Textbook of anatomy. Section 2. The muscular system: the nervous system: the organs of sense and integument / By D.J.Cunningham,Robert Howden and A.M.Patterson.

Cunningham, D. J.

Date:: 1906

Credit: Textbook of anatomy. Section 2. The muscular system: the nervous system: the organs of sense and integument / By D.J.Cunningham,Robert Howden and A.M.Patterson. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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$insertion, and the inner head is attached to its deep surface. A small thick-walled bursa separates the tendon of the triceps from the posterior ligament of the elbow- joint and the anterior part of the upper end of the olecranon process. The long head of the triceps is concealed at first by the teres major and teres minor, and by the deltoid muscle. Along with the outer head it conceals the musculo- spiral nerve and superior profunda artery, and covers the inner head of the muscle. The inner is the deep head, and is only visible at the lateral borders of the muscle. Tlie subanconeus is a small muscle occasionally present, which consists of scattered fibres arising from the lower end of tlie liumerus beneath tlie triceps, and inserted into tlie posterior ligament of the elbow-joint. Nerve-Supply. The following nerves supply the muscles of the arm :— Muscles. Nerves. Origin. Coraco-bi-achialis -\ Biceps I . Bracliialis anticusj Brachial is anticus Triceps | Outer head j Middle and inner heads j Musculo-cutaneous Musculo-spira] rC. 7. \ C. 5. 6. ic. 5. 6. rC. (5) 6. - C. (6) 7. 8. \ C. 7. 8. Actions. (1) The chief action of these muscles (excepting the coraco-brachialis) is on the elbow-joint, producing along with other muscles flexion and extension. The flexor muscles are much more powei-ful than the extensors. Table of Muscles acting on the Elbow-Joint. Flexors. Extensors. Biceps Bracliialis anticus Bracliio-radialis P]'onator radii teres Flexors of wrist and fingers Extensors of wrist (in pronation) Triceps Anconeus Extensors of wrist and fingers (in suj)ination) (2) The coraco-brachialis muscle acts only on the shoulder-joint, assisting the biceps as an adductor and flexor of the humerus. (3) Subordinate and accessory movements are performed by all the muscles of this group except the bracliialis anticus. Tlie biceps supiiiates the forearm, flexes the elbow, and with the aid of the coraco-brachialis adducts and flexes the humerus at the shoulder-joint. The triceps through its scapular head adducts and extends the humerus, besides extending the elbow-joint. FASCLE AND MUSCLES OF THE FOEEAEM AND HAND. FASCI.E. The superficial fascia in the forearm presents no exceptional features. On the dorsum of the hand it is loose and thin; in the palm it is generally well furnished with fat, forming piads for the protection of the vessels and nerves. It is closely adherent to the palmar fascia and to the skin, especially along the lines of flexure. The palmaris brevis is a quadrilateral subcutaneous muscle occupying the inner side of the hand under the superficial fascia. It arises from the inner border of the thick central portion of the palmar fascia and from the front of the anterior annular ligament of the wrist, and is inserted into the skin of the inner border of the hand for a variable distance. It covers the ulnar artery and nerve, branches of which supply it. Its action is to wrinkle the skin of the inner border of the$