Veterinary Anatomy PDF - Body Cavities & Ribs

## The Body Cavities ### The animal body cavities are divided into: * **Cephalic cavity** - present in head * **Cranial cavity** (cranium) in brain * **Oral cavity** * **Nasal cavity** * **Coelomic cavity** - present in trunk * **Thoracic cavity** (Cr. smaller one) * **Abdomin...

## The Body Cavities ### The animal body cavities are divided into: * **Cephalic cavity** - present in head * **Cranial cavity** (cranium) in brain * **Oral cavity** * **Nasal cavity** * **Coelomic cavity** - present in trunk * **Thoracic cavity** (Cr. smaller one) * **Abdominal Cavity** (cd. larger one) * **Pelvic cavity** (cd. Continuation of abd. cavity) **The thoracic cavity is smaller than the thoracic cage** * Diaphragm separates the thoracic cavity from the abdominal cavity * The Linea terminalis (imaginary line) separates the abdominal cavity from pelvic cavity ### Thoracic cavity 2nd large cavity of the body **Boundaries:** * **Dorsally** → thoracic vertebra * **Caudally** → diaphragm * **Laterally** → ribs & inter costal muscles **Thoracic inlet** - Small-narrow-oval **Bounded:** * **Dorsally** → by first thoracic vertebra * **Ventrally** → by manubrium of Sternum * **Laterally** by first pairs of ribs. **Passage for:** * **Longus Coli M** * **Lymphatic duct** * **Trachea - esophagus - jugular** * **Recurrent laryngeal M** * **Common Carotid a** **Bounded:** * **Dorsally by** → last thoracic vertebra * **Laterally by** → last pair of ribs & costal arch * **Ventrally by** → last sternebrae & xiphoid Process ### Ribs Ribs are classified into: * **Sternal (true) ribs:** most cranial group of ribs whose cartilages join the sternum directly * **Asternal (false) ribs:** located caudal to the sternum. * Their costal cartilages merge to form the costal arch, which indirectly joins them to the sternum. * **Floating ribs:** false rips present at the caudal of the series in some animal didn't join the sternum or costal arch and end in flank musculature (mainly represented by last pair or last two pairs) ## The abdominal cavity * The abdominal cavity extends from the diaphragm to the pelvic inlet. * It divided into * **The most Cranial part** (which extends into the thorax termed **The intra thoracic part of the abdominal Cavity**) * **Fleshy part** termec flank region * Separated from pelvic cavity by imaginary line called linea terminalis (imaginary line between 2 tuber coxae of illum) **Cr. Part of abdominal cavity pounded by:** * Lumber vertebrae .....dorsally * Last part of sternum ( xiphoid cartilage)....ventrally * Ribs ....laterally * Fleshy part bounded by abdominal wall & muscles **The abdominal region can be divided into 3 main regions by 2 transverse imaginary lines:** 1. **Cr. Plane** → passes through the last rib 2. **Cd.plane** → passes through the tuber coxхае ### The 3 regions of the abd. Cavity: 1. **Cranial abdominal region (Epigastric)**: Extends from the diaphragm to 1st transverse plane, pass through the most caudal point of the Costal arch 2. **Middle abdominal region (Mesogastric)**: Extends from 1st transverse plane, pass through the most caudal point of the costal arch to another transverse plane pass through the most Cranial point of the tuber coxae 3. **Caudal abdominal region (Hypogastric)**: Begins from the caudal limit of the middle segment to the pelvic inlet. **Each of 3 divisions are subdivided into 3 sub regions by 2 para median planes:** * **Epigastric region:** * R. hypochondraic region. * L. hypochondraic region * Xiphoid region * **Mesogastric region:** * R. lateral abdominal region (R. flank) * L. laterai abdominal region. (L. flank) * **Hypogastric region:** * umbilical region * R. inguinal region * L. inguinal region * pubic region ## Structures of abdominal wall * **Cutaneus tranki:** * It's an extensive muscle layer, which Covers the wall of the trunk. * tenses & twitches the skin * (a) Superficial fascia * (b) Deep fascia * **Tunica flava abdominalis:** * This is a Sheet of elastic tissue which assists the muscles in supporting the great weight of the abdominal Viscera * **Linea Alba:** * It's a median fibro-tendinous card extends. * from the xiphoid Cartilage to the perpubic tendon * It's formed chiefly by the junction of the aponeurosis of the external & internal abdominal oblique & transverses Abdominis muscles ## The abdominal muscles : * **flat** * **The muscle is composed of Fleshy & aponeurotic part** * **They include:** * External oblique abdominal muscle * Internal oblique abdominal muscle * M. transverses abdominis * M. Rectus abdominis ## Rectus Sheath: * **It's a sheath wich enclose the Rectus abdominis m. * **is formed of:** * 1. Internal (dorsal) lamina: the aponeurosis of the transverse abdominis m. * 2. External (ventral) lamina: the aponeurosis of external & internal abdominal oblique m. ## Openings abdominal wall * **1-3 orifices of the diaphragm:** * (a) aortic hiatus .......pass aorta * (b) esophageal hiatus..... pass esophagus * (c) Ceval hiatus.........pass cd. Vena cava * **2- umbilical opening:** * present in the fetus then after birth, it fibrosis & form fibrous scar umbilicus * **3- Lumbo-Costal arch:** * It's slit-like passage, lie bet. tne ribs and sub-lumbar muscles * It by pass the sympathetic nerve chain & splanchnic nerves * **4- 2 openings of the fallopian tube in female** * **5-2 orifices of the Inguinal Canal (internal, external)** ## The peritoneum * **It's the largest serous membrane in the body.** * **Lining the organs contained in the abdominal & pelvic Cavities.** **The peritoneum can be divided into:** 1. **parietal peritoneum** * Single layer of serous membrane lining the wall of the body cavity * loosely attached to the parietal wall 2. **visceral peritoneum** * single layer of serous membrane that cover or invest the visceral organ. * closely attached to the Visceral organ 3. **Connecting peritoneum** * double layer of Serous membrane. * connecting bet the parietal layer & visceral layer. * **Types :** * **Omentum** * fold attached to the stomach. * There are 2 types: * 1. Greater omentum. * 2. Lesser omentum * **Mesentery:** * fold of peritoneum which suspend the intestinal tract from the dorsal wall of the abdomen * **Ligament:** * fold of peritoneum which pass between Viscera other than parts of the digestive tube or Connect them with the abdominal wall. ## Function * **Act as a pathway for blood vessels & nerves.** * **fixation of organs** ## Intra peritoneal organs * organs that are enclosed by a fold of visceral peritoneum. ## Retro peritoneal organs * organs located behind the parietal peritoneu * include: * cd. half of urinary bladder * cd. half of rectum. * 2 kidney * **In the male** :- it's completely closed Sac * **In female** :- it has 2 small openings * abdominal orifices of the uterine (fallopian tube). ## Pelvic cavity **The smallest and the most caudal cavity** **Bounded by:** * sacrum..... dorsally * Ilium ......laterally * Pubis + ischium .......ventrally **N.B:** * the 1st 3 vertebra of coccygeal vertebrae share in the roof of pelvic * Bony pelvis = iliurn + pubis + ischium (os coxae laterally & ventrally) **Inlet:** * dorsally.....1st vertebra of sacrum * Ventrally.... pubis * Laterally......imagine line (ilio-pectineal line) **Outlet:** * dorsally ....3rd vertebra of coccygeal vertebrae * Ventrally .... ischial arch * Laterally ..... sacro-sciatic lig.