In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint and the elbow joint. The distal part of the upper limb between the elbow and the radiocarpal joint is known as the forearm or "lower" arm, and the extremity beyond the wrist is the hand.
The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.
The pons is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum.
The brachial artery is the major blood vessel of the (upper) arm. It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries which run down the forearm. In some individuals, the bifurcation occurs much earlier and the ulnar and radial arteries extend through the upper arm. The pulse of the brachial artery is palpable on the anterior aspect of the elbow, medial to the tendon of the biceps, and, with the use of a stethoscope and sphygmomanometer, often used to measure the blood pressure.
The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus.
The brachial plexus is a network of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve. This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit, it supplies afferent and efferent nerve fibers to the chest, shoulder, arm, forearm, and hand.
The brachialis, also known as the Teichmann muscle, is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa. It originates from the anterior aspect of the distal humerus; it inserts onto the tuberosity of the ulna. It is innervated by the musculocutaneous nerve, and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion generating about 50% more power than the biceps.
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, technically, means only the region of the upper arm, whereas the lower "arm" is called the forearm. It is homologous to the region of the leg that lies between the knee and the ankle joints, the crus.
In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is common. This nerve is directly connected to the little finger, and the adjacent half of the ring finger, innervating the palmar aspect of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds.
Wrist drop is a medical condition in which the wrist and the fingers cannot extend at the metacarpophalangeal joints. The wrist remains partially flexed due to an opposing action of flexor muscles of the forearm. As a result, the extensor muscles in the posterior compartment remain paralyzed.
The cubital fossa,chelidon, grivet or elbow pit, is the triangular area on the anterior side of the upper limb between the arm and forearm of a human or other hominid animals. It lies anteriorly to the elbow when in standard anatomical position.
The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery. It is palpable on the anterior and medial aspect of the wrist.
The medial cutaneous nerve of the forearm is a sensory branch of the medial cord of the brachial plexus derived from the ventral rami of spinal nerves C8-T1. It provides sensory innervation to the skin of the medial forearm and skin overlying the olecranon. It descends through the (upper) arm within the brachial fascia alongside the basilic vein, then divides into an anterior branch and a posterior branch upon emerging from the brachial fascia; the two terminal branches travel as far distally as the wrist.
The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward.
The deep artery of arm is a large artery of the arm which arises from the brachial artery. It descends in the arm before ending by anastomosing with the radial recurrent artery.
The infraorbital groove is located in the middle of the posterior part of the orbital surface of the maxilla. Its function is to act as the passage of the infraorbital artery, the infraorbital vein, and the infraorbital nerve.
The bicipital aponeurosis is a broad aponeurosis of the biceps brachii, which is located in the cubital fossa of the elbow. It separates superficial from deep structures in much of the fossa.
The fascial compartments of arm refers to the specific anatomical term of the compartments within the upper segment of the upper limb of the body. The upper limb is divided into two segments, the arm and the forearm. Each of these segments is further divided into two compartments which are formed by deep fascia – tough connective tissue septa (walls). Each compartment encloses specific muscles and nerves.
The superior surface of the body of the sphenoid bone is bounded behind by a ridge, which forms the anterior border of a narrow, transverse groove, the chiasmatic groove, above and behind which lies the optic chiasma of cranial nerve 2.
