Muscles Flashcards
Name elbow flexors
3 muscles:
Brachialis
Biceps Brachii
Brachioradialis
Briefly describe position and arrangement of brachialis
Fusiform muscle located on the anterior surface of the shaft of the humerus, deep to the muscle belly of biceps brachii and distally to its tendon
Tendon forms part of the floor of the cubital fossa
Give attachments of brachialis
Origin: Distal ½ , anterior surface shaft of humerus
Insertion: Anterior surface of Ulna tuberosity
Give actions of brachialis
Main flexor of elbow (in midline of anterior elbow joint)
Briefly describe arrangement and location of biceps brachii
large, thick muscle of the arm consisting of long head and short head
superficial to the brachialis and coracobrachialis muscles, and essentially forms the anterior side of the arm
Give attachments of biceps brachii
Origin:
Short head- tendon from apex of coracoid process of scapula.
Long head- tendon from supraglenoid tubercle of scapula. Long head tendon passes in a synovial sheath under the transverse ligament passing through intertubercular sulcus of the humerus
Insertion:
Tendon conjoined and twists before attaching to the radial tuberosity of the Radius. From the medial borders forms bicipital aponeurosis, it runs down and medially across cubital fossa to attach to the posterior border of the upper end of the ulna
Give actions of biceps brachii
Powerful Flexion at the elbow,
supination of the radio-ulnar joints (forearm)
weak flexor of the shoulder
Briefly describe the position and arrangement of brachioradialis
Superficial layer of the posterior forearm muscles on the lateral aspect extending from the elbow almost to the wrist
Give attachments of brachioradialis
Origin:
Lateral supracondylar ridge of humerus, Lateral intermuscular septum
Insertion:
Lateral distal radius proximal to the styloid process
Give actions of brachioradialis
Flexes the elbow when forearm mid-prone
Returns forearm from full supination or full pronation to mid-range (insertion anterior to point of rotation; most powerful in neutral)
State 1 functional activity in which brachioradialis is important
Hammering, pulling a pint of beer, chopping
State nerve supply of elbow flexors
Brachialis & biceps brachii:
Musculocutaneous nerve C5-6
Brachioradialis:
Radial nerve C5-6
Name elbow extensors
2 muscles
Triceps brachii
Anconeus
Briefly describe location and arrangement of triceps brachii
only constituent of the posterior muscle group of the arm, spanning almost the entire length of the humerus
consists of a long, medial and lateral head and makes up all the muscle bulk in the posterior region of the arm
Give the attachments of triceps brachii
Proximal:
Long head - infraglenoid tubercle and glenoid labrum of the scapula
Lateral head- posterior surface of the shaft of the humerus, supralateral to the spiral groove
Medial head- posterior surface of humerus, inframedial to the spiral groove.
Distal:
Three heads converge to a tendon
tendon attaches to the superior surface of the olecranon of the ulna and deep fascia of forearm.
Give actions of triceps brachii
As a whole - Prime mover of Extension at elbow joint
long head - extends arm at shoulder joint, assists in adduction of humerus
Name two functional activities in which triceps brachii has a prime action
Triceps extends the elevated arm to put books on a shelf. Works strong in punching
Pushing up from a chair, pushing a car etc
Briefly describe location and arrangement of anconeus
triangular muscle in the posterior compartment of the forearm
Give attachments of anconeus
Origin: Lateral epicondyle of humerus
Insertion: Descends to lateral olecranon, coronoid process of ulna, proximal ulna
Give actions of anconeus
Assists elbow extension
Give nerve supply of elbow extensors
Radial nerve
Triceps brachii - C6-8
Anconeus - C7-8
Give names of forearm pronators
Pronator teres
Pronator quadratus
Brachioradialis
Briefly describe location and arrangement of pronator teres
fusiform muscle found in the anterior forearm, consisting of a humeral head and ulna head
most lateral muscle of the superficial flexors of the forearm
forms the medial margin of the cubital fossa (elbow pit)
Give attachments of pronator teres
Origin:
Humeral head - Medial epicondyle of humerus
Ulna head - medial part of coronoid process of ulna
Insertion:
Middle of lateral surface of radius (distal to supinator)
Give actions of pronator teres
Powerful pronation of forearm (rotates radial head on radial notch of ulna)
Humeral head - assists elbow flexion
Briefly describe location and arrangement of pronator quadratus
quadrangular, thin, short and flat muscle lying within the anterior compartment of forearm
deepest muscle in the anterior (flexor) compartment of forearm
located distally in the forearm, covering the interosseous membrane superficially
Give attachments of pronator quadratus
Origins - Distal anterior surface of ulna
Insertion - Distal anterior surface of radius
Give actions of pronator quadratus
Pronation of forearm (rotates radial head on radial notch of ulna)
Stabilises bones (inf RUJ) in weight-bearing
Give nerve supply of the forearm pronators
Pronator teres -
Median nerve C6-7 (passes through gap between 2 heads)
Pronator quadratus-
Anterior Interosseous nerve C8 - T1
Brachioradialis
Radial nerve C5-6
Name forearm supinators
3 muscles
Supinator
Biceps brachii
Brachioradialis
Briefly describe location and arrangement of supinator
spiral muscle contained in the posterior compartment of the forearm, consisting of a humeral head and ulna head
found deep in the forearm, superficial only to the parts of the radius and ulna over which the muscle lies.
Along with the brachialis muscle, it forms the floor of the cubital fossa
Give attachments of supinator
Origin:
Humeral head - Lateral epicondyle of humerus, slips to radial collateral and annular ligaments
Ulna head - supinator fossa and crest of ulna (inferior to radial notch)
Insertion:
Heads conjoin and wrap around lateral, posterior and anterior surfaces of proximal 1/3 of radius
Give actions of supinator
Prime mover of supination of forearm (de-rotate radial head on radial notch)
Give nerve supply of forearm supinators
Supinator- Radial nerve (motor branch through gap of two heads) C5-6
Biceps brachii-
Musculocutaneous nerve C5-6
Brachioradialis -
Radial nerve C5-6
