group. 43-Flexor group (hind). 49-Transversus thoraeis. 51-Transversus abdominis. 52-Ilio-psoas major. 52A-Iliacus (Iliopsoas major). 53-Psoas minor. 54-Quadratus lumborum. 56-Sartorius. 57-Pectineus. 58-Semimembranosus. 59-Adductor femoris. 61A-Longissimus dorsi-cervical part. 62-Longus colli. 63-Intertransversales colli. 65-Multifidus cervicis. 66- Multifidus dorsi. 67-Intercostals. 68-0bturators. 71-Diaphragm (cut). 72-Thick skirt (crus muscle). Fig. 8.-Carcass showing the deeper thigh and neck muscles. N-Ligamentum nuchae. 4-Subclavius. 12-Scalenus ventralis. 18-0bliquus capitis posterior. 28-Tensor fasciae lactae. 31-Semitendinosus. 32-Quadriceps femoris. 33-Gastrocnemius. 37-Peroneus tertius and long extensor group. 43-Flexor group (hind). 49-Transversus thoracis. 51-Transversus abdominis. 52-Ilio-psoas major. 52A-Iliacus (Iliopsoas major). 53-Psoas minor. 54-Quadratus lumborum. 56-Sartorius. 57-Pectineus. 58-Semimembranosus. 59-Adductor femoris. 62-Longus colli. 63-Intertransversales colli. 65-Multifidus cervicis. 66-Multifidus dorsi. 67--lntcrcostals. 68-0bturators. 71-Diaphragm (cut). 72-Thick skirt (crus muscle). Fig. 9.-The deepest thigh and neck muscles. N-Ligamentum nuchae. 4-Subclavius. 12-Scalenus ventralis. 18-0bliquus capitis posterior. 28-Tensor fascia" latae. 31-Semitendinosus. 32-Quadriceps femoris. 33-Gastrocnemius. 37-Peroneus tertius and long extensor group. 43.-Flexor group (hind). 49-Transversus thoracis. 51-Transversus abdominis. 52-Ilio-psoas major. 52A-Iliacus (Iliopsoas major). 53-Psoas minor. 54-Quadratus lumborum. 56-Sartorius. 57-Pectineus. 58-Semimembranosus. 59-Ad ductor femoris. 62-Longus colli. 63-Intertransversales colli. 65-Multifidus cervicis. 66-Multifidus dorsi. 67--Intercostals. 68-0bturators. 71-Diaphragm. 72-Thick skirt (crus muscle). ~... '-' 'T1 C C?: -tri >-'- <.0 w

6 Fig. l.- The carcass of a mature R omney ewe. P- Panniculus carnosus muscle.

7 Fig. 2.-The carcass stripped of subcutaneous fat and ready for dissection.

8 Fig. 3.-Carcass with some first-layer muscles removed.

9 Fig. 4.-The carcass with the shoulder removed.

10 Fig. 5.-Carcass showing deeper muscle layers.

11 Fig. 6.-Carcass showing the deepest muscles.

12 Fig. 7.-Carcass showing medial thigh, sublumbar, and deep neck muscles.

13 Fig. B.- Carcass showing the deeper thigh and neck muscles.

14 Fig. 9.-The deepest thigh and n eck muscles.

15 P. D. FOURIE 203 At this stage the leader, a technician, and a casual worker are present. The animal is killed by slitting the throat. Blood is not collected, but sufficient time is allowed for thorough bleeding. The butcher then carefully removes the pelt, the head, and the feet. (With a 7-days-old animal the pelt comes off quite easily without any fat or tissue attached to it, although it is quite difficult to remove cleanly from a newborn lamb). The right hind foot and fore foot are immediately weighed, wrapped in damp towels, and placed in a refrigerator for laboratory dissection. The head pelt is removed and weighed. Before the head and jaw are dispatched with the feet to the laboratory, the eyes, brain, tongue, and pituitary gland are removed, cleaned, and weighed. The organs are removed by the normal dressing procedure. As the body is eviscerated the organs are trimmed of fat and waste before being weighed. All parts of the digestive tract are washed out under cold running water and allowed to drip comparatively dry before weighing. Trimmings are weighed as abdominal fat and waste, thoracic fat and waste, or head waste. Immediately after evisceration the carcass is weighed (this being the "hot carcass weight") then hung on a standard gambel for overnight storage in the refrigerator (34 F). Thus the first stage is completed in approximately It hr. The organs will be fully discussed in a later paper. LABORATORY PROCEDURE At 6.45 a.m. the following morning the leader and 2 technicians commence dissection. After the cold carcass has been weighed, the udder is removed and weighed. The tail is cut off, using the standard butcher's cut which follows up the posterior border of the sacro-sciatic ligament and divides the first coccygeal vertebra from the last sacral vertebra. Subcutaneous fat from around the tail head is removed, that from the right side weighed, and the tail weighed and discarded without further dissection. The pelt is removed from the feet, and the bones are separated for cleaning. The skull, jawbone, and hyoidbone are scraped as clean as possible, but no attempt is made to differentiate between various tissues. All the soft tissues from these head bones arc collected and weighed as "head waste." At this stage the kidneys, kidney fat, adrenals, and diaphragm are removed. The above-mentioned parts are included in the cold carcass weight. The carcass is then "soft sided." This is done by carefully cutting the soft tissue of the left half away from the vertebral column, starting well to the left side in the crutch and detaching the head of the femur from the pelvis. The cut is then made towards the ribs, so that the whole of the vertebral column remains undamaged with the right half of the carcass. The ribs are cut through about 2 in. from the vertebrae, and the left front leg and shoulder cut off. By "soft siding," the carcass is rendered much easier to handle. It can be turned over at any stag-e to remove sub-lumbar muscles, the medial muscles of the thigh, and those muscles which are attached inside the rib cage. Fig. 1 shows the "soft sided" carcass ready for dissection. In this case the head was left on to show the points of attachment of the neck muscles.

