Joint extension in exercise is when you increase the angle in a joint between two bones. This is opposite of joint flexion.
For example in a glute bridge as you lift your glutes off the ground, you are increasing the angle of your hip joint.
The muscles that help you extend at a joint are extensor muscles.
The sternocleidomastoid muscle, AKA sternomastoid or SCM muscle take its name from their connection to three bony structures.
- The sternum or breastbone
- The clavicle or collarbone
- Mastoid process of the occipital bone of the skull
Origin: The clavicular division originates at superior medial third of clavicle and the sternal division originates at superior manubrium of sternum. Insertion: Both divisions of sternocleidomastoid muscle insert into mastoid process of the skull. Action:
- Rotate the head to the opposite side
- Oblique rotation and lifting the head
- Neck Flexion
- Assist scalene in inspiration
- Cervical plexus nerve of sternocleidomastoid provides proprioception, spacial body orientation in static posture and during movement. 1
Muscles Attached to Scapula
- Rhomboid Major
- Rhomboid Minor
- Teres Major
- Teres Minor
- Pectoralis Minor
- Biceps brachii
- Triceps brachii
- Latisimus Dorsi
- Levator Scaupla
- Serratus Anterior
Origin of upper trapezius: External occipital protuberance, medial third of the superior nuchal line,, ligamentum nuchae, spinous processes of 7th cervical vertebrae.
Insertion: lateral third of the clavicle, medial side of the acromion process.
Actions: Elevates the scapula, rotates the scapula upward, retracts scapula when contracting with other sections of trapezius muscle.