11.5 Muscles of the Pectoral Girdle and Upper Limbs
4 min read•june 18, 2024
The muscles of the pectoral girdle and upper limbs are key players in arm movement. From the powerful to the versatile , these muscles work together to enable a wide range of motions, including , , and rotation of the arm and shoulder.
The rotator cuff, a group of four muscles surrounding the shoulder joint, plays a crucial role in stabilizing the arm. Meanwhile, muscles like the biceps and triceps control elbow movements, while forearm muscles manage wrist and hand actions. Understanding these muscles is essential for grasping upper body function.
Muscles of the Pectoral Girdle and Upper Limbs
Muscles of pectoral girdle and upper limbs
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- muscle spans from the anterior chest wall () to the (), enabling (moving arm toward body), (rotating arm inward), and (moving arm forward and upward) of the (upper arm bone)
- muscle originates from the posterior trunk, inferior to the (shoulder blade), and inserts on the humerus, facilitating extension (moving arm backward), , and medial rotation of the humerus
- Deltoid muscle covers the lateral aspect of the shoulder and assists in (moving arm away from body laterally), flexion, and extension of the humerus
- muscle lies on the anterior aspect of the upper arm and enables flexion of the elbow joint and (rotating forearm so palm faces upward) of the forearm
- muscle is located on the posterior aspect of the upper arm and is responsible for extension of the elbow joint
- muscle originates from the anterior aspect of the lower humerus and inserts on the (medial forearm bone), contributing to flexion of the elbow joint
- muscle runs along the lateral aspect of the forearm and assists in flexion of the elbow joint, especially when the forearm is in a neutral position (between and )
- Wrist and hand flexor muscles, such as and , are situated on the anterior aspect of the forearm and enable flexion (bending) of the wrist and fingers
- Wrist and hand extensor muscles, including and , are located on the posterior aspect of the forearm and facilitate extension (straightening) of the wrist and fingers
Movements of upper extremity joints
- Shoulder joint movements:
- Flexion: Moving the arm forward and upward
- Extension: Moving the arm backward
- : Moving the arm away from the body laterally
- Adduction: Moving the arm toward the body
- Medial rotation: Rotating the arm inward (e.g., touching the opposite shoulder)
- : Rotating the arm outward
- Elbow joint movements:
- Flexion: Decreasing the angle between the forearm and the upper arm (e.g., bringing hand toward shoulder)
- Extension: Increasing the angle between the forearm and the upper arm (e.g., straightening the arm)
- Forearm movements:
- : Rotating the forearm so that the palm faces downward (e.g., turning a doorknob)
- Supination: Rotating the forearm so that the palm faces upward (e.g., holding a bowl of soup)
- Wrist joint movements:
- Flexion: Moving the palm toward the anterior forearm
- Extension: Moving the back of the hand toward the posterior forearm
- : Moving the hand toward the thumb side (e.g., waving hello)
- : Moving the hand toward the little finger side
- Hand and finger movements:
- Flexion: Bending the fingers toward the palm (e.g., making a fist)
- Extension: Straightening the fingers
- Abduction: Spreading the fingers apart (e.g., playing piano)
- Adduction: Bringing the fingers together
Rotator cuff structure and function
- Rotator cuff is a group of four muscles and their tendons that surround the shoulder joint, providing stability and enabling dynamic movements of the arm
- muscle originates from the superior aspect of the scapula and assists in arm abduction (lifting arm away from body) and stabilization of the humeral head (top of upper arm bone) within the shoulder joint
- muscle arises from the posterior aspect of the scapula and contributes to lateral rotation (rotating arm outward) and stabilization of the humeral head
- muscle originates from the lateral border of the scapula and aids in lateral rotation and stabilization of the humeral head
- muscle lies on the anterior surface of the scapula and enables medial rotation (rotating arm inward) and stabilization of the humeral head
- Rotator cuff muscles work together to maintain shoulder stability by:
- Compressing the humeral head against the (socket of the shoulder blade), preventing dislocation
- Counteracting the upward pull of the deltoid muscle, which could cause the humeral head to migrate superiorly
- Maintaining proper alignment of the humeral head during various arm movements
- Preventing excessive translation (sliding) of the humeral head within the glenoid fossa, thus reducing the risk of impingement and injury
Muscle Interactions and Characteristics
- work in opposition to each other, such as the and in elbow flexion and extension
- work together to produce a specific movement, like the biceps brachii and in elbow flexion
- of upper limb muscles is primarily through branches of the brachial plexus, which determines their function and control
- in the upper limbs vary depending on the muscle's function, with a mix of slow-twitch (Type I) and fast-twitch (Type II) fibers to accommodate different movement needs
Key Terms to Review (108)
Abduction: Abduction in anatomy and physiology is the movement of a limb or other part away from the midline of the body or from another part. It is a key action in joints, enabling movements such as spreading the fingers or arms.
