Carnivore Anatomy Lab 12 Introduction

CONTENTS:

Lab Objectives
Anatomical Terms
Instructor Commentary
Dissection Steps
Dissection Videos
Dissection Images

Lab Objectives:

• Examine autonomic (visceral efferent) nerves of the thoracic cavity and identify them as:
      - sympathetic (most of the nerves and all of the ganglia in the thoracic cavity)
      - parasympathetic (the vagus nerve and its visceral branches)
      - sympathetic & parasympathetic combined (vagosympathetic nerve trunk)

• Identify somatic efferent branches of the vagus nerve:
      - right recurrent laryngeal n. (loops around subclavian a.)
      - left recurrent laryngeal n. (loops around ligametum arteriosum)

      (also, the phrenic n. is somatic efferent in fiber type)

• Identify serous membrane and endothoracic fascia tissues surrounding the heart.

• Dissect the heart to learn its anatomy and develop an understanding of blood flow through the
four chambers of the heart.

CONTENTS

Anatomical Terms:

Nerves and ganglia (the following nerves are autonomic & bilateral)
        sympathetic trunk
                cervicothoracic ganglion
                        vertebral nerve
                        ansa subclavia
                middle cervical ganglion
                        cardiac nerves
        vagosympathetic trunk
                cranial cervical ganglion (not visible, will be dissected in Lab 25)
        vagus nerve
                recurrent laryngeal nerve
                        caudal laryngeal nerve
                dorsal & ventral vagal branches
                        dorsal & ventral vagal trunks

Heart and pericardium
         (Know: valve locations in a live animal & blood flow though the heart)

        fibrous pericardium (fibrous wall of the pericardial cavity/sac)
                phrenicopericardial ligament
        serous pericardium (lines the pericardial cavity/sac)
                parietal pericardium
                visceral pericardium (epicardium)
        Note: the wall of the pericardial cavity/sac consists physically of three inseparable layers:
                pericardial mediastinal pleura
                fibrous pericardium &
                parietal (serous) pericardium )

        heart surfaces: auricular (left) & atrial (right )
        coronary groove
        subsinuosal interventricular groove
        paraconal interventricular groove
        right atrium
                sinus venarum, contains the following four openings:
                        caudal vena cava
                        cranial vena cava
                        coronary sinus
                        right atrioventricular orifice
                interatrial septum
                        intervenous tubercle
                        fossa ovalis
                crista terminalis
                right auricle
                        pectinate muscles
        endocardium (lining of the heart)
        right atrioventricular orifice
                right atrioventricular valve (human tricuspid valve)
                        (parietal & septal cusps)
        right ventricle
                chordae tendineae
                papillary muscles
                trabeculae carneae
                trabecula septomarginalis (moderator band)
                conus arteriosus
        pulmonary valve (three semilunar cusps)
        pulmonary trunk (splits into right & left pulmonary aa.)
                ligamentum arteriosum (fetal ductus arteriosus; connection to the aorta)

        Note: pulmonary vv. from the lungs enter the left atrium:
        left atrium
                left auricle
        left atrioventricular orifice
                left atrioventricular valve (human mitral/bicuspid valve)
                        (parietal & septal cusps)
        left ventricle
                aortic valve (three semilunar cusps)
        right coronary artery
        left coronary artery
                        circumflex branch
                        paraconal interventricular branch
        great cardiac vein (drains into the coronary sinus)

Note:
autonomic [Greek: auto = self; nomos = rule/govern] = self governing

CONTENTS

Instructor Commentary:

The nerves found in the thoracic cavity are either sympathetic or parasympathetic autonomic nerves, with two exceptions. The recurrent laryngeal nerve carries somatic efferent axons to the larynx while the phrenic nerve carries somatic efferent fibers to the diaphragm.

The connection between the vagus nerve and the pharyngeal arches that give rise to the larynx is established early in development. As the heart migrates from the region of the pharynx to the thoracic cavity, it pulls nerves with it, causing the laryngeal nerve supply to detour into the thoracic cavity on its way to the larynx.

Because of right/left differences in vessel formation, the recurrent laryngeal nerve goes around a different vessels on the right side (subclavian a.) than on the left side (ligamentum arteriosum). The recurrent laryngeal nerve is named caudal laryngeal nerve in the vicinity of the larynx.

The heart is more easily studied in ungulates because the large animal hearts are larger and not filled with latex. Learn what you can now and reinforce that knowledge later in the course

You may choose to read pages 109-115 in Guide to the Dissection of the Dog regarding the Autonomic Nervous System.

Also, when you are on-line, you could click this link to explore the courseware web site: Canine Autonomic Nervous System Pathways (http://vanat.cvm.umn.edu/ans/).

CONTENTS

Dissection Steps:

Click to view a PDF list of dissection procedures for this lab:

Show List of Dissection Steps (PDF)

Dissection Videos:

CONTENTS

Dissection Images:

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