Muscles Flashcards
Action of Longus Colli
Bilaterally flexes the neck
Attachments of Sternocleidomastoid
Sternal head: anterosuperior surface of manubrium sterni.
Clavicular head: superior surface of medial two thirds of the clavicle.
Distal: lateral surface of mastoid process of temporal bone and a thin aponeurosis to lateral third of superior nuchal line of occipital bone.
Actions of Sternocleidomastoid
Ipsilateral side flexion of the neck.
Contralateral rotation of the head.
Bilateral flexion of the neck against resistance.
Posterior fibres extend the head at the Atlanta-occipital joint.
Raise the clavicle and manubrium sterni when head and neck are fixed.
Attachments of Scalenus Anterior
Proximal: anterior tubercles of transverse processes of C3-C6.
Distal: scalene tubercle on inner border of 1st rib.
Actions of Scalenus Anterior
Ipsilateral side flexion of the neck.
Contralateral rotation of the head.
Bilateral neck flexion.
Attachments of Scalenus Medius
Proximal: transverse processes of C1 and C2 and posterior tubercles of C3-C7 vertebrae.
Distal: superior surface of 1st rib, between tubercle of the rib and the groove for the subclavian artery.
Attachment of Scalenus Posterior
Proximal: posterior tubercles of transverse processes of C4, C5 and C6.
Distal: outer surface of 2nd rib behind the attachment of Serratus Anterior.
Actions of Scalenus Medius and Scalenus Posterior
Ipsilateral side flexion of the neck
Attachments of Rectus Abdominis
Proximal: two tendons from anterior aspect of pubic symphysis and pubic crest.
Distal: anterior aspect of xiphoid process and the costal cartilages of 5th, 6th and 7th ribs.
Actions of Rectus Abdominis
Flexion of the trunk.
Unilaterally it assists the obliques in ipsilateral side flexion of the trunk,
Attachments of External Oblique
Proximal: fleshy strips to outer borders of lower eight ribs and their costal cartilages. Interdigitates with Serratus Anterior above and Latissimus Dorsi below.
Distal: vertical fibres from lower two ribs attach to outer lip of anterior two thirds of iliac crest. Remainder of fibres give rise to a large aponeurosis, the fibres of which sweep across Rectus Abdominis, participating in the rectus sheath, and pass towards the midline to fuse with that of the opposite side at the linea alba.
Lower border stretches between the pubic tubercle and the ASIS and forms the inguinal ligament.
Actions of External Oblique
Contralateral rotation and ipsilateral side flexion of the thorax and shoulders when pelvis is fixed.
Ipsilateral rotation of the pelvis when the shoulders are fixed.
Draws the hip and pelvis up if the trunk if fixed (hop hitching).
Attachments of Internal Oblique
Proximal: lateral two thirds of the inguinal ligament, anterior two thirds of iliac crest and the thoracolumbar fascia.
Distal: posterior fibres attach to inferior borders of lower four ribs.
Anterior and lower fibres form an aponeurosis which interlaces with the muscle of the opposite side at the linea alba.
The part of the muscle arising from the inguinal ligament attaches by the conjoint tendon to the pubic crest and pectin pubis.
Actions of Internal Oblique
Ipsilateral rotation and side flexion if the pelvis is fixed.
Attachments of Transversus Abdominus
Proximal: inferiorly it arises from the lateral third of the inguinal ligament and anterior two thirds of the inner lip of the iliac crest. Posteriorly it arises from the thoracolumbar fascia. Superiorly it arises from the inner surface of the costal cartilages of the lower six ribs and interdigitates with the attachment of the diaphragm.
Distal: attaches to the linea alba by the aponeurotic sheet. By the conjoint tendon it attaches to the pubic crest and pectin pubis.
Actions of Transversus Abdominus
Compression and support of the abdominal viscera.
Attachments of Quadratus Lumborum
Proximal: inferiorly to the posterior abdominal wall running between the pelvis and the 12th rib, deep to Erector Spinae.
Distal: medial half of the lower border of the twelfth rib. Medial border of Quadratus Lumborum attaches to the lateral part of the transverse processes of all the lumbar vertebrae.
Actions of Quadratus Lumborum
Bilateral extension of the lumbar spine.
Ipsilateral side flexion of the spine.
Attachments of Erector Spinae
Proximal: strong, thick flat tendon with an extensive attachment to the processes of the T11 to L5 vertebrae and the iliac crest and sacral crests and sacral ligaments.
Distal: cervical spine C2
Actions of Erector Spinae
Extension of the trunk.
Ipsilateral side flexion and rotation against resistance.
Controls flexion of the trunk against the effects of gravity.
Attachments of the Diaphragm
Lumbar part: two crura attach to anterolateral aspect of the lumbar vertebral bodies. Right crus comes from bodies and discs of L1-L3. Left crus comes from bodies and discs of L1-L2.
Two crura cross at each other at level of body of T12 and are connected at this point by the median arcuate ligament.
Remainder of lumbar part of diaphragm arises from medial and lateral arcuate ligaments.
Costal part: inner surfaces of lower six ribs and there costal cartilages.
Sternal part: two slips from posterior surface of xiphoid process of sternum.
Central tendon attached to pericardium of heart.
Actions of the diaphragm
Initially, 12th rib is fixed by Quadratus Lumborum, the diaphragm contracts and the central tendon is pulled down and forwards for level T8 to approximately T10, enlarging the thoracic cavity in the vertical dimension.
The central tendon then becomes the fixed point, the lower ribs begin to lift upwards and outwards, increasing the transverse diameter of the thorax (bucket handle).
The upper ribs are raised to push the sternum forwards, increasing the anteroposterior diameter (pump handle).