Abduction: Abduction is the movement of a limb or body part away from the midline of the body. It is one of the primary types of body movements that occur at synovial joints, allowing for a wide range of motion and flexibility in the limbs and extremities.
Abductor digiti minimi: The abductor digiti minimi is a muscle located in the hand that is responsible for abducting, or moving away, the little finger from the other fingers. It plays a crucial role in grasping and manipulating objects by allowing independent movement of the pinky finger.
Abductor pollicis brevis: The abductor pollicis brevis is a muscle in the hand that allows for the abduction of the thumb, moving it away from the palm and other fingers. It plays a crucial role in grasping objects and manipulating tools by enabling thumb movement.
Abductor pollicis longus: The abductor pollicis longus is a muscle in the forearm that facilitates the abduction and extension of the thumb away from the hand's palm. It plays an essential role in movements requiring thumb mobility, such as grasping or manipulating objects.
Adduction: Adduction is a movement that brings a limb closer to the midline of the body or decreases the angle between two bones at a joint. It is opposite to abduction, which moves limbs away from the body's midline.
Adduction: Adduction is a type of body movement that involves the action of moving a limb or body part towards the midline of the body. It is a key concept in understanding the mechanics of the pectoral girdle, synovial joints, and the muscles that control movement of the upper and lower limbs.
Adductor pollicis: The adductor pollicis is a muscle in the hand that plays a crucial role in bringing the thumb towards the palm, assisting in gripping and manipulating objects. It is located deep in the palm and acts to adduct the thumb, contributing to hand functionality.
Anconeus: The anconeus is a small triangular muscle located at the posterior aspect of the elbow, which plays a role in extending the forearm and stabilizing the elbow joint. It originates from the lateral epicondyle of the humerus and inserts into the lateral aspect of the ulna.
Antagonist Muscles: Antagonist muscles are a pair of muscles that work in opposition to one another, causing opposing movements at a joint. They are essential for coordinated and controlled movement of the body's limbs and joints.
Anterior compartment of the arm: The anterior compartment of the arm is a region containing muscles that primarily function in flexing the forearm at the elbow joint. It is innervated by the musculocutaneous nerve and includes muscles such as the biceps brachii, brachialis, and coracobrachialis.
Anterior compartment of the forearm: The anterior compartment of the forearm consists of muscles that are primarily involved in flexion and pronation of the wrist and fingers. These muscles are innervated mainly by the median and ulnar nerves.
Biceps brachii: The biceps brachii is a major muscle of the upper arm that is involved in the flexion of the elbow and the supination of the forearm. It consists of two heads, known as the long head and the short head, which originate from different parts of the scapula and insert into the radial tuberosity on the radius.
Biceps Brachii: The biceps brachii is a two-headed muscle located in the anterior (front) compartment of the upper arm. It is a major flexor of the elbow joint and also acts to supinate the forearm. This muscle plays a crucial role in the interactions of skeletal muscles, their fascicle arrangement, and their lever systems, as well as being one of the key muscles of the pectoral girdle and upper limbs.
Brachialis: The brachialis is a muscle located in the upper arm that plays a crucial role in flexing the elbow joint. It lies beneath the biceps brachii and is considered one of the primary movers for elbow flexion.
Brachialis: The brachialis is a muscle located in the anterior compartment of the arm, responsible for flexing the elbow joint. It is a key muscle involved in the movements of the pectoral girdle and upper limbs.
Brachioradialis: The brachioradialis is a muscle of the forearm that flexes the forearm at the elbow. It is located in the lateral part of the forearm and is easily visible when the forearm is flexed.