16 204 GJ'owth and development of sheep. 1. Fig. 10.-Shoulder-Iateral view. 22-Supraspinatus. 25-Triceps brachii. 26-Biceps brachii. 70~-Extensor group (fore). 73-Teres minor. Fig Shoulder-medial view. 20-Tensor fasciae antibrachii. 22-Supraspinatus. 23-Subscapularis. 24- Teres major. 25-Triceps brachii. 26-Biceps brachii. 70-Extensor group (fore).

17 P. D. FOURIE 205 The first step in the dissection process is to take off the Panniculus carnosus muscle (P). After its removal, subcutaneous fat, which includes the fat found directly under this muscle, must be stripped off. It is amassed in cold damp towels and weighed at intervals. Fig. 2 shows the stripped carcass ready for further dissection. In some cases where the work involved does not seem warranted for the slight additional information gained, closely related muscle groups are not separated, and particular reference to these muscles will be made later. The work of breaking down the body can proceed simultaneously on the fore and hind ends. It is difficult to give any specific order for removal of the muscles, particularly in the later stages. The nomenclature used is that of Sisson and Grossman (1940) and May (1955). Figs. 2 to 11 show the carcass at various stages during the dissection process. Figs. 12 to 24 show the individual muscles in their respective groups. DISSECTION PROCEDURE If sufficient skilled help is available, it is expeditious first to remove the muscles that tie down the shoulder, so that the fore limb can be removed and work can proceed on it. On the fore end the first muscle to be removed is the TRAPEZIUS ( 1 ). It is a large fan-shaped muscle which lies over the proximal end of the scapula and arises on the Ligamentum nuchae and supraspinous ligament from the atlas to the twelfth thoracic vertebra and ends on the scapular spine. BRACHIOCEPHALICUS (2) and OMO-TRANSVERSARIUS (3) are the next muscles to be detached from the neck. While lifting the Brachiocephalicus later, care must be taken not to damage the small muscle, called by Sisson and Grossman (1940) "the homologue of the subclavius in man," which traverses the triangular space bounded by the Pectoral muscles, the Sternocephalic and the Brachiocephalic muscles. The SUBCLAVIUS (4) is a small band of muscle fibres which runs from the lateral surface of the presternal cartilage and the first sternal segment at the level of the first rib into the Brachiocephalicus. The Omo-transversarius is a thin ribbon-like muscle which passes under the brachiocephalic muscle. It arises from the wing of the atlas and is inserted by an aponeurotic band to the suprascapular fascia which passes over the distal end of the spine of the scapula. The Brachiocephalicus is left attached to the shoulder at this stage. It has 2 distinct parts. The dorsal division arises from the occipital bone and the Ligamentum nuchae. The ventral part arises from the mastoid process of the temporal bone, the Rectus capitis ventralis major, and a thin tendon on the mandible. It is inserted on to the deltoid tuberosity and crest of the humerus and the fascia of the shoulder and arm. It can be easily detached once the shoulder has been removed from the body. The removal of LATISSIMUS DORSI (5) may now be commenced. This muscle originates from the tendon of the Teres major

