Levator Anguli Scapulae.
Rhomboideus Minor.
Rhomboideus Major.

Dissection. The Trapezius must be removed in order to expose the next layer ; to effect this, the muscle must be detached from its attachment to the clavicle and spine of the scapula, and turned back towards the spine.

The Levator Anguli Scapula is a long, thick, and somewhat flattened muscle, situated at the posterior part and side of the neck. It arises by four tendons from the posterior tubercles of the transverse processes of the three or four upper cervical vertebrae, these becoming fleshy are united so as to form a flat muscle, which, passing downwards and backwards, is inserted into the posterior border of the scapula, between the superior angle and the triangular smooth surface at the root of the spine.

Relations. By its superficial surface, with the integument, Trapezius, and Sterno-mastoid. By its deep surface, with the Splenius colli, Transversalis colli, Cervicalis ascendens, and Serratus posticus superior, and with the transverse cervical and posterior scapular arteries.

The Rhomboideus Minor arises from the ligamentum nuchaa, and spinous processes of the seventh cervical and first dorsal vertebrae, its fibres of origin being intimately united with those of the Trapezius. Passing downwards and outwards, it is inserted into the margin of the triangular smooth surface at the root of the spine of the scapula. This small muscle is usually separated from the Rhomboideus major by a slight cellular interval.

The Rhomboideus Major is situated immediately below the preceding, the adjacent margins of the two being occasionally united. It arises by tendinous fibres from the spinous processes of the four or five upper dorsal vertebrae and their inter-spinous ligaments, and is inserted into the posterior border of the scapula, between the triangular surface at the base of the spine and the inferior angle. The insertion of this muscle takes place by means of a narrow, tendinous arch, attached above, to the triangular surface near the spine; below, to the inferior angle, the arch being connected to the border of the scapula by a thin membrane. When the arch extends, as it occasionally does, but a short distance, the muscular fibres are inserted into the scapula itself.

Relations. By their superficial surface, with the integument, and Trapezius, the Rhomboideus major, with the Latissimus dorsi. By their deep surface, with the Serratus posticus superior, posterior scapular artery, part of the Erector spin*, the Intercostal muscles and ribs.

Nerves. These muscles are supplied by branches from the fifth cervical nerve, and additional filaments from the deep branches of the cervical plexus are distributed to the Levator anguli scapulae. the upper extremity. It consists of longitudinal and transverse fibres blended together, forming .a thin lamella, which is attached in the median line to the spi-nous processes of the dorsal vertebrae; externally, to the angles of the ribs; and below, to the upper border of the Inferior serratus and tendon of the Latissimus dorsi; above, it passes beneath the Serratus posticus superior, and blends with the deep fascia of the neck.

The Serratus posticus superior should now be detached from its origin and turned outwards, when the Splenius muscle will be brought into view.

The Splenius is a broad muscle, situated at the posterior part of the neck and upper part of the dorsal region. At its origin, it is a single muscle, narrow and pointed in form; but it soon becomes broader, and divides into two portions, which have separate insertions. It arises, by tendinous fibres, from the lower half of the Ligamcntum nucha>, from the spinous processes of the last cervical and of the six upper dorsal vertebrae, and from the supra-spinous ligament. From this origin, the fleshy fibres proceed oblicpjely upwards and outwards, forming a broad flat muscle, which divides as it ascends into two portions, the Splenius capitis and Splenius colli.

The Splenius capitis is inserted into the mastoid process of the temporal bone, and into the rough surface on the occipital bone beneath the superior curved line.

The Splenius colli is inserted, by tendinous fasciculi, into the posterior tubercles of the transverse processes of the three or four upper cervical vertebras.

The Splenius is separated from its fellow of the opposite side by a triangular interval, in which is seen the Complexus.

Relations, liy its superficial surface, with the Trapezius, from which it is separated below by the Rhomboidei and the Serratus posticus superior. It is also covered by the Sterno-mastoid and Levator anguli scapulae. By its deep surface, with the Spinalis dorsi, Longissimus dorsi, Semi-spinalis colli, Complexus, Trachelo-mastoid, and Transversalis colli.

Nerves. The Splenius and Superior serratus are supplied from the external posterior branches of the cervical nerves; the Inferior serratus, from the external branches of the dorsal nerves.

Actions. The Serrati are respiratory muscles acting in antagonism to each other. The Serratus posticus superior elevates the ribs; it is, therefore, an inspi-ratory muscle; while the Serratus inferior draws the lower ribs downwards, and is a muscle of expiration. This muscle is also probably a tensor of the vertebral aponeurosis. The Splenii muscles of the two sides, acting together, draw the head directly backwards, assisting the Trapezius and Complexus; acting separately, they draw the head to one or the other side, and slightly rotate it, turning the face to the same side. They also assist in supporting the head in the erect position.