Brachioradialis: The brachioradialis is a muscle located in the anterior compartment of the forearm. It is responsible for flexing the forearm at the elbow joint and is an important muscle involved in the movements of the pectoral girdle and upper limbs.
Coracobrachialis: The coracobrachialis is a muscle of the upper arm that lies beneath the biceps brachii, extending from the coracoid process of the scapula to the middle of the humerus. It functions to flex and adduct the humerus at the shoulder joint.
Deep anterior compartment: The deep anterior compartment is a section within the forearm or lower leg that contains specific muscles, nerves, and blood vessels, responsible for fine motor movements. In the context of the upper limb, it primarily focuses on the muscles involved in flexion and pronation of the wrist and fingers.
Deep posterior compartment of the forearm: The deep posterior compartment of the forearm is a group of muscles located on the backside of the forearm, responsible for various movements including finger extension and wrist abduction. These muscles are separated from those in the superficial layer by a fascial plane, and they play a critical role in hand and forearm function.
Deltoid: The deltoid is a thick, triangular muscle covering the shoulder joint, responsible for lifting the arm and giving the shoulder its range of motion. It plays a pivotal role in both the power and precision needed for arm movement.
Dorsal interossei: The dorsal interossei are four muscles located in the hand, between the metacarpal bones, responsible for abducting (moving away) the fingers from the hand's midline and also assist in finger flexion at the metacarpophalangeal joints and extension at the interphalangeal joints. They play a crucial role in fine motor movements and dexterity of the hand.
Extension: Extension refers to the movement of a joint or body part that increases the angle between the bones involved, straightening or lengthening the limb or structure. It is one of the fundamental types of body movements that occurs at synovial joints and is facilitated by the contraction of specific muscle groups.
Extensor carpi radialis brevis: The extensor carpi radialis brevis is a muscle located in the forearm that plays a crucial role in extending and abducting the wrist. It works alongside other muscles to control movements of the hand and wrist, enabling activities like typing or playing an instrument.
Extensor Carpi Radialis Longus: The extensor carpi radialis longus is a muscle in the posterior compartment of the forearm that extends and abducts the wrist. It is one of the key muscles involved in the movements of the pectoral girdle and upper limbs.
Extensor carpi ulnaris: The extensor carpi ulnaris is a muscle located in the forearm that extends and adducts the wrist. It runs from the elbow to the hand, attaching to the ulna and the base of the fifth metacarpal bone.
Extensor digiti minimi: The extensor digiti minimi is a muscle located in the forearm that extends the little finger at all its joints. It plays a crucial role in the control and movement of the pinky finger, especially during tasks that require spreading the fingers apart or extending them.
Extensor digitorum: The extensor digitorum is a muscle in the forearm that helps to extend the fingers and the wrist. It originates from the lateral epicondyle of the humerus and inserts into the extensor expansions of the middle phalanges of the four fingers.
Extensor Digitorum: The extensor digitorum is a muscle located in the posterior compartment of the forearm that is responsible for extending the fingers. It is a key muscle involved in the movement and dexterity of the hand and fingers.
Extensor indicis: The extensor indicis is a muscle in the forearm that extends along the index finger, aiding in its extension. It originates from the ulna and inserts into the extensor expansion of the index finger.
Extensor pollicis brevis: The extensor pollicis brevis is a small skeletal muscle located in the forearm that helps to extend and abduct the thumb at the carpometacarpal and metacarpophalangeal joints. It is part of the deep posterior compartment of the forearm and plays a crucial role in thumb movement.
Extensor pollicis longus: The extensor pollicis longus is a skeletal muscle located in the forearm that extends the thumb away from the palm, facilitating movements such as grasping or manipulating objects. It works by pulling on the distal phalanx of the thumb, allowing it to extend and rotate.
Extensor radialis longus: The extensor radialis longus is a muscle in the forearm that helps to extend and abduct the wrist. It runs from the lateral supracondylar ridge of the humerus to the base of the second metacarpal bone.
Extensor retinaculum: The extensor retinaculum is a fibrous band that wraps around the dorsum of the wrist, securing tendons of the extensor muscles in place as they cross into the hand. It ensures smooth and coordinated movements of the fingers and wrist by preventing bowstringing of the tendons during extension.