18 206 Growth and delleiopmellt of Jheep. I. muscle, the fasciae on the medial surface of the long head of the Triceps muscle and a tendon to the coracoid process of the scapula. It may not be possible to free it completely until the shoulder has been lifted. The Superficial and Deep PECTORAL (6A and 6B) muscles were next loosened from their shoulder insertions. The fibres of the Superficial Pectoral muscle run transversely to the long axis of the carcass, and, unlike that of the cattle beast, this muscle is divided into 2 parts. The origin of the cranial part is from the sternal segment and its fellow on the opposite side, and the insertion is into the fasciae over the medial surface of the fore arm. The posterior part is thin and poorly developed. It originates from the second to the sixth sternal segments and from its fellow of the opposite side. It is inserted into the fascia of the medial aspect of the fore arm. Next the insertions of the RHOMBOIDEUS (7) into the scapula are loosened. The Rhomboideus arises on the Ligamentum nuchae from the first or second cervical vertebra to the fifth thoracic vertebra, and is inserted into the cranial, medial, and posterior parts of the vertebral border of the cartilage of the scapula. ~.""=-62 Fig. 12.-Ventral muscles of the neck. 2-Brachiocephalicus. 4-Subclavius. 9-Scalenus dorsalis. IO-Sternocephalicus. 12-Scalenus ventralis. 13-Rectus capitis ventralis major. 14-0mohyoideus. 62-Longus colli. 63-Intertransversales colli.

19 P. D. FOURIE 207 Fig. 13,- Lateral muscles of the neck, 3-Dmo-transversarius, II-Splenius, 15--Longissimus capitis et atlantis, 16-Complexus. 17-Rectus capitis dorsalis major, 18-0bliquus capitis posterior, 65-- Multifidus cervicis. With the shoulder freed from these attachments it can be lifted. As it is lifted the removal of Latissimus dorsi can be completed and the shoulder finally freed from its last attachment, the SERRATUS VENTRALIS muscle (8 ). The Serratus ventralis is a fan-shaped muscle which is divided into 2 parts. The cervical part (A) arises by digitations from the transverse processes of the third to the seventh cervical vertebrae and extends to the first 5 or 6 ribs, The thoracic part (B) arises from the second or third to the ninth rib by digitations, Both parts are inserted into the costal surface of the scapula, The Superficial and Deep Pectoral muscles can now be completely detached. The thoracic part of Rhomboideus is free, but the cervical part is united with its counterpart on the left side of the body and must be carefully divided, The 2 parts of the large Serratus ventralis muscle are then lifted. The next muscle to be taken off is the SCALENUS DORSALIS (9 ). It arises from the transverse processes of the fourth, fifth, and sixth cervical vertebrae, The muscle has been found to terminate in front of the first rib in the breeds concerned, although May (1955 ) describes it as extending to the third and fourth ribs.

20 208 Growth and development of sheep. I. This muscle's removal is followed by that of STERNO-CEPHALI CUS (10) which is taken off together with the Sterno-thyro-hyoideus (lob) which may be mutilated during dressing and require adjustment. The Sterno-cephalicus arises from the manubrium sterni and first costal cartilage and is inserted into the anterior border of the masseter and on the mastoid process and basilar part of the occipital bone. The SPLENIUS (11) can now be removed. It is a thin muscle which arises directly from the first 3 or 4 thoracic spines, and ends by a thin tendon on the occipital bone, the wing of the atlas and the transverse process of the axis. Next to be taken off are the SCALENUS VENTRALIS (12) and the RECTUS CAPITIS VENTRALIS MAJOR (13). Rectus capitis ventralis minor is small and lies dorsal to and under the above muscle and is taken off with it. The Scalenus ventralis arises from the transverse processes of the third to the seventh cervical vertebrae and ends on the first rib. It is traversed by the roots of the brachial plexus, which divide it into bundles. The Rectus capitis ventralis major is taken out from between the Intertransversales of the neck and the Longus colli. This muscle arises on the third to the sixth cervical transverse processes, and blends at its insertion with the Sterno-cephalicus. In young animals the OMO-HYOIDEUS (14) is taken off with the Rectus capitis ventralis major beca~lse of its smallness. Intercu3:al. 71-Dia Fig. l4.- Muscles of the thorax. 49-Transversus thoracis. 50-Rectus thoracis. 67- phragm (lower part). 72-Diaphragm (thick skirt).

