Changes

==Lungs==

==Lungs==

The left and right lungs lie within their [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity. The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]].

The left and right lungs lie within their [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.

The lungs are divided into lobes by the bronchial tree:

The lungs are divided into lobes by the bronchial tree:

**Cranial, caudal and accessory lobes. The middle lobe is absent.

**Cranial, caudal and accessory lobes. The middle lobe is absent.

Although lobulated, the lobes are not divided by deep fissures in the horse; making them appear the least lobulated of the common domestic species.

The right lung is larger than the left, as it includes the accessory lobe. Although lobulated, the lobes are not divided by deep fissures in the horse; making the lobulation indistinct. The cranial and caudal lobes are only separated by the cardiac notch. Part of mediastinal surface of both lungs fuses caudal to hilus.

==Pleural Cavity and Membranes==

==Pleural Cavity and Membranes==