Extrinsic muscles of the hand: Extrinsic muscles of the hand are muscles that originate outside of the hand, typically in the forearm, and insert into the bones of the hand, controlling movements such as grasping, flexion, and extension. These muscles are crucial for executing complex motions and strength tasks involving the fingers and wrist.
Flexion: Flexion is the action of bending a joint or limb in the body which decreases the angle between the bones of the limb at the joint. It is a fundamental movement in daily activities and exercises, contrasting with extension which increases the angle.
Flexion: Flexion is a type of body movement that decreases the angle between two body parts, bringing them closer together. This term is closely related to the structure and function of muscles, the pectoral girdle, synovial joints, and various body movements and joint anatomy.
Flexor carpi radialis: The flexor carpi radialis is a muscle in the forearm that helps in bending (flexing) the wrist and abducting (moving away from the midline of the body) the hand towards the thumb side. It runs from the humerus (upper arm bone) down to the bases of the second and third metacarpal bones in the hand.
Flexor Carpi Radialis: The flexor carpi radialis is a muscle located in the anterior compartment of the forearm. It is responsible for flexing and abducting the wrist, allowing for movements such as gripping and grasping.
Flexor carpi ulnaris: The Flexor Carpi Ulnaris is a major muscle of the forearm that acts to flex and adduct (move toward the body) the wrist. It is positioned on the ulnar side of the forearm and plays a key role in gripping movements.
Flexor digiti minimi brevis: The Flexor Digiti Minimi Brevis is a small muscle located in the hand that is responsible for bending or flexing the little finger. It plays a crucial role in the intricate movements of the pinky finger, allowing for grip strength and dexterity.
Flexor digitorum profundus: The flexor digitorum profundus is a muscle in the forearm that plays a crucial role in flexing the fingers, particularly enabling the bending of the distal phalanges, which are the fingertips. It originates from the upper part of the ulna and inserts into the bases of the distal phalanges of the four fingers.
Flexor digitorum superficialis: The flexor digitorum superficialis is a muscle in the forearm that flexes the fingers at the proximal interphalangeal joints. It acts primarily on the middle phalanges of the four fingers excluding the thumb.
Flexor Digitorum Superficialis: The flexor digitorum superficialis is a muscle located in the anterior compartment of the forearm. It is responsible for flexing the fingers at the proximal interphalangeal joints, allowing for grasping and manipulation of objects.
Flexor pollicis brevis: The Flexor Pollicis Brevis is a small muscle located in the hand that assists in bending (flexing) the thumb towards the palm. It plays a crucial role in grip and manipulation of objects by enabling precise thumb movements.
Flexor pollicis longus: The flexor pollicis longus is a muscle in the forearm that enables the thumb to move towards the palm, facilitating grip and precision movements. It originates from the radius and the interosseous membrane, inserting into the base of the distal phalanx of the thumb.
Glenohumeral joint: The glenohumeral joint is the ball-and-socket joint where the head of the humerus fits into the shallow socket of the scapula, allowing a wide range of movement for the upper arm. It is a key component of the shoulder's flexibility and stability.
Glenohumeral Joint: The glenohumeral joint, also known as the shoulder joint, is the main joint of the shoulder that allows for a wide range of motion in the upper limb. It is a ball-and-socket type of synovial joint formed by the articulation between the rounded head of the humerus and the shallow, cup-like glenoid cavity of the scapula.
Glenoid Fossa: The glenoid fossa is a shallow, cup-shaped depression on the lateral aspect of the scapula that forms the socket portion of the shoulder joint, also known as the glenohumeral joint. It serves as the articulation point for the head of the humerus bone, allowing for a wide range of motion in the upper limb.
Humerus: The humerus is the long bone in the upper arm that runs from the shoulder to the elbow, connecting with both the scapula at the shoulder joint and the radius and ulna at the elbow joint. It plays a critical role in both the mobility and stability of the upper limb.
Humerus: The humerus is the upper arm bone, connecting the shoulder to the elbow. It is the longest, largest, and strongest bone in the upper limb and plays a crucial role in the structure and function of the arm and shoulder.