21 P. D. FOURIE 209 Fig Musdes of the back and loins Serratus dorsalis anterior. 45--Serratus dorsalis posterior. 50-Longissimus costarum. 5IA-- Longissimus dorsi-cervical part Longissimus dorsi Multifidus dorsi. Before the LONGISSIMUS CAPITIS ET ATLANTIS (15) and the COMPLEXUS (16) can be removed the thoracic part of the Longissimus dorsi must be lifted. Longissumus capitis et a tlantis has its origin on the transverse process of the first two thoracic vertebrae and the articular processes of the cervical vertebrae. It is inserted to the mastoid process and the wing of the atlas. Complexus is a large triangular muscle which lies on the Ligamentum nuchae, under cover of the Splenius. It originates from the third to the fifth thoracic vertebral spines, the transverse processes of the first 6 thoracic vertebrae and the articular processes of the cervical vertebrae, and is inserted into the occipital bone. 60 After the above muscles have been removed, the deepest muscles of the neck, the RECTUS CAPITIS DORSALIS MAJOR (17) and OBLIQUUS CAPITIS POSTERIOR (18), can be taken off. The Rectus capitis dorsalis minor is a small muscle covered by the Rectus capitis dorsalis major, and these are taken off together, both having been cut if the carcass has been decapitated. R ectus capitis dorsalis major extends from the spinous process of the axis to the occipital bone underneath the Complexus. The Obliquus capitis posterior is a strong muscle which covers the dorso-lateral aspect of the a tlas and the axis. I t stretches from the side of the spine and the posterior articular process of the axis to the dorsal surface of the wing of the atlas.

22 210 Growtb and development of.rheep. I. When starting dissection of the shoulder, the first muscle to be removed is the DEL TOlD (19 ), the 2 parts of which are most easily detached by lifting the muscle from its insertion into the deltoid tuberosity of the humerus and working towards its origin at the spine and posterior border of the scapula. The TENSOR FASCIAE ANTIBRACHII (20) is then stripped off from the poster;or edge of the long head of the Triceps and lifted towards its insertion into the m~dial aspect of the olecranon process of the ulna. Next the INFRASPINATUS (21 ) can be removed from the infraspinous fossa of the scapula, working towards its inser tion into the medial surface of the posterior eminence of the greater tuberosity of the humerus. Care must be taken with the posterior distal part in separating it from the underlying Teres minor. TERES MINOR (73 ) lies on the long head of the Triceps brachii muscle. It originates from the distal and posterior part of the infraspinous fossa, at the posterior border of the scapula. It is inserted into a small area above, and to the deltoid tuberosity of the humerus. The SUPRASPINATUS (22 ) is clearly defined by its occupation of the supraspinous fossa of the scapula. It stretches from the lower '. Fig. 16.-Abdominal muscles. 46-0bliquus abdominis extemus. 47- Rectus abdominis. 4B-Obliquus abdominis internus. 51-Transversus abdominis.

23 P. D. FOURIE 211 Fig. 17 A.- Muscles of the shoulder girdle. I- Trapezius. 5-Latissimus dorsi. 7- Rhomboideus. part of the cartilage of the scapula to the cranial part of the greater tubercle of the humerus. The SUBSCAPULARIS (23) is attached to the costal surface of the scapula. This muscle is divided into 3 parts, with a common insertion into the posterior portion of the m~dia[ tuberosity of the humerus. The CORACO-BRACHIALIS (74) lies on the medial surface of the shoulder joint and originates from the coracoid process of the scapula, also from the Supraspinatus muscle by a tendinous band. The insertion is into a small area above the teres tuberosity of the humerus, above the insertion of the Teres major muscle. TERES MAJOR (24 ) runs between the Coraco-brachialis and the medial head of the Triceps brachii for its insertion into the vestigial teres tubercle of the humerus, in common with the Latissimus dorsi muscle. The TRICEPS BRACH II (25) is a muscle with 3 parts. The m~dial head arises from the medial surface of the shaft of the humerus, behind and below the insertion of the Teres major muscle. It is inserted into the summit of the olecranon on the medial side. The long head is thick and triangular and runs from the posterior border of the scapula to the medial aspect of the olecranon. The lateral head arises from the deltoid tuberosity to the neck of the humerus and is inserted into the lateral head of the olecranon. The Anconeus muscle is removed with it to save a difficult separation.

24 212 Growth and development of Jheep. I. BICEPS BRACHII (26) is easily removed, as is BRACHIALIS (27). The Biceps muscle arises from the coracoid process of the scapula and has 3 points of insertion: (i) the fascia over the fore arm, (ii) the tuberosity of the radius, and (iii) the ligament between the radius and the ulna. The Brachialis twists around the musculo-spiral groove of the humerus. It starts from the proximal part of the posterior surface of the humerus, relates deeply to the lateral head of the Triceps muscle, and extends to the ligament between the radius and the ulna. This leaves only the FLEXOR (69) and EXTENSOR (70) muscles to be removed. These are taken off as groups, no effort being made to separate the individual muscles. In dissecting the hind leg, the TENSOR FASCIAE LA T AE (28) and the BICEPS FEMORIS (29) are removed first, but the head of the Semitendinosus may have to be lifted before the latter can be detached from the tuber ischii. Tensor fasciae latae is a relatively large muscle in the sheep due to the probable inclusion of part of the superficial Gluteal muscle. It arises from tuber coxae and the intermuscular septum between the Biceps femoris and the medial Gluteal muscles. The muscle is triangular in shape and ends in the fascia lata. The Biceps femoris is a large, extensive, and very powerful muscle. The origin is from Fig. 17B.~Muscies of the shoulder girdle. 6A~Superficial Pectoral. 6B~Deep Pectoral. 8A~-Serratus ventralis (cervical part). 8B~Serratus ventralis (thoracic part).

