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The bones are rigid yet elastic structures that articulate with other bones or cartilages to form the skeleton. They are covered by a connective tissue coat called the periosteum. At the periphery all bones are compact. There is a lamellar spongy tissue inside the bones. There are three major types of bones: long, short, and irregular. The long bones (the majority of the bones of the limbs) have a body and one or two articular extremities, and are cen- tered by a medullary canal. The short bones (the carpal and the tarsal bones) do not have a medullary canal. The irregu- lar bones (the vertebrae) do not fi t in any geometrical shape.

The skeletal system of the goat, as of all of the domestic mammals, consists of the axial skeleton and the appendicu- lar skeleton.

The Axial Skeleton (the Skull, the Vertebral Column, the Sternum, and the Ribs)

THE SKULL

As a mammalian type, the skull of the goat consists of several bones fused with each other, except the mandibles (usually called “ mandible ” ), the only bones with mobility against the rest of the skull. All bones of the skull are sym- metrical, except the vomer, ethmoid, sphenoid, and occipi- tal bones. In addition, there is a hyoid apparatus, consisting of small bones and located between the tongue, the pharynx, and the larynx. The skull of the goat is different from that of the large ruminants and even the sheep. As a common characteristic of a ruminant skull, the goat lacks the superior incisive teeth. The skull of the goat (except the mandible; see Figure 6.25 ) is illustrated in Figures 6.7 Figure 6.6 Anatomical region of the head (lateral side).

to 6.9 . The structures marked with an “ L ” are landmarks for clinical purposes.

The functional anatomy of the skull is much more complex than that of the other bones, because it protects the brain and two of the endocrine glands, the initial segment of the respiratory system, and the initial segment of the digestive system. Also, some of the prominences and foramina are landmarks for clinical purposes.

THE VERTEBRAL COLUMN

The vertebral column has a multiple role in the normal functioning of the body: it protects the spinal cord (within the vertebral canal), contributes to the roofs of the thoracic and abdominal cavities, and provides attachments for liga- ments and muscles. Also as part of the functional anatomy, the vertebral column provides landmarks for epidural and paravertebral anesthesia. Each vertebra consists of a body and the arch, both enclosing the vertebral canal. There is an intervertebral disc between the bodies of the vertebrae,

with a fi brous ring surrounding a gelatinous center. The functional role of the intervertebral discs is to allow a certain degree of mobility of the vertebral column as a whole. There are fi ve regions of the vertebral column: cervical, thoracic, lumbar, sacral, and caudal. The cervical vertebrae in all domestic mammals are much longer than in humans, but the total number is the same for all mammals. The thoracic vertebrae form part of the roof of the thoracic cavity. The lumbar vertebrae form the roof of the abdominal cavity, whereas the sacrum is the roof of the pelvic cavity. Using symbols, the following are the numbers of vertebrae for each region: C7, T13, L6, S5, Cd11 – 14. Their profi les are illustrated in Figure 6.10 and Figure 6.11 .

THE STERNUM

The sternum is a unique structure, consisting of seven sternebrae as shown in Figure 6.10 , and is the bony fl oor of the thoracic cavity.

Figure 6.7 Skull, lateral view (without mandible). (L) = landmark for physical examination and/or clinical approach.

incisive bone palatine fissure

Figure 6.8 Skull, frontal view. (L) = landmark for physical examination and/or clinical approach.

foramen

magnum occipital condyle

cornual process (L)

paracondylar (jugular) process (L) external acoustic meatus (L) tympanic bulla oval foramen zygomatic arch (L) foramen orbitorotundum orbita vomer

caudal palatine foramen major palatine foramen hard palate facial tubercle palatine fissure incisive bone sphenopalatine foramen maxillary foramen optic canal pterygoid crest muscular process styloid process jugular foramen

Figure 6.9 Skull, ventral aspect (without the mandible).

(L) = landmark for physical examination and/or clinical approach.

D A B atlas axis C3 C4 spinous processes T1

facets for a rib head transverse process C5 C6 C7 T13 Figure 6.10 Bones of the axial skeleton: A. Cervical vertebrae, lateral view; B. Thoracic vertebrae, lateral view; C. Sternum; D. Rib. A C L6 L6 L1 Cd1 Cd2 Cd1 Cd2 L1 sacrum lateral view sacrum B dorsal view Figure 6.11 Bones of the axial skeleton: A. Lumbar vertebrae, sacrum, lateral view; B. Lumbar vertebrae, sacrum, dorsal view; C. Caudal vertebrae.

sternum, and ribs is important for the normal activity of the respiratory and cardiovascular systems. They build up the thoracic cavity for the protection of the lungs and the heart with the major vessels and nerves, lymph nodes, and the thoracic thymus, and facilitate the act of respiration.

The Appendicular Skeleton

THE THORACIC LIMB

The thoracic (fore) limb consists in a proximo - distal direction of the scapula (the bone of the shoulder), the humerus (the bone of the arm, or brachium), the radius and ulna (the bones of the forearm, or antebrachium), the carpal bones (the bones of the knee), the metacarpal bones (the bones of the metacarpus), and the phalanges with the sesamoid bones (the bones of the digits). They are illus- trated in Figure 6.12 . Similar to the skull, the structures marked with an “ L ” are landmarks for clinical purposes.

THE PELVIC LIMB

The pelvic (rear) limb consists in a proximo - distal direc- tion of the coxal (the bone of the rump), the femur and patella (the bones of the thigh), the tibia (the bone of the crus, or leg), the tarsal (the bones of the hock), the meta- tarsal (the bones of the metatarsus), and the phalanges with the sesamoid bones (the bones of the digits). A specifi c note for the coxal bone: it is formed by the fusion of three bones — the ilium, the pubis, and the ischium. By the pubis and ischium, the symmetrical bones are articulated with each other. The bones of the pelvic limb are illustrated in Figure 6.13 . Similar to the skull and the thoracic limb, the structures marked with an “ L ” are landmarks for clinical purposes.

The functional anatomy of the appendicular skeleton refers to the following roles: they connect with the body;

joints (the intervertebral joints) allow very reduced move- ments. The immobile joints immobilize the bones of the skull, for example, in the adult life after the brain devel- opes fully.

The joints of the vertebral column provide for the bodies and arches of the vertebrae. Intervertebral discs are inter- posed between two adjacent vertebral bodies. The joints of the ribs include ligaments between the heads of the ribs and the bodies of vertebrae and the intervertebral discs (dorsally), and the cartilages and the sternum (ventrally). The joints of the sternum provide for the sternebrae.

The joints of the limbs consist of joint capsules and liga- ments. The joint capsules are fi brous externally, and syno- vial internally. The fi brous joint capsule is the continuation of the periosteum from one bone to another. The synovial membrane, a thin and delicate structure, contains synovial fl uid, which allows a smooth gliding of the bones against each other.

Most of the joints of the skull are sutures, with the exception of the temporomandibular joint (symmetrical), which is mobile. From the functional point of view, it allows the movements of the mandible against the rest of the skull, during the prehension of food and the mastication process. The movements of the mandible open or close the mouth, and move laterally during the mastication (the latter is a species - specifi c feature for all ruminants).

THE MUSCULAR SYSTEM (THE