Hyperextension: Hyperextension is the movement of a joint beyond its normal range of motion, resulting in an excessive straightening or opening angle. This action can occur in various joints, such as the knee, elbow, and spine, potentially leading to injury if performed excessively.
Hypothenar: The hypothenar is the group of muscles located on the palm side of the hand, beneath the little finger. These muscles are responsible for the movement of the little finger and contribute to grip strength.
Hypothenar eminence: The hypothenar eminence is a group of three muscles found on the palm side of the hand, specifically at the base of the little finger. These muscles are involved in the movement and control of the pinky finger.
Infraspinatus: The infraspinatus is a thick, triangular muscle located in the upper back, part of the rotator cuff that helps with the rotation and stabilization of the shoulder joint. It covers part of the scapula (shoulder blade) and attaches to the humerus (upper arm bone).
Infraspinatus: The infraspinatus is a muscle located in the posterior compartment of the shoulder. It is one of the four rotator cuff muscles and plays a crucial role in the stability and movement of the shoulder joint.
Innervation: Innervation refers to the supply of nerves to a specific tissue or organ, which allows for the transmission of sensory and motor signals between the central nervous system and the target structure. This term is particularly relevant in the context of understanding the muscle movements and functions associated with the axial and appendicular muscles of the body.
Insertion: In the context of anatomy and physiology, particularly within the chapter on The Muscular System, insertion refers to the point at which a muscle attaches to a bone, tendon, or other muscle that moves when the muscle contracts. It is typically located on the bone that moves most during the muscle's action.
Insertion: Insertion refers to the attachment point of a muscle on the bone that moves, as opposed to the origin, which is the attachment point on the stationary bone. The insertion is the distal attachment of a muscle, allowing it to exert force and produce movement.
Intermediate: In the context of the muscular system, specifically relating to the muscles of the pectoral girdle and upper limbs, "intermediate" refers to muscles that are positioned between two other significant groups or structures. These muscles play crucial roles in movement and stabilization but are not as superficial as some muscles nor as deep as others.
Intrinsic muscles of the hand: Intrinsic muscles of the hand are located within the hand itself and are responsible for fine motor movements such as gripping, pinching, and typing. They contrast with extrinsic muscles, which originate outside the hand but also facilitate its movement.
Lateral Rotation: Lateral rotation refers to the rotational movement of a body part or joint around its longitudinal axis, where the distal end of the structure moves away from the midline of the body. This movement is an essential component in the anatomy and function of various synovial joints, as well as the coordinated actions of the muscles of the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.
Latissimus dorsi: The latissimus dorsi is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. It is responsible for various movements of the shoulder joint, including extension, adduction, horizontal abduction, and internal rotation.
Latissimus Dorsi: The latissimus dorsi is a large, flat muscle located on the back that plays a crucial role in the movements of the pectoral girdle and upper limb. It is one of the most powerful muscles involved in the rotation and extension of the shoulder joint.
Lumbrical: Lumbricals are small, worm-like muscles located in the hand and foot, primarily involved in flexing the metacarpophalangeal joints and extending the interphalangeal joints of the fingers. They play a pivotal role in fine motor control and the dexterous movements required for tasks such as typing or playing musical instruments.
Medial Rotation: Medial rotation refers to the movement of a body part, such as a joint or limb, around its longitudinal axis towards the midline of the body. This action involves the rotation of a structure in a direction that brings it closer to the body's central axis.
Muscle Fiber Types: Muscle fiber types refer to the different classifications of skeletal muscle fibers based on their structural, functional, and metabolic properties. These fiber types play a crucial role in determining the performance and characteristics of skeletal muscles throughout the body.
Opponens digiti minimi: The opponens digiti minimi is a small muscle located in the palm of the hand, primarily responsible for enabling the pinky finger to move towards the thumb, facilitating opposition and grip. It plays a crucial role in the dexterity and range of motion of the pinky finger.
Opponens pollicis: The opponens pollicis is a small, triangular muscle in the hand that allows the thumb to move across the palm, facilitating opposition and gripping actions. It plays a crucial role in enabling fine motor skills such as writing and manipulating objects.
Origin: In the context of anatomy and physiology, especially within the chapter on the muscular system, "origin" refers to the fixed attachment point of a muscle that remains stationary during muscle contraction. It is typically attached to a bone or other structure that does not move when the muscle contracts.
