Page 145 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 11
VetBooks.ir

Thoracic wall anatomy and

surgical approaches

Zoë J. Halfacree and Julius M. Liptak

Introduction articulates directly with the manubrium. The sternum is
laterally flattened, creating a narrow midline to follow when
Surgery is required to manage pathology of the thoracic performing a median sternotomy.
wall, including neoplasia and trauma, and to access the The first ribs delineate the cranial extent of the thoracic
thoracic cavity. Knowledge of anatomy is important to cavity: the thoracic inlet. There is no dividing structure at
guide selection of an appropriate surgical approach and this anatomical boundary and the cervical tissue planes
to ensure that vital structures are not inadvertently are continuous with the cranial mediastinum; disease
damaged. Thor ough patient assessment, stabilization and processes within the neck may readily extend into the
careful attention to anaesthesia and analgesia regimens thor acic cavity via this route. The caudal boundary of
are essential. the thoracic cavity is delineated by the diaphragm.

Muscles
Thoracic wall anatomy Muscular attachments to the thoracic skeleton create

respiratory movement and contribute to thoracic limb
Skeleton and anatomical boundaries loco motion, in addition to creating a robust thoracic wall
The thoracic wall is composed of 13 paired ribs (Figure and origins for the muscular abdominal wall. The manu-
11.1). The most cranial nine ribs join the sternum ventrally, brium serves as an attachment for the sternocephalic
via the costal cartilages, while the last four ribs create the muscles, whilst the xiphoid provides diaphragmatic inser-
costal arch. The sternum is composed of eight sternebrae tion and the origin of the linea alba, which merges with
joined by fibrocartilage articulations; the most cranial the tendinous sheath of the rectus abdominis muscles.
sternebra is the manubrium and the most caudal sternebra The ribs are connected by the internal and external
is the xiphoid. The costal cartilages articulate with the intercostal muscles. Internally, the transversus thoracis
intersternebral cartilages, apart from the first rib, which muscle runs ventrally between the sternum and the

Cr

Ca

(a) (b)
Skeletal anatomy of the thorax. (a) The left thorax, demonstrating the positions of incisions for lateral thoracotomy required to perform, for
11.1 e ample patent ductus arteriosus ligation fourth lung lobectomy or pericardectomy fifth or thoracic duct ligation ninth left in the cat
right in the dog). (b) Anatomy of the sternum, showing the extent of sternotomy incisions for procedures such as resection of a cranial (Cr) or caudal (Ca)
mediastinal mass.
(Redrawn after Evans, 1993)

136 BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, second edition. Edited by Daniel J. Brockman, David E. Holt and Gert ter Haar. ©BSAVA 2018

Ch11 HNT.indd 136 31/08/2018 11:51