Upper Limbs and Thorax
Give the attachments, nerve supply and actions of: Trapezius, deltoid, serratus anterior, triceps brachii, biceps brachii, pronator teres, flexor digitorum superficialis, flexor digitorum profundus, supinator, muscles of thenar eminence, lumbricals.
TRAPEZIUS : a) Flat muscle. b) It covers back of neck and upper part of trunk
1
Origin : External occipital protuberance Medial one‐third of superior nuchal line Ligamentum nuchae Spine of 7th cervical vertebra Spines all twelve thoracic vertebrae and supraspinous ligaments Insertion : Posterior border of lateral one third of clavicle (superior fibres) Medial margin of acromion and superior edge of crest of spine of scapula (middle fibres. Apex of triangular area at the root of spine of scapula (inferior fibres) Nerve supply : Motor supply from spinal accessory nerve. Proprioceptive fibres from ventral rami of C3, C4 nerves Main actions DELTOID It is a triangular muscle
2
Origin Anterior border and superior surface of lateral third of clavicle (anterior part). Lateral border of acromion (middle part). Lower edge of crest of spine of scapula (posterior part). The anterior and posterior fibres converge towards its tendon of insertion. The middle part is multipennate. Four inter‐muscular septa descend from four tubercles on acromion or interdigitate with three septa ascending from deltoid tuberosity. Insertion Is on V‐shaped rough deltoid tuberosity on middle of anterolateral surface of shaft of humerus. Nerve supply Nerve supply is by axillary nerve (C5, C6). Actions : Anterior fibres help pectoralis major in flexion and medial rotation of arm. Posterior fibres help latissimus dorsi and teres major in extension and lateral rotation of arm. The multipennate middle part is powerful abductor of arm up to 90°, initiated by supraspinatus. During abduction, the anterior and posterior fibres help to steady the humerus.
TRAPEZIUS : a) Flat muscle. b) It covers back of neck and upper part of trunk
1
Origin : External occipital protuberance Medial one‐third of superior nuchal line Ligamentum nuchae Spine of 7th cervical vertebra Spines all twelve thoracic vertebrae and supraspinous ligaments Insertion : Posterior border of lateral one third of clavicle (superior fibres) Medial margin of acromion and superior edge of crest of spine of scapula (middle fibres. Apex of triangular area at the root of spine of scapula (inferior fibres) Nerve supply : Motor supply from spinal accessory nerve. Proprioceptive fibres from ventral rami of C3, C4 nerves Main actions DELTOID It is a triangular muscle
2
Origin Anterior border and superior surface of lateral third of clavicle (anterior part). Lateral border of acromion (middle part). Lower edge of crest of spine of scapula (posterior part). The anterior and posterior fibres converge towards its tendon of insertion. The middle part is multipennate. Four inter‐muscular septa descend from four tubercles on acromion or interdigitate with three septa ascending from deltoid tuberosity. Insertion Is on V‐shaped rough deltoid tuberosity on middle of anterolateral surface of shaft of humerus. Nerve supply Nerve supply is by axillary nerve (C5, C6). Actions : Anterior fibres help pectoralis major in flexion and medial rotation of arm. Posterior fibres help latissimus dorsi and teres major in extension and lateral rotation of arm. The multipennate middle part is powerful abductor of arm up to 90°, initiated by supraspinatus. During abduction, the anterior and posterior fibres help to steady the humerus.