Origin: The origin of a skeletal muscle refers to the fixed, immovable end of the muscle that remains stationary during contraction. It is the point of attachment where the muscle originates from the bone or other connective tissue, and serves as the anchor point for the muscle's movement.
Palmar interossei: The palmar interossei are a group of three small muscles located in the palm of the hand that originate from the metacarpal bones and insert into the proximal phalanges and the extensor expansion. They are responsible for adducting (bringing together) the fingers towards the middle finger and assisting in finger flexion at the metacarpophalangeal joints, while also extending the interphalangeal joints.
Palmaris longus: The palmaris longus is a slender muscle located in the forearm that plays a role in flexing the wrist and tensing the palmar aponeurosis, contributing to hand movement. It is not present in all individuals, with some people lacking this muscle entirely without any loss of function.
Pectoralis major: The pectoralis major is a large muscle in the upper chest, fanning across the chest from the shoulder to the sternum. It is responsible for movements such as flexing, rotating, and adducting the arm.
Pectoralis Major: The pectoralis major is a large, fan-shaped muscle located on the anterior aspect of the chest. It is a key muscle involved in the movement and function of the pectoral girdle and upper limb.
Pectoralis minor: The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major in the chest. It plays a crucial role in movements of the shoulder blade, including downward rotation and drawing it forward against the thoracic wall.
Pronation: Pronation is the inward rotation of the forearm causing the palm to face downward or backward. This movement occurs at the radioulnar joint and is essential for various tasks involving hand movements.
Pronation: Pronation is the rotation of the forearm and hand that occurs when the palm faces downward or backward. It is an important movement that allows for the proper positioning and function of the upper limb during various activities.
Pronator quadratus: The pronator quadratus is a square-shaped muscle on the distal forearm that acts to pronate (rotate) the forearm and wrist, turning the palm downward. It lies between the ulna and radius bones of the forearm.
Pronator teres: The pronator teres is a muscle in the forearm that enables the hand to turn so the palm faces downwards or backwards. It originates from the medial epicondyle of the humerus and inserts into the radius bone of the forearm.
Radial Deviation: Radial deviation, also known as abduction, is the movement of the hand or wrist towards the thumb side of the forearm. It is an important motion that allows for various functional movements of the upper limb, particularly in the context of the muscles of the pectoral girdle and upper limbs.
Rhomboid major: The Rhomboid Major is a skeletal muscle located in the upper back, between the spine and the scapula. It acts to retract and rotate the scapula, playing a crucial role in maintaining posture and enabling shoulder movements.
Rhomboid minor: The rhomboid minor is a small skeletal muscle located in the upper back, between the spine and the scapula. It functions to retract and elevate the scapula, playing a crucial role in the movement of the shoulder.
Scapula: The scapula, also known as the shoulder blade, is a flat, triangular bone that forms the posterior part of the pectoral girdle. It is a key component of the skeletal system, playing a crucial role in the structure and function of the upper limb.
Serratus anterior: The serratus anterior is a muscle located on each side of the thorax, spanning from the upper ribs to the scapula (shoulder blade). It functions to pull the scapula forward and around the rib cage, playing a crucial role in shoulder and arm movement.
Subclavius: The subclavius is a small muscle located beneath the clavicle (collarbone), playing a role in stabilizing and moving the clavicle during shoulder movements. It helps in lowering the shoulder, acting as a protective buffer for the underlying nerves and blood vessels.
Subscapular fossa: The subscapular fossa is a concave depression located on the anterior (frontal) surface of the scapula bone, serving as the attachment site for the subscapularis muscle. It plays a critical role in arm and shoulder movement by allowing for muscle attachment and facilitating upper limb mobility.
Subscapularis: The subscapularis is a large triangular muscle that forms part of the rotator cuff, located between the scapula and the rib cage. It plays a critical role in the internal rotation and stabilization of the shoulder joint.
Subscapularis: The subscapularis is a muscle located on the anterior (front) surface of the scapula. It is one of the key muscles involved in the movement and stabilization of the shoulder joint, playing a crucial role in the Muscles of the Pectoral Girdle and Upper Limbs.
