J FASCLA AND MUSCLES OF THE PECTORAL REGION. 309 
humerus, behind the coraco-brachialis and biceps, and the axillary vessels and 
nerves. It les in front of the insertion of the teres major, from which it is 
separated by a bursa. 
In the back the latissimus dorsi is superficial, except in its upper part, which is 
concealed by the trapezius. It hes upon the lumbar fascia, ribs, and lower angle 
of the scapula, and at its borders two triangular spaces are formed; at the upper 
border is the so-called triangle of auscultation: at the outer border is the triangle 
of Petit, a small space bounded by the ihac crest, the latissimus dorsi, and the 
obliquus externus abdominis. This is the site of an occasional lumbar hernia. 
The levator anguli scapule (levator scapule) is a strap-like muscle, arising 
by tendinous slips from the posterior tubercles of the transverse processes of the 
first three or four cervical vertebrae, between the attachments of the scalenus 
medius and splenius colli. It is directed downwards along the side of the neck, to 
be inserted into the vertebral border of the scapula in its upper fourth, from the 
superior angle to the spine. It is concealed in its upper third by the sternomastoid 
and deep muscles of the neck. In its middle third it occupies the floor of the 
posterior triangle. In its lower third it is again hidden from view by the trapezius. 
It conceals the splenius colli and cervicalis ascendens muscles. 
The rhomboideus minor may be regarded as a separated slip of the rhom- 
boideus major, with which it is often continuous. It arises from the /igamentum 
nuche and the spines of the seventh cervical and first thoracic vertebrae. Passing 
obliquely downwards and outwards, it is inserted into the vertebral border of the 
scapula below the levator anguli scapule muscle, and opposite to the base of the 
spine. 
The rhomboideus major arises from the spinous processes of the thoracic 
vertebrae from the second to the fifth inclusive, and from the corresponding supra- 
spinous ligaments. Passing downwards and outwards, it is inserted below the 
rhomboideus minor into the vertebral border of the scapula, between the spine and 
the lower angle. The muscle is only inserted directly into the scapula by means 
of its lower fibres. Its upper part is attached to a membranous band, which, 
connected for the most part by loose areolar tissue to the vertebral border of the 
scapula, is fixed to the bone at its extremities, above near the base of the spine, 
and below at the inferior angle. 
The rhomboid muscles are concealed for the most part by the trapezius. The 
lower part of the rhomboideus major is superficial in the triangle of auscultation. 
The muscles cover the serratus posticus superior and the vertebral aponeurosis. 
THE FASCLZ AND MUSCLES OF THE PECTORAL REGION. 
FASCLA. 
The fascize and muscles of the chest occupy the space below the clavicle, between 
the sternum and the humerus, and form at the same time the anterior boundary 
of the axilla. 
The superficial fascia of the chest usually contains a quantity of fat, in which 
the mamma is embedded. The platysma myoides muscle lies beneath its upper part. 
The deep fascia is attached above to the clavicle, and internally to the 
sternum. Below it is continuous with the fascia of the abdominal wall. It gives 
origin to the platysma myoides, and invests the pectoralis major. At the outer 
border of the great pectoral muscle it is thickened, and forms the floor of the 
axillary space (axillary fascia), continued posteriorly on to the posterior fold of the 
axilla (teres major and latissimus dorsi), and externally into connexion with the 
deep fascia of the arm. 
Costo-Coracoid Membrane.—Beneath the pectoralis major a deeper stratum of 
fascia invests the pectoralis minor muscle. At the upper border of this muscle it 
forms the costo-coracoid membrane, which passes upwards to the lower border of the 
subclavius muscle, where it splits into two layers, attached in front of and behind 
that muscle to the borders of the under surface of the clavicle. The membrane 
traced inwards along the subclavius muscle is attached to the first costal cartilage ; 