25 P. D. FOURIE 213 Fig. lb.-muscles of the shoulder. 19- D eltoid Infraspinatus. 22-Supraspinatus. 23-Subscapularis. 24- T eres major. 73--Teres minor. 74- Coraco-brachialis. the second to the fourth sacral spines, the dorsal and ventral aspect of the tuber ischii and the sacro-sciatic ligament. It inserts into the patellar ligament, tibial tuberosity, and, by an aponeurotic shee t, to the tibial crest and the fascia of the leg. The GLUTEUS MEDIUS (30) with its origin from the lumbodorsal fasciae and the gluteal surface and coxal tuberosity of the ilium, extends to the greater trochanter of the femur. This muscle and the SEMITENDINOSUS (31 ) can now be removed. The Semitendinosus lies between the Semimembranosus and the Biceps femoris muscles, stretching from the ventral surface of the tuber ischii towards the crest of the tibia. Now the QUADRICEPS FEMORIS (32) can be partially freed. The patella is removed from it during the cleaning process. The Quadriceps femoris comprises 4 separate heads which are arranged around the femur. It is inserted into the patella and the medial femoro-patellar ligament. From the lower leg it is necessary partially to free GASTROC NEMIUS (33), to enable SOLEUS (34) to be detached from its deep insertion into the lateral head of this muscle. The Soleus is a very small ribbon-like muscle and arises from the lateral condyle of the tibia and

26 214 Growth and development of Jheep. 1. from the posterior tibial muscle. Gastrocnemius arises by 2 heads from the distal end of the femur, and between them lies the Plantaris muscle which is taken out with it. These 2 heads have a single insertion into the tuber calcis. The next muscles, the LATERAL EXTENSOR (35), PERONEUS LONGUS (36), PERONEUS TERTIUS and LONG EXTENSOR group (37), and TIBIALIS ANTERIOR (38) can be dissected out in the above-mentioned order. The extensors are not further divided. The Lateral extensor arises from the lateral condyle of the tibia and passes over the lateral surface of the hock. The Peroneus longus stretches from the lateral condyle of the tibia to the first tarsal bone. Peroneus tertius arises from the extensor fossa of the femur and is inserted into the base of the large metatarsal bone and the third tarsal bone. Tibialis anterior is a flat muscle which lies on the lateral surface of the tibia. It runs from the lateral surface of the crest and the condyle of the tibia to the first tarsal bone. Next, 4 small muscles which are closely related to the pelvis and femur are taken off. They are GLUTEUS ACCESSORIUS (39), GLUTEUS PROFUNDUS (40), GEMELLUS (41), and QUADRA TUS FEMORIS (42). In very young animals the 2 latter muscles are Fig. 19.-Muscles of the arm. 20-Tensor fasciae antibrachii. 25-Triceps brachii. 26--Biceps brachii. 27-Brachialis.

27 P. D. FOURIE 215 Fig. 20.-Muscles of the fore arm. 69-Flexor group (fore). 70-Extensor group (fore). very small and they are therefore weighed together. Gluteus accessorius is, in actual fact, a deep portion of Gluteus medius, but it is clearly defined and its strong tendon is inserted into the femur below the trochanter major. Gluteus profundus arises from the shaft of the ilium, sacro-sciatic ligament, and the acetabular ramus of the ischium. It is inserted into the neck of the femur under that of the middle Gluteal muscle. Gemellus is a small fan-shaped muscle. It arises from the ischium immediately behind the Gluteus profundus and as far back as the tuber ischii. It is inserted into the trochanteric fossa, the fibres running cranially and ventrally. Quadratus femoris is a flat, thin muscle stretching from the ventral surface of the ischiium to the trochanteric crest. As with Gastrocnemius, the FLEXOR GROUP (43) can be partially detached at this stage. The Flexor group consists of 3 parts. It arises approximately from the lateral condyle of the tibia, and the insertion tendon passes down the metatarsus. At this stage it is as well to remove the SERRATUS DORSALIS ANTERIOR (44) and SERRATUS DORSALIS POSTERIOR (45). The anterior muscle is very small and comprises only 1 or 2 digitations which arise from the lumbo-dorsal fascia under the scapula, and run back and downwards to their insertion into the fourth and fifth ribs. When dealing with young animals these 2 muscles are weighed together because they are so small.

28 216 Growth and development of sheep. I. In the abdominal region, the OBLIQUUS ABDOMINIS EXTER NUS (46), RECTUS ABDOMINIS (4.7), and OBLIQUUS ABDO MINIS INTERNUS (48) are all now accessible. The first-mentioned muscle (46) takes origin from the lower part of the fifth intercostal space to the last rib above its centre. Passing ventrally the fibres gradually alter their direction to become almost vertical. The muscle ends laterally in a lamina of fascia extending to the region of the udder of the ewe and ventrally the fibres end in a thin aponeurotic tendon which blends with the aponeurotic tendon of the Internal abdominal oblique muscle. The combined tendon ends at the linea alba and posteriorly at the prepubic tendon. The Rectus abdominis arises on the lateral border of the sternum as far forward as the third rib cartilage. The left and right side muscles lie side by side along the linea alba, separated by approximately an inch in a mature animal. There are 5 transverse tendinous inscriptions crossing the muscle along its course. Its insertion is into the pubic tendon which is strongly attached to the symphysis pelvis. The aponeurosis is taken off with the latter and removed during "cleaning." The Obliquus abdominis internus is attached dorsally to the lumbo-dorsal fascia, the tuber coxae, and part of the inguinal ligament. Ventrally, the aponeurosis blends with that of the external abdominal oblique muscle near the linea alba. It is inserted by an aponeurosis into the last 3 or 4 ribs along the rib arch, and to the linea alba. Fig. 21.-Sublumbar muscles. 52A-Iliacus. 52-Ilia-psoas major. 53-Psoas minor. 54-Quadratus lumborum.

29 P. D. FOURIE 217 Fig Lateral muscles of hip and thigh. 28-Tensor fasciae latae. 29- Biceps femoris Gluteus medius. 31- Semitendinosus. 39-Gluteus accessorius. 40-Gluteus profundus. 58- Semimembranosus. Next the TRANSVERSUS THORACIS (49) can be removed from inside the rib cage. It lies on the sternum and the cartilages of the sternal ribs. It arises from the sternal ligament meeting the opposite muscle and is inserted into the cartilages of the second to the eighth ribs. Then the RECTUS THORACIS (50), which is embedded in the fat on the sternum, can be taken off. (In some sheep this muscle was found to be missing.) If present it is thin and arises on the first rib, ventral to the insertion of the ventral Scalenus muscle. It continues caudo-ventrally to be inserted into the third and fourth costal cartilages and adjacent parts of the sternum. The TRANSVERSUS ABDOMINIS (51 ) can now be removed. This muscle arises from the medial surfaces of the ventral cartilages of the asternal ribs meeting the costal attachment of the diaphragm, and from the transverse processes of the lumbar vertebrae by the deep layer of the lumbo-dorsal fascia. It is inserted into the xiphoid cartilage and the linea alba.. In the sub-lumbar region the ILIO-PSOAS MAJOR (52), PSOAS MINOR (53), and QUADRATUS LUMBORUM (54) can be removed in this order. The Ilio-psoas major originates from the posterior border of the last 2 ribs near the lumbar vertebrae and from the bodies

30 218 Growth and development of sheep. 1. of the lumbar vertebrae. It extends back to the pelvis to which it is attached. In removing it the inter-transverse ligament between the lateral processes of the lumbar vertebrae is left intact. The Psoas minor begins at the disc between the twelfth and thirteenth thoracic vertebrae and is inserted by a flattened tendon into the psoas tubercle on the ilium. The Quandratus lumborum lies between the ventral surface of the lumbar processes and the Ilio-psoas major muscle. It arises as far forward as the body of the tenth or eleventh thoracic vertebra, as well as the bodies of the succeeding thoracic vertebrae and the transverse processes of the lumbar vertebrae. This muscle extends out beyond the lateral border of the Ilio-psoas major muscle. With the bulk of muscle no longer attached, the hind leg can now be raised to facilitate the removal of the medial muscles of the thigh in the following order: GRACILIS (55 ), SARTORIUS (56), and PECTINEUS (57). Gracilis is a broad flat muscle lying on the medial aspect of the thigh. It has an extensive origin from the pelvic symphysis in common with its fellow of the opposite side and with the Pectineus muscle from the ventral surface of the pubis. It is closely associated with the Pectineus muscle anteriorly and is inserted into the m~dial border of the tibia and to the fascia over the Gastrocnemius muscle. Sartorious lies in front of Gracilis and Pectineus. It has 2 heads, one originating on the iliac fascia and the tendon of the Psoas minor muscle, and the other on the shaft of the ilum. The insertion is in common with that of Fig. 23.-Medial and anterior muscles of the thigh. 32-Quadriceps femoris. 41-Gemellus. 42-Quadratus femoris. 55-Gracilis. 56-Sartorius. 57-Pectineus. 59-Adductor femoris. 68A-Obturator internus. 68-0bturator extern us.