Superficial anterior compartment of the forearm: The superficial anterior compartment of the forearm is a muscle group located on the front side of the forearm, responsible for flexing the wrist and fingers. It includes several muscles such as the flexor carpi radialis, palmaris longus, and flexor carpi ulnaris that are innervated primarily by the median nerve.
Superficial posterior compartment of the forearm: The superficial posterior compartment of the forearm is a group of muscles located on the back side of the forearm, primarily responsible for extending the wrist and fingers. These muscles are innervated by the radial nerve and include the extensor carpi radialis brevis, extensor digitorum, and extensor carpi ulnaris.
Supination: Supination is a rotational movement of the forearm that positions the palm of the hand face up or forward. It occurs at the radioulnar joint and is opposite to pronation, which turns the palm down or backward.
Supination: Supination is the rotation of the forearm and hand such that the palm faces upward or forward. It is a key movement involved in the function of the muscles of the pectoral girdle and upper limbs, as well as one of the fundamental types of body movements.
Supinator: The supinator is a muscle in the forearm that helps rotate the forearm to turn the palm upward or forward. It plays a crucial role in movements such as turning a doorknob or opening a jar.
Supraspinatus: The supraspinatus is a small muscle located in the upper back, part of the rotator cuff that helps with the abduction (lifting away) of the arm at the shoulder joint. It sits above the spine of the scapula and inserts into the head of the humerus.
Supraspinatus: The supraspinatus is a muscle located in the posterior region of the shoulder, specifically within the supraspinous fossa of the scapula. It is one of the four muscles that make up the rotator cuff, a group of muscles and tendons responsible for stabilizing the shoulder joint and enabling a wide range of shoulder movements.
Synergist Muscles: Synergist muscles are a group of muscles that work together to produce a specific movement or action. They act in coordination with the agonist muscle, the primary mover, to enhance and support its function. Synergist muscles are essential for efficient and coordinated movement across various skeletal muscle interactions, fascicle arrangements, and lever systems in the body.
Tendon: A tendon is a tough, fibrous connective tissue that attaches muscle to bone, transmitting the force generated by the muscle to the bone, allowing for movement of the skeletal system. Tendons are essential components of the musculoskeletal system, particularly in the context of the muscles of the pectoral girdle and upper limbs.
Teres major: The teres major is a thick muscle of the upper limb that extends from the lower lateral border of the scapula to the upper part of the humerus. It plays a crucial role in the rotation and movement of the arm.
Teres minor: The teres minor is a small muscle of the rotator cuff that assists in rotating the arm laterally and stabilizing the shoulder joint. It is located in the upper portion of the arm, just below the shoulder.
Thenar: The thenar refers to the group of muscles found in the palm of the hand, primarily at the base of the thumb. These muscles are responsible for the movement and strength of the thumb, allowing for grip and manipulation of objects.
Thenar eminence: The thenar eminence is the rounded group of muscles on the palm side of the human hand, just below the thumb. These muscles are primarily responsible for the movement and strength of the thumb.
Triceps brachii: The triceps brachii is a major muscle on the back of the upper arm responsible for extending the elbow. It comprises three heads (long, medial, and lateral) that converge to attach to the ulna, one of the forearm bones.
Triceps Brachii: The triceps brachii is a large muscle on the posterior (back) aspect of the upper arm. It is the main extensor of the elbow joint, responsible for straightening the arm. This muscle plays a crucial role in the interactions of skeletal muscles, their fascicle arrangement, and their lever systems, as well as in the muscles of the pectoral girdle and upper limbs.
Ulna: The ulna is one of the two bones that make up the forearm, located on the little finger side. It is responsible for several important functions related to the skeletal system, joint anatomy, and upper limb movement.
Ulnar Deviation: Ulnar deviation is the movement of the hand or wrist towards the ulnar (little finger) side of the forearm. It is an important motion for various functions of the upper limb and is facilitated by the actions of specific muscles in the pectoral girdle and upper limbs.
Ulnar nerve: The ulnar nerve is one of the major nerves of the arm, responsible for innervating (supplying with nerves) parts of the hand and facilitating muscle movement and sensation in the forearm and hand. It runs from the shoulder to the hand, passing through areas such as the inner elbow (often referred to when talking about hitting your "funny bone").