31 P. D. FOURIE 219 Fig. 24.-Muscles of the leg and foot. 33~-Gastrocnemius. 34-Soleus. 35-Lateral extensor. 36-Peroneus longus. 37-Peroneus tertius and long extensor group. 38-~Tibialis anterior. 43-~Flexor group (hind). Gracilis by an aponeurotic tendon into the medial surface of the tibia. Pectineus is a relatively thick triangular muscle lying between the Quadriceps femoris and Adductor muscles in the proximal part of the thigh. It extends from the anterior border of the pubis to the middle of the medial border of the femur, from the lesser trochanter to the medial epicondyle with fibres attached to the Quadriceps femoris muscle. Next the SEMIMEMBRANOSUS (58) and the ADDUCTOR FEMORIS (59) are taken out together and then separated. The Semimembranosus lies posteriorly to the Quadriceps femoris and femur. Its origin is from the ventral aspect of the tuber ischii and the pelvic symphysis under that of the Gracilis muscle. The origin of the Adductor femoris is under that of the Semimembranosus. There is only an intermuscular septum between these 2 muscles, and they are inserted into the medial epicondyle of the femur. The detachment of the Quadriceps femoris, Gastrocnemius and the Flexor group at this stage, completes the dissection of the hind leg. LONGISSIMUS COSTARUM (60) is the next muscle to be removed. This muscle arises from the lumbo-dorsal fascia, the transverse processes of the first 2 lumbar vertebrae, the lateral surfaces of the ribs, and their anterior borders. It is inserted by means of long

32 220 Growth and development of Jheep. I. narrow flattened tendons, usually across 2 or more ribs to end on the posterior borders of the ribs, the last tendons ending on the transverse processes of the last cervical vertebra. The LONGISSIMUS DORSI (61) can now be removed. The cervical part of this muscle is independent, and requires patient dissection to separate it from the dorsal row of the Intertransversales of the neck. The Longissimus dorsi extends from the sacrum to the fifth cervical vertebra. Over the lumbar region it is covered with a thick tendinous sheet. It becomes thinner towards the neck. This is the heaviest and longest muscle in the body. It originates from the ventral surface of the ilium, the first 2 sacral spines, and the supraspinous ligament. It fills up the space between the spinous processes medially, the lumbar transverse processes, and the upper articulations of the ribs ventrally until it ends in the spinous and transverse processes of the last 3 cervical vertebrae. The INTERTRANSVERSALES COLLI (63) and LONGUS COLLI (62) can be removed more easily after the cervical vertebrae have been separated from the thoracic vertebrae. This necessitates cutting Longus colli or else detaching it first from the thoracic vertebrae. The Longus colli covers the ventral surface of the vertebrae from the fifth thoracic to the ventral tubercle of the atlas, and is closely united with is counterpart. The intertransversales of the neck occupy the spaces between the lateral aspects of the vertebrae and the transverse and articular processes. There is, therefore, a bundle for each intervertebral articulation except the first. Each bundle is thus divided into 2 parts. The dorsal parts pass from a transverse process to an articular process, while the ventral parts extend between adjacent transverse processes. The ObJiquus capitis anterior is severed when the head is cut off and the part remaining on the head is added to the head waste. The part on the neck is weighed with the muscle fragments. The division between MULTIFIDUS CERVICIS (65) and MULTI FIDUS DORSI (66) is not always very clear, but they can be separated in animals that are 2 months of age or older. (In l-week-old animals they are taken off together.) Multifidus dorsi comprises a series of small muscles lying close to the vertebral column, and arising from the sacrum, the articular and mammillary processes of the lumbar, and the last 2 thoracic vertebrae. I ts insertions are to the spinous processes of the first 2 sacral, the lumbar, thoracic vertebrae, and the cervical part ends on the spinous and articular processes of the cervical vertebrae. (The Intertransversales of the back are taken off with the Multifidus dorsi because separation is hardly possible). Before the ribs can be detached from the vertebrae, the INTER COSTALS (67) must be removed. Here, also, the slight additional information which would be gained by separating the Retractor costae, Levatores costae, and Intercostals, does not warrant the work entailed and they are all weighed together as InfercoJfalJ. The only muscles left on the carcass at this stage should be the OBTURA TORS (68). The fibres of the Obturator externus and the

33 P. D. FOURIE 221 Obturator internus are so intermingled as to be almost inseparable. They are therefore taken out together. The internal Obturator muscle takes origin from the cranial and medial borders of the obturator foramen and the body and symphysis of the pubis and ischium. I t is fan-shaped, covering the greater part of the ventral wall of the pelvis. It emerges through the obturator foramen and passes along the lateral border of the external Obturator muscle to be inserted in common with the latter in the trochanteric fossa of the femur. The Obturator externus is also fan-shaped and arises from the ventral surface of the ischium and pubis and the medial edge of the obturator foramen. The small fragments of muscle that remain on the carcass are weighed collectively as muscle fragments (e.g., the Retractor ani, part of the Rectus capitis dorsalis minor, and part of the Obliquus capitis anterior). Also included under this heading are the small fragments unavoidably left on the bones in the course of dissection. When all muscles have been removed the bones are detached and set aside for cleaning. The vertebral column is taken out in sections after the muscles on the left side have been cut away. The cervical vertebrae are separated from the thoracic vertebrae at the articulation point of the first rib. The dorsal process of the first thoracic vertebra is always much longer than that of the last cervical vertebra. In cleaning the bones of the limbs, fat, tendon, and muscle fragments are first removed and the bones then scraped down, removing the periosteum. These scrapings are weighed as tendon and waste. With the vertebrae the cleanings from the left side are discarded. The fat and any tendon from the right side is weighed with other intermuscular fat and tendon. The bone scrapings from each section are weighed separately as a check on cleanness of dissection, but these weights are eventually added to the "muscle fragment" weight in accordance with the technique used for meat animals, because this material is edible, and little tendon is involved. Finally the spinal cord and its surrounding fat are taken out. If possible the same section of vertebrae from each animal is cleaned by the same person with a view to standardising the cleaning process. The ribs and sternum are treated similarly to the vertebrae. Muscles are relatively easy to clean. Intermuscular fat and fasciae are removed from the surfaces, and tendons are cut off squarely at the limit of the muscle to which they belong. All fasciae and blood vessels are weighed with the intermuscular fat since they are difficult to separate from it. DISCUSSION As has already been mentioned, the technique described is being used in a study of growth and development in sheep. Since the material is experimentally valuable it has not been possible in the course of this work to check accurately the origins and insertions of the muscles. Such checking would involve a certain amount of destruction. Because it is

34 222 Growth and development of sheep. I. felt that the inclusion of some such descriptive details could be of great assistance to other workers wishing to carry out similar investigations, brief descriptions have been drawn from outside sources (Sisson and Grossman 1940; May 1955). Since the purpose of this paper is to describe a technique rather than to provide an anatomical treatise, these descriptions have deliberately been simplified as much as possible. Where deviations from the texts quoted have been noticed they have been pointed out. The advantages and disadvantages of using this technique have been fully discussed by Walker (1961). Obviously much labour, time, and expense is involved. For this reason the possibilities of circumventing much of this outlay in future by using sample muscles and bones to provide indices of the totals in the carcass is being investigated. The importance of this aspect is self-evident. ACKNOWLEDGMENTS Thanks are due to Dr C. P. McMeekan, Director of the Ruakura Animal Research Station, for providing the facilities to carry out such a detailed study on growth and development in sheep. The technique described is based on Walker's (1961) method for the dissection of cattle, and her advice and valuable criticism are appreciated. The photographic work was performed by D. Macqueen, whose assistance is gratefully acknowledged. For assistance in the dissection work, thanks are due to M. Evans, R. Truscott, and A. Treleaven, and for abattoir work to W. Carter and D. Patterson. REFERENCES HAMMOND, J. 1932: "Growth and development of mutton qualities in the sheep". pp Oliver and Boyd, Edinburgh. 597 pp. JOUBERT, D. M. 1956: A study of prenatal growth and development in the sheep. f. agric. Sci. 47: McMEEKAN, C. P. 1940: Growth and development in the pig with special reference to carcass quality characters. Ibid. 30: : Growth and development in the pig with special reference to carcass quality characters. Ibid. 31: MAY, N. D. S. 1955: "The anatomy of the sheep". University of Queensland Press, Brisbane, Queensland. PALSSON, H. 1939: Meat qualities in the sheep with special reference to the Scottish breeds and crosses. f. agric. Sci. 29: : Meat qualities in the sheep with special reference to the Scottish breeds and crosses. Ibid. 30: SISSON, S.; GROSSMAN, J D. 1940: "The anatomy of domestic animals." pp W. B. Saunders, Philadelphia. 972 pp. WALKER, D. E. 1961: A study of the growth and development of Jersey cattle. I. A new carcass dissection technique. N.Z. J. agric. Res. 4: WALKER, D. E; McMEEKAN, C. P. 1944a: Canterbury lamb. N.Z. J. Sci. Tech. A26 (2): b: Canterbury lamb. Ibid. A